ArticleLiterature Review

Insects as drivers of ecosystem processes

August 2014
Current Opinion in Insect Science 2

DOI:10.1016/j.cois.2014.06.004

Authors:

Claudio Gratton

University of Wisconsin–Madison

A study to access the significant role of insects in decomposition and nutrient recycling

Article

Jan 2024

Exploring the Diversity and Distribution of Terrestrial Arthropods in the Cactus Biosphere Reserve of Morocco

Article

Full-text available

Sep 2024

The diversity, spatial patterns, and temporal trends of terrestrial arthropod communities in the cactus Biosphere Reserve of Morocco are not well understood. This study aimed to investigate the species richness, relative abundance, and diversity of arthropods across three sampling sites in the cactus Biosphere. A total of 50,723 arthropods were collected and identified, belonging to 250 morphospecies, 17 orders, and 61 families. Insects were the dominant group, comprising 73% of the total trapped arthropods. The study found significant differences in species abundance and richness among the sampling sites and seasons, with Mettouh having the highest abundance and Zemamra having the highest species richness. The composition of arthropod communities differed among sites, with Settat showing a different fauna adapted to the drier and semi-arid environment. The study also investigated the similarity of arthropod communities among sites during different seasons and the dynamics of the dominant arthropod orders (Hymenoptera, Coleoptera, and Hemiptera). Hymenoptera was the most abundant order, with Tapinoma magnum, Pheidole pallidula, and Polistes fuscatus being the most common species. Coleoptera was the most diverse group, followed by Hemiptera. The study also explored the variation in abundance and richness of trophic guilds across four seasons. Significant variations were observed in both abundance and richness among seasons, with the highest abundance during summer and the lowest during winter. Saprophagous was the most abundant group across all seasons, followed by Predators. The richness of trophic guilds changed among seasons, highlighting the importance of understanding seasonal variation for effective ecosystem management and conservation. Exploration de la diversité et de la distribution des arthropodes terrestres dans la Réserve de biosphère des cactus au Maroc Résumé-La compréhension de la diversité, des schémas spatiaux et des tendances temporelles des communautés d'arthropodes terrestres dans la Réserve de biosphère de cactus au Maroc reste limitée. Cette étude avait pour objectif d'examiner la richesse spécifique, l'abondance relative et la diversité des arthropodes sur trois sites d'échantillonnage au sein de cette Réserve. Au total, 50 723 arthropodes ont été collectés et identifiés, appartenant à 250 morphospecies, 17 ordres et 61 familles. Les insectes ont dominé le groupe, représentant 73 % des arthropodes capturés. Des différences significatives d'abondance et de richesse des espèces ont été constatées entre les sites d'échantillonnage et les saisons, Mettouh affichant la plus haute abondance et Zemamra la plus grande richesse spécifique. La composition des communautés d'arthropodes variait selon les sites, Settat présentant une faune différente adaptée à un environnement plus sec et semi-aride. L'étude a également examiné la similarité des communautés d'arthropodes entre les sites pendant différentes saisons, ainsi que la dynamique des ordres d'arthropodes dominants (Hyménoptères, Coléoptères et Hémiptères). Les Hyménoptères constituaient l'ordre le plus abondant, avec Tapinoma magnum, Pheidole pallidula et Polistes fuscatus étant les espèces les plus communes. Les Coléoptères étaient le groupe le plus diversifié, suivi des Hémiptères. L'étude s'est également penchée sur les variations d'abondance et de richesse des guildes trophiques au cours des quatre saisons, révélant des variations significatives tant en abondance qu'en richesse entre les saisons, avec une abondance maximale en été et minimale en hiver. Les saprophages étaient le groupe le plus abondant en toutes saisons, suivis des prédateurs. La richesse des guildes trophiques a évolué selon les saisons, soulignant l'importance de comprendre les variations saisonnières pour une gestion et une conservation efficaces des écosystèmes. Mots-clés : Arthropodes terrestres, Réserve de biosphère de cactus, abondance des espèces, variation saisonnière, guildes trophiques. ‫للصبار‬ ‫الحيوي‬ ‫المحيط‬ ‫محمية‬ ‫في‬ ‫األرضية‬ ‫الحشرات‬ ‫وتوزيع‬ ‫تنوع‬ ‫استكشاف‬ ‫المغرب‬ ‫في‬ ‫العالوي‬ ‫محمد‬ ‫و‬ ‫سباغي‬ ‫محمد‬ ‫ملخص‬-‫الحشرات‬ ‫لمجتمعات‬ ‫الزمنية‬ ‫واالتجاهات‬ ‫المكانية‬ ‫واألنماط‬ ‫التنوع‬ ‫اليزال‬ ‫األرضية‬ ‫فهم‬ ‫إلى‬ ‫تحتاج‬ ‫المغرب‬ ‫في‬ ‫للصبار‬ ‫الحيوي‬ ‫المحيط‬ ‫محمية‬ ‫في‬ ‫عميق‬ ‫هدفت‬. ‫داخل‬ ‫مواقع‬ ‫ثالثة‬ ‫في‬ ‫الحشرات‬ ‫وتنوع‬ ‫وثراء‬ ‫وفرة‬ ‫استكشاف‬ ‫إلى‬ ‫الدراسة‬ ‫هذه‬ ‫مجموع‬ ‫على‬ ‫التعرف‬ ‫تم‬ ‫للصبار.‬ ‫الحيوي‬ ‫المحيط‬ ‫محميات‬ 50،723 ‫تنتمي‬ ‫حشرة،‬ ‫إلى‬ 250 ‫ًا،‬ ‫مورفولوجي‬ ‫ًا‬ ‫نوع‬ 17 ‫مجموعة‬ (ordres) ‫و‬ ، 61 ‫عائل‬ ‫كانت‬ ‫الحشرات‬ ‫ة.‬ ‫شكلت‬ ‫حيث‬ ‫السائدة،‬ ‫المجموعة‬ 73 % ‫الحشرات‬ ‫إجمالي‬ ‫من‬ ‫اصطيادها‬ ‫تم‬ ‫التي‬. ‫وثرائها‬ ‫األنواع‬ ‫وفرة‬ ‫في‬ ‫ملحوظة‬ ‫اختالفات‬ ‫لوحظت‬ ‫وكذلك‬ ‫العينات‬ ‫جمع‬ ‫مواقع‬ ‫بين‬ ‫العينات‬ ‫هذه‬ ‫جمع‬ ‫فيها‬ ‫تم‬ ‫التي‬ ‫المواسم‬ ‫بين‬ ‫ذو‬ ‫الموقع‬ ‫هو‬ ‫متوح‬ ‫كان‬ ‫حيث‬ ، ‫أعلى‬ ‫وفرة‬ ‫زمامرة‬ ‫وموقع‬ ‫لألنواع،‬ ‫ثراء‬ ‫أعلى‬ ‫ذو‬ ‫لألنواع‬ ‫الحشرات‬ ‫مجتمعات‬ ‫تكوين‬ ‫اختلف‬. ‫حيث‬ ‫المواقع،‬ ‫بين‬ ‫سطات‬ ‫موقع‬ ‫أظهر‬ ‫ا‬ ً ‫جفاف‬ ‫أكثر‬ ‫بيئة‬ ‫مع‬ ‫متكيفة‬ ‫مختلفة‬ ‫تكوينات‬ ‫خالل‬ ‫المواقع‬ ‫بين‬ ‫الحشرات‬ ‫مجتمعات‬ ‫تشابه‬ ‫بدراسة‬ ‫ًا‬ ‫أيض‬ ‫الدراسة‬ ‫قامت‬ ‫قاحلة.‬ ‫وشبه‬ ‫المجموعات‬ ‫دينامية‬ ‫وكذلك‬ ‫مختلفة،‬ ‫مواسم‬ ‫الحشرية‬ ‫السائدة،‬ ‫األجنحة‬ ‫نصفيات‬ (Hemiptera) , ‫األجنحة‬ ‫غمديات‬ ,(Coleoptera) ‫و‬ ‫األجنحة‬ ‫غشائيات‬ (Hymenoptera) ‫وتعتبر‬ ‫هاته‬ ‫كانت‬ ‫حيث‬ ‫األكبر،‬ ‫التنوع‬ ‫ذات‬ ‫المجموعة‬ Tapinoma magnum ‫و‬ Pheidole pallidula ‫و‬ Polistes fuscatus ‫هي‬ ‫ا.‬ ‫انتشارً‬ ‫األكثر‬ ‫األنواع‬ ‫األجنحة‬ ‫غمديات‬ ‫تليها‬ ‫ًا،‬ ‫تنوع‬ ‫األكثر‬ ‫المجموعة‬ ‫كانت‬ ‫األجنحة‬ ‫نصفيات‬ ‫الغذاء‬ ‫نقابات‬ ‫وثراء‬ ‫وفرة‬ ‫في‬ ‫التغيرات‬ ‫ًا‬ ‫أيض‬ ‫الدراسة‬ ‫استقصت‬. ‫المواسم،‬ ‫بين‬ ‫والثراء‬ ‫الوفرة‬ ‫في‬ ‫ملحوظة‬ ‫تغيرات‬ ‫وجدت‬ ‫حيث‬ ‫مواسم،‬ ‫أربعة‬ ‫عبر‬ ‫الشتاء‬ ‫فصل‬ ‫في‬ ‫وفرة‬ ‫وأدنى‬ ‫الصيف‬ ‫فصل‬ ‫في‬ ‫وجدت‬ ‫وفرة‬ ‫أعلى‬ ‫أن‬ ‫حيث‬ ‫ك‬. ‫انت‬ ‫رم‬ ‫حشرات‬ ‫التغذية‬ ‫ية‬ Saprophages ‫المواسم،‬ ‫جميع‬ ‫مر‬ ‫على‬ ‫وفرة‬ ‫األكثر‬ ‫هي‬ ‫المفترسات.‬ ‫تليها‬ ‫أبانت‬ ‫يسلط‬ ‫مما‬ ‫المواسم،‬ ‫بحسب‬ ‫الغذاء‬ ‫نقابات‬ ‫ثراء‬ ‫ر‬ ‫تغي‬ ‫الدراسة‬ ‫بفعالية‬ ‫البيئي‬ ‫النظام‬ ‫وحفظ‬ ‫إلدارة‬ ‫الموسمية‬ ‫التغييرات‬ ‫فهم‬ ‫أهمية‬ ‫على‬ ‫الضوء‬. ‫المفتاح‬ ‫الكلمات‬ ‫ية‬ : ‫وفرة‬ ‫للصبار،‬ ‫الحيوي‬ ‫المحيط‬ ‫محمية‬ ‫األرضية،‬ ‫الحشرات‬ ‫المو‬ ‫تغيير‬ ‫األنواع،‬ ‫ا‬ ‫سم،‬ ‫الغذاء‬ ‫نقابات‬ .

Phenology of microhymenoptera and their potential threat by insect decline

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Aug 2024
J HYMENOPT RES

Although microhymenoptera are highly abundant in all terrestrial ecosystems, they are overlooked in most of insect monitoring studies due to their small-size and demanding identification linked with lack of taxonomic experts. Until now, it is unclear to what extent microhymenoptera are affected by insect decline, as there is a huge knowledge gap on their abundance. To fill this knowledge gap, we used Malaise trap samples from three study sites of a complete vegetation period (March to November) of an ongoing insect monitoring study in south-western Germany (i) to study the relationship of insect total biomass, and abundance and diversity of microhymenoptera, and (ii) to assess the phenology of microhymenoptera families. Our results show that microhymenoptera abundance and diversity are positively correlated with total insect biomass, indicating that insect biomass is a valuable proxy for insect abundancy trends even for small-sized insects. In total, we counted 90,452 specimens from 26 families belonging to 10 superfamilies of Hymenoptera. Microhymenoptera numbers peaked twice during the year, first between June and July and second between July and August. Interestingly, egg-parasitoids, such as Scelionidae, Mymaridae and Trichogrammatidae had a slightly shifted second activity period in August and September. Our data provides a baseline for the occurrence of microhymenoptera in meadow ecosystems in south-western Germany and underlines the potential of mass samples to study microhymenoptera in the context of insect decline.

Day-Flying Lepidopteran Species Abundance, Diversity, and Distribution in Wolaita Sodo University, Ethiopia

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Aug 2024
Psyche

Lepidoptera account for the second largest, most diverse, widespread, and widely recognized insect order in the class Insecta. At four microhabitats at Wolaita Sodo University (WSU) in Ethiopia, lepidopteran diversity and abundance were studied for the first time using transects between January 2022 and December 2023. Data were analyzed using analysis of variance, correlation analysis, diversity indices, and ordination and cluster analysis. Altogether 50 species of 367 individuals were collected throughout the study period distributed in 6 families. The Nymphalidae family contained the highest species abundance 20 (34%). In comparison to other ecosystems, open forest regions (35%) included more species, followed by shrub forest (30%). Species such as Danaus plexippus, Tirumala septentrionis, and Melanargia lachesis were abundant in open forest habitat. Idea leuconoe and Eurema brigitta were also abundant, regardless of location. About 36% of species were recorded only in dry season and 36% of total were recorded only in wet season. Spearman’s rho correlation analysis showed that butterfly families had strong positive relationships with flying habitat and flight seasons. Therefore, adequate conservation measures should be taken to ensure their survival, as well as the preservation of their habitats for the benefit of the ecosystem as a whole.

Taxonomic Reasoning for Rare Arthropods: Combining Dense Image Captioning and RAG for Interpretable Classification

Preprint

Full-text available

Mar 2025

In the context of pressing climate change challenges and the significant biodiversity loss among arthropods, automated taxonomic classification from organismal images is a subject of intense research. However, traditional AI pipelines based on deep neural visual architectures such as CNNs or ViTs face limitations such as degraded performance on the long-tail of classes and the inability to reason about their predictions. We integrate image captioning and retrieval-augmented generation (RAG) with large language models (LLMs) to enhance biodiversity monitoring, showing particular promise for characterizing rare and unknown arthropod species. While a naive Vision-Language Model (VLM) excels in classifying images of common species, the RAG model enables classification of rarer taxa by matching explicit textual descriptions of taxonomic features to contextual biodiversity text data from external sources. The RAG model shows promise in reducing overconfidence and enhancing accuracy relative to naive LLMs, suggesting its viability in capturing the nuances of taxonomic hierarchy, particularly at the challenging family and genus levels. Our findings highlight the potential for modern vision-language AI pipelines to support biodiversity conservation initiatives, emphasizing the role of comprehensive data curation and collaboration with citizen science platforms to improve species identification, unknown species characterization and ultimately inform conservation strategies.

An in-depth dataset of northwestern European arthropod life histories and ecological traits

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Full-text available

Mar 2025

Background In response to the ongoing biodiversity crisis amongst arthropods, it is essential to implement efficient conservation strategies to safeguard both species diversity and the vital ecosystem services they provide. Developing such strategies requires reliable predictive models that can identify the species that are the most vulnerable to current and future threats, including those posed by climate and land-use change. Species life histories are central to these models, as they influence both population dynamics and spread rates. New information To support this effort, we compiled a dataset with key traits for arthropods based on several literature sources and expert knowledge. The dataset contains data on body size, life history, thermal niche and ecology for 4874 northwestern European species across 10 different orders. By gathering these essential trait data, we aim to create a robust foundation for predicting species vulnerability and anticipating shifts in arthropod communities in response to global change.

THE FAUNAL DIVERSITY OF MEMORIAL PARK ČAČALICA

Conference Paper

Full-text available

Dec 2023

The Previous studies on the fauna diversity were included only the identification and determination of the presence of phytophagous insects based on the traces on leaves and tree bark. Forest litter was not investigated. To gain a better understanding of the fauna diversity this study included the research which was conducted on forest litter and the surface layer of soil in order to determine the presence of living organisms in this forest stratum because this was the only way to obtain a more comprehensive picture of the biodiversity of this microhabitat. As the aim of this Paper is to collect and analyze various species of invertebrate and vertebrate fauna in order to create a preliminary list of species present at several locations within Memorial Park Čačalica, the scientific material was collected by using various research methods. Identified species that belongs classes Insecta, Diplopoda, Chilopoda, Malacostraca, Gastropoda and Aves are shown further in this work.

Identification of potential insect ecological interactions using a metabarcoding approach

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Full-text available

Feb 2025

Species interactions are challenging to quantify, particularly when they happen cryptically. Molecular methods have become a key tool to uncover these interactions when they leave behind a DNA trace from the interacting organism ( e.g ., pollen on a bee) or when the taxa are still present but morphologically challenging to identify ( e.g ., microbial or fungal interactions). The decreasing costs of sequencing makes the mass analysis of thousands of target species possible. However, the challenge has shifted to selecting molecular markers which maximize information recovery while analyzing these data at broad biological scales. In this manuscript we use model arthropod groups to compare molecular markers and their analysis across life stages. We develop protocols for two ecologically and economically devastating pests, the spongy moth ( Lymantria dispar dispar ) and the emerald ash borer ( Agrilus planipennis ), and a group of pollinators including bees and wasps which regularly deposit eggs in “bee hotels” where the larvae develop. Using Illumina MiSeq and Oxford Nanopore MinION platforms we evaluate seven primer pairs for five molecular markers which target plants, fungi, microbes, insects, and parasitic phyla ( e.g. , nematodes). Our data reveals hundreds of potential ecological interactions and establishes generalized methods which can be applied across arthropod host taxa with recommendations on the appropriate markers in different systems. However, we also discuss the challenge of differentiating co-occurring DNA signals and true ecological interactions, a problem only starting to be recognized as eDNA from the environment accumulates on living organisms.

Understanding and counteracting the denial of insect biodiversity loss

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Full-text available

Jan 2025

Radiocaesium and radiostrontium transfer to an insect herbivore and an insect detritivore through holometabolous development: A comparison between the cabbage butterfly (Pieris brassicae) and the black soldier fly (Hermetia illucens)

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Jan 2025

Odonata assemblages in highland hydrosystems of northeastern Algeria, with notes on elevational patterns: application of species occupancy models

Article

Full-text available

Jan 2025

We aim in this study to increase our knowledge of the Odonata in the Aures, an unexplored region of northeastern Algeria, using single-species occupancy model (spOccupancy R package) coupled with spatial interpolation technique (kriging ArcGis) to assess the relationships between elevation and odonatan species distribution. From time windows of about 90 days (June to August 2021), a total of 22 odonatan species belonging to 2 suborders (Anisoptera and Zygoptera) have been recorded in 15 sampling wet biotopes; among them the endangered Calopteryx exul. Our modelling shows that 62% of the odonatological community has a uniform probability of being present in the studied area. The probability of detecting a species is similar during each survey for 90% of the odonatological community except for the endangered Calopteryx exul (p ˂ 0.05) and Crocothemis erythraea (p ˂ 0.05). We also found that Ischnura graellsii and I. saharensis are the most common species; they are predicted to occur in more than 60% of sites, followed by Anax imperator, Orthetrum chrysostigma, and Platycnemis subdilatata, where they occur in about 50% of the wet biotopes sampled. Finally, our modelling revealed no evidence for a significant altitudinal variation (500 to 1900 meters above sea level) impact on both occupancy and detectability of the majority of the odonatan species, except for Crocothemis erythraea and Sympetrum fonscolombii. The kriging interpolation indicates that they are concentrated within the altitude range of 400 m to 1000 m.

Topic: Arthropod Biodiversity: Ecological and Functional Aspects

Article

Full-text available

Oct 2024

Invertebrate animals with a segmented body, exoskeleton, and articulated appendages represent the largest phylum in the animal kingdom, Arthropoda, and account for over 80% of all known living species [...]

Mitigating the extinction risk of globally threatened and endemic mountainous Orthoptera species: Parnassiana parnassica and Oropodisma parnassica

Article

Full-text available

Sep 2024
INSECT CONSERV DIVER

Orthoptera species are vulnerable to extinction on a global scale. Greece hosts 35% (380 species) of the European Orthoptera fauna with a high degree of endemic (37%) and threatened species (37%). We sampled 46 plots (100 m ² ) to investigate the distribution and ecological requirement of two Greek mountain endemic and red‐listed species: Parnassiana parnassica (Ramme, 1926; Orthoptera: Tettigoniidae; Critically Endangered [CR]) and Oropodisma parnassica (Scudder, 1897; Orthoptera: Caelifera; Endangered [EN]). Species had a restricted geographical range, with two isolated populations confined to high altitudes (1527–2320 m) of Mts. Parnassos and Elikonas. Species distribution models showed that slope affected their suitable habitat, together with the topographic position index and the annual temperature range ( P. parnassica ), and the amount of green vegetation and evapotranspiration ( O. parnassica ). Connectivity analysis showed that P. parnassica ‐suitable habitat consisted of few larger and well‐connected patches (26 patches: effective mesh size of 1.57 km ² ) and that O. parnassica ‐suitable habitat consisted of more but smaller and less connected patches (56 patches: effective mesh size of 0.3 km ² ). Generalised linear models showed that the population density of P. parnassica was negatively influenced by the height of herbaceous vegetation and that of O. parnassica was positively influenced by altitude. The species face three main imminent threats: land take, wildfires and global warming, whereas livestock grazing seems to have a positive impact and skiing a neutral impact on their populations. We assessed both species as EN after International Union for Conservation of Nature (IUCN) criteria and a suite of conservation measures are suggested for their status improvement.

The genome sequence of the Violet Carpenter Bee, Xylocopa violacea (Linnaeus, 1785): a hymenopteran species undergoing range expansion

Article

Full-text available

Sep 2024
HEREDITY

We present a reference genome assembly from an individual male Violet Carpenter Bee (Xylocopa violacea, Linnaeus 1758). The assembly is 1.02 gigabases in span. 48% of the assembly is scaffolded into 17 pseudo-chromosomal units. The mitochondrial genome has also been assembled and is 21.8 kilobases in length. The genome is highly repetitive, likely representing a highly heterochromatic architecture expected of bees from the genus Xylocopa. We also use an evidence-based methodology to annotate 10,152 high confidence coding genes. This genome was sequenced as part of the pilot project of the European Reference Genome Atlas (ERGA) and represents an important addition to the genomic resources available for Hymenoptera.

The genome sequence of the Violet Carpenter Bee, Xylocopa violacea (Linnaeus, 1785): a hymenopteran species undergoing range expansion

Article

Full-text available

Sep 2024
HEREDITY

Elevation and Human Disturbance Interactively Influence the Patterns of Insect Diversity on the Southeastern Periphery of the Tibetan Plateau

Article

Full-text available

Sep 2024

The maintenance of biodiversity and ecological balance heavily relies on the diversity of insects. In order to investigate the impacts of elevation and human disturbance, as well as their interactions on insect diversity, we conducted an intensive survey of insects in the Hengduan Mountain Range, which is situated on the southeastern periphery of the Tibetan Plateau in China. A total of 50 line transects were established in this study to investigate the impact of elevation and human disturbance on insect diversity and distribution patterns. Designed insect surveys were conducted at various elevations and levels of human disturbance, and statistical methods such as generalized linear modeling and redundancy analysis were employed for data analysis. The results of this study indicated a negative correlation between insect diversity and elevation. Additionally, moderate disturbance was found to have a positive impact on insect diversity to some extent. The explanatory power of the model for the distribution of insect diversity could be improved if elevation and human disturbance were included as an interaction effect into the model, and there were differences in the effects of human disturbances on insect diversity at different elevation levels. The highest insect diversity was observed under low disturbance conditions below elevation of ~2200 m, whereas above this threshold, insect diversity was the highest under moderate disturbance compared to low disturbance. The response of different insect taxa to the interactions of elevation and human disturbance varied. The findings imply that when formulating strategies for managing insect diversity, it is crucial to thoroughly consider the interaction of environmental factors and disturbance response of individual insect taxa.

Vertical stratification of leaf physical traits exerts bottom-up pressures on insect herbivory in a sugar maple temperate forest

Article

Full-text available

Aug 2024
INSECT CONSERV DIVER

Do light vertical gradients in temperate forest structure insect herbivore communities? We tested the hypothesis that the increase in light intensity from understory to forest canopy drives differences in leaf physical traits and bud burst phenology that impact insect herbivores and thus play a role in structuring both herbivore communities and the leaf damage they cause. Understanding these interactions is essential for addressing knowledge gaps in the dynamics of temperate deciduous forest ecosystems. Twelve sugar maple (Acer saccharum) sites were monitored in southern Quebec, examining insect herbivore patterns from understory saplings to mature tree-shaded and sun canopy (where intensity is highest and canopy cover lowest) over the summers of 2020, 2021 and 2022. Additionally, we recorded leaf physical traits and sun exposure. Our findings revealed that leaf thickness increased along the vertical gradient in 2021, making mature tree leaves in the canopy less favourable to herbivores than understory sapling leaves. Accordingly, we recorded a consistent decrease in insect herbivory damage rates from understory to shaded and to sun canopy in 2020 and 2021, driven by leaf cutters, skeletonizers, stipplers and leaf miners. These results support our hypothesis that variation in leaf physical traits contributes to the vertical stratification of insect damage. This variation in leaf traits can be linked to light levels or to tree ontogeny. In 2022, the gradient of insect herbivore abundance corroborated the observed damage trends from the previous years. We calculated an average annual herbivory rate of 9.1% of the leaf surface in our study site. Overall, our study highlights the importance of vertical gradients in structuring insect herbivore communities and emphasizes the role of leaf traits in mediating these interactions. In addition, the average annual herbivory rate suggests limited evidence supporting a significant contribution of background herbivory to the decline of sugar maple forests.

Landscape change and alien invasions drive shifts in native lady beetle communities over a century

Article

Full-text available

Aug 2024
ECOL APPL

Understanding causes of insect population declines is essential for the development of successful conservation plans, but data limitations restrict assessment across spatial and temporal scales. Museum records represent a source of historical data that can be leveraged to investigate temporal trends in insect communities. Native lady beetle decline has been attributed to competition with established alien species and landscape change, but the relative importance of these drivers is difficult to measure with short‐term field‐based studies. We assessed distribution patterns for native lady beetles over 12 decades using museum records, and evaluated the relative importance of alien species and landscape change as factors contributing to changes in communities. We compiled occurrence records for 28 lady beetle species collected in Ohio, USA, from 1900 to 2018. Taxonomic beta‐diversity was used to evaluate changes in lady beetle community composition over time. To evaluate the relative influence of temporal, spatial, landscape, and community factors on the captures of native species, we constructed negative binomial generalized additive models. We report evidence of declines in captures for several native species. Importantly, the timing, severity, and drivers of these documented declines were species‐specific. Land cover change was associated with declines in captures, particularly for Coccinella novemnotata which declined prior to the arrival of alien species. Following the establishment and spread of alien lady beetles, processes of species loss/gain and turnover shifted communities toward the dominance of a few alien species beginning in the 1980s. Because factors associated with declines in captures were highly species‐specific, this emphasizes that mechanisms driving population losses cannot be generalized even among closely related native species. These findings also indicate the importance of museum holdings and the analysis of species‐level data when studying temporal trends in insect populations.

Spatial differentiation characteristics of the Hemiptera insects in China

Article

Full-text available

Aug 2024

The Hemiptera insects are the largest incomplete metamorphosis insect group in Insecta and play a vital role in ecosystems and biodiversity. Previous studies on the spatial distribution of Hemiptera insects mainly focused on a specific region and insect, this study explored the spatial distribution characteristics of Hemiptera insects in China (national scale), and further clarified the dominant factors affecting their spatial distribution. We used spatial autocorrelation analysis, hot spot analysis, and standard ellipse to investigate the spatial distribution characteristics of Hemiptera insects in China. Furthermore, we used geographic detectors to identify the main factors affecting their spatial distribution under China's six agricultural natural divisions and explore the influencing mechanism of dominant factors. The results show that: (i) The spatial differentiation characteristics of Hemiptera insects in China are significant, and their distribution has obvious spatial agglomeration. The Hu Huanyong Line is an important dividing line for the spatial distribution of Hemiptera insects in China. From the city scale, the HH type (high‐high cluster) is mainly distributed on both sides of the Hu Huanyong Line. (ii) The hot spots of Hemiptera insects are mainly distributed in southwest China, along the Qinling Mountains, the western side of the Wuyi Mountains, the Yinshan Mountains, the Liupanshan Mountains, the Xuefeng Mountains, the Nanling Mountains, and other mountainous areas. (iii) Under agricultural natural divisions, the influence of natural environmental factors on the spatial distribution of Hemiptera insects is obviously different. Temperature and precipitation are the dominant factors. Natural factors and socio‐economic factors have formed a positive reinforcement interaction mode on the spatial distribution of Hemiptera insects. These can provide the decision‐making basis for biodiversity conservation and efficient pest control.

Unravelling arthropod movement in natural landscapes: Small‐scale effects of body size and weather conditions

Article

Full-text available

Aug 2024
J ANIM ECOL

Arthropod movement has been noticeably understudied compared to vertebrates. A crucial knowledge gap pertains to the factors influencing arthropod movement at habitat boundaries, which has direct implications for population dynamics and gene flow. While larger arthropod species generally achieve greater dispersal distances and large‐scale movements are affected by weather conditions, the applicability of these relationships at a local scale remains uncertain. Existing studies on this subject are not only scarce but often limited to a few species or laboratory conditions. To address this knowledge gap, we conducted a field study in two nature reserves in Belgium, focusing on both flying and cursorial (non‐flying) arthropods. Over 200 different arthropod species were captured and released within a circular setup placed in a resource‐poor environment, allowing quantification of movement speed and direction. By analysing the relationship between these movement variables and morphological (body size) as well as environmental factors (temperature and wind), we aimed to gain insights into the mechanisms driving arthropod movement at natural habitat boundaries. For flying species, movement speed was positively correlated with both body size and tailwind speed. In contrast, movement speed of cursorial individuals was solely positively related with temperature. Notably, movement direction was biased towards the vegetated areas where the arthropods were originally caught, suggesting an internal drive to move towards suitable habitat. This tendency was particularly strong in larger flying individuals and under tailwind conditions. Furthermore, both flying and cursorial taxa were hindered from moving towards the habitat by strong upwind. In conclusion, movement speed and direction at patch boundaries are dependent on body size and prevailing weather conditions, and reflect an active decision‐making process.

Ground-dwelling invertebrate community responses to bison and prescribed fire management in tallgrass prairies

Article

Full-text available

Jul 2024
J INSECT CONSERV

Disturbances are drivers of ecosystem function and play important roles in shaping ecological communities. Prescribed fire and grazing disturbances are common management tools in restored and remnant grasslands. The effects of these management actions on plant communities and on vegetation-dwelling invertebrates are generally well studied. However, less is known about their effects on ground-dwelling invertebrates, which can contribute to important ecosystem processes like herbivory, predation, and decomposition. We examined bison grazing and prescribed fire effects on abundance, diversity, and community composition of ground-dwelling invertebrate groups in restored tallgrass prairies using pitfall trap samples. Surprisingly, invertebrate Shannon diversity decreased when bison were present and was unaffected by fire or the fire–bison interaction. Bison, and to a lesser extent fire, also shifted community composition, increasing abundance of ground, rove, and dung beetles, as well as orthopterans and spiders. Prescribed fire generally increased beetles but caused declines in several ecologically diverse invertebrate groups, including harvestmen and true bugs, although these reduced abundances did not lead to differences in overall diversity. Bison presence may amplify the abundances of dominant groups, such as ground and dung beetles and orthopterans, that outcompete other invertebrates and reduce diversity. Implications for insect conservation Prescribed fire and grazing by bison change ground-dwelling invertebrate community composition, but bison presence did not reduce the abundance of most taxonomic groups. Fire may have short-term negative impacts on some invertebrate groups that promote desirable invertebrate-driven ecosystem processes, but these effects are likely short-lived, and the resulting environmental mosaic under bison and fire management could support biodiversity over the long-term.

Assessment of the Impact of Land-Use Change on the Abundance, Composition and Diversity of Mangrove Insects in Bundu-Ama, Niger Delta

Research

Full-text available

Jul 2024

Mangrove insect abundance, richness and diversity are currently experiencing a huge decline due to human activities especially in developing nations. In this study, we set out to assess the impact of land use change on the abundance, composition and diversity of mangrove insects in Bundu-Ama, Niger Delta, between the year 2017 and 2023. For this to be achieved, sampling exercise was conducted every other week for a period of three months. Insects were collected and documented with reference to the particular tree species where it was foraging at the point of collection. Insect identification was conducted in the field and later verified in the lab. A Geographic information systems software was used to determine the change in mangrove vegetation between both study periods. The result showed that about 3.39Ha of mangrove in the immediate surroundings of the sample site have been lost to infrastructure development during the period. This also resulted in a huge decline in the insect biodiversity of the mangrove ecosystem. In Avicennia, the insect population reduced from twenty-two to nine insect species, twenty-one to nine insect families, with a shift in dominance from Formicidae to Tabanidae. More so, diversity reduced to 1.766, evenness reduced to 80% and a dissimilarity value of 58% was recorded during the period. Meanwhile in Rhizophora, the insect community reduced from seven to three insect species; the family also reduced from seven to three, with Formicidae retaining its dominance. The ecological indices showed that diversity was very low (0.874), evenness increased slightly to 80% and the dissimilarity index was 41%. The study asserts that consequence of the loss of insect communities in the area would result in the decline in ecosystem services such as food provision, diseases control, loss of gene pool, plus an alteration in the natural, biological and environmental cycles. Hence, there is an urgent need for action from stakeholder groups to halt this menace and rehabilitate the mangrove ecosystem halting the detrimental impact on insect biodiversity. Moreover, there is an imminent need to educate the citizens on the consequences of their activities on the environment.

Automated handling of biological objects with a flexible gripper for biodiversity research

Article

Full-text available

Jun 2024
AT-AUTOM

With the increasing loss of insect species, their ecosystem services such as pollination of plants and pest control are also under threat. This means that more intense monitoring is needed, but this poses many challenges: Collecting is comparatively easy and carried out at many locations worldwide using standardized methods such as Malaise traps that preserve the specimens in ethanol. However, a comprehensive, systematic evaluation of these samples at the specimen-level is not yet possible due to the large number of specimens and the lack of taxonomic experts who can identify the specimens to species level. We thus here present a new mini-gripper for the automated handling of insects preserved in ethanol. The mini-gripper automatically picks insects from bulk samples as long as they are in the 7.5 mm–15 mm size range to be transferred to the DiversityScanner, where they are classified using a trained AI model. This automated approach is currently tested in an EU project to identify new invasive pests.

OPEN ACCESS Effect of different feed on nutritional content of black soldier fly (Hermetia illucens): A systematic review and meta-analysis

Article

Full-text available

Jun 2024

Black Soldier Fly (Hermetia illucens) or BSF is commonly used in food industry as a meat substitute to reduce food waste and environmental pollution. It could grow effectively using organic material such as manure and food waste. In this study, a comparison of the nutritional content of BSF fed with manure and food waste will be determined by conducting a systematic review and meta-analysis. The information about protein, fat, carbohydrate, ash, and calcium content of manure or food waste fed BSF from various scientific database sources was analyzed and discussed. There were 720 literatures selected to be included in the meta-analysis dataset, with the main selection criteria: original research articles published in the last ten years with nutritional data on manure and food waste fed BSF. From the literature screening process, 8 articles were obtained and included in the meta-analysis. Based on meta-analysis, it was found that the food waste fed BSF group has approximately 16% higher protein content, 33% higher fat content, but 59% lower ash content if compared to manure fed BSF group. However, the use of food waste as BSF feed did not give a significant effect on BSF carbohydrate and calcium content when compared to manure fed BSF.

Temperature and water availability drive insect seasonality across a temperate and a tropical region

Article

Full-text available

Jun 2024

The more insects there are, the more food there is for insectivores and the higher the likelihood for insect-associated ecosystem services. Yet, we lack insights into the drivers of insect biomass over space and seasons, for both tropical and temperate zones. We used 245 Malaise traps, managed by 191 volunteers and park guards, to characterize year-round flying insect biomass in a temperate (Sweden) and a tropical (Madagascar) country. Surprisingly, we found that local insect biomass was similar across zones. In Sweden, local insect biomass increased with accumulated heat and varied across habitats, while biomass in Madagascar was unrelated to the environmental predictors measured. Drivers behind seasonality partly converged: In both countries, the seasonality of insect biomass differed between warmer and colder sites, and wetter and drier sites. In Sweden, short-term deviations from expected season-specific biomass were explained by week-to-week fluctuations in accumulated heat, rainfall and soil moisture, whereas in Madagascar, weeks with higher soil moisture had higher insect biomass. Overall, our study identifies key drivers of the seasonal distribution of flying insect biomass in a temperate and a tropical climate. This knowledge is key to understanding the spatial and seasonal availability of insects—as well as predicting future scenarios of insect biomass change.

Beta diversity of plant–herbivore interactions is unaffected by urbanization levels in Brazilian Cerrado

Article

Full-text available

Jun 2024
ARTHROPOD-PLANT INTE

Plant–herbivore interactions are pivotal in shaping terrestrial ecosystems, influencing plant populations and insect diversity; however, little is known about how anthropogenic impacts affect the beta diversity of these interactions. In our study, we investigated plant–herbivore networks across an urbanization gradient in Brazilian Cerrado. We tested two hypotheses: (1) urbanization decreases interaction dissimilarity, and (2) herbivorous insects show greater dissimilarity than plants. To test these hypotheses, we conducted data collection across 16 sites, representing different urbanization levels—urban, rural, and wild. We sampled plant–herbivore interactions for 310 insect herbivore species and 97 host plant species. Our analysis revealed that beta diversity of interactions was consistently high across all environments studied. However, we did not find any significant differences in total interaction dissimilarity among the different levels of urbanization. We found that the primary driver of dissimilarity was species composition turnover, with herbivorous insects contributing more to dissimilarity. Our findings challenge the conventional wisdom that urbanization significantly alters plant–herbivore interactions. Instead, we observed consistent interaction dissimilarity, highlighting the resilience of ecological networks in the face of anthropogenic impacts. Our results underscore the complexity of these interactions and emphasize that plant–herbivore interactions can exhibit a high degree of dissimilarity even in urban environments.

Unveiling South African insect diversity: DNA barcoding’s contribution to biodiversity data

Article

Full-text available

May 2024
S AFR J SCI

Insects are one of the most species-rich groups on Earth. They comprise much of animal diversity and play vital roles in ecosystems, including pollination, pest control, and decomposition. However, only a fraction of this diversity has been formally described. South Africa is recognised as one of the most biologically diverse countries globally, with an estimated 44 000 insect species. Many crops rely on insect pollinators, including canola, apples, oranges, and sunflowers. A shortage of wild pollinators currently threatens crop yields, yet our knowledge of insect diversity within South Africa is sparse. There are few taxonomic specialists relative to South Africa’s biodiversity, and the methods used for insect identification can be time-consuming and expensive. DNA barcoding provides an important research tool to accelerate insect biodiversity research. In this review, we queried the public DNA barcoding BOLD (Barcode of Life Data System) database for records of “Insecta” within South Africa, and 416 211 published records assigned to 28 239 unique BINs (Barcode Index Numbers) were returned. We identified five taxonomic orders with more BINs than known species in southern Africa (Hymenoptera, Diptera, Thysanoptera, Plecoptera, and Strepsiptera). Most of the barcoded records were derived from Malaise trap sampling in Gauteng, Mpumalanga and Limpopo, while the rest of South Africa remains poorly sampled. We suggest that there is a need for a comprehensive national sampling effort alongside increased investment in taxonomic expertise to generate critical baseline data on insect biodiversity before species are lost to extinction.

Insects as functional components of communities and ecosystems

Chapter

Apr 2024

Insects play a critical role in multiple processes and functions related to energy flow, biogeochemical cycles, and environmental successions. Insects represent a wide range of trophic relationships and ecological functions in terrestrial and aquatic ecosystems. However, it is necessary to comprehend their function to understand the construction of functional groups. In this chapter, we analyze some approaches to categorizing functional groups. We present three different perspectives to define functional groups: (i) Trophic groups – according to the type and use of their food resource (carnivores, detritivores, and herbivores); (ii) Functional groups – according to the function and processes that they fulfill (animal regulators, decomposers, plant regulators, pollinators, scavengers, seed dispersers, and seed predators); and (iii) Ecosystem services groups – according to the ecosystem service they provide (biological control, carbon dynamics, decomposition, nutrient cycling, food chain, plant propagation, plant regulation, and soil development). With the increasing degree of disturbance and the growing pressure of climate change, it is essential to identify functional groups that are in danger of extinction. A research priority for future studies is to fill in the little knowledge we have about resource use, functions, and ecosystem services provided by many insect groups. Finally, insect functional groups that included in conservation strategies and prioritized as tools to preserve our biodiversity are presented.

Contribution à l’évaluation écologique des milieux humides à l’aide d’un bioindicateur basé sur les Lépidoptères : étude des relations entre les pressions anthropiques et les communautés d’hétérocères dans le nord de la France

Thesis

Full-text available

Dec 2023

Jérémy Lebrun

Wetland environments play a major role in hydrological, biogeochemical and biological functions. Their evolutionary trend is towards a reduction in surface area, the artificialization of environments and a decline in their biological diversity as a result of increasing anthropization. There are a limited number of bioindicators available to detect the effects of pressures on these environments and the responses implemented to reduce them. Managers of wetlands in northern France are therefore considering the use of Heteroceran Lepidoptera to complement existing ecological assessment systems, which presupposes the prior identification of community descriptors reflecting the state of an environment in relation to pressures. To this end, we studied the links between species' functional traits and pressures, and tested the response of communities according to their ecological specialization. These communities were sampled by varying the levels of artificialisation and agricultural intensification at 113 sites and 22 catchments across northern France. Field observations coupled with information on species traits were used to analyze correlations between 79 species, their traits and pressure proxies, and to model relationships between species richness and these proxies for different levels of specialization. The results reveal associations between certain traits and pressure variables notably trophic traits according to an increasing anthropization, which is characterized by aquatic environments with a strong presence of invasive exotic plants and forest environments planted with non-native species. The rural-urban gradient plays a major role in community structuring, but its link with traits is less clear-cut. The richness of specialist and generalist species decreases in a comparable way as a function of artificialization and agricultural pressures. These results indicate that the trait-based approach is well-suited to capture a general pattern of heteroceran community structuring and trends in species richness under the impact of human activities. They suggest a possible tolerance of the communities most characteristic of wetlands under certain conditions, even if the underlying processes are not identified. With regard to the use of this taxonomic group as a bioindicator, this exploratory stage moderates the orientations taken for the integration of specialization traits into the indicator. Finally, the elements discussed guide the next steps in the indicator's development and identify a need for experiments to test the response of communities to different modes of ecological restoration of wetlands.

Black soldier fly: a new model for bioremediation of antibiotic pollutants

Article

Feb 2025

Insight into the Relationships Between Chemical, Protein and Functional Variables in the PBP/GOBP Family in Moths Based on Machine Learning

Article

Full-text available

Mar 2025
INT J MOL SCI

During their lives, insects must cope with a plethora of chemicals, of which a few will have an impact at the behavioral level. To detect these chemicals, insects use several protein families located in their main olfactory organs, the antennae. Inside the antennae, odorant-binding proteins (OBPs), as the most studied protein family, bind volatile chemicals to transport them. Pheromone-binding proteins (PBPs) and general-odorant-binding proteins (GOPBs) are two subclasses of OBPs and have evolved in moths with a putative olfactory role. Predictions for OBP–chemical interactions have remained limited, and functional data collected over the years unused. In this study, chemical, protein and functional data were curated, and related datasets were created with descriptors. Regression algorithms were implemented and their performance evaluated. Our results indicate that XGBoostRegressor exhibits the best performance (R² of 0.76, RMSE of 0.28 and MAE of 0.20), followed by GradientBoostingRegressor and LightGBMRegressor. To the best of our knowledge, this is the first study showing a correlation among chemical, protein and functional data, particularly in the context of the PBP/GOBP family of proteins in moths.

Invertebrate Decline Has Minimal Effects on Oak‐Associated Microbiomes

Article

Feb 2025
ENVIRON MICROBIOL

Recently, biomass of invertebrates has declined substantially at many locations with the implications of this biodiversity loss for ecosystems yet unknown. Through multitrophic interactions, plant‐ and soil‐associated microbiomes might be altered, causing a cascade of changes on diverse ecosystem processes. We simulated aboveground invertebrate decline in grassland ecosystems with two levels of invertebrate biomass (36% and 100% of current ambient conditions), plus a control with no invertebrates present. Each standardised grassland mesocosm additionally contained one clonal Quercus robur L. sapling to investigate the extent of invertebrate decline effects exceeding grasslands. We investigated oak biomass partitioning and mycorrhiza formation, oak leaf transcriptome and microbiome composition of leaves, roots and rhizosphere. While invertebrate decline did not significantly affect oak performance and herbivory‐related gene expression, fungal communities presented an increase of saprotrophs and pathogens, especially in leaves. Among leaf‐inhabiting bacteria, Proteobacteria and Actinobacteria increased under invertebrate decline. The belowground microbiome was only little affected. But, invertebrate decline came along with a reduced influence on predators leading to an elevated aphids infestation that proofed able to alter microbiota. Our findings establish a strong difference between above‐ and belowground, with the impacts of invertebrate decline being more pronounced in the leaf microbiome.

Butterfly Diversity Patterns Provide New Insights Into Biodiversity Conservation in China

Article

Dec 2024

Aim Globally, the knowledge of insect distributions is largely insufficient, and that hinders conservation actions against biodiversity loss. Focusing on butterfly diversity, we aimed to fill knowledge gaps and provide new insights into biodiversity conservation in China. Location China. Time Period Occurrence records from 1950 to 2023. Major Taxa Studied Butterflies, Lepidoptera. Methods We collected butterfly occurrence records from published literature, online databases and our butterfly specimens, and then used either species distribution models or expansion from actual occurrence sites to estimate species distribution ranges in China. We identified key environmental variables that are related to butterfly biodiversity patterns, and delineated priority conservation areas based on butterfly distributions. Results We report the first country‐wide inventory and mapping of China's 1920 butterfly species. The identified hotspots of species richness are distributed mainly in southwestern, southern and southeastern China. Among variables strongly correlated with species richness, the most important one is actual evapotranspiration. Conservation priority areas under the Convention on Biological Diversity 17% area target overlapped well with the hotspots, but only 29.8% of them are covered by existing nature reserves. When that protection target increases to 30%, the additional areas are located mainly in southern China, with its large cities and intensive agriculture. Main Conclusions We find that some protected butterfly species have a larger area of habitat than most species, implying that the list of protected butterflies in China should be revised. Urban and farmland landscapes may help sustain butterfly diversity and they should be considered in conservation planning.

Climate and regional plant richness drive diet specialization in butterfly caterpillars

Preprint

Full-text available

Jan 2025

Studies of coevolution, ecosystem processes, and latitudinal diversity gradients are improved by understanding variation in resource specialization. Insect herbivory is one of the most ubiquitous terrestrial ecological associations that drives the evolution of plants and insects. However, a broad understanding of how and why herbivore diet specificity varies worldwide is lacking. Here, we use global datasets of butterfly and plant distributions to investigate patterns and drivers of butterfly larval diet breadth. Hostplant richness and phylogenetic diversity showed non-monotonic latitudinal patterns that narrowed near the equator and temperate latitudes and broadened at mid-tropical latitudes and the poles. Diet breadth showed a negative relationship with plant family richness, but we also uncovered an interaction between precipitation seasonality and temperature. Our study builds on 60 years of study of butterfly-hostplant evolution to provide valuable insights into how these processes continue to shape plant and herbivore dynamics in response to global environmental changes.

Insectos, biodiversidad amenazada en un mundo cambiante

Article

Full-text available

Dec 2023

Eduardo Galante

Resumen: Los insectos, con más de un millón de especies conocidas, representan más del 60 por ciento de toda la biodiversidad existente. Es un grupo imprescindible para la vida, que proporciona importantes beneficios a nuestra salud y la del planeta. Actualmente asistimos a un grave descenso de sus poblaciones en todo el mundo y a una creciente desaparición de especies. Las causas de su declive son múltiples, pero hay una a la que se ha prestado poca atención a pesar de su alto impacto y que se debe al abandono de usos tradicionales agropecuarios que provocan profundos cambios en el paisaje, por lo que se pierde diversidad de hábitats a través de la intensificación agrícola y ganadera, que busca productividad sin tener en cuenta la biodiversidad. Palabras clave: insectos, biodiversidad, salud, declive de especies, agrosistema, intensificación agraria. Abstract: Insects, with more than a million known species, represent more than 60 percent of all existing biodiversity. They are an essential group for life, providing significant benefits to our health and that of the planet. We are currently witnessing a severe decline in their populations worldwide and an increasing disappearance of species. The causes of their decline are multiple, but there is one that has received little attention despite its high impact, the abandonment of traditional agricultural uses that cause profound changes in the landscape, resulting in a loss of habitat diversity through agricultural and livestock intensification, which seeks productivity without taking into account biodiversity. Keywords: insects, biodiversity, health, species decline, agrosystem, agricultural intensification.

An in-depth dataset of northwestern European arthropod life histories and ecological traits

Preprint

Full-text available

Dec 2024

In response to the ongoing biodiversity crisis among arthropods, it is essential to implement efficient conservation strategies to safeguard both species diversity and the vital ecosystem services they provide. Developing such strategies requires reliable predictive models that can identify the species that are the most vulnerable to current and future threats, including those posed by climate and land-use change. Species life histories are central to these models, as they influence both population dynamics and spread rates. To support this effort, we compiled a dataset with key traits for arthropods based on several literature sources and expert knowledge. The dataset contains data on body size, life history, thermal niche and ecology for 4874 northwestern European species across 10 different orders. By gathering these essential trait data, we aim to create a robust foundation for predicting species vulnerability and anticipating shifts in arthropod communities in response to global change.

Behavioural biomechanics: leaf-cutter ant cutting behaviour depends on leaf edge geometry

Preprint

Full-text available

Dec 2024

Leaf-cutter ants cut fresh leaves to grow a symbiotic fungus as crop. During cutting, one mandible is typically anchored onto the leaf lamina while the other slices through it like a knife. When initiating cuts into the leaf edge, however, foragers sometimes deviate from this behaviour, and instead used their mandibles symmetrically, akin to scissors. In-vivo behavioural assays revealed that the preference for either of the two cutting strategies depended on leaf edge geometry, and differed between natural leaf margins that were straight or serrated with notch-like folds: leaf-cutter ants displayed a strong preference for scissor-cutting when leaf edges were straight or had wide notches. This preference, however, reversed in favour of knife-cutting when notches were narrow. To investigate whether this behavioural difference had a mechanical origin, we mimicked knife-cutting in ex-vivo cutting experiments: for wide notches, all but the sharpest mandibles failed to initiate cuts, or only did so at large forces, caused by substantial leaf buckling and bending. This increased force demand would substantially limit the ability of foragers to cut leaves, and so reduce the colony's access to food sources. Scissor-cutting may thus be an adaptation to the mechanical difficulties associated with bending and buckling of thin leaves.

Is climate change to blame? Increased rainfall reduces emergence of Taiwanosemia hoppoensis (Hemiptera: Cicadidae) in coastal windbreak forests

Article

Jan 2025
BIOTROPICA

We found that increased rainfall reduced exuvial numbers and impacted populations of Taiwanosemia hoppoensis from coastal regions, likely due to prolonged soil flooding harming the subterranean nymphs. As climate change advances, long‐term monitoring is essential to track cicada populations across taxa and regions, given their important ecological roles. Abstract in Chinese is available with online material.

Consequences of fire and grazing to conservation of arthropod functional diversity in a protected Afrotropical savanna

Article

Nov 2024
BIOL CONSERV

Biological control of locusts and grasshoppers: A review

Article

Full-text available

Nov 2024

Locusts and grasshoppers (Orthoptera: Acrididae) are pests of agricultural importance, devastating crops and pastures. This group includes hundreds of pest species and affects the livelihoods of one in every ten people worldwide. Their outbreaks can be chronic or episodic, with alternating periods of invasion and recession. Here, we review the natural enemies of locusts and grasshoppers in both their native and invaded ranges across the globe to assess the need for their conservation and maintenance as part of the natural suppression of outbreaks and to augment outbreak suppression as potential biological control agents. More than 70 natural enemies have been reported to attack locusts and grasshoppers, including entomopathogenic fungi, bacteria, nematodes, predatory insects, birds, reptiles, and mammals. Particular attention is given to the well-studied species of locusts and grasshoppers for which more information is available and to natural enemies in the locust-affected countries as part of the recent trend of looking for indigenous natural enemies. Such organisms can play a vital role in integrated pest management strategies for locusts and grasshoppers, particularly entomopathogens that can be incorporated with chemical pesticides into the management system. Among the organisms considered, Metarhizium acridum is noteworthy for inclusion in integrated pest management programs.

Data of the Insect Biome Atlas: a metabarcoding survey of the terrestrial arthropods of Sweden and Madagascar

Preprint

Full-text available

Oct 2024

We present the data from the Insect Biome Atlas project (IBA), characterizing the terrestrial arthropod faunas of Sweden and Madagascar. Over 12 months, weekly Malaise trap samples were collected at 203 locations within 100 sites in Sweden and at 50 locations within 33 sites in Madagascar; this was complemented by soil and litter samples from each site. The field samples comprise 4,749 Malaise trap, 192 soil and 192 litter samples from Sweden and 2,566 Malaise trap and 190 litter samples from Madagascar. Samples were processed using mild lysis or homogenization, followed by DNA metabarcoding of COI (418 bp). The data comprise 698,378 non-chimeric sequence variants from Sweden and 687,958 from Madagascar, representing 33,989 (33,046 Arthropoda) and 77,600 (77,381 Arthropoda) operational taxonomic units, respectively. These are the most comprehensive data presented on these faunas so far, allowing unique analyses of the size, composition, spatial turnover and seasonal dynamics of the sampled communities. They also provide an invaluable baseline against which to gauge future changes.

Riparian buffer strips promote biomass, species richness and abundance of flying insects in agricultural landscapes

Article

Oct 2024
AGR ECOSYST ENVIRON

Consumer biodiversity increases organic nutrient availability across aquatic and terrestrial ecosystems

Article

Oct 2024
SCIENCE

Human land-use intensification threatens arthropod (for example, insect and spider) biodiversity across aquatic and terrestrial ecosystems. Insects and spiders play critical roles in ecosystems by accumulating and synthesizing organic nutrients such as polyunsaturated fatty acids (PUFAs). However, links between biodiversity and nutrient content of insect and spider communities have yet to be quantified. We relate insect and spider richness to biomass and PUFA-mass from stream and terrestrial communities encompassing nine land uses. PUFA-mass and biomass relate positively to biodiversity across ecosystems. In terrestrial systems, human-dominated areas have lower biomass and PUFA-mass than more natural areas, even at equivalent levels of richness. Aquatic ecosystems have consistently higher PUFA-mass than terrestrial ecosystems. Our findings reinforce the importance of conserving biodiversity and highlight the distinctive benefits of aquatic biodiversity.

Ladybird Beetle Diversity in Natural and Human-Modified Habitats in the San Cristóbal Island, Galapagos, Ecuador

Article

Full-text available

Sep 2024

This study investigates the species richness and distribution of ladybird beetles (Coccinellidae) across various habitats on San Cristóbal Island in the Galápagos Archipelago, Ecuador. Through extensive field surveys, we catalogued nineteen species, including four previously known species (two endemics, Psyllobora bisigma and Scymnobius scalesius, and two natives, Cycloneda sanguinea and Tenuisvalvae bromelicola). We also identified nine possibly native species reported for the first time in the Galapagos islands in this study or correspond to the first voucher specimens for the island. We collected three previously reported non-native species: Cheilomenes sexmaculata, Novius cardinalis, and Paraneda guticollis. Three species belonging to the genera Stethorus, Calloeneis, and Delphastus remain undetermined, pending further taxonomic analyses. Our findings reveal a rich and complex community with notable differences in species abundance and habitat preference. Endemic species were found to be particularly scarce and restricted mainly to crops undergoing forest regeneration and deciduous forests, emphasising their vulnerability and specialised habitat requirements. The native Cycloneda sanguinea emerged as the most prevalent species, exhibiting broad ecological adaptability. Non-native species, like Cheilomenes sexmaculata, were predominantly found in disturbed habitats, with some showing early signs of spreading into more natural environments, raising concerns about their potential impact on local biodiversity. These findings contribute valuable knowledge to understanding Coccinellidae diversity on San Cristóbal Island and highlight the importance of continued monitoring, particularly in the face of ongoing environmental change and the introduction of non-native species. This study underscores the need for targeted conservation efforts to protect the unique and fragile ecosystems of the Galápagos Archipelago.

The genome sequence of the Violet Carpenter Bee, Xylocopa violacea (Linnaeus, 1785): a hymenopteran species undergoing range expansion

Preprint

Full-text available

Sep 2024

We present a reference genome assembly from an individual male Violet Carpenter Bee (Xylocopa violacea, Linnaeus, 1758). The assembly is 1.02 gigabases in span. 48% of the assembly is scaffolded into 17 pseudo-chromosomal units. The mitochondrial genome has also been assembled and is 21.8 kilobases in length. The genome is highly repetitive, likely representing a highly heterochromatic architecture expected of bees from the genus Xylocopa. We also use an evidence-based methodology to annotate 10,152 high confidence coding genes. This genome was sequenced as part of the pilot project of the European Reference Genome Atlas (ERGA) and represents an important addition to the genomic resources available for Hymenoptera.

L’entomophagie en France

Article

Full-text available

Oct 2023

Clement Viaud

State of the art of entomophagy in France in 2023 and reminder of the interest in entomophagy as a sustainable diet.

Role of epigenetic molecular mechanisms in insect evolutionary innovations

Chapter

Jan 2024

Cristian Villagra

Exposure Pathways and Toxicity of Microplastics in Terrestrial Insects

Article

Jun 2024
ENVIRON SCI TECHNOL

The detrimental effects of plastics on aquatic organisms, including those of macroplastics, microplastics, and nanoplastics, have been well established. However, knowledge on the interaction between plastics and terrestrial insects is limited. To develop effective strategies for mitigating the impact of plastic pollution on terrestrial ecosystems, it is necessary to understand the toxicity effects and influencing factors of plastic ingestion by insects. An overview of current knowledge regarding plastic ingestion by terrestrial insects is provided in this Review, and the factors influencing this interaction are identified. The pathways through which insects interact with plastics, which can lead to plastic accumulation and microplastic transfer to higher trophic levels, are also discussed using an overview and a conceptual model. The diverse impacts of plastic exposure on insects are discussed, and the challenges in existing studies, such as a limited focus on certain plastic types, are identified. Further research on standardized methods for sampling and analysis is crucial for reliable research, and long-term monitoring is essential to assess plastic trends and ecological impacts in terrestrial ecosystems. The mechanisms underlying these effects need to be uncovered, and their potential long-term consequences for insect populations and ecosystems require evaluation.

Sensory Systems and Behaviour of Insects

Chapter

Full-text available

Jun 2023

Cropland Microclimate And Leaf-Nesting Behavior Shape The Growth of Caterpillar Under Future Warming

Article

May 2024
INTEGR COMP BIOL

Synopsis Predicting performance responses of insects to climate change is crucial for biodiversity conservation and pest management. While most projections on insects’ performance under climate change have used macro-scale weather station data, few incorporated the microclimates within vegetation that insects inhabit and their feeding behaviors (e.g., leaf-nesting: building leaf nests or feeding inside). Here, taking advantage of relatively homogenous vegetation structures in agricultural fields, we built microclimate models to examine fine-scale air temperatures within two important crop systems (maize and rice) and compared microclimate air temperatures to temperatures from weather stations. We deployed physical models of caterpillars and quantified effects of leaf-nesting behavior on operative temperatures of two Lepidoptera pests: Ostrinia furnacalis (Pyralidae) and Cnaphalocrocis medinalis (Crambidae). We built temperature-growth rate curves and predicted the growth rate of caterpillars with and without leaf-nesting behavior based on downscaled microclimate changes under different climate change scenarios. We identified widespread differences between microclimates in our crop systems and air temperatures reported by local weather stations. Leaf-nesting individuals in general had much lower body temperatures compared to non-leaf-nesting individuals. When considering microclimates, we predicted leaf-nesting individuals grow slower compared to non-leaf-nesting individuals with rising temperature. Our findings highlight the importance of considering microclimate and habitat-modifying behavior in predicting performance responses to climate change. Understanding the thermal biology of pests and other insects would allow us to make more accurate projections on crop yields and biodiversity responses to environmental changes.

Plant-mediated links between detritivores and aboveground herbivores

Article

Full-text available

Sep 2013

Susanne Wurst

Most studies on plant-mediated above–belowground interactions focus on soil biota with direct trophic links to plant roots such as root herbivores, pathogens, and symbionts. Detritivorous soil fauna, though ubiquitous and present in high abundances and biomasses in soil, are under-represented in those studies. Understanding of their impact on plants is mainly restricted to growth and nutrient uptake parameters. Detritivores have been shown to affect secondary metabolites and defense gene expression in aboveground parts of plants, with potential impacts on aboveground plant–herbivore interactions. The proposed mechanisms range from nutrient mobilization effects and impacts on soil microorganisms to defense induction by passive or active ingestion of roots. Since their negative effects (disruption or direct feeding of roots) may be counterbalanced by their overall beneficial effects (nutrient mobilization), detritivores may not harm, but rather enable plants to respond to aboveground herbivore attacks in a more efficient way. Both more mechanistic and holistic approaches are needed to better understand the involvement of detritivores in plant-mediated above–belowground interactions and their potential for sustainable agriculture.

Prokaryotes: The unseen majority

Article

Full-text available

Sep 1998

The number of prokaryotes and the total amount of their cellular carbon on earth are estimated to be 4–6 × 1030 cells and 350–550 Pg of C (1 Pg = 1015 g), respectively. Thus, the total amount of prokaryotic carbon is 60–100% of the estimated total carbon in plants, and inclusion of prokaryotic carbon in global models will almost double estimates of the amount of carbon stored in living organisms. In addition, the earth’s prokaryotes contain 85–130 Pg of N and 9–14 Pg of P, or about 10-fold more of these nutrients than do plants, and represent the largest pool of these nutrients in living organisms. Most of the earth’s prokaryotes occur in the open ocean, in soil, and in oceanic and terrestrial subsurfaces, where the numbers of cells are 1.2 × 1029, 2.6 × 1029, 3.5 × 1030, and 0.25–2.5 × 1030, respectively. The numbers of heterotrophic prokaryotes in the upper 200 m of the open ocean, the ocean below 200 m, and soil are consistent with average turnover times of 6–25 days, 0.8 yr, and 2.5 yr, respectively. Although subject to a great deal of uncertainty, the estimate for the average turnover time of prokaryotes in the subsurface is on the order of 1–2 × 103 yr. The cellular production rate for all prokaryotes on earth is estimated at 1.7 × 1030 cells/yr and is highest in the open ocean. The large population size and rapid growth of prokaryotes provides an enormous capacity for genetic diversity.

Manna from heaven: Refuse from an arboreal ant links aboveground and belowground processes in a lowland tropical forest

Article

Full-text available

Nov 2013

Aboveground consumers can shape belowground processes by serving as conduits for resources. Social insects dominate in terms of biomass in tropical forests, but compared to studies on large mammals, or aggregate solitary insects, we know relatively little about the role of social insects as nutrient conduits particularly in complex environments like tropical forests. Social insects like ants in the tropical forest canopy can connect aboveground and belowground food webs by producing a nutrient stream (excreta) from large, long-lived and stationary nests. The excreta, in turn, would create enduring spatial heterogeneity in the forest floor. Here we evaluate this scenario in a lowland Neotropical forest using Azteca trigona, a dominant canopy ant that feeds on honeydew and insects and rains refuse out of its hanging nests onto the leaf litter below. We investigate decomposition rates and detrital communities associated with areas near nests versus 10 m away. Further, we directly test refuse's impact on decomposition and detrital communities in a common garden experiment. Relative to leaf litter, refuse is enriched 7-fold in P, 23-fold in K, and 3-fold in N, all elements shown to limit decomposition in this forest. Accordingly, both artificial substrates and natural leaf litter substrates decomposed over 1.5- and 1.2-fold faster respectively below A. trigona nests and areas under nests supported more invertebrate detritivores and predators compared to controls 10 m away. These decomposition results were replicated in a 6-wk common garden experiment, but the changes in detrital invertebrate composition were not. Canopy ants like A. trigona act as dependable nutritional conduits to patches of the forest floor, transferring significant quantities of aboveground exudates and necromass. The general capacity for such social insect colonies to generate ecosystem heterogeneity remains an open question.

Animating the Carbon Cycle

Article

Full-text available

Mar 2014

Understanding the biogeochemical processes regulating carbon cycling is central to mitigating atmospheric CO2 emissions. The role of living organisms has been accounted for, but the focus has traditionally been on contributions of plants and microbes. We develop the case that fully “animating” the carbon cycle requires broader consideration of the functional role of animals in mediating biogeochemical processes and quantification of their effects on carbon storage and exchange among terrestrial and aquatic reservoirs and the atmosphere. To encourage more hypothesis-driven experimental research that quantifies animal effects we discuss the mechanisms by which animals may affect carbon exchanges and storage within and among ecosystems and the atmosphere. We illustrate how those mechanisms lead to multiplier effects whose magnitudes may rival those of more traditional carbon storage and exchange rate estimates currently used in the carbon budget. Many animal species are already directly managed. Thus improved quantitative understanding of their influence on carbon budgets may create opportunity for management and policy to identify and implement new options for mitigating CO2 release at regional scales.

A brown-world cascade in the dung decomposer food web of an alpine meadow: Effects of predator interactions and warming

Article

Full-text available

May 2011

Top-down control has been extensively documented in food webs based on living plants, where predator limitation of herbivores can cascade to facilitate plant growth (the green-world hypothesis), particularly in grasslands and aquatic systems. Yet the ecosystem role of predators in detrital food webs is less explored, as is the potential effect of climate warming on detritus-based communities. We here show that predators have a "brown-world" role in decomposer communities via a cascading top-down control on plant growth, based on the results of an experiment that factorially manipulated presence and size of two predator species as well as temperature (warmed vs. unwarmed). The inclusion of predatory beetles significantly decreased abundance of coprophagous beetles and thus the rate of dung decomposition and productivity of plants growing surrounding the dung. Moreover, the magnitude of these decreases differed between predator species and, for dung loss, was temperature dependent. At ambient temperature, the larger predators tended to more strongly influence the dung loss rate than did the smaller predators; when both predators were present, the dung loss rate was higher relative to the treatments with the smaller predators but comparable to those with the larger ones, suggesting an antagonistic effect of predator interaction. However, warming substantially reduced dung decomposition rates and eliminated the effects of predation on dung decomposition. Although warming substantially decreased dung loss rates, warming only modestly reduced primary productivity. Consistent with these results, a second experiment exploring the influence of the two predator species and warming on dung loss over time revealed that predatory beetles significantly decreased the abundance of coprophagous beetles, which was positively correlated with dung loss rates. Moreover, experimental warming decreased the water content of dung and hence the survival of coprophagous beetles. These results confirm that the "brown-world" effect of predator beetles was due to cascading top-down control through coprophagous beetles to nutrient cycling and primary productivity. Our results also highlight potentially counterintuitive effects of climate warming. For example, global warming might significantly decrease animal-mediated decomposition of organic matter and recycling of nutrients in a future warmed world.

Mycorrhiza-mediated competition between plants and decomposers drives soil carbon storage

Article

Full-text available

Jan 2014
NATURE

Soil contains more carbon than the atmosphere and vegetation combined. Understanding the mechanisms controlling the accumulation and stability of soil carbon is critical to predicting the Earth's future climate. Recent studies suggest that decomposition of soil organic matter is often limited by nitrogen availability to microbes and that plants, via their fungal symbionts, compete directly with free-living decomposers for nitrogen. Ectomycorrhizal and ericoid mycorrhizal (EEM) fungi produce nitrogen-degrading enzymes, allowing them greater access to organic nitrogen sources than arbuscular mycorrhizal (AM) fungi. This leads to the theoretical prediction that soil carbon storage is greater in ecosystems dominated by EEM fungi than in those dominated by AM fungi. Using global data sets, we show that soil in ecosystems dominated by EEM-associated plants contains 70% more carbon per unit nitrogen than soil in ecosystems dominated by AM-associated plants. The effect of mycorrhizal type on soil carbon is independent of, and of far larger consequence than, the effects of net primary production, temperature, precipitation and soil clay content. Hence the effect of mycorrhizal type on soil carbon content holds at the global scale. This finding links the functional traits of mycorrhizal fungi to carbon storage at ecosystem-to-global scales, suggesting that plant-decomposer competition for nutrients exerts a fundamental control over the terrestrial carbon cycle.

Connecting the Green and Brown Worlds: Allometric and stoichiometric predictability of above- and below-ground networks

Article

Full-text available

Nov 2013
ADV ECOL RES

We examine the potential of trait-based parameters of taxa for linking above-ground and below-ground ecological networks (hereafter ‘green’ and ‘brown’ worlds) to understand and predict community dynamics. This synthesis considers carbon, nitrogen and phosphorus-related traits, the abundance of component species and their size-distribution across trophic levels under different forms of management. We have analyzed existing and novel databases on plants, microbes and invertebrates that combine physico-chemical and biological information from (agro)ecosystems spanning the globe. We found (1) evidence that traits from above-ground and below-ground systems may be integrated in the same model and (2) a much greater than expected stoichiometric plasticity of plants and microbes which has implications for the entire food-web mass–abundance scaling. Nitrogen and phosphorus are primary basal resources (hence, drivers) and more retranslocation of P than of N from leaves will lead to higher N:P in the litter and soil organic matter. Thus, under nutrient-rich conditions, higher foliar concentrations of N and P are reflected by lower N:P in the brown litter, suggesting less P retranslocated than N. This apparent stoichiometric dichotomy between green and brown could result in shifts in threshold elemental ratios critical for ecosystem functioning. It has important implications for a general food-web model, given that resource C:N:P ratios are generally assumed to reflect environmental C:N:P ratios. We also provide the first evidence for large-scale allometric changes according to the stoichiometry of agroecosystems. Finally, we discuss insights that can be gained from integrating carbon and nitrogen isotope data into trait-based approaches, and address the origin of changes in Δ13C and Δ15N fractionation values in relation to consumer–resource body-mass ratios.

Regional-Level Inputs of Emergent Aquatic Insects from Water to Land

Article

Full-text available

Nov 2013

Emergent aquatic insects can provide inputs to terrestrial ecosystems near lentic and lotic waterbodies, producing ecosystem linkages at the aquatic–terrestrial interface. Although aquatic insect emergence has been examined for individual sites, the magnitude and spatial distribution of this phenomenon has not been examined at regional spatial scales. Here, we characterize this cross-habitat linkage for the state of Wisconsin, USA (169,639 km2). We combined GIS hydrological data with empirical data and predictive models of aquatic insect production to estimate annual aquatic emergence for the state of Wisconsin. Total emergence (lentic + lotic) was estimated to be about 6,800 metric tons of C y−1. Lentic systems comprised 79% of total estimated insect emergence, primarily due to the large amount of lake surface area relative to streams. This is due to both basic ecosystem geometry and the overall abundance of lakes in Wisconsin. Spatial variation was high: insect emergence in southwestern Wisconsin was dominated by streams, whereas for most of the rest of the state insect emergence was dominated by lakes. Lentic inputs to land were highly concentrated (relative to lotic inputs) because lakes have a high ratio of surface area to buffer area. Although less concentrated, the spatial extent of lotic influence was greater: statewide, four times more land area fell within the 100 m buffer zones of streams compared to lakes. Large waterbodies (almost all of which were lakes) were hotspots of insect emergence and input to land. Aquatic insect inputs exceed estimated terrestrial secondary production in 13% of buffer area, and by a factor of 100 or more adjacent to large lakes (>50,000 ha). The model sensitivity analysis showed that the simplifying assumptions and sources of potential error in the input variables had a minor impact on the overall results.

Plant-mediated links between detritivores and aboveground herbivores

Article

Full-text available

Sep 2013

Susanne Wurst

Most studies on plant-mediated above-belowground interactions focus on soil biota with direct trophic links to plant roots such as root herbivores, pathogens, and symbionts. Detritivorous soil fauna, though ubiquitous and present in high abundances and biomasses in soil, are under-represented in those studies. Understanding of their impact on plants is mainly restricted to growth and nutrient uptake parameters. Detritivores have been shown to affect secondary metabolites and defense gene expression in aboveground parts of plants, with potential impacts on aboveground plant-herbivore interactions. The proposed mechanisms range from nutrient mobilization effects and impacts on soil microorganisms to defense induction by passive or active ingestion of roots. Since their negative effects (disruption or direct feeding of roots) may be counterbalanced by their overall beneficial effects (nutrient mobilization), detritivores may not harm, but rather enable plants to respond to aboveground herbivore attacks in a more efficient way. Both more mechanistic and holistic approaches are needed to better understand the involvement of detritivores in plant-mediated above-belowground interactions and their potential for sustainable agriculture.

River-Watershed Exchange: Effects of Riverine Subsidies on Riparian Lizards and Their Terrestrial Prey

Article

Full-text available

Jul 2002

Resource subsidies from external habitats can enhance the performance or population density of local consumers, altering their effects on in situ prey. Indirect effects of subsidies may be either positive or negative depending on the behavior of the shared consumer. Here we document strong links between riverine insects, riparian lizards (Sce- loporus occidentalis), and terrestrial invertebrates. We hypothesized that aquatic insects subsidize riparian lizard populations leading to higher growth rates of these lizards in near- river habitats, and that subsidies exert short-term positive effects on terrestrial resources as a result of diet shifts by lizards to aquatic insects. To test these hypotheses, we used 2 m high fences, or ''subsidy shields,'' to experimentally reduce aquatic insect flux to large (91 m 2) enclosures of lizards. Subsidy shields reduced aquatic insect flux by 55-65%. Growth rates of lizards were 73 higher in subsidized (no-shield) enclosures during the early summer but were not significantly different later in the summer, when ambient fluxes of aquatic insects dropped to 20% of their early season levels. Within the watershed, lizard growth rates (in mass) were positively correlated with the numerical abundance of aquatic insects. Thus, lizard growth rates tracked both seasonal and spatial availability of riverine insect subsidies during our experiment. Subsidies also had indirect effects on the ground- dwelling, terrestrial prey of lizards. Declines of diurnal terrestrial invertebrates were sig- nificantly higher in shield than no-shield enclosures, and the most common ground spider (Arctosa sp. (Lycosidae)) disappeared completely from shield enclosures by the end of the experiment. Declines in terrestrial invertebrate abundance did not differ between no-shield enclosures and lizard exclosures. These data suggest that riverine insects subsidize riparian Sceloporus and, in the short term, reduce their predation on terrestrial arthropods.

Biomass of termites and their emissions of methane and carbon dioxide: A global database

Article

Full-text available

Dec 1996

Michael Sanderson

A global database describing the geographical distribution of the biomass of termites and their emissions of methane and carbon dioxide has been constructed. Termite biomasses were assigned to various ecosystems using published measurements and a recent high-resolution (10' × 10') database of vegetation categories. The assigned biomasses were then combined with literature measurements of fluxes of methane and carbon dioxide from termites and extrapolated to give global emission estimates for each gas. The global emissions of methane and carbon dioxide are 19.7 ± 1.5 and 3500 ± 700 Mt yr-1, respectively (1 Mt = 1012 g). These emissions contribute approximately 4% and 2%, respectively, to the total global fluxes of these gases. This database gives an accurate distribution of the biomasses and gaseous emissions by termites and may be incorporated into global models of the atmosphere.

Trophic Cascade Alters Ecosystem Carbon Exchange

Article

Full-text available

Jun 2013
P NATL ACAD SCI USA

Trophic cascades-the indirect effects of carnivores on plants mediated by herbivores-are common across ecosystems, but their influence on biogeochemical cycles, particularly the terrestrial carbon cycle, are largely unexplored. Here, using a (13)C pulse-chase experiment, we demonstrate how trophic structure influences ecosystem carbon dynamics in a meadow system. By manipulating the presence of herbivores and predators, we show that even without an initial change in total plant or herbivore biomass, the cascading effects of predators in this system begin to affect carbon cycling through enhanced carbon fixation by plants. Prolonged cascading effects on plant biomass lead to slowing of carbon loss via ecosystem respiration and reallocation of carbon among plant aboveground and belowground tissues. Consequently, up to 1.4-fold more carbon is retained in plant biomass when carnivores are present compared with when they are absent, owing primarily to greater carbon storage in grass and belowground plant biomass driven largely by predator nonconsumptive (fear) effects on herbivores. Our data highlight the influence that the mere presence of predators, as opposed to direct consumption of herbivores, can have on carbon uptake, allocation, and retention in terrestrial ecosystems.

Long-term insect herbivory slows soil development in an arid ecosystem

Article

Full-text available

May 2013

Although herbivores are well known to alter litter inputs and soil nutrient fluxes, their long-term influences on soil development are largely unknown because of the difficulty of detecting and attributing changes in carbon and nutrient pools against large background levels. The early phase of primary succession reduces this signal-to-noise problem, particularly in arid systems where individual plants can form islands of fertility. We used natural variation in tree-resistance to herbivory, and a 15 year herbivore-removal experiment in an Arizona pinon-juniper woodland that was established on cinder soils following a volcanic eruption, to quantify how herbivory shapes the development of soil carbon (C) and nitrogen (N) over 36-54 years (i.e., the ages of the trees used in our study). In this semi-arid ecosystem, trees are widely spaced on the landscape, which allows direct examination of herbivore impacts on the nutrient-poor cinder soils. Although chronic insect herbivory increased annual litterfall N per unit area by 50% in this woodland, it slowed annual tree-level soil C and N accumulation by 111% and 96%, respectively. Despite the reduction in soil C accumulation, short-term litterfall-C inputs and soil C-efflux rates per unit soil surface were not impacted by herbivory. Our results demonstrate that the effects of herbivores on soil C and N fluxes and soil C and N accumulation are not necessarily congruent: herbivores can increase N in litterfall, but over time their impact on plant growth and development can slow soil development. In sum, because herbivores slow tree growth, they slow soil development on the landscape.

Predator-induced reduction of freshwater carbon dioxide emissions

Article

Full-text available

Feb 2013
NAT GEOSCI

Predators can influence the exchange of carbon dioxide between ecosystems and the atmosphere by altering ecosystem processes such as decomposition and primary production, according to food web theory1, 2. Empirical knowledge of such an effect in freshwater systems is limited, but it has been suggested that predators in odd-numbered food chains suppress freshwater carbon dioxide emissions, and predators in even-numbered food chains enhance emissions2, 3. Here, we report experiments in three-tier food chains in experimental ponds, streams and bromeliads in Canada and Costa Rica in the presence or absence of fish (Gasterosteus aculeatus) and invertebrate (Hesperoperla pacifica and Mecistogaster modesta) predators. We monitored carbon dioxide fluxes along with prey and primary producer biomass. We found substantially reduced carbon dioxide emissions in the presence of predators in all systems, despite differences in predator type, hydrology, climatic region, ecological zone and level of in situ primary production. We also observed lower amounts of prey biomass and higher amounts of algal and detrital biomass in the presence of predators. We conclude that predators have the potential to markedly influence carbon dioxide dynamics in freshwater systems.

Insect Defoliation and Nitrogen Cycling in Forests

Article

Full-text available

Apr 2002

effects on forest ecosystems. Studies have shown that de-foliation can decrease transpiration and tree growth and in-crease tree mortality, light penetration to the forest floor, and water drainage (Stephens et al. 1972, Campbell and Sloan 1977, Houston 1981). The allocation of carbon to various parts of the tree may be altered, production of defensive com-pounds in foliage may increase (Schultz and Baldwin 1982), and seed production may decline for many years after defo-liation (McConnell 1988, Gottschalk 1990). Shifts in tree species composition (Doane and McManus 1981, Glitzenstein et al. 1990) and changes in the population size of insectivo-rous birds and other wildlife may also occur (Holmes et al. 1986, USDA Forest Service 1994).

Insect herbivory increases litter quality and decomposition: An extension of the acceleration hypothesis

Article

Full-text available

Nov 2003

Herbivore alteration of litter inputs may change litter decomposition rates and influence ecosystem nutrient cycling. In a semiarid woodland at Sunset Crater National Monument, Arizona, long-term insect herbivore removal experiments and the presence of herbivore resistant and susceptible pinyon pines (Pinus edulis) have allowed characteriza-tion of the population-and community-level effects of herbivory. Here we report how these same two herbivores, the mesophyll-feeding scale insect Matsucoccus acalyptus and the stem-boring moth Dioryctria albovittella alter litter quality, dynamics, and decomposition in this ecosystem. We measured aboveground litterfall, litter chemical composition, and first-year litter decomposition rates for trees resistant and susceptible to both herbivores and for susceptible trees from which herbivores had been experimentally removed for 16– 18 years. Both herbivores significantly increased nitrogen concentration and decreased lignin:nitrogen and carbon:nitrogen ratios of aboveground litter. Herbivory by scale insects also increased litter phosphorus concentration and annual needle litterfall mass. Consistent with its increased chemical quality, litter from herbivore-susceptible trees decomposed more rapidly in the first year. These results suggest that herbivory may increase nutrient cycling rates in this system by altering the chemical quality of litter, a mechanism that augments the nutrient acceleration hypothesis. The distribution of trees resistant and susceptible to the two herbivores at our site, and their associated variation in litter quality and decom-position, likely creates a mosaic of litter quality and nutrient cycling rates at the landscape scale. Further, because the differences in litter quality are associated with tree resistance and susceptibility traits, our findings are among the first to establish that intraspecific genetic variation may affect ecosystem function.

Predation risk, stoichiometric plasticity and ecosystem elemental cycling

Article

Full-text available

Aug 2012
Proc Biol Sci

It is widely held that herbivore growth and production is limited by dietary nitrogen (N) that in turn constrains ecosystem elemental cycling. Yet, emerging evidence suggests that this conception of limitation may be incomplete, because chronic predation risk heightens herbivore metabolic rate and shifts demand from N-rich proteins to soluble carbohydrate-carbon (C). Because soluble C can be limiting, predation risk may cause ecosystem elemental cycling rates and stoichiometric balance to depend on herbivore physiological plasticity. We report on a stoichiometrically explicit ecosystem model that investigates this problem. The model tracks N, and soluble and recalcitrant C through ecosystem compartments. We evaluate how soluble plant C influences C and N stocks and flows in the presence and absence of predation risk. Without risk, herbivores are limited by N and respire excess C so that plant-soluble C has small effects only on elemental stocks and flows. With predation risk, herbivores are limited by soluble C and release excess N, so plant-soluble C critically influences ecosystem elemental stocks flows. Our results emphasize that expressing ecosystem stoichiometric balance using customary C : N ratios that do not distinguish between soluble and recalcitrant C may not adequately describe limitations on elemental cycling.

Emergence of Periodical Cicadas (Magicicada cassini) From a Kansas Riparian Forest: Densities, Biomass and Nitrogen Flux

Article

Full-text available

Jan 2001

The 1998 emergence of 17-y periodical cicadas (Magicicada cassini) on Konza Prairie Research Natural Area (KPRNA), Kansas, was quantified using emergence trap tran-sects and counts of emergence holes. Emergence density, biomass (emergence production) and associated nitrogen flux were estimated for the entire 100 ha gallery forest of Kings Creek, the major drainage network on KPRNA. Emergence commenced on 22 May 1998 and lasted for 24 d, with 87% of the individuals emerging within the first 9 d. Males domi-nated early during the emergence, and the sex ratio for the entire population was estimated at 54:46 male:female. Average emergence abundance and biomass estimated from trap tran-sects located in low areas where cicadas were most abundant were 152/m 2 and 34.9 g ash-free dry mass (AFDM)/m 2 , respectively. Based on emergence hole counts, average density and biomass for the 59 ha of gallery forest where cicadas emerged were 27.2 individuals/m 2 and 6.3 g AFDM/m 2 , and emergence hole densities 100/m 2 were evident in low areas of the drainage. Emergence density generally decreased with increasing elevation in the catch-ment. Belowground to aboveground N flux associated with M. cassini emergence in high density areas was 3 g N/m 2 , and the average for the entire emergence area was 0.63 g N/ m 2 . The total number of individuals that emerged from the Kings Creek riparian forest was estimated at 19.6 million, which represents 4.6 metric tons AFDM and 0.5 metric tons N. This linear, fragmented, gallery forest of the Flint Hills supports a high density of M. cassini, and an emergence event constitutes a significant belowground to aboveground flux of energy and nutrients. Thus, the periodical cicada may be an exception to the notion that insects generally do not represent important resource pools at the ecosystem level.

Global decomposition experiment shows soil animal impacts on decomposition are climate-dependent

Article

Full-text available

Nov 2008
GLOBAL CHANGE BIOL

Climate and litter quality are primary drivers of terrestrial decomposition and, based on evidence from multisite experiments at regional and global scales, are universally factored into global decomposition models. In contrast, soil animals are considered key regulators of decomposition at local scales but their role at larger scales is unresolved. Soil animals are consequently excluded from global models of organic mineralization processes. Incomplete assessment of the roles of soil animals stems from the difficulties of manipulating invertebrate animals experimentally across large geographic gradients. This is compounded by deficient or inconsistent taxonomy. We report a global decomposition experiment to assess the importance of soil animals in C mineralization, in which a common grass litter substrate was exposed to natural decomposition in either control or reduced animal treatments across 30 sites distributed from 43°S to 68°N on six continents. Animals in the mesofaunal size range were recovered from the litter by Tullgren extraction and identified to common specifications, mostly at the ordinal level. The design of the trials enabled faunal contribution to be evaluated against abiotic parameters between sites. Soil animals increase decomposition rates in temperate and wet tropical climates, but have neutral effects where temperature or moisture constrain biological activity. Our findings highlight that faunal influences on decomposition are dependent on prevailing climatic conditions. We conclude that (1) inclusion of soil animals will improve the predictive capabilities of region- or biome-scale decomposition models, (2) soil animal influences on decomposition are important at the regional scale when attempting to predict global change scenarios, and (3) the statistical relationship between decomposition rates and climate, at the global scale, is robust against changes in soil faunal abundance and diversity.

Bridging the gap between micro - and macro-scale perspectives on the role of microbial communities in global change ecology

Article

Full-text available

Nov 2006

In order to understand the role microbial communities play in mediating ecosystem response to disturbances it is essential to address the methodological and conceptual gap that exists between micro- and macro-scale perspectives in ecology. While there is little doubt microorganisms play a central role in ecosystem functioning and therefore in ecosystem response to global change-induced disturbance, our ability to investigate the exact nature of that role is limited by disciplinary and methodological differences among microbial and ecosystem ecologists. In this paper we present results from an interdisciplinary graduate-level seminar class focused on this topic. Through the medium of case studies in global change ecology (soil respiration, nitrogen cycling, plant species invasion and land use/cover change) we highlight differences in our respective approach to ecology and give examples where disciplinary perspective influences our interpretation of the system under study. Finally, we suggest a model for integrating perspectives that may lead to greater interdisciplinary collaboration and enhanced conceptual and mechanistic modeling of ecosystem response to disturbance.

Ecosystem Linkages Between Lakes and the Surrounding Terrestrial Landscape in Northeast Iceland

Article

Full-text available

Aug 2008

Despite a recent emphasis on understanding cross-habitat interactions, few studies have examined the ecological linkages between lakes and surrounding terrestrial habitats. The current paradigm of land–lake interactions is typically unidirectional: the view is that nutrients and matter are transported downslope from the surrounding watershed to their ultimate lacustrine destination. Emergent aquatic insects, which spend their larval stages in lake sediments and emerge as adults to mate over land, can act as vectors of material, energy and nutrients from aquatic to terrestrial habitats. In this study, we document a gradient of midge (Diptera: Chironomidae) infall rates into terrestrial habitats (measured as g dw midges m−2 d−1) surrounding eight lakes in Northern Iceland (≈66°N latitude). Lakes ranged from having virtually no midge infall (for example, Helluvaðstjörn, 0.03 g m−2 d−1) to extreme levels (for example, Mývatn, 19 g m−2 d−1) with abundances of midges decreasing logarithmically with distance from shore. Annual midge input rates are estimated as high as 1200–2500kg midges ha−1 y−1. As midges are approximately 9.2% total N, this can result in a significant fertilization effect of terrestrial habitats with consequences for plant quality and community structure. In addition, we used naturally-occurring δ13C and δ15N isotopes to examine food web structure and diet sources of terrestrial arthropod consumers surrounding lakes with differing amounts of midge input. Terrestrial arthropods showed increased utilization of aquatic-derived (that is, midge) C relative to terrestrial sources as midge infall increased. This pattern was particularly pronounced for predators, such as spiders and opiliones, and some detritivores (Collembola). These findings suggest that, despite being largely ignored, aquatic-to-terrestrial linkages can be large and midges can fuel terrestrial communities by directly serving as resources for predators and decomposers.

Fear of Predation Slows Plant-Litter Decomposition

Article

Full-text available

Jun 2012
SCIENCE

Fear Itself A direct connection exists between aboveground communities and belowground soil microbiota: Soil microbes break down detrital inputs from above. Generally, it has been assumed that this relationship is largely driven by the soil community and the quality of the unconsumed plant-matter that makes up the majority of detritus in most ecosystems. However, Hawlena et al. (p. 1434 ) found that grasshoppers exposed to the threat of spider predation have an altered carbon to nitrogen ratio. When these grasshopper carcasses were subsequently integrated into the plant litter, they significantly slowed the decomposition rate, although there was no impact on the rate of decomposition of the grasshoppers themselves. Thus, the mere presence of predators, and the stress they impose, can have cascading trophic impacts and even influence the process of decomposition.

Ecosystem linkages revealed by experimental lake-derived isotope signal in heathland food webs

Article

Full-text available

Apr 2012
OECOLOGIA

Cross-ecosystem movement of nutrients and biomass can have important effects on recipient systems. Emerging aquatic insects are subsidies to terrestrial ecosystems and can influence foodweb interactions in riparian systems. In a 2-year field experiment, we simulated aquatic insect deposition by adding adult midge carcasses (150 g dry mass m(-2) year(-1)) to 1-m(2) heathland plots at a site with low natural midge deposition. We established four levels of midge-addition treatments and measured stable isotopes (δ(13)C and δ(15)N) in plants and arthropods within each treatment. We used a multiple-source isotope Bayesian mixing model to estimate the terrestrial versus aquatic contribution to the diets of arthropods. Aquatic resources were incorporated into plant, detritivore, and predator biomass. Detritivorous Collembola showed the greatest difference in isotope values (+3 ‰ δ(15)N and +4 ‰ δ(13)C) between midge-addition and reference treatments. Isotope values of small spiders followed the same trend of enrichment as Collembola while other arthropods (mites and large spiders) were only enriched after 2 years of midge addition. Although predator diets did not change, they became isotopically enriched via their likely prey (Collembola). Plants also had elevated δ(15)N (+1 ‰) in midge-addition treatments. The time required and amount of midge-derived C and N detected varied and depended on trophic position. Midge-derived nutrients were no longer present in arthropod biomass in the year following midge addition. Aquatic insect carcasses can be rapidly incorporated into terrestrial food webs in nearshore habitats, and repeated inputs can be detected at multiple trophic levels, thus highlighting the importance of the detrital pathway for aquatic to terrestrial cross-ecosystem subsidies.

BIOLOGICAL-CONTROL HERBIVORES MAY INCREASE COMPETITIVE ABILITY OF THE NOXIOUS WEED CENTAUREA MACULOSA

Article

Jun 1999

Biocontrol organisms are generally applied in an attempt to reduce the vigor of target species and provide native species with an competitive advantage. We tested the effectiveness of a widely used biocontrol moth, Agapeta zoegana (knapweed root moth) for two years in the field and found that it had no significant direct effect on the biomass of Centaurea maculosa (spotted knapweed), one of the most destructive invasive plants in North America. Instead of releasing a native grass from competition, the reproductive output of Festuca idahoensis planted with Centaurea was significantly lower when neighboring Centaurea had been attacked by Agapeta. In a greenhouse experiment, we found that Festuca planted in pots with Centaurea that had been attacked by Trichoplusia ni (another nonnative herbivore) had significantly smaller root systems than when they were planted with Centaurea that were protected from herbivory. Root systems of Centaurea that had been attacked by Trichoplusia exuded higher levels of total sugars, but not total phenols. We hypothesize that moderate herbivory stimulated compensatory growth, induced the production of defense chemicals that also had allelopathic effects, or stimulated root exudates that altered the relationship between Centaurea and Festuca via soil microbes. Our data suggest that herbivory may increase the negative effects of C. maculosa on neighboring plants, and that some biocontrols may have indirect negative effects on native species that are not currently recognized. Biocontrol organisms are generally applied in an attempt to reduce the vigor of target species and provide native species with an competitive advantage. We tested the effectiveness of a widely used biocontrol moth, Agapeta zoegana (knapweed root moth) for two years in the field and found that it had no significant direct effect on the biomass of Centaurea maculosa (spotted knapweed), one of the most destructive invasive plants in North America. Instead of releasing a native grass from competition, the reproductive output of Festuca idahoensis planted with Centaurea was significantly lower when neighboring Centaurea had been attacked by Agapeta. In a greenhouse experiment, we found that Festuca planted in pots with Centaurea that had been attacked by Trichoplusia ni (another nonnative herbivore) had significantly smaller root systems than when they were planted with Centaurea that were protected from herbivory. Root systems of Centaurea that had been attacked by Trichoplusia exuded higher levels of total sugars, but not total phenols. We hypothesize that moderate herbivory stimulated compensatory growth, induced the production of defense chemicals that also had allelopathic effects, or stimulated root exudates that altered the relationship between Centaurea and Festuca via soil microbes. Our data suggest that herbivory may increase the negative effects of C. maculosa on neighboring plants, and that some biocontrols may have indirect negative effects on native species that are not currently recognized.

The unseen majority: Soil microbes as drivers of plant diversity and productivity in terrestrial ecosystems (Ecology Letters (2008) 11, 3 (296-310))

Article

Jun 2008

Resolving ecosystem complexity (MPB-47)

Article

Jan 2010

Oswald J Schmitz

An ecosystem's complexity develops from the vast numbers of species interacting in ecological communities. The nature of these interactions, in turn, depends on environmental context. How do these components together influence an ecosystem's behavior as a whole? Can ecologists resolve an ecosystem's complexity in order to predict its response to disturbances? Resolving Ecosystem Complexity develops a framework for anticipating the ways environmental context determines the functioning of ecosystems. Oswald Schmitz addresses the critical questions of contemporary ecology: How should an ecosystem be conceptualized to blend its biotic and biophysical components? How should evolutionary ecological principles be used to derive an operational understanding of complex, adaptive ecosystems? How should the relationship between the functional biotic diversity of ecosystems and their properties be understood? Schmitz begins with the universal concept that ecosystems are comprised of species that consume resources and which are then resources for other consumers. From this, he deduces a fundamental rule or evolutionary ecological mechanism for explaining context dependency: individuals within a species trade off foraging gains against the risk of being consumed by predators. Through empirical examples, Schmitz illustrates how species use evolutionary ecological strategies to negotiate a predator-eat-predator world, and he suggests that the implications of species trade-offs are critical to making ecology a predictive science. Bridging the traditional divides between individuals, populations, and communities in ecology, Resolving Ecosystem Complexity builds a systematic foundation for thinking about natural systems.

Introduced Dung Beetles and Australian Pasture Ecosystems: Papers Presented at a Symposium During the Meeting of the Australia and New Zealand Association for the Advancement of Science at Canberra in January 1975

Article

Dec 1975

Insect Outbreaks Revisited

Chapter

Jun 2012

Louie H. Yang

Decomposition in Terrestrial Ecosystems. Studies in Ecology Vol. 5.

Article

Mar 1981

Taking the trophic bypass: Aquatic-terrestrial linkage reduces methylmercury in a terrestrial food web

Article

Aug 2015

Ecosystems can be linked by the movement of matter and nutrients across habitat boundaries via aquatic insect emergence. Aquatic organisms tend to have higher concentrations of certain toxic contaminants such as methylmercury (MeHg) compared to their terrestrial counterparts. If aquatic organisms come to land, terrestrial organisms that consume them are expected to have elevated MeHg concentrations. But emergent aquatic insects could have other impacts as well, such as altering consumer trophic position or increasing ecosystem productivity as a result of nutrient inputs from insect carcasses. We measure MeHg in terrestrial arthropods at two lakes in northeastern Iceland and use carbon and nitrogen stable isotopes to quantify aquatic reliance and trophic position. Across all terrestrial focal arthropod taxa (Lycosidae, Linyphiidae, Acari, Opiliones), aquatic reliance had significant direct and indirect (via changes in trophic position) effects on terrestrial consumer MeHg. However, contrary to our expectations, terrestrial consumers that consumed aquatic prey had lower MeHg concentrations than consumers that ate mostly terrestrial prey. We hypothesize that this is due to the lower trophic position of consumers feeding directly on midges relative to those that fed mostly on terrestrial prey and that had, on average, higher trophic positions. Thus, direct consumption of aquatic inputs results in a trophic bypass that creates a shorter terrestrial food web and reduced biomagnification of MeHg across the food web. Our finding that MeHg was lower at terrestrial sites with aquatic inputs runs counter to the conventional wisdom that aquatic systems are a source of MeHg contamination to surrounding terrestrial ecosystems.

Decomposition Rates and Nutrient Contents of Arthropod Remains in Forest Litter

Article

Feb 1981

Decomposition rates and amounts of calcium, magnesium, potassium, and phosphorus were measured for dead millipedes and crickets buried in forest litter in North Carolina and Georgia. An average of 30% of the original mass of millipedes and 14% of the original mass of crickets was recovered after 1 yr in the litter. Elemental losses generally followed the pattern: K @> P > Mg > Ca; however, elemental amounts occasionally stabilized and in one experiment calcium increased in amount over time. Decomposition of arthropod carcasses was described by a two-component, negative exponential decay model. Decay coefficients were used with literature estimates of arthropod standing crops to estimate standing crops of mass and elements of arthropod remains in forest litter and soil. Estimates of standing crops of mass, calcium, and magnesium of arthropod remains were greater than those of living forest floor arthropods.

Terrestrial deposition of aquatic insects increases plant quality for insect herbivores and herbivore density

Article

Apr 2014
ECOL ENTOMOL

1. Mobile organisms such as emergent aquatic insects can subsidise land with aquatic nutrients, creating a link between terrestrial and aquatic ecosystems. 2. Deposition of aquatic insects on land produces bottom‐up effects in arthropod detritivore communities and may also affect plants and plant–herbivore interactions. 3. To investigate the effects of insect deposition on plant–herbivore interactions, we conducted a field experiment and surveys of tealeaf willow ( S alicaceae; Salix phylicifolia Coste) and J uly highflyer caterpillars ( G eometridae; Hydriomena furcata Thunberg) at lakes in N ortheast I celand with either high‐ or low‐midge density and deposition to land. 4. It was found that willow at high‐midge lakes had 8–11% higher nitrogen content compared with willow at low‐midge lakes. In addition, natural caterpillar density was 4–6 times higher and caterpillars were 72% heavier at high‐midge lakes than low‐midge lakes. 5. A fully reciprocal caterpillar transplant experiment among willow at high‐ and low‐midge lakes was performed to separate the influence of habitat and midge effects on caterpillar performance. 6. After transplant, pupae of J uly H ighflyer caterpillars were on average 11% heavier at high‐midge sites compared with low‐midge sites. However, this difference was not statistically significant. 7. The present findings indicate that cross‐ecosystem subsidies in the form of aquatic insects can increase plant foliar quality and the abundance of insect herbivores in recipient ecosystems.

Decomposition rates and nutrient contents of arthropod remains in forest litter

Article

Jan 1981

A meta-analysis of resource pulse-consumer interactions

Article

Feb 2010

Resource pulses are infrequent, large-magnitude, and short-duration events of increased resource availability. They include a diverse set of extreme events in a wide range of ecosystems, but identifying general patterns among the diversity of pulsed resource phenomena in nature remains an important challenge. Here we present a meta-analysis of resource pulse–consumer interactions that addresses four key questions: (1) Which characteristics of pulsed resources best predict their effects on consumers? (2) Which characteristics of consumers best predict their responses to resource pulses? (3) How do the effects of resource pulses differ in different ecosystems? (4) What are the indirect effects of resource pulses in communities? To investigate these questions, we built a data set of diverse pulsed resource–consumer interactions from around the world, developed metrics to compare the effects of resource pulses across disparate systems, and conducted multilevel regression analyses to examine the manner in which variation in the characteristics of resource pulse–consumer interactions affects important aspects of consumer responses. Resource pulse magnitude, resource trophic level, resource pulse duration, ecosystem type and subtype, consumer response mechanisms, and consumer body mass were found to be key explanatory factors predicting the magnitude, duration, and timing of consumer responses. Larger consumers showed more persistent responses to resource pulses, and reproductive responses were more persistent than aggregative responses. Aquatic systems showed shorter temporal lags between peaks of resource availability and consumer response compared to terrestrial systems, and temporal lags were also shorter for smaller consumers compared to larger consumers. The magnitude of consumer responses relative to their resource pulses was generally smaller for the direct consumers of primary resource pulses, compared to consumers at greater trophic distances from the initial resource pulse. In specific systems, this data set showed both attenuating and amplifying indirect effects. We consider the mechanistic processes behind these patterns and their implications for the ecology of resource pulses.

Herbivory makes major contributions to ecosystem carbon and nutrient cycling in tropical forests

Article

Dec 2013
ECOL LETT

The functional role of herbivores in tropical rainforests remains poorly understood. We quantified the magnitude of, and underlying controls on, carbon, nitrogen and phosphorus cycled by invertebrate herbivory along a 2800 m elevational gradient in the tropical Andes spanning 12°C mean annual temperature. We find, firstly, that leaf area loss is greater at warmer sites with lower foliar phosphorus, and secondly, that the estimated herbivore-mediated flux of foliar nitrogen and phosphorus from plants to soil via leaf area loss is similar to, or greater than, other major sources of these nutrients in tropical forests. Finally, we estimate that herbivores consume a significant portion of plant carbon, potentially causing major shifts in the pattern of plant and soil carbon cycling. We conclude that future shifts in herbivore abundance and activity as a result of environmental change could have major impacts on soil fertility and ecosystem carbon sequestration in tropical forests.

Biological-Control Herbivores May Increase Competitive Ability of the Noxious Weed Centaurea maculosa

Article

Jun 1999

The Magnitude of Global Insect Species Richness

Article

Sep 1991
CONSERV BIOL

Kevin J. Gaston

Recent suggestions that insects number tens of millions of species have received much attention. Little consideration, however, has been given to how such estimates compare with what else we know about insect species richness. Perhaps most significantly, the specialist knowledge of the taxonomic community at large has generally been ignored Collation of published and unpublished information from this source provides little to encourage belief in truly vast numbers of undescribed species of insects. For the insect groups for which figures are available, estimates of global total numbers of species are typically less than ten times the numbers of described species. Although minimum global estimates are more readily constructed than upper estimates, these figures uniformly fail to support assertions that there are 30 million or more species of insects. Rather, a figure of less than ten million seems more tenable, and one of around five million feasible. Additional, more circumstantial, evidence tends to support the idea that insect species numbers may not be as vast as has been claimed First, the contribution of canopy specialists to global richness may be less than often suggested. Second, a higher proportion of species than commonly entertained may have moderate to large geographic ranges. Third, the number of groups failing to increase in richness in the tropics may have been underestimated. Finally, the proportion of undescribed species encountered by many taxonomists seems insufficient to justify estimates of vast species numbers.

Forest canopy arthropods as sodium, potassium, magnesium and calcium pools in forests

Article

Dec 1983
FOREST ECOL MANAG

We measured concentrations of sodium, potassium, magnesium, and calcium in forest canopy arthropod functional groups collected from vegetation of clearcut and uncut hardwood forests at Coweeta Hydrologic Laboratory, North Carolina during 1977 and 1978. Functional groups differed significantly in concentrations of the four elements. Spiders had the significantly highest sodium concentrations, followed in decreasing order by some other predators and then herbivores. Caterpillars and sawfly larvae had the significantly highest potassium and magnesium concentrations and high calcium concentration. Detritivores had the significantly highest calcium concentrations. Our data indicate that nutrients contained in nominal biomass of canopy arthropods do not contribute significantly to litter nutrient pools.

The Influence of Arthropods on Ecosystems

Article

Mar 1984
BIOSCIENCE

Arthropod interactions with plants and microbes influence the amounts of living and dead organic matter and transfers of nutrients in terrestrial ecosystems. Arthropods in the canopy have their greatest effect on mobile elements such as potassium, whereas soil detritivores influence mineralization rates of less mobile elements such as nitrogen, phosphorus, and calcium. Nominal (baseline) herbivory and detritivory combine to speed nutrient cycling and reduce standing crops of decaying plant materials. 49 references, 1 figure, 3 tables.

Moth herbivory enhances resource turnover in subarctic mountain birch forests?

Article

Feb 2013

Massive moth outbreaks cause large-scale damage in subarctic mountain birch forests with a concomitant decrease in carbon flux to mycorrhizal fungi and an increased deposition of dissolved carbon and nutrients as moth frass into soil. We investigated impacts of moth herbivory along three replicated gradients with three levels of moth herbivory (undamaged, once damaged, repeatedly damaged) on soil nutrient levels and biological parameters. We found an increase in soil nutrients and in the biomass of enchytraeid worms, which are key faunal decomposers. Fungi bacteria ratio and C:N ratio decreased in humus with increasing severity of herbivory. Our findings suggest enhanced resource turnover in mountain birch forests due to massive moth herbivory. This may provide a shortcut for carbon and nutrient input to subarctic soils, which largely bypasses the main routes of carbon from plants to soil via mycorrhizal and litter-decomposing fungi. Moreover, a temporal shift occurs in carbon allocation to soil, providing decomposers an opportunity to use an early-season peak in resource availability. Our results suggest a hitherto unappreciated role of massive insect herbivore attacks on resource dynamics in subarctic ecosystems.

Phytophagous Insects as Regulators of Forest Primary Production

Article

Oct 1975

Lake-derived midges increase abundance of shoreline terrestrial arthropods

Article

Nov 2011
OIKOS

Aquatic insects link adjacent ecosystems by transporting nutrients, energy, and material as they move from bodies of water into terrestrial habitats. Insects emerging from streams and rivers are known to benefit arthropod predators such as spiders, but their influence may extend to other arthropod feeding groups as well. We conducted a terrestrial arthropod survey at a series of lakes spanning a strong gradient of midge (Chironomidae, Diptera) emergence. These small, short-lived insects reach high densities in some areas such that their carcasses litter the ground, and serve as a potential resource for non-predatory arthropods. Our study revealed that arthropod assemblages in areas of high midge density were significantly different from those with few midges, the result of an increase of all taxa rather than changes in taxonomic composition. Eight of nine terrestrial arthropod taxa sampled showed a strong positive response to the presence of midges including detritivores and herbivores in addition to predators. Taxa that could consume living or dead midges directly responded especially strongly to midge gradients. Our results strongly suggest that midges enter the terrestrial arthropod food web through multiple pathways, increasing numbers of a wide range of arthropods. Furthermore, they emphasize the importance of lakes as sources of aquatic insects that significantly alter processes in the neighboring terrestrial environment.

Top predator control of plant biodiversity and productivity in an old-field ecosystem

Article

Jan 2003
ECOL LETT

Oswald J Schmitz

Abstract Predators can have strong indirect effects on plants by altering the way herbivores impact plants. Yet, many current evaluations of plant species diversity and ecosystem function ignore the effects of predators and focus directly on the plant trophic level. This report presents results of a 3-year field experiment in a temperate old-field ecosystem that excluded either predators, or predators and herbivores and evaluated the consequence of those manipulations on plant species diversity (richness and evenness) and plant productivity. Sustained predator and predator and herbivore exclusion resulted in lower plant species evenness and higher plant biomass production than control field plots representing the intact natural ecosystem. Predators had this diversity-enhancing effect on plants by causing herbivores to suppress the abundance of a competitively dominant plant species that offered herbivores a refuge from predation risk.

Indirect effect of aquatic insect emergence on a terrestrial insect population through by birds predation

Article

May 2002
ECOL LETT

A manipulative field experiment was performed to determine the effect of birds, subsidized by aquatic insect emergence, on the insect herbivores in a riparian deciduous forest. Insectivorous birds were observed more frequently in the riparian forest than in upland forest away from the stream, utilizing both herbivorous insects feeding on the riparian vegetation and aquatic insects emerging from the stream as their prey. Field experiments revealed that the insect herbivore population in the riparian forest was more depressed by bird predation than that in the upland forest. This suggests that allochthonous prey input to the in situ prey population was responsible for a modification in the interaction between birds and herbivorous insects, resulting in a heterogeneous food web structure in the forest.

Insect population dynamics meets ecosystem ecology: Effects of herbivory on soil nutrient dynamics

Article

May 2001

Mark D Hunter

Genetic‐based plant resistance and susceptibility traits to herbivory influence needle and root litter nutrient dynamics

Article

Sep 2007
J ECOL

1. It is generally assumed that the same factors drive the decomposition of both litter and roots and that nutrient release from litter and roots is synchronized. However, few studies have explicitly tested these assumptions, and no studies have examined whether plant genetics (i.e. plant susceptibility to herbivory) could affect these relationships. 2. Here we examine the effects of herbivore susceptibility and resistance on needle and fine root litter decomposition of pinon pine, Pinus edulis. The study population consists of individual trees that are either susceptible or resistant to herbivory by the pinon needle scale, Matsucoccus acalyptus, or the stem-boring moth, Dioryctria albovittella. Genetic analyses and long-term experimental removals and additions of these insects to individual trees have identified trees that are naturally resistant or susceptible to M. acalyptus and D. albovittella. In addition, these herbivores increase litter chemical quality and alter soil microclimate, both of which mediate decomposition in ecosystems. 3. The effects of herbivore susceptibility and resistance on needle litter mass and phosphorus (P) loss, when significant, are largely mediated by herbivore-induced changes to microclimate. But the effects of herbivore susceptibility and resistance on root litter nitrogen (N) and P retention, and needle litter N retention, are largely governed by herbivore-induced changes to litter chemical quality. Whether a particular tree was resistant or susceptible to herbivores exerted a large influence on net nutrient release, but the direction of herbivore influence varied temporally. 4. The controls on decomposition vary between herbivore-susceptible and herbivore-resistant phenotypes. This suggests that understanding decomposition and nutrient retention in some ecosystems may require considering the effects of herbivores on above- and below-ground processes and how these effects may be governed by plant genetics. 5. Synthesis. Because so few studies have attempted to quantify genetic components of ecosystem processes, the integration of ecosystem ecology with population genetics has the potential to place ecosystem science within a genetic and evolutionary framework. Using field trials of known genetic composition, ecosystem scientists may use quantitative genetics techniques to explore ecosystem traits just as population geneticists have used these techniques to explore traditional traits such as resistance to insects.

Effects of a massive swarm of ants on ammonium concentration in a subalpine lake

Article

Apr 1984

On two occasions in August 1979, massive aerial swarms of Lasius alienus (Foerster) (Hymenoptera: Formicidae) occurred over Castle Lake, California. Each event resulted in the delivery of millions of ants to the lake surface. Consumption and subsequent excretion by fish, in addition to direct release from ants, produced a brief, but marked increase in water column ammonium levels. Castle Lake phytoplankton are often nitrogen limited and possess a high affinity for ammonium. The events and effects are described and discussed with respect to nutrient limitation in an unproductive ecosystem.

Species shift drives decomposition rates following invasion by hemlock woolly adelgid

Article

Aug 2010

Richard C Cobb

Insect and disease outbreak is an important cause of selective species removal and accompanying functional change in North American forests. Outbreak of hemlock woolly adelgid, Adelgies tsugae HWA, is causing selective removal of eastern hemlock Tsuga canadensis at a regional scale. Impacts of outbreak-caused canopy mortality and shifts in dominant species on litter decay were compared across sites that range in HWA-caused canopy damage and subsequent canopy dominance by black birch Betula lenta. Senescent litter from eastern hemlock, black birch, and equal litter mixes were decomposed in the field for 36 months within nine sites in Connecticut and Massachusetts USA. Mass loss and % N accumulation of black birch was 65% and 52% greater compared to eastern hemlock. In contrast, outbreak related canopy damage increased litter mass loss by 11.5% in high mortality stands relative to uninfested stands but canopy damage had no impact on % N dynamics. Non-additive effects of litter mixing influenced chemical dynamics of decaying litter; black birch accumulated less N and eastern hemlock accumulated more N compared to each species decaying alone. However, these changes offset and mixed litter bags overall showed no differences in N dynamics compared to values from each species decaying alone. In eastern hemlock stands invaded by hemlock woolly adelgid, canopy damage influences the rates and dynamics of decay but species differences between hemlock and black birch leaf litter are the dominant mechanisms of decomposition changes and a long-lasting driver of increased N cycling rates. Species shifts may be the dominant driver of altered ecosystem processes for other insect outbreaks, particularly when replacement species have very different characteristics regulating decomposition and N cycling.

Carbon and nitrogen mineralization from decomposing Gypsy moth frass

Article

Oct 1995

Defoliation of forests by insects is often assumed to produce a pulse of available nitrogen (N) from the decomposition of frass pellets. In this study we measured rates of carbon (C) and N mineralization from gypsy moth frass incubated with and without soil, and for soil alone. Incubations were at constant temperature and soil moisture conditions and lasted for 120 days. We found that gypsy moth frass contains much labile C as well as extractable N, and that the stimulation of microbial growth by the labile C results in immobilization of essentially all of the extractable N in the frass. The response of the microbes is fast, beginning within 1 day and lasting at least 90 days. This immobilization response represents an efficient mechanism for conserving N within a forest ecosystem after a defoliation event.

Herbivory and the cycling of nitrogen and phosphorus in isolated California oak Trees

Article

Sep 1986

David Y. Hollinger

Nitrogen and phosphorus flow in litterfall and throughfall were studied in two California Quercus species (the evergreen Q. agrifolia and deciduous Q. lobata) before, during, and after an outbreak of the California oak moth, Phryganidia californica. All of the foliage of both oak species was removed by the herbivore during the course of this outbreak. During the outbreak, total N and P flow to the ground more than doubled from Q. agrifolia and increased to a lesser extent from Q. lobata over the previous year. The composition of the litter during the outbreak year shifted so that in Q. agrifolia, almost 70% of the total N and P flow to the ground moved through frass and insect remains, while in Q. lobata, approximately 60% of the N and 40% of the P moved through frass and insect remains. Short-term leaching experiments showed that nitrogen was far more rapidly lost from Phryganidia frass than from leaf litter of either species. These results and the relative frequency of Phryganidia outbreaks suggest that this herbivore has significant effects on the nutrient cycling beneath these trees.

Insects as drivers of ecosystem processes

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