Marcel Dicke

Wageningen University & Research | WUR · Department of Entomology

Rapid systemic signals travel within the first seconds and minutes after herbivore infestation to mount defense responses in distal tissues. Recent studies have revealed that wound-induced hydraulic pressure changes play an important role in systemic electrical signaling and subsequent calcium and reactive oxygen species waves. These insights raise...

With climate change, the occurrence of extreme weather events such as heatwaves is expected to increase. Extreme temperature events are short periods of high temperature (i.e., >95th percentile of temperature distribution), and their occurrences are difficult to predict. These extreme temperature events pose great challenges to living organisms, es...

Plants face attackers above and belowground. Insect root herbivores can lead to severe crop losses, yet the underlying transcriptomic responses have rarely been studied. We studied the dynamics of the transcriptomic response of Brussels sprouts (Brassica oleracea var. gemmifera) primary roots to feeding damage by cabbage root fly larvae (Delia radi...

During the last decade the potential of insects for human nutritional protein is increasingly recognised. Direct consumption of insects contributes to a reduction of the ecological footprint of human food production and is claimed to have health benefits. An alternative is feeding poultry (broilers and layers) with insect-derived protein. This offe...

Plants developing into the flowering stage undergo major physiological changes. Because flowers are reproductive tissues and resource sinks, strategies to defend them may differ from those for leaves. Thus, this study investigates defences of flowering plants by assessing processes that sustain resistance (constitutive and induced) and tolerance to...

Saprophagous fly larvae interact with a rich community of bacteria in decomposing organic matter. Larvae of some species, such as the black soldier fly, can process a wide range of organic residual streams into edible insect biomass and thus produce protein as a sustainable component of livestock feed. The microbiological safety of the insects and...

The larvae of insect herbivores feed on plants that may vary nutritionally (qualitatively and/or quantitatively) over the course of insect development. Plant quality may change in response to interactions with the biotic environment that in turn may affect development and biomass of the insects feeding on these plants. However, the larvae of many g...

Thrips (Thysanoptera: Thripidae) are major pests in horticulture worldwide. Longstanding biological control strategies that have been developed for flower thrips such as Frankliniella occidentalis (Pergande) are being disrupted by the recent introduction of leaf-inhabiting thrips such as Echinothrips americanus Morgan and Thrips setosus Moulton in...

The COVID-19 pandemic has illustrated the need for the development of fast and reliable testing methods for novel, zoonotic, viral diseases in both humans and animals. Pathologies lead to detectable changes in the volatile organic compound (VOC) profile of animals, which can be monitored, thus allowing the development of a rapid VOC-based test. In...

Honeydew is the sugar-rich excretion of phloem-feeding hemipteran insects such as aphids, mealybugs, whiteflies, and psyllids, and can be a main carbohydrate source for beneficial insects in some ecosystems. Recent research has revealed that water-soluble, systemic insecticides contaminate honeydew excreted by hemipterans that feed on plants treate...

Many studies in the last decades addressed the antifeedant and repellent effects of neem (Azadirachta indica)-based pesticides on arthropod herbivores with azadirachtin as the leading active ingredient. However, results for aphids regarding repellence and feeding were often contradictory and mainly based on laboratory studies with self-made neem ex...

Rearing insects for food and feed is a rapidly growing industry, because it provides excellent opportunities for a sustainable approach to animal protein production. Two fly species, the black soldier fly (BSF) and the house fly (HF), naturally live in decaying organic matter (e.g. compost), and can thus be effectively reared on organic rest stream...

Beneficial soil microorganisms can contribute to biocontrol of plant pests and diseases, induce systemic resistance (ISR) against attackers, and enhance crop yield. Using organic soil amendments has been suggested to stimulate the abundance and/or activity of beneficial indigenous microbes in the soil. Residual streams from insect farming (frass an...

Plants interact with a diversity of phytophagous insects above- and belowground. By inducing plant defence, one insect herbivore species can antagonize or facilitate other herbivore species feeding on the same plant, even when they are separated in space and time. Through systemic plant-mediated interactions, leaf-chewing herbivores may affect the...

Biological control (biocontrol) of crop pests is a sustainable alternative to the use of biodiversity and organismal health harming chemical pesticides. Aphids can be biologically controlled with parasitoid wasps, however, variable results of parasitoid‐based aphid biocontrol in greenhouses are reported. Aphids may display genetically encoded (endo...

Many insect herbivores engage in apparent competition whereby two species interact through shared natural enemies. Upon insect attack, plants release volatile blends that attract natural enemies, but whether these volatiles mediate apparent competition between herbivores is not yet known. We investigate the role of volatiles that are emitted by bea...

Changing the spectral composition of light has numerous advantages for the production and quality of horticultural crops. However, changing the light spectrum to stimulate growth can have negative consequences for plant responses to biotic stress. Especially changes in the ratio between red and far-red light (R:FR) have an important effect on plant...

The Dutch Minister of Agriculture aims to shift the focus of the Netherlands as exporter of goods to exporting knowledge and experience. The aim is also to contribute internationally to “building back better”. Proteins from fish are very important to the health of especially poor people. Moreover, it is important to exploit organic residual streams...

Natural insecticides often do not provide a strong knock-down effect and have a lower efficacy than synthetic pesticides. For an effective application of natural insecticides, it is essential to know the product’s mode of action in detail. The efficacy of the commercial neem [Azadirachta indica A. Juss (Sapindales)] product NeemAzal-T/S and its inf...

Terpenoids play important roles in flavour, pollinator attraction and defence of plants. In cucumber (Cucumis sativus) they are important components of the herbivore‐induced plant volatile blend that attracts natural enemies of herbivores. We annotated the cucumber TERPENE SYNTHASE gene (CsTPS) family and characterized their involvement in the resp...

The phenotypic plasticity of flowering plants in response to herbivore damage to vegetative tissues can affect plant interactions with flower‐feeding organisms. Such induced systemic responses are probably regulated by defence‐related phytohormones that signal flowers to alter secondary chemistry that affects resistance to florivores. Current knowl...

The COVID19 pandemic has illustrated the need for the development of fast and reliable testing methods for novel, zoonotic, viral diseases in both humans and animals. Pathologies lead to detectable changes in the Volatile Organic Compound (VOC) profile of animals, which can be monitored, thus allowing the development of a rapid VOC-based test. In t...

Background The microbiome of many insects consists of a diverse community of microorganisms that can play critical roles in the functioning and overall health of their hosts. Although the microbial communities of insects have been studied thoroughly over the past decade, little is still known about how biotic interactions affect the microbial commu...

Invasive alien species have environmental, economic and social impacts, disproportionally threatening livelihood and food security of smallholder farmers in low-and medium-income countries. Fall armyworm (FAW) (Spodoptera frugiperda), an invasive insect pest from the Americas, causes considerable losses on maize to smallholder farmers in Africa sin...

Plant‐soil feedback (PSF) may influence plant‐insect interactions. Although plant defense differs between shoot and root tissues, few studies have examined root‐feeding insect herbivores in a PSF context. We examined here how plant growth and resistance against root‐feeding Delia radicum larvae was influenced by PSF. We conditioned soil with cabbag...

There is increasing awareness that interactions between plants and insects can be mediated by microbial symbionts. Nonetheless, evidence showing that symbionts associated with organisms beyond the second trophic level affect plant-insect interactions are restricted to a few cases belonging to parasitoid-associated bracoviruses. Insect parasitoids h...

Plants are members of complex communities of which arthropods are the most speciose members. The role of carnivores in shaping the outcome of multi‐trophic interactions by top‐down control of herbivores has been well studied. Particularly, the positive impacts of natural enemies of herbivores on plants through direct (consumptive) and indirect (non...

Seed coating (‘seed treatment’) is the leading delivery method of neonicotinoid insecticides in major crops such as soybean, wheat, cotton and maize. However, this prophylactic use of neonicotinoids is widely discussed from the standpoint of environmental costs. Growing soybean plants from neonicotinoid-coated seeds in field, we demonstrate that so...

Worldwide, French beans (Phaseolus vulgaris L.), tomato (Solanum lycopersicum L.), and kales (Brassica oleracea L. var. acephala) are considered economically important food crops. There is a rapid decline in their yield due to severe soil degradation. Thus, high commercial fertilizer inputs are crucial, though they remain expensive and inaccessible...

The acceptance of eco-friendly black soldier fly larvae meal (BSFLM) as sustainable alternative protein ingredient in poultry feeds continues to gain momentum worldwide. This study evaluates the impact of BSFLM in layer chick and grower diets on the growth, carcass quality and economic returns. Mean weekly weight gain and total live weight per chic...

Resistance (R) genes usually compete in a coevolutionary arms race with reciprocal effectors to confer strain‐specific resistance to pathogens or herbivorous insects. Here, we investigate the specificity of SLI1, a recently identified R gene in Arabidopsis that encodes a small heat shock‐like protein involved in resistance to Myzus persicae aphids....

Larvae of the black soldier fly (BSF) can be used to convert organic waste into insect biomass for animal feed. In this process, they interact with microorganisms originating from the substrate, the insect, and the environment. The substrate is the main determinant of the larval gut microbiota composition, but inoculation of the substrate with egg-...

Larvae of the black soldier fly (BSF) can be used to convert organic waste into insect biomass for animal feed. In this process, they interact with microorganisms originating from the substrate, the insect, and the environment. The substrate is the main determinant of the larval gut microbiota composition, but inoculation of the substrate with egg-...

Using black soldier fly (BSF, Hermetia illucens) larvae as a novel protein source substituting fishmeal (FM) in animal feeds is globally gaining momentum. BSF can be reared on agro-industrial residues. However, incorporating BSF larval meal (BSFLM) into finisher pig diets has received inadequate attention. This study evaluated the effects of replac...

Insects have tremendous potential for utilising the waste generated from other agricultural sectors to produce high value protein. The by-product of insect production, insect waste streams, can be recycled and repurposed for promoting the health of crops and soil as the chitin, present in the moulted skins, acts as a substrate for beneficial microb...

Plants in the flowering stage need to ensure reproduction by protecting themselves from attack and by preserving interactions with mutualist pollinators. When different plant mutualists are using the same type of cues, such as volatile compounds, attraction of parasitoids and pollinators may trade off. To explore this, we compared volatile emission...

Plants are often attacked by multiple insect herbivores. How plants deal with an increasing richness of attackers from a single or multiple feeding guilds is poorly understood. We subjected black mustard (Brassica nigra) plants to 51 treatments representing attack by an increasing species richness (1, 2 or 4 species) of either phloem feeders, leaf...

One of the most studied and best-known mutualistic relationships between insects is that between ants and phloem-feeding insects. Ants feed on honeydew excreted by phloem-feeding insects and, in exchange, attack the phloem feeders' natural enemies, including parasitic wasps. However, parasitic wasps are under selection to exploit information on haz...

Onder de grond vindt een levendige conversatie plaats. Tussen plant en micro-organismen, nuttig of schadelijk. Tussen micro-organismen onderling. Het communicatiemiddel bestaat voor een belangrijk deel uit vluchtige stoffen. Een beter begrip daarvan maakt het op termijn mogelijk gericht te verdelen of wellicht de teelt aan te passen. Onderzoek op d...

This report presents the results of a research project that analyzes the feasibility of learning from experiences of the Kenyan productive peasant developments in farming insect for animal feed to develop insect farming in Colombia, specifically to foster the current reincorporation process of ex-insurgents. The research, carried out by scientists...

Light spectral composition influences plant growth and metabolism, and has important consequences for interactions with plant-feeding arthropods and their natural enemies. In greenhouse horticulture, light spectral composition can be precisely manipulated by light-emitting diodes (LEDs), and LEDs are already used to optimize crop production and qua...

Purpose The Farmer Field School (FFS) has been used to enable farmers to adapt their farming decisions according to the field situation. This paper explores the methodological state, challenges and lessons learned, of the FFS around the World. Design/methodology/approach We used a 52-item questionnaire to capture issues of design, implementation a...

Reliance on broad-spectrum insecticides and chemotherapeutic agents to control hematophagous insect vectors, and their related diseases is threatened by increasing insecticide and drug resistance, respectively. Thus, development of novel, alternative, complementary and effective technologies for surveillance and control of such insects is strongly...

Plant growth-promoting rhizobacteria (PGPR) can enhance plant growth and defence. Via plant-mediated effects, PGPR have been reported to impact the performance of generalist leaf-chewing insects either negatively or positively. However, only a few insect species, mainly feeding on aboveground tissues, have thus far been investigated. Here, we inves...

Vector control is an important component of the interventions aimed at mosquito-borne disease control. Current and future mosquito control strategies are likely to rely largely on the understanding of the behavior of the vector, by exploiting mosquito biology and behavior, while using cost-effective, carefully timed larvicidal and high-impact, low-...

The growing human population, changing dietary habits and intensifying competition between food and feed production underline the urgent need to explore novel sustainable production chains. In the past, the poultry sector has gained popularity due to its superior environmental and economic benefits comared to other livestock production systems. The...

De duurzaamheid van de huidige vleesproductie staat ter discussie door het beslag op het landbouwareaal, gebruik van water, de uitstoot van broeikasgassen en de verzuring van het milieu. De productie van insecten als voedsel en veevoer is voor deze vier aspecten duurzamer per kilogram eiwit dan de productie van andere dierlijke eiwitten.

1. Plants interact with various organisms, aboveground as well as below-ground. Such interactions result in changes in plant traits with consequences for members of the plant-associated community at different trophic levels. Research thus far focussed on interactions of plants with individual species. However, studying such interactions in a commun...

1. Soil is a diverse and heterogeneous environment where chemicals mediate numerous interactions between soil organisms and plants. To date, studies have extensively addressed volatile‐mediated interactions between soil microorganisms and the effects of microbial volatiles on plant growth. Yet, to our knowledge, it remains to be explored whether vo...

Volatiles play major roles in mediating ecological interactions between soil (micro) organisms and plants. It is well-established that microbial volatiles can increase root biomass and lateral root formation. To date, however, it is unknown whether microbial volatiles can affect directional root growth. Here, we present a novel method to study belo...

Protein (P) and carbohydrate (C) concentrations present in food affect larval performance, larval body nutrient concentration, and fecundity of the black soldier fly (BSF). We substantially expanded the range of dietary P- and C-concentrations investigated thus far to assess the effects of nutritionally – unbalanced diets on BSF larval and adult li...

The oilseed crops Crambe abyssinica and Camelina sativa produce oils rich in erucic acid and n-3 polyunsaturated fatty acids (PUFA), respectively. After pressing the oil, a seed cake remains as a protein-rich by-product. Edible insects may convert this seed press cake and the defatted seed meal produced from it into insect biomass suitable for anim...

The use of some systemic insecticides has been banned in Europe because they are toxic to beneficial insects when these feed on nectar. A recent study shows that systemic insecticides can also kill beneficial insects when they feed on honeydew. Honeydew is the sugar-rich excretion of hemipterans and is the most abundant carbohydrate source for bene...

Biological control is widely successful at controlling pests, but effective biocontrol agents are now more difficult to import from countries of origin due to more restrictive international trade laws (the Nagoya Protocol). Coupled with increasing demand, the efficacy of existing and new biocontrol agents needs to be improved with genetic and genom...