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Life Cycle Ecophysiology of Osmia Mason Bees Used as Crop Pollinators
Abstract
Several solitary bee species in the genus Osmia have been studied as potential pollinators of fruit trees and other early-blooming crops. Methods to manage large populations in agro-ecosystems have been developed for at least three species. This chapter reviews current knowledge on the life cycle of Osmia and emphasizes the need to establish a solid ecophysiological basis to develop adequate rearing methods for these species. Two phenological events - the timing of adult diapause in the autumn, and the timing of emergence in the spring - require particular attention when managing Osmia populations. The timing of adult diapause is critical because prewintering temperatures have a profound effect on fat body depletion, winter survival, and vigor at emergence. Timing of emergence and its synchronization with bloom of the target crop is important to maximize pollination and production of bee progeny. Both events can be adjusted with proper temperature management.
... The red mason bee, O. bicornis L. (Megachilidae), is a solitary bee nesting in existing aboveground cavities and a native to Europe (Bosch et al., 2008). During its flying season in early to mid-spring, the species collects pollen and nectar from a range of flowering plants. ...
... In semifield studies, different timings of application (relative to the bees' average emergence date) can have impacts on observed effects because the postemergent life span of the females is an important factor in the bees' overall reproductive output. Species differ in their variability in emergence timing within a population, from highly synchronized species, for instance, O. bicornis, to bees with longer time windows during which emergence occurs, for instance, E. pruinosa (Bosch et al., 2008;Hurd et al., 1974). To illustrate the interaction between application timing and population-level effects, we tested three temporal scenarios with SolBeePop ecotox : (1) average female emergence occurring 10 days prior to application, which corresponds approximately to the 2019 and 2021 O. bicornis semifield studies, (2) average female emergence 17 days prior to application, and (3) 3 days prior to application ( Table 3). ...
... Eucera pruinosa was assumed with a maturation time of 4 days (Willis Chan et al., 2019) and an extended time period of female emergence, resulting in sizeable brood production prior to application and female emergence and brood production after application. In contrast, O. bicornis has an extended time period of maturation (9 days, calibrated to the 2021 semifield study data and in line with reported maturation times of multiple days [Bosch et al., 2008]). At time of application, the bees had just begun nesting, with only a few brood cells produced. ...
In agricultural landscapes, solitary bees occur in a large diversity of species and are important for crop and wildflower pollination. They are distinguished from honey bees and bumble bees by their solitary lifestyle as well as different nesting strategies, phenologies, and floral preferences. Their ecological traits and presence in agricultural landscapes imply potential exposure to pesticides and suggest a need to conduct ecological risk assessments for solitary bees. However, assessing risks to the large diversity of managed and wild bees across landscapes and regions poses a formidable challenge. Population models provide tools to estimate potential population-level effects of pesticide exposures , can support field study design and interpretation, and can be applied to expand study data to untested conditions. We present a population model for solitary bees, SolBeePop ecotox , developed for use in the context of ecological risk assessments. The trait-based model extends a previous version with the explicit representation of exposures to pesticides from relevant routes. Effects are implemented in the model using a simplified toxicokinetic-toxicodynamic model, BeeGUTS (GUTS = generalized unified threshold model for survival), adapted specifically for bees. We evaluated the model with data from semifield studies conducted with the red mason bee, Osmia bicornis, in which bees were foraging in tunnels over control and insecticide-treated oilseed rape fields. We extended the simulations to capture hypothetical semifield studies with two soil-nesting species, Nomia melanderi and Eucera pruinosa, which are difficult to test in empirical studies. The model provides a versatile tool for higher-tier risk assessments, for instance, to estimate effects of potential exposures, expanding available study data to untested species, environmental conditions, or exposure scenarios. Environ Toxicol Chem 2024;00:1-17. © 2024 SETAC
... Phenological differences, such as emergence timing, can be assumed to have a genetic basis if responding to climate in a different manner under the same climactic conditions. These populations can undergo local selection when responding to changes in natal climatic conditions (Bosch et al., 2008). When bees are translocated to a warmer climate or used for orchard pollination earlier than their natural phenology, high mortality occurs if bees are not managed under artificial conditions (i.e., removed from the field and stored in a climate-controlled shed or refrigeration unit). ...
... At the end of 2 weeks, bees were placed at a winter storage temperature of 4-5°C where they remained until the following spring Kemp, 2000, 2001). These management steps were made to avoid an excessively long (>45 days) pre-wintering period, which can cause high winter and pre-emergence mortality (Bosch and Kemp, 2004;Bosch et al., 2008). As possible, UT and WA bees for the constant treatment remained in the same incubator. ...
... Managing bees via artificial conditions to time their release for commercial pollination is thought to be more effective than allowing for natural emergence (Bosch and Blas, 1994;Bosch et al., , 2008. In our study, the use of a constant thermal regimen for both an early and late cherry bloom event resulted in synchronous and quick bee emergence from cocoons. ...
Introduction
The blue orchard bee, Osmia lignaria, is a widespread North American native pollinator that can be employed for commercial fruit and nut crop production. The largest supplies of these bees are collected in the wildlands ssssof Utah and Washington, United States. How O. lignaria from different geographic regions respond to current recommended management practices or translocation to novel environments is not fully understood.
Methods
Utah- and Washington-originated O. lignaria were reared in laboratory incubators under two thermal regimens: (1) constant temperatures used to manage bees through immature development, adult winter dormancy, and for spring emergence, and (2) hourly fluctuating temperatures programmed to mimic the natural daily (24 h) thermal cycles of the nearest cherry orchard growing region through their life cycles.
Results
In comparison to rearing bees at orchard temperatures, we found that rearing bees at a constant temperature increased survival and shortened egg–adult development periods. Washington bees were more adversely affected by the consistent warm rearing temperatures than were Utah bees, possibly due to their adaptations to Washington’s relatively moderate climate. At orchard temperatures, Utah bees suffered high prepupal and pupal mortality, while Washington bees suffered high pupal and adult mortality. These late life stages coincided with the hottest maximum temperatures in their respective thermal regimens. Adult females from both states naturally emerged in synchrony with local bloom time, but their emergence period overall was prolonged compared to bees in the constant thermal regimen that were induced to emerge at orchard bloom times.
Discussion
Our data support that bees originating from cool montane habitats of different U.S. states suffer from the warmer climatic conditions at lower altitudes of their respective crop-growing regions. A better understanding of optimal management temperatures for O. lignaria from different geographic regions and the effect of bee origin and temperature on survival and development timing is needed for best managing these pollinators when they are translocated or when climate change results in increased temperatures during bee development periods.
... In many cases, solitary species are only active during a few weeks of the year, and their cocooned offspring remain dormant in the nest until the following nesting season. Reproductive solitary females may produce less than one to several eggs/d compared with >1000 eggs/d laid by honey bee queens (Winston 1987;Michener 2007;Bosch et al. 2008). The variety of phenotypic or ecological characteristics (traits) of these many species may result in differences in sensitivity and exposure routes of non-Apis bees in comparison with honey bees (Rubach et al. 2011;Hinarejos et al. 2019;Uhl and Brühl 2019). ...
... Each egg with its provision is sealed in an individual cell within a nest (Michener 2007). The 4 species of Osmia nest above ground in existing cavities, for example, hollow plant stems, and use soil or mud to cap each cell and the end of the nest (Bosch et al. 2001(Bosch et al. , 2008. Megachile rotundata (a leaf-cutting bee) lines each of many nest cells with leaf pieces before filling it with provision; each cell and nest is capped with leaf discs (Tasei and Masure 1978;Kemp and Bosch 2000;Gemmill-Herren and Strohm 2014). ...
... Values were compiled from multiple sources that reflect different study locations and designs. For instance, the larval development time strongly depends on temperature, resulting in potentially very different development times under controlled conditions in the laboratory compared with field conditions (Kemp and Bosch 2000;Bosch et al. 2008). The vulnerability concept assumes a linear relationship between trait values and vulnerability, but this may not hold for all traits. ...
In many countries, the Western honey bee is used as surrogate in pesticide risk assessments for bees. However, uncertainty remains in the estimation of pesticide risk to non-Apis bees because their potential routes of exposure to pesticides, life histories, and ecologies differ from honey bees. We applied the vulnerability concept in pesticide risk assessment to 10 bee species including the honey bee, two bumble bee species, and seven solitary bee species with different nesting strategies. The trait-based vulnerability considers the evaluation of a species both at the level of the organism (exposure and effect) and the population (recovery) that goes beyond the sensitivity of individuals to a toxicant assessed in standard laboratory toxicity studies by including effects on populations in the field. Based on expert judgement, each trait was classified by its relationship to the vulnerability to pesticide exposure, effects (intrinsic sensitivity), and population recovery. The results suggested that the non-Apis bees included in our approach are potentially more vulnerable to pesticides than the honey bee due to traits governing exposure and population recovery potential. Our analysis highlights many uncertainties related to the interaction between bee ecology and the potential exposures and population-level effects of pesticides, emphasizing the need for more research to identify suitable surrogate species for higher-tier bee risk assessments. This article is protected by copyright. All rights reserved.
... In fact, several Osmia species are currently reared and managed as crop pollinators in Europe, the US, and Asia (Bosch and Kemp, 2002). The developmental biology of the mason bees is well known and appropriate rearing methods and management systems have been established (Bosch et al., 2008). All species of the genus Osmia are solitary bees (Hymenoptera, Megachilidae) with a Holarctic distribution . ...
... Osmia bicornis L.) and Osmia cornuta (Latr.), have been used as pollinators in several fruit crops (apple, pear, almond) and in caged Brassicaceae for seed production (Bosch et al., 2008). Species of the genus Osmia have already been used in ecotoxicological studies and some protocols are available in literature (e.g. ...
... After mating, females start nesting in pre-established cavities. In the cavities, the females build a series of cells separated with mud partitions (Bosch et al., 2008). Each cell is provided with a mass of pollen and nectar, on top of which an egg is deposited. ...
In this paper we assessed, under laboratory conditions, the toxicity of an active substance on solitary bee larvae of Osmia cornuta (Hymenoptera: Megachilidae). A field-realistic dose of the systemic insecticide spirotetramat was applied to the mass provisions. The insecticide’s effects on several life-cycle parameters were studied in males and females. Our results showed a significantly shorter post-emergence longevity in bees exposed to spirotetramat during the larval stage, compared to the control. The observed reduction in longevity was 18 and 15%, respectively, in males and females. Mortality rate and other biological traits (larval and spinning duration, emergence time, food/body conversion rate) did not show significant differences between the two treatments. The method described in this study can be used to test the effects of toxic substances (i.e. agrochemicals) on bees. Moreover, it can constitute a basis for the development of a standardised protocol in the first tier of the Environmental Risk Assessment for solitary bees.
... Likewise, solitary bees that are managed for springtime pollination sometimes are forced to emerge early from winter diapause, in their case by means of prescribed overwintering and incubation protocols. Management protocols use thermal regulation for solitary bees to time bee emergence with the seasonal availability of bloom (Bosch et al., 2008). Additionally, weather conditions must be favorable for bees to fly in search of mates, food, and nesting sites; later, favorable conditions are needed for progeny to fully develop within appropriate seasonal timeframes (Bosch et al., 2008, 2010). ...
... Management protocols use thermal regulation for solitary bees to time bee emergence with the seasonal availability of bloom (Bosch et al., 2008). Additionally, weather conditions must be favorable for bees to fly in search of mates, food, and nesting sites; later, favorable conditions are needed for progeny to fully develop within appropriate seasonal timeframes (Bosch et al., 2008, 2010). Lastly, recent climate changes are fostering earlier springs and later autumns, which may desynchronize insects and hosts, or plants and pollinators , due to mismatched physiological responses to environmental cues (e.g., day length, temperature, etc.). ...
... The duration of the prepupal stage was shown to directly affect the timing of adult eclosion. In addition, the time spent as a metabolically active adult in the cocoon prior to wintering was found to affect subsequent spring survival, emergence timing, and synchronization of emergence (Bosch et al., 2008). Prolonged adult exposure to warm fall temperatures continued the bees' metabolic activity, depleted lipid reserves, and diminished survival and adult performance (Sgolastra et al., 2011), which are consequences that underscore the need to better understand phenotypic variation in prepupal duration and adult eclosion under natural circumstances. ...
The blue orchard bee, Osmia lignaria, is a solitary cavity-nesting bee and effective pollinator of fruit trees. To acquire stocks of O. lignaria for pollination, trap-nesting has traditionally been done in Washington and Utah. Management protocols are needed for bees originating from Washington and Utah where overall climate is cooler compared to central California where the bees are used in February for almond pollination. To evaluate climatic adaptations of O. lignaria relevant to their management, we released in separate orchards trap-caught O. lignaria adults from California, Washington, and Utah. Freshly completed nests were shipped to the laboratory for continued development in an incubator set for 10-year average Stockton, CA temperatures. We monitored developmental rates and survival of these offspring to adulthood. Prepupal duration for Washington and Utah progeny was half that of the California progeny. Washington and Utah progeny also became adults in the summer about two weeks prior to the California progeny. Left at ambient California conditions (i.e., no management) after adults had formed in the cocoon in the summer until adult emergence the following spring, survival of the Washington and Utah progeny was 25% and 21% respectively; survival of California progeny was 86%. Survival of Utah and Washington progeny managed using pre- and overwintering regimes were at least 90% and 81%, respectively; survival of managed California progeny was 73%. Accommodating regional thermal adaptations (i.e. region-defined developmental rates) will be critical to successful management of this bee for almond pollination.
... The Japanese hornfaced bee, Osmia cornifrons Radoszkowski (Hymenoptera: Megachilidae), has been recognized as an economically important pollinator of apple, blueberry and lettuce in China, Japan, Korea and United States (Maeta and Kitamura, 1964;Yamada et al., 1971;Xu et al., 1995;Goubara and Takasaki, 2003;Lee et al., 2008;Matsumoto et al., 2008;Lee et al., 2009;Matsumoto et al., 2009;West and McCutcheon, 2009;Matsumoto and Maejima, 2010). Compared to honeybees, O. cornifrons can pollinate in cooler and damper weather and requires less management (Wilson and Abel, 1996;Bosch et al., 2008). ...
... O. cornifrons is a solitary bee nesting in reeds and holes in nature and exhibits a strong flower constancy in orchard (Bosch and Kemp, 2002;Bosch et al., 2008;Matsumoto et al., 2009;Matsumoto and Maejima, 2010;McKinney and Park, 2012). O. cornifrons is also known as mason bees because it uses mud to construct cell partitions and build linear series of cells in a nest. ...
... In such management practice, release timing of managed population is one of the important components to synchronize emergence of O. cornifrons females with apple blossoming and wild bee emergence because managed and wild population of O. cornifrons work together for pollinating in the apple orchards (Lee et al., 2008). Winter periods and spring incubation temperature are important factors to determine the emergence time of O. cornifrons adults (Kim, 1999;Bosch et al., 2008;White et al., 2009). Although previous studies (Adams, 2001;White et al., 2009) developed temperature-dependent emergence models for O. cornifrons emergence in the eastern United States, the model does not predict accurately when it was applied to predict emergence of Korean populations of O. cornifrons (Fig. 1A). ...
The Japanese hornfaced bee, Osmia cornifrons Radoszkowski (Hymenoptera: Megachilidae), is an important pollinator of apple. It overwinters as diapausing adult in cocoon and the synchronization of the adult emergence in spring with apple blossom is critical for successful pollination, specifically in the environment with variable climate. To this end, prediction model of adult emergence would help manage O. cornifrons populations for planed pollination. In this study, by using temperature-dependent emergence data of O. cornifrons, emergence rate were mathematically described using linear and Lactin's nonlinear regression methods. The lower emergence thresholds estimated from linear regression for female was 7.98 °C and the thermal constant (DD, degree days) was 112.43DD. Pattern of emergence completion was described by using Weibull function and prediction of spring emergence was modeled based on functions of emergence rate and distribution. The model predicted the emergence of O. cornifrons between 100–130 Julian date and the observation fell between 108–129 Julian date. The prediction ranges of O. cornifrons emergence were wider than that of observation. This model could help predict spring emergence of O. cornifrons in the field and optimize planed pollination program for pollination service in agricultural systems in the climate change era.
... Successful colonization generally requires understanding the insect's natural seasonal phenology. Seasonal climate and daily weather can influence many physiological and behavioral aspects of insect life cycles, including general activity, diapause, and reproduction (e.g., Hahn and Denlinger, 2011), for which many examples are illustrative (e.g., Caltagirone, 1981;Harman, 1999;Bosch et al., , 2008Bernal et al., 2001;Kemp and Bosch, 2005;Skinner et al., 2006). Most of these examples represent introductions of biological control agents. ...
... Likewise, solitary bees that are managed for springtime pollination sometimes are forced to emerge early from winter diapause, in their case by means of prescribed overwintering and incubation protocols. Management protocols use thermal regulation for solitary bees to time bee emergence with the seasonal availability of bloom (Bosch et al., 2008). Additionally, weather conditions must be favorable for bees to fly in search of mates, food, and nesting sites; later, favorable conditions are needed for progeny to fully develop within appropriate seasonal timeframes (Bosch et al., 2008. ...
... Management protocols use thermal regulation for solitary bees to time bee emergence with the seasonal availability of bloom (Bosch et al., 2008). Additionally, weather conditions must be favorable for bees to fly in search of mates, food, and nesting sites; later, favorable conditions are needed for progeny to fully develop within appropriate seasonal timeframes (Bosch et al., 2008. Lastly, recent climate changes are fostering earlier springs and later autumns, which may desynchronize insects and hosts, or plants and pollinators, due to mismatched physiological responses to environmental cues (e.g., day length, temperature, etc.). ...
... In Osmia bees, the wintering period, during which cocooned adults are exposed to low temperatures, lasts about 150 days in temperate climates [31]. Thirty days of low temperature in the laboratory is not enough to terminate the diapause of these insects, and the survival rate of these adult bees is very low at 0-40% [32]. ...
... During the experiment, newly eclosed adults inside their cocoons remained at 22 °C and after the last methoprene application at 25 °C to activate the bees and emerge. This time corresponds to the pre-wintering period, which is mentioned as one of the life cycle phases of Osmia bees [31]. ...
Osmia bicornis syn. O. rufa is a univoltine bee species in which adults fly in spring and the offspring overwinter as cocooned imagoes. The flight period of solitary bees is short, so methods of control for development and emergence time are needed to synchronize the activity of managed pollinators with blooming. In our study, we tested the effectiveness of a juvenile hormone analog for the prevention of winter diapause. Bees developed in settled nests outdoors or in the laboratory (22 °C) until the end of the pre-pupa stage, then cocoons were removed from the nest cells and treated with a JH analog—methoprene—during the pupa and young imago stages. Then, bees were activated at 25 °C until the adults left the cocoons. Topical application of methoprene to the cocoon at the pupa or imago stage induced the emergence of some adult bees in the pre-diapause period, while no adults emerged when the bees were not treated with methoprene. Most adults emerged (about 50%) when treated with methoprene on 3-week-old cocooned imagoes. Bees treated in the pupal stage had a lower emergence rate (20–30%), but adult bees emerged earlier. The emergence time of adults for the laboratory group was, on average, from 70 to 91 days, and that for outdoor groups was from 57 to 72 days.
... Recently, cavity nesting bees have recently garnered considerable attention due to their relative ease of propagation and pollination proficiency (Batra, 1984;Sedivy and Dorn, 2014). Increases in propagation and commercial availability has resulted in cavity nesting bees becoming an important agricultural pollinator (Bloom et al., 2018;Bosch et al., 2008;Bosch and Kemp, 2002;Kopit and Pitts-Singer, 2018). The vast majority of cavity nesting bee species are within the cosmopolitan family Megachilidae, which includes leafcutter, mason, and resin bees (Ebeling et al., 2012;Sheffield et al., 2008;von Königslöw et al., 2019). ...
... The vast majority of cavity nesting bee species are within the cosmopolitan family Megachilidae, which includes leafcutter, mason, and resin bees (Ebeling et al., 2012;Sheffield et al., 2008;von Königslöw et al., 2019). Cavity nesting bees contribute substantively to agricultural pollination services in North America and Eurasia, and even exceed portions of A. mellifera pollination services (Bosch et al., 2008;Kopit and Pitts-Singer, 2018). Compared to A. mellifera, Megachilidae are considered more efficient pollinators of crops such as apples, almonds, and blueberries (Bosch, 1994;Bosch and Blas, 1994;Bosch and Kemp, 2002;Vicens and Bosch, 2000). ...
Cavity nesting bees are proficient and important pollinators that can augment or replace honey bee pollination services for some crops. Relatively little is known about specific pesticide concentrations present in cavity nesting insect reed matrices and associated potential risks to cavity nesting bees. Nesting substrates (Phragmites australis reeds in bundles) were deployed in an agriculturally intensive landscape to evaluate colonization and agrochemical exposure among cavity nesting pollinators over two consecutive field seasons. Composition of insect species colonizing reeds within nest bundles varied considerably; those placed near beef cattle feed yards were dominated by wasps (93% of the total number of individuals occupying reed nest bundles), whereas nest bundles deployed in cropland-dominated landscapes were colonized primarily by leaf cutter bees (71%). All nesting/brood matrices in reeds (mud, leaves, brood, pollen) contained agrochemicals. Mud used in brood chamber construction at feed yard sites contained 21 of 23 agrochemicals included in analysis and >70% of leaf substrate stored in reeds contained at least one agrochemical. Moxidectin was most frequently detected across all reed matrices from feed yard sites, and moxidectin concentrations in nonviable larvae were more than four times higher than those quantified in viable larvae. Agrochemical concentrations in leaf material and pollen were also quantified at levels that may have induced toxic effects among developing larvae. To our knowledge, this is the first study to characterize agrochemical concentrations in multiple reed matrices provisioned by cavity-nesting insects. Use of nest bundles revealed that cavity nesting pollinators in agriculturally intensive regions are exposed to agrochemicals during all life stages, at relatively high frequencies, and at potentially lethal concentrations. These results demonstrate the utility of nest bundles for characterizing risks to cavity nesting insects inhabiting agriculturally intensive regions.
... Pupation of O. bicornis starts in nature in spring/early summer, approximately 45-50 days after egg laying to larval chambers. After another 50 days, an adult bee becomes formed inside the cocoon 31,32 . The adult spends the whole summer, autumn and winter inside its cocoon, emerging to the environment in the spring (next season), ready for reproduction (Fig. 1). ...
... What is exceptionally interesting is that female cocoons have higher concentrations of these two elements than male cocoons (see supplement). This sexual dimorphism might be related to the higher production costs of female progeny and lower fitness value of single male progeny 31,40,41,[49][50][51] . From the perspective of fitness maximization, the life strategy of a solitary bee might involve the production of female progeny characterized by increased protection from cocoons and male progeny characterized by increased strength of their sexual organs or mandibles. ...
Life histories of species may be shaped by nutritional limitations posed on populations. Yet, populations contain individuals that differ according to sex and life stage, each of which having different nutritional demands and experiencing specific limitations. We studied patterns of resource assimilation, allocation and excretion during the growth of the solitary bee Osmia bicornis (two sexes) under natural conditions. Adopting an ecological perspective, we assert that organisms ingest mutable organic molecules that are transformed during physiological processes and that the immutable atoms of the chemical elements composing these molecules may be allocated to specific functions, thereby influencing organismal fitness and life history. Therefore, using the framework of ecological stoichiometry, we investigated the multielemental (C, N, S, P, K, Na, Ca, Mg, Fe, Zn, Mn, Cu) compositions of six components of the bee elemental budget: food (pollen), eggs, pupae, adults, cocoons and excreta. The sexes differed fundamentally in the assimilation and allocation of acquired atoms, elemental phenotypes, and stoichiometric niches for all six components. Phosphorus, which supports larval growth, was allocated mainly (55-75%) to the cocoon after larval development was complete. Additionally, the majority (60-99%) of the Mn, Ca, Mg and Zn acquired during larval development was allocated to the cocoon, probably influencing bee fitness by conferring protection. We conclude that for holometabolous insects, considering only the chemical composition of the adult body within the context of nutritional ecology does not provide a complete picture. Low ratios of C to other nutrients, low N:P and high Na concentrations in excreta and cocoons may be important for local-scale nutrient cycling. Limited access to specific nutritional elements may hinder bee development in a sex-dependent manner, and N and P limitations, commonly considered elsewhere, may not play important roles in O. bicornis. Sexual dimorphism in nutritional limitations due to nutrient scarcity during the larval stage may influence bee population function and should be considered in bee conservation efforts.
... All of our results suggest the observed cocoons are Mason bees, Osmia cornifrons. Mason bees generally nest in cavities with several offspring lined up end-to-end (Bosch et al., 2008;Boyle and Pitts-Singer, 2019) and show a preference for twigs or tubes, like bamboo, or man-made nesting tubes or tunnels. They are solitary when building their nests, but can be gregarious. ...
... The life cycle of O. cornifrons states that the larval stage occurs from May-June to September-October (Bosch et al., 2008;Boyle and Pitts-Singer, 2019;McKinney, 2011). This is consistent with the phenology found for our samples in September, which were prepupae. ...
Potential biological threats to honey bees must be identified quickly, before making disruptive and costly decisions. Here we describe numerous Osmia cornifrons (Hymenoptera: Megachillidae) cocoons in honey bee cells from one bee hive in Ohio. The developing Osmia cells presented themselves as a mystery at first, catching the attention of regulatory agencies. Along with identifying this species as a presumably benign resident in honey bee colonies, our observations suggest Osmia may use stored honey bee resources to provision offspring. Conceivably, resident honey bees might even act as surrogates because Osmia cocoons were attached to one another with honey bee wax, it seems likely that honey bee hosts were present during Osmia development. Along with resolving a potentially new biotic threat to honey bees, this diagnosis suggests a method for mass production of Osmia pollinators using an array of single-cell foundation
... Over the course of a few weeks, a mated female builds mud partitions to create separate cells within a trap nest or other hollow stem. Within each partitioned cell, she lays an egg on top of a ball of pollen and nectar [17,[21][22]. Larvae consume this pollen provision, build a cocoon, pupate, and overwinter in the nest as diapausing adults (Fig 1; [17,[21][22]). Thus, trap nests can be collected after nest completion, stored over winter, and placed in an orchard coincident with flowering the following season, where emerging bees will pollinate the fruit trees. ...
... Within each partitioned cell, she lays an egg on top of a ball of pollen and nectar [17,[21][22]. Larvae consume this pollen provision, build a cocoon, pupate, and overwinter in the nest as diapausing adults (Fig 1; [17,[21][22]). Thus, trap nests can be collected after nest completion, stored over winter, and placed in an orchard coincident with flowering the following season, where emerging bees will pollinate the fruit trees. ...
Bees are essential pollinators for many flowering plants, including agriculturally important crops such as apple. As geographic ranges of bees or their host plants change as a result of human activities, we need to identify pathogens that could be transmitted among newly sympatric species to evaluate and anticipate their effects on bee communities. We used PCR screening and DNA sequencing to evaluate exposure to potentially disease-causing microorganisms in a pollinator of apple, the horned mason bee (Osmia cornifrons). We did not detect microsporidia, Wolbachia, or trypanosomes, which are common pathogens of bees, in any of the hundreds of mason bees screened. We did detect both pathogenic and apathogenic (saprophytic) fungal species in the genus Ascosphaera (chalkbrood), an unidentified species of Aspergillus fungus, and a strain of bacteria in the genus Paenibacillus that is probably apathogenic. We detected pathogenic fungal strains in asymptomatic adult bees that therefore may be carriers of disease. We demonstrate that fungi from the genus Ascosphaera have been transported to North America along with the bee from its native range in Japan, and that O. cornifrons is exposed to fungi previously only identified from nests of other related bee species. Further study will be required to quantify pathogenicity and health effects of these different microbial species on O. cornifrons and on closely-related native North American mason bees that may now be exposed to novel pathogens. A global perspective is required for pathogen research as geographic ranges of insects and microorganisms shift due to intentional or accidental introductions.
... Species of the Osmia genus are generalists, pollinating over 150 plant species [21,22], thus positively influencing the quantity and quality of crops. This is why they have been successfully used for many years to pollinate various crops, such as orchards [23][24][25][26][27][28][29][30][31], rapeseed [32], blackcurrant [23], and strawberries [33]. Recent reports show that mason bees are also used to pollinate forest orchards of European seed trees-Tilia cordata Mill. ...
Osmia bicornis L. is a widespread and valued pollinator species. It is considered to be easy to breed, provided that the nesting material in which the bees build their nests is of sufficient quality and quantity. The aim of this study was to test several different types of nesting materials: reeds and commercial structures, including wood, MDF (Medium Density Fibreboard), plastic, paper or polystyrene. The highest levels of nest cavity occupancy were found in reeds (90%) and grooved MDF (over 80%). We have shown that maintaining mason bee colonies in polystyrene leads to reproductive losses (occupancy only 2% of nesting holes). Mason bees built the most cells in MDF (8.02 cells/hole) and wood (7.34 cells/hole), slightly fewer in plastic (6.83 cells/hole) and reeds (6.74 cells/hole), and the fewest in paper (3.67 cells/hole). The most cocoons per nest were obtained from reed (average 5.47), MDF (4.84) and plastic (4.74). We observed the highest mortality in plastic (2 larvae/hole), and the lowest in reeds (0.92 larvae/hole). In nests made of wood, MDF and paper, large nesting losses were caused by the migration of Ch. osmiae mites along and through the nest holes. The most hygienic nesting material turned out to be reed and plastic forms.
... Most of bee species are solitary and show specific foraging and nesting habits that influence their exposure to pesticides (Sgolastra et al., 2019). Among solitary bee species, mason bees in the genus Osmia have received special attention due to their use as managed crop pollinators (Bosch et al., 2008) and their inclusion as model species in pesticide risk assessment (EFSA, 2013). Honey bees and mason bees show widely contrasting ecological traits. ...
Agricultural environments, including crop and non-crop areas, often provide important pollen and nectar resources for managed and wild bees. However, these resources may be contaminated with pesticides detrimental to bees and other non-target organisms, including humans. Differences in life-history traits among bee species influence food resource exploitation and pesticide exposure. This study assesses the potential of honey bees (Apis mellifera) and mason bees (Osmia), two bee species with highly contrasting functional traits, as biological indicators of pesticide exposure in 34 Italian agricultural farms. Pollen loads of both species were used to identify pollen species collected and to analyse multi-residue levels of pesticides. Pesticide risk indexes were calculated for honey bees, mason bees and humans. In mason bees, pesticide risk was not influenced by plant diversity. In agreement with their pollen preferences and short foraging ranges, mason bees collected a high proportion of pollen from flowers of the target crop. Conversely, pesticide risk decreased with increasing pollen diversity in honey bees. In agreement with their generalist foraging habits and long foraging ranges honey bees collected a greater diversity of pollen species and a lower proportion of target crop pollen. Although honey bees and mason bees showed similar toxic loads and pesticide composition, at a field scale pesticide risk of one species is not a good indicator of the risk to the other species. Our study confirms that bees in agricultural environments are pervasively exposed to multi-residue pesticide loads. Exposure is conditioned by specific bee traits but is also highly context-dependent.
... The traits driving these differences included the daily brood cell production rate and nesting female longevity.O. bicornis shares the ability to produce at least two brood cells per day with M. rotundata under favourable conditions(Bosch et al., 2008;Pitts-Singer & Cane, 2011). With the species also having a longer assumed life span after emergence than N. melanderi, O. bicornis shows simulated population dynamics comparable to M. ...
With their large diversity of species, solitary bees are important pollinators of crops and native plant communities in agricultural landscapes. Stressors such as changing landscapes, climate and pesticide exposures may affect populations differently, dependent on each species' ecological traits.
We developed a population model for solitary bees, SolBeePop, which can be applied to simulate a variety of species by using species‐specific traits, including the nesting strategies. Species' phenological traits are mechanistically combined with input time series capturing temporal and spatial variability in landscape compositions.
Calibration and validation of the model with empirical study data demonstrate that the model can capture realistic dynamics in bee populations. In simulations conducted representing four species, Osmia bicornis, Megachile rotundata, Nomia melanderi and Eucera pruinosa, identical conditions and assumed nesting resource limitations resulted in different population‐level outcomes, indicating the importance of interactions between external factors and species‐specific traits including phenological, survival and reproductive traits.
Synthesis and applications. The publicly available model is intended as a tool for the assessment of population‐level outcomes of stressors, for instance, the limitation of floral resources in agricultural landscapes, limitation of nesting habitat and the exposure to pesticides. Realistic landscape scenarios can be tested and available data for one species can be used to estimate outcomes in other solitary bee species, informing conservation plans and risk assessment approaches to support managed and natural populations in the field.
... The sex ratio is strongly male-biased (Raw 1972;Bosch and Vicens 2005). Females of both mason bee species are monogamous and immediately receptive when they emerge from the maternal nest (Raw 1972;Bosch et al. 2008;Seidelmann 2014). Thus, protandry is a strategy to avoid missing mating opportunities (Kokko et al. 2014). ...
Finding a mate is the central task in the lives of many male insects. In many solitary bees, sexual competition between males is high due to monandry and a pronounced male-biased sex ratio. Males searching for females will inspect and mount any object of suitable size and habitus. Species, sex, and reproductive status are encoded in the bee’s bouquet of cuticular hydrocarbons (CHCs) and can only be identified at a short distance from the object encountered. In two species of mason bees, this CHC-based system for recognizing newly emerged, virgin females is not error-free. Newly emerged individuals of both sexes carry similar CHC bouquets, facilitating the confusion of newly emerged males with newly emerged, virgin females. Misidentification leads to same-sex sexual behavior by males seeking a mate. However, individuals of both sexes modify their CHC bouquet sex-specifically within a few days. The changes in the bouquet prevent further sexual harassment. In addition, within 3 days of emergence, males begin to release species-specific carboxylic acid esters, which may act as courtship-inhibiting pheromones to extend the range of their sex-specific scent tag. Due to the pronounced protandry of both species, SSB is restricted to the early flight season, when females are not yet present, and imposes no apparent cost on the two males involved.
... Once developed, larvae pupate and then egress as adults. In some species, the freshly emerged adults still remain in the cocoon until the spring of the following year (Bosch et al. 2008). ...
Wild bees (Hymenoptera: Apoidea) play an important role as pollinators of many crops and managed populations of Osmia spp. (Megachilidae), through the installation of trap-nests, proved to be efficient in several fruit orchards. In order to optimize the trap-nest protocols, it is necessary to understand which environmental factors play a major role in the reproductive success of these bees. Here, we studied how climate, land use and vegetation affect nest occupation rate (OR, i.e. total number of colonized tunnels/total number of tunnels in the trap-nest), brood productivity (BP, i.e. total number of brood cells built in a completed nest tunnel) and parasitism rate (PR, i.e. total number of parasitized brood cells/BP) in Osmia bees nearby almond orchards in South-East Spain, a largely understudied Mediterranean area. We found that the summer solar radiation positively influenced all three parameters, while spring solar radiation positively affected OR and BP, and negatively PR. Higher abundance of pastures and forests compared with crops increased OR, though not BP, and reduced PR. Vegetation evenness and diversity of dominant plant species also positively affected OR and BP, while they were unimportant for PR. OR was not affected by climate, but BP increased with maximum temperature in the warmest month and decreased with temperature annual range. PR also increased with high temperature, as well as with precipitation. Arid conditions limited OR and BP and boosted parasitism. Overall, it seems that Osmia bees nearby almond field in this area would benefit from trap-nest installation in well solar-radiated, hot and humid sites with a diverse vegetation. Since we have also found a negative association between PR and BP in nests with at least one parasitized cell, environmental conditions which improve productivity will also likely reduce parasitism in these bees. Implications for insect conservation: Optimization of trap-nesting protocols for maintaining abundant Osmia populations is crucial to an effective use of these bees as managed pollinators. In our study we suggest that trap-nests locations should be chosen also taking into account a number of local climatic and habitat factors, given their importance in affecting key traits of reproductive success in these solitary bees.
... Once the pollen provision is completely consumed, the larva forms a cocoon, pupates, and becomes an adult in the same brood cell, usually by the end of summer (17,19). The adult emerges from the cocoon and the tubular nest in the following spring (20). Adult survival is correlated with net energy gain (weight gain) based on the provisions consumed. ...
Fungicides are frequently used during tree fruit bloom and can threaten insect pollinators. However, little is known about how non-honey bee pollinators such as the solitary bee, Osmia cornifrons , respond to contact and systemic fungicides commonly used in apple production during bloom. This knowledge gap limits regulatory decisions on determining safe concentrations and timing for fungicide spraying. We evaluated the effects of two contact fungicides (captan and mancozeb) and four translaminar/plant systemic fungicides (cyprodinil, myclobutanil, penthiopyrad, and trifloxystrobin) on larval weight gain, survival, sex ratio, and bacterial diversity. This assessment was carried out through chronic oral ingestion bioassays where pollen provisions were treated with three dosages based on the currently recommended field use dose (1X), half dose (0.5X), and low dose (0.1X). We found that mancozeb and penthiopyrad significantly reduced larval weight and survival at all doses. We then sequenced the 16S gene to characterize the larvae bacteriome of mancozeb, the fungicide that caused the highest mortality. We found that larvae fed on mancozeb-treated pollen carried significantly lower bacterial diversity and abundance. Our laboratory results suggest that some of these fungicides can be particularly harmful to the health of O. cornifrons when sprayed during bloom. This information is relevant for future management decisions about the sustainable use of fruit tree crop protection products and informing regulatory processes that aim to protect pollinators.
... The diversity of DNA from pollen samples collected from Osmia rufa L. bee breeding chambers was analyzed using PCR with primer RP01 (5′-AATTTTCAAGCGTCGTGCCA-3′) as described by Bosch, Sgolastra & Kemp [2008]. The PCR was carried out using Allegro Taq DNA polymerase (Novazym, Poznań, Poland) under the following conditions: initial denaturation at 95°C for 2 min.; ...
The red mason ( Osmia rufa L. syn. O . bicornis ) is a solitary bee that is commonly used for pollination of fruit crops. Given the declining numbers of pollinators in various environments, the mason bee has not only become an effective insect as an additional pollinator, but sometimes it becomes the main species that is used to increase the yield of crops. Due to easy rearing and not showing aggressiveness towards people. The individual features of the mason bee have made the interest in this species constantly growing. Currently, the wild bees is more important for the forestry and production the seeds. So far, only the honeybee ( Apis mellifera mellifera ) has been successfully used to work in forest areas, especially with the flowers of Tilia cordata Mill. The rearing of mason bee ( Osmia rufa L.) in forest areas is new. The paper presents information on the microbiome of pollen collected from the brood chambers of the solitary bee Osmia rufa L. in various forest biotopes: Tilia cordata Mill, Quercus petraea Liebl. and Prunus avium L. The presence of five groups of bacteria was found in all analyzed pollens were rich in α-Proteabacteria , Actinobacteria and Firmicutes , while β -Proteobacteria and Bacteroides were present in a lower level. Despite the presence of bacteria in the pollen, no increased bee mortality was observed in any of the bee nests of forest biotopes. It was found that the forest environment does not pose a threat to the development of Osmia rufa L. bees.
... Our findings complement prior research showing climate change can alter host-pathogen systems and may influence the evolution and maintenance of species function within the ecosystems like plant pollination. The consequences of EHE may result in phenological asynchrony of host emergence, along with reductions in body mass and fat content and disruption of pathogen development (Bosch et al., 2008). Finally, we suggest that heat tolerance and thermal boldness of hosts may limit pathogen growth, but the ultimate consequences for disease dynamics shall depend on EHE effects on both hosts and pathogens. ...
The frequency and intensity of extreme heat in the environment have increased in the last decade. Extreme heating events (EHE) have wide-ranging impacts on biological systems from the molecular to the community level. However, the impacts of EHE have been poorly studied in pathogen–host systems. Here, we explore how EHE affects the interaction among the insect hosts, Osmia cornifrons and Osmia lignaria, and a protozoan pathogen, Crithidia mellificae. We compared changes in the upper limit for locomotion of hosts (Ctmax), thermal boldness (voluntary exposure to Extreme Temperature Zones – ETZ) between healthy and infected host exposed to EHE, and the effect of host Ctmax on pathogen growth rate. Our results showed that 1-day EHE significantly reduced the upper limit for locomotion of hosts by an average of 4 °C in healthy and 7 °C in infected hosts. Further, EHE significantly reduced the protozoan pathogen growth rate. EHE also reduced the hosts’ voluntary exposure to (or transit across) extreme (hot or cold) temperature zones (ETZ). Our results show that EHE reduces both hosts’ heat tolerance and pathogen fitness, and shed light on the implications of EHE on host–pathogen dynamics under warmer world.
... Many bee species are abundant, diverse, and effective pollinators of agroecosystems. Nevertheless, the lack of knowledge concerning biology and rearing methods hampers their rational use (Bosch et al. 2008;Giannini et al. 2015). Among the Apinae, bees of the Centridini tribe stand out as potential pollinators of various Brazilian crops, including passion fruit (Gaglianone et al. 2010), cashew (Freitas and Paxton 1998), nance (Rego et al. 2006), tamarind (Castro 2002), and acerola cherry (Freitas et al 1999). ...
Centris analis (Fabricius, 1804) is a solitary, cavity-nesting bee that is often recorded in studies through the use of trap nests. This species is considered to be a good candidate as a manageable pollinator for some orchards. However, further studies are still needed to optimize its rational rearing. This study sought to analyze female preference for different lengths and diameters of trap nests, as well as the effects of nest dimensions on the number of constructed cells, mortality rates, parasitism rates, and sex ratio. We used compact trap nests comprised of tubes with internal diameters ranging from 0.6 to 0.8 cm, and lengths ranging from 8 to 12 cm. The results showed that females preferred the narrowest (0.6 and 0.7 cm) and two of the longest cavities (10 and 12 cm). The greatest number of cells built was observed in the most used lengths. The lengths that were tested did not affect the mortality or parasitism rates or the sex ratio. Based on our findings concerning the dimensions examined, we recommend using the narrowest and longest cavities. The combined analyses of the tested parameters (diameter and length) demonstrated new data that can help improve the rearing and maintenance techniques applied to C. analis populations.
... (2) cocoons are secretions made for a speci c purpose to enhance bee tness (providing protection during prewintering and overwintering, i.e., during the rst ten months of the adult part of the life cycle) (Bosch et al., 2008;Giejdasz and Wilkaniec, 2002); and (3) the mass of adults is correlated with the tness of O. bicornis solitary bee females (this effect is not observed in males (Kim, 1997;Seidelmann, 2014)). ...
We investigated nutrition as a potential mechanism underlying the link between floral diversity/composition and wild bee performance. The health, resilience, and fitness of bees may be limited by a lack of nutritionally balanced larval food (pollen), influencing the entire population, even if adults are not limited nutritionally by the availability and quality of their food (mainly nectar). We hypothesized that the nutritional quality of bee larval food is indirectly connected to the species diversity of pollen provisions and is directly driven by the pollen species composition. Therefore, the accessibility of specific, nutritionally desirable key plant species for larvae might promote bee populations. Using a fully controlled feeding experiment, we simulated different pollen resources that could be available to bees in various environments, reflecting potential changes in floral species diversity and composition that could be caused by landscape changes. Suboptimal concentrations of certain nutrients in pollen produced by specific plant species resulted in reduced bee fitness. The negative effects were alleviated when scarce nutrients were added to these pollen diets. The scarcity of specific nutrients was associated with certain plant species but not with plant diversity. Thus, one of the mechanisms underlying the decreased fitness of wild bees in homogenous landscapes may be nutritional imbalance, i.e., the scarcity of specific nutrients associated with the presence of certain plant species and not with species diversity in pollen provisions eaten by larvae. Accordingly, we provide a conceptual representation of how the floral species composition and diversity can impact bee populations by affecting fitness-related life history traits. Additionally, we suggest that mixes of ‘bee-friendly’ plants used to improve the nutritional base for wild bees should be composed considering the local flora to supplement bees with vital nutrients that are scarce in the considered environment.
... The dates of pupation and adult eclosion were recorded for each bee. Samples were collected starting with fifth instar larvae, through pupal development, adult diapause (autumn-winter), and finally adults emerging in the spring of 2004 (Bosch et al., 2008). 11 non-diapausing prepupal samples were collected for sequencing, 15 diapausing adult samples, and 3 non-diapausing adults. ...
Diapause is a complex physiological phenomenon that allows insects to weather stressful environmental conditions. The regulation of diapause is accordingly complex, including signaling pathways that involve both small RNA and mRNA and affect the cell cycle, stress resistance, and developmental timing. Transposable elements, mobile genetic elements that replicate within the genome, are also thought to be stress responsive and regulated by the small RNA pathway. Therefore, we asked what the relationship was between environmental stress, diapause status, and transposable element expression in two species of agriculturally important bees, Megachile rotundata and Osmia lignaria. We characterized the TE content of the genomes of both species, then evaluated the expression of TE families during temperature stress, general environmental stress, and diapause stage. We found that the genomic TE content of the two species was very different, and M. rotundata has a larger number of annotated TEs compared to O. lignaria. We also found that both diapause stage and temperature stress had large effects on TE expression. The fold change of TE famlies tended to be larger in those expressed during diapause, however there was only a small majority that were upregulated during diapause. This suggests that stress and diapause do not break down to a simple up-regulation or down-regulation of TEs, but rather that the TE family, the genomic position of its insertions, and the exact heterochromatin formation of the organism at any given environmental state or life stage may affect overall expression of TEs.
... Unlike rapeseed that blooms in spring, sunflower is a summer crop. The different relationships with bee reproduction may confirm that mud-sealed tubes are mainly produced by solitary bees active in early spring, such as Osmia, which are known to pollinate spring-blooming crops (Bosch et al. 2008). Sunflower area was negatively correlated with next-year reproduction of pollinators using mud in the presence model in field crop edges. ...
- Context
Wild pollinators depend on floral resources available in the landscape, partly provided by mass flowering crops (MFCs), such as rapeseed or sunflower. MFCs are however often grown conventionally, implying insecticide use, with potential negative effects on pollinators.
- Objectives
To understand whether and to what extent these crops could contribute to the maintenance of pollinator populations, we investigated the inter-annual correlation between MFC resources and the reproduction of cavity-nesting pollinators (solitary bees and wasps) at a national scale.
- Methods
We studied a standardized citizen science dataset, in which farmers collected data on the abundance of sealed tubes in trap nests, between 2012 and 2017, in nearly 600 fields distributed across France. We modelled the relation between nesting and landscape resources of the current and previous year, taking local farming practices into account.
-Results
Pollinator nesting was positively correlated with the quantity of rapeseed floral resources the year preceding observations, as well as with the area of permanent meadows. On the contrary, we found more variable relations with sunflower floral resources, depending on the type of sealing material, hence likely on the phenology of pollinators. Our models also confirm that local practices should be accounted for when assessing the influence of the landscape context, although their effects were difficult to interpret.
- Conclusions
Solitary bee and wasp reproduction is likely to be positively and durably affected by rapeseed cover. Moderate areas of rapeseed may help maintain pollinators, in combination with semi-natural habitats, which provide more diverse and stable food and nesting sites.
... Briefly, seven concentrations of each insecticide and 0.2% acetone were made ( Table 1). The newly hatched female larvae with pollen provisions were selected based on the cell position within the nest and provision size according to Bosch et al. (2008). Female larvae were gently removed from the top of pollen provisions with a soft brush to petri dishes (60 mm diameter) and set aside. ...
... (2) cocoons are secretions made for a speci c purpose to enhance bee tness (providing protection during prewintering and overwintering, i.e., during the rst ten months of the adult part of the life cycle) (Bosch et al., 2008;Giejdasz and Wilkaniec, 2002); and (3) the mass of adults is correlated with the tness of O. bicornis solitary bee females (this effect is not observed in males (Kim, 1997;Seidelmann, 2014)). ...
Local and global changes affect which pollen varieties are available to bees in the environment. Therefore, wild bees cannot always access the optimally balanced diet required for their survival. Our feeding experiment showed that the nutritional quality of the pollen diet eaten by bee larvae is shaped not by pollen diversity but by a specific pollen species composition that results in specific nutrients being scarce or sufficient; this species composition influences bee survivability, development and mass. We proposed that the functioning of bee populations and communities may depend on the floral diversity of the local habitat, which determines whether a nutritionally balanced pollen diet obtained from specific species can be provided to bee larvae. Holistically considering wild bee fitness and health and the different characteristics of the food base at both the ecosystem and bee biology levels can provide new, important knowledge for conserving bees and their critical ecological roles.
... Briefly, seven concentrations of each insecticide and 0.2% acetone were made ( Table 1). The newly hatched female larvae with pollen provisions were selected based on the cell position within the nest and provision size according to Bosch et al. (2008). Female larvae were gently removed from the top of pollen provisions with a soft brush to petri dishes (60 mm diameter) and set aside. ...
Osmia excavata is an important pollinator in commercial fruit orchards. Little information has been published about ecotoxicity to O. excavata, especially the larvae. To clarify the risk of commonly used insecticides with different modes of action to the larvae of O. excavata, six insecticides (clothianidin, acetamiprid, sulfoxaflor, lambda-cyhalothrin, chlorfenapyr and abamectin) were selected for evaluation of their acute lethal toxicity and sublethal effects. Clothianidin and abamectin were the two most toxic insecticides to the larvae of O. excavata with LD50 values of 0.007 (0.006–0.008) and 0.0004 (0.0003–0.0006) μg active ingredient (a.i.) bee⁻¹, respectively. And their ecological risks were high according to the hazard quotient values (HQ > 2500). Sulfoxaflor was identified as the only safe insecticide for O. excavata (HQ < 50) under field conditions. Sublethal toxicity tests showed that larval weight was significantly decreased by ingesting food treated with clothianidin, lambda-cyhalothrin and abamectin (less than the maximum field registered concentrations on fruit trees) due to interference with consumption per larva and reduction of the efficiency of conversion of ingested food. Additionally, above three insecticides significantly prolonged larval developmental duration before cocooning and decreased eclosion rate. Overall, there results suggested that clothianidin and abamectin should not be applied, especially during the flowering phase, the application frequency of lambda-cyhalothrin should be minimized for the purpose of conserving O. excavata. Our results provided important evidences for selecting appropriate insecticides for use in fruit orchards.
... We used O. cornifrons for our study because they inhabit artificial trap-nests, are polylectic, mass provisioning, and univoltine (Bosch et al. 2008). Individual female O. cornifrons establish nests in hollow cavities, including reeds, holes bored into wood, and artificial paper tubes, in which they sequentially provision an average of 10 cells divided by mud walls, with female offspring at the rear of the nest and male offspring at the front (Batra 1997, Bosch andKemp 2002). ...
Both ecosystem function and agricultural productivity depend on services provided by bees; these services are at risk from bee declines which have been linked to land use change, pesticide exposure, and pathogens. Although these stressors often co-occur in agroecosystems, a majority of pollinator health studies have focused on these factors in isolation, therefore limiting our ability to make informed policy and management decisions. Here, we investigate the combined impact of altered landscape composition and fungicide exposure on the prevalence of chalkbrood disease, caused by fungi in the genus Ascosphaera Olive and Spiltoir 1955 (Ascosphaeraceae: Onygenales), in the introduced solitary bee, Osmia cornifrons (Radoszkowski 1887) (Megachilidae: Hymenoptera). We used both field studies and laboratory assays to evaluate the potential for interactions between altered landscape composition, fungicide exposure, and Ascosphaera on O. cornifrons mortality. Chalkbrood incidence in larval O. cornifrons decreased with high open natural habitat cover, whereas Ascosphaera prevalence in adults decreased with high urban habitat cover. Conversely, high fungicide concentration and high forest cover increased chalkbrood incidence in larval O. cornifrons and decreased Ascosphaera incidence in adults. Our laboratory assay revealed an additive effect of fungicides and fungal pathogen exposure on the mortality of a common solitary bee. Additionally, we utilized phylogenetic methods and identified four species of Ascosphaera with O. cornifrons, both confirming previous reports and shedding light on new associates. Our findings highlight the impact of fungicides on bee health and underscore the importance of studying interactions among factors associated with bee decline.
... bicornis) larvae fed food (pollen) nutritionally balanced or scarce in specific nutrients (physiologically important chemical elements: K, Na, and Zn). Fitness-related life history traits were chosen for study because: (1) mortality is an evident and relevant trait; (2) cocoons are fitness-enhancing secretions that protect bees for approximately ten months of pre-and overwintering [34,35]; and (3) body mass is positively related to fitness in O. bicornis and other solitary bee females but not males [36,37]. The three studied life history traits are considered separate and competing "sinks" into which organisms allocate resources from the available pool (see, e.g., [38] for more information). ...
Bee nutrition studies have focused on food quantity rather than quality, and on details of bee biology rather than on the functioning of bees in ecosystems. Ecological stoichiometry has been proposed for studies on bee nutritional ecology as an ecosystem-oriented approach complementary to traditional approaches. It uses atomic ratios of chemical elements in foods and organisms as metrics to ask ecological questions. However, information is needed on the fitness effects of nutritional mismatches between bee demand and the supply of specific elements in food. We performed the first laboratory feeding experiment on the wild bee Osmia bicornis, investigating the impact of Na, K, and Zn scarcity in larval food on fitness-related life history traits (mortality, cocoon development, and imago body mass). We showed that bee fitness is shaped by chemical element availability in larval food; this effect may be sex-specific, where Na might influence female body mass, while Zn influences male mortality and body mass, and the trade-off between K allocation in cocoons and adults may influence cocoon and body development. These results elucidate the nutritional mechanisms underlying the nutritional ecology, behavioral ecology, and population functioning of bees within the context of nutrient cycling in the food web.
... A carência de informações sobre a biologia reprodutiva das espécies de abelhas solitárias potenciais polinizadoras de culturas representa um dos principais entraves para a utilização dos serviços de polinização destes polinizadores em sistemas agrícolas tropicais. Bosch et al. (2008) ressaltaram que "muitos polinizadores altamente eficientes tem permanecido como potenciais polinizadores por causa da carência de estudos básicos sobre sua biologia do desenvolvimento", o que limita as possibilidades de estabelecimento de métodos apropriados de criação para estas espécies. ...
... Well-known bumblebees are pollinators of many endangered plants, crop fields and orchards, although their greatest commercial use is for greenhouse crops such as tomato (Torchio and Asensio 1985;Ptáček 1988;Vicens and Bosch 2000;Mommaerts et al. 2011;Pitts-Singer and Cane 2011). Several species of non-Apis bees are managed and multiplied for sale to growers (Bosch et al. 2008). More of these solitary bees are becoming endangered in Europe too (Biesmeijer et al. 2006;Potts et al. 2010;Brittain et al. 2010) and the Communicated by Christina Mogren and Heikki Hokkanen. ...
Non-parasitic bees differ in the degree of their taxonomic specialisation for pollen collection to feed their brood. Surveys of published data on pollen specialisation by bees of central Europe showed that about two-thirds of species are pollen generalists (polylectic) while the remainder only collect pollen of one family, genus or species (monolectic and oligolectic). Proportions of monolectic and oligolectic species among bee families and genera in central Europe varies widely, from the entirely pollen-specialised but small family Melittidae, to the mostly polylectic Halictidae and Apidae. The Asteraceae plant family attracts the most monolectic and oligolectic species, followed by Fabaceae, Brassicaceae and Campanulaceae. Several plant families in central Europe host only a single bee species. Of the species included in the Red List of bees of Czechia, oligoleges are proportionally more strongly represented than polyleges. Most of these red-listed oligoleges are associated with specific and regionally endangered habitats, i.e. steppes or wetlands. Most of the bees are more limited by the presence of their habitat or nesting site than by the host plant, although this fact is not simple to evaluate due to the incomplete data on the floral relations and distribution of bee species.
... Many species of solitary bees are pollen specialists (oligolectic) and forage on select pollen types sourced from a narrow range of related host plants (Cane & Sipes, 2006). The nest of a solitary bee is provisioned by a single foraging female and contains several chambers that are stocked with a one-time supply of pollen, nectar, and sometimes oils (Bosch et al., 2008;Danforth et al., 2019). The pollen provisions also harbour a diverse and biologically important microbial community, often sourced from the environment and nest building material (Keller et al., 2013). ...
1. For solitary bees that specialise on select pollen types (oligoleges), larval development depends on the availability of forage pollen from appropriate host plants and the naturally occurring microbiota present therein. While access to host pollen may be critical for the development of oligolectic bees, the extent to which pollen microbiota contribute to their brood success is unknown.
2. To investigate, we used a diet manipulation experiment to rear larvae of the oligolege, Osmia ribifloris , under in‐vitro conditions. Larvae were reared either on host pollen provisioned by their mother or on non‐host pollen collected by honey bees, in the presence or absence of the respective pollen‐associated microbiota. We assessed impacts on components of larval fitness: developmental time, biomass, and survivorship.
3. Our results revealed a significant interaction between pollen type and pollen‐associated microbes. The relative effect of microbes on larval performance was substantially greater than that of pollen type. Host pollen substrate produced the fittest larvae but only when combined with its full complement of naturally occurring microbiota. In contrast, host pollen without microbes resulted in a marked decline in fitness components. Larvae consuming non‐host pollen showed intermediate fitness, regardless of whether microbes were present or not.
4. These findings imply that the microbiota associated with maternally provisioned host pollen perform critical functions in larval nutrition and survival. For oligoleges in particular, the ability to develop on poorer quality host pollen likely derives from this sustained symbiosis with their microbial exosymbionts, rather than the biochemical characteristics of pollen type alone.
... 40% (Sekita and Yamada, 1993 . (Bosch, 2008). ...
... Only recently have studies examined the effects of fungicides and fungicide + insecticide and/or adjuvant mixtures on managed solitary bees, such as commercially used blue orchard bees Osmia lignaria Say (Megachilidae), red mason bees O. bicornis L., O. cornifrons, and alfalfa leafcutting bees Megachile rotundata (F.) (Megachilidae) [36,39,[47][48][49][50][51][52][53][54]. O. lignaria is noted to be an excellent pollinator of fruit and nut trees such as almond, cherry, and apple [55][56][57][58][59]. M. rotundata is the primary pollinator for alfalfa seed production in the United States and Canada [60,61]. ...
There is a growing body of empirical evidence showing that wild and managed bees are negatively impacted by various pesticides that are applied in agroecosystems around the world. The lethal and sublethal effects of two widely used fungicides and one adjuvant were assessed in cage studies in California on blue orchard bees, Osmia lignaria, and in cage studies in Utah on alfalfa leafcutting bees, Megachile rotundata. The fungicides tested were Rovral 4F (iprodione) and Pristine (mixture of pyraclostrobin + boscalid), and the adjuvant tested was N-90, a non-ionic wetting agent (90% polyethoxylated nonylphenol) added to certain tank mixtures of fungicides to improve the distribution and contact of sprays to plants. In separate trials, we erected screened cages and released 20 paint-marked females plus 30–50 males per cage to document the behavior of nesting bees under treated and control conditions. For all females in each cage, we recorded pollen-collecting trip times, nest substrate-collecting trip times (i.e., mud for O. lignaria and cut leaf pieces for M. rotundata), cell production rate, and the number of attempts each female made to enter her own or to enter other nest entrances upon returning from a foraging trip. No lethal effects of treatments were observed on adults, nor were there effects on time spent foraging for pollen and nest substrates and on cell production rate. However, Rovral 4F, Pristine, and N-90 disrupted the nest recognition abilities of O. lignaria females. Pristine, N-90, and Pristine + N-90 disrupted nest recognition ability of M. rotundata females. Electroantennogram responses of antennae of O. lignaria females maintained in the laboratory did not differ significantly between the fungicide-exposed and control bees. Our results provide the first empirical evidence that two commonly used fungicides and a non-ionic adjuvant can disrupt nest recognition in two managed solitary bee species.
... Al menos el 80% de los cultivos polinizados por animales dependen de abejas y otros animales silvestres (FAO, 2004). Por lo tanto, estudiar la apifauna asociada a los cultivos entomófilos posibilitaría identificar especies nativas con potencial como polinizadores, y el conocimiento de su biología permitiría trazar planes de manejo, como ya ocurre en diversas partes del mundo, con abejas solitarias como Megachile rotundata Fabricius, Osmia cornifrons (Radoszkowski), O. lignaria Say, Nomia melanderi Cockerell, y algunas especies de Centris Fabricius y Xylocopa Latreille, entre otras (Richards, 1993;Stephen, 2003;Torchio, 2003;Bosch & Kemp, 2004;Buchmann, 2004;Bosch et al., 2008). ...
El girasol (Helianthus annuus L.) es un importante cultivo oleaginoso en la Argentina. Durante tres campañas agrícolas, se determinaron la diversidad y la abundancia del elenco de los visitantes florales diurnos de capítulos de girasol, en ocho sitios que cubren gran parte del área cultivada en Argentina. Setenta y seis morfo-especies de visitantes florales, pertenecientes a ocho órdenes, fueron capturados sobre capítulos de este cultivo. El principal orden fue Hymenoptera, con 37 especies o morfoespecies, de las cuales 32 fueron abejas (Apoidea). Las familias de abejas más representadas fueron Apidae (13), Megachilidae (11) y Halictidae (7). La abeja doméstica (Apis mellifera L.) realizó el 93% de las visitas. La composición del elenco de visitantes no mostró un patrón de variación identificable a lo largo del día, ni con respecto a la distancia al borde del cultivo, pero varió entre sitios de muestreo. Se concluye que la abeja doméstica es el principal polinizador del girasol en la Argentina, aunque varias especies nativas de abejas (Melissodes tintinnans (Holmberg), M. rufithorax Brèthes, Melissoptila tandilensis Holmberg, y Megachile spp.) podrían ser consideradas como potenciales polinizadores del cultivo.Sunflower (Helianthus annuus L.) is an important oilseed crop in Argentina. During three agricultural years, the diversity and abundance of diurnal floral visitors of sunflower heads were determined in eight sites spanning much of this crop's cultivation area in Argentina. Seventysix morpho-species of floral visitors, belonging to eight orders, were captured on sunflower. The principal order was Hymenoptera, with 37 species or morpho-species, of which 32 were bees (Apoidea). The most represented bee families were Apidae (13), Megachilidae (11) and Halictidae (7). The domestic bee (Apis mellifera L.) accounted for 93% of the visits. Floral visitor composition did not show an identifiable variation pattern either throughout the day or with respect to the distance to the edge of the crop, but varied among sites. It is concluded that the domestic bee is the main sunflower pollinator in Argentina, although several native bee species (Melissodes tintinnans (Holmberg), M. rufithorax Brèthes, Melissoptila tandilensis Holmberg, and Megachile spp.) could be considered as potential crop pollinators.
Managed crop pollination strongly relies on the honeybee Apis mellifera and the bumblebee Bombus terrestris , which is risky, may impact wild pollinator communities and does not always give the best pollination outcomes. The mason bees Osmia cornuta and Osmia bicornis are increasingly used as alternative crop pollinators, but it is not clear how suitable these species are for fruit pollination. Here we assessed the suitability of O. cornuta and O. bicornis as managed pollinators in two cherry and four apple orchards. O. cornuta and O. bicornis were introduced in the orchards at the start of blooming. We assessed their time till emergence, nesting rate, abundance in orchards via transect walks, flower visitation rate in 20‐min time counts and pollen composition on their bodies. O. cornuta emerged 4 ± 2 days earlier and had a minimum of 5‐fold higher nesting rate than O. bicornis in cherry and apple orchards. Transect walks revealed that O. cornuta was more abundant in orchards than O. bicornis (21.2% ± 10.1% vs. 1.3% ± 1.8% of all observed pollinators) and more frequently observed visiting flowers (53 vs. 5 visits for O. cornuta and O. bicornis , respectively). Pollen loads of O. cornuta contained 95% of Rosacea plants (likely apple and cherry), whereas this was 30% for O. bicornis , indicating that O. bicornis mainly foraged outside the orchards. These findings indicate that O. cornuta is a better pollinator than O. bicornis for early blooming crops, such as cherry and apple, in the relatively cool and rainy weather conditions during our study.
Fungicides are frequently used during tree fruit bloom and can threaten insect pollinators. However, little is known about how non-honey bee pollinators such as the solitary bee, Osmia cornifrons, respond to contact and systemic fungicides commonly used in apple production during bloom. This knowledge gap limits regulatory decisions that determine safe concentrations and timing for fungicide spraying. We evaluated the effects of two contact fungicides (captan and mancozeb) and four translaminar/plant systemic fungicides (cyprodinil, myclobutanil, penthiopyrad, and trifloxystrobin) on larval weight gain, survival, sex ratio, and bacterial diversity. This assessment was carried out using chronic oral ingestion bioassays where pollen provisions were treated with three doses based on the currently recommended field use dose (1X), half dose (0.5X), and low dose (0.1X). Mancozeb and penthiopyrad significantly reduced larval weight and survival at all doses. We then sequenced the 16S gene to characterize the larvae bacteriome of mancozeb, the fungicide that caused the highest mortality. We found that larvae fed on mancozeb-treated pollen carried significantly lower bacterial diversity and abundance. Our laboratory results suggest that some of these fungicides can be particularly harmful to the health of O. cornifrons when sprayed during bloom. This information is relevant for future management decisions about the sustainable use of fruit tree crop protection products and informing regulatory processes that aim to protect pollinators.
Floral resource loss and pesticide exposure are major threats to bees in intensively managed agroecosystems, but interactions among these drivers remain poorly understood. Altered composition and lowered diversity of pollen nutrition may reinforce negative pesticide impacts on bees. Here we investigated the development and survival of the solitary bee Osmia bicornis provisioned with three different pollen types, as well as a mixture of these types representing a higher pollen diversity. We exposed bees of each nutritional treatment to five pesticides at different concentrations in the laboratory. Two field-realistic concentrations of three nicotinic acetylcholine receptor (nAChR) modulating insecticides (thiacloprid, sulfoxaflor and flupyradifurone), as well as of two fungicides (azoxystrobin and tebuconazole) were examined. We further measured the expression of two detoxification genes (CYP9BU1, CYP9BU2) under exposure to thiacloprid across different nutrition treatments as a potential mechanistic pathway driving pesticide-nutrition interactions. We found that more diverse pollen nutrition reduced development time, enhanced pollen efficacy (cocoon weight divided by consumed pollen weight) and pollen consumption, and increased weight of O. bicornis after larval development (cocoon weight). Contrary to fungicides, high field-realistic concentrations of all three insecticides negatively affected O. bicornis by extending development times. Moreover, sulfoxaflor and flupyradifurone also reduced pollen efficacy and cocoon weight, and sulfoxaflor reduced pollen consumption and increased mortality. The expression of detoxification genes differed across pollen nutrition types, but was not enhanced after exposure to thiacloprid. Our findings highlight that lowered diversity of pollen nutrition and high field-realistic exposure to nAChR modulating insecticides negatively affected the development of O. bicornis, but we found no mitigation of negative pesticide impacts through increased pollen diversity. These results have important implications for risk assessment for bee pollinators, indicating that negative effects of nAChR modulating insecticides to developing solitary bees are currently underestimated.
Urbanisation is a main driver of land-use change, leading to rising in temperatures and fragmentation and reduction of green areas. Bees and wasps, which are important insect groups due to the ecosystem services they provide, may respond to this disturbance via changes in morphological traits which are functionally relevant. To date, studies focusing on this aspect only investigated few social bee species, and often gave contrasting results even at intra-generic level. Here, we studied how body size, wing loading, wing aspect ratio and wing fluctuating asymmetry vary in a social ground-nesting bee (Halictus scabiosae), a solitary hole-nesting bee (Osmia cornuta) and a social paper wasp (Polistes dominula) along an urbanisation gradient within Milan (Italy). By assessing the effects of temperature, green areas fragmentation and vegetation productivity on the above-listed functional traits, we found the three species to variably respond to increasing urbanisation, albeit the driving environmental parameters differed among species. More specifically, smaller individuals were sampled in warmer (for bees) and in less productive (for wasps) areas along the urbanisation gradient. Furthermore, greater wing aspect ratio values were recorded at warmer locations for H. scabiosae, lower wing loading was recorded at more fragmented sites for O. cornuta, and greater wing loading was recorded at locations with greater productivity for P. dominula. H. scabiosae and P. dominula showed greater wing fluctuating asymmetry at more fragmented sites. Although distinct species seemed sensitive to different driving factors, our results point toward a consistent response: smaller body but potentially improved flight performance in more urbanised environments.
In March 2019, the European Commission mandated EFSA to revise itsguidance document on the risk assessment of plant protection products on bees (Apis mellifera, Bombus spp. and solitary bees). One of the aspectsof this revision involvesareview of the evidence on bee background mortality, which is addressed in this report. Eight different assessment questions were formulated in order to account for the variousbee groups, the difference between active and inactive periods, and to specifically consider the influence of beekeeping practices on honey bees. A systematic literature review and a survey ofbeekeepers from several EU countries were used as the main sources of information.The available dataset for honey bees is large enough to draw rather robust conclusions. The results of the analysis highlight important differences in levels of background mortality between the castes and roles of the bees in the colony. The impact of beekeeping practices on mortalityappears to be very limited, but not completely absent. The dataset for bumble bees and solitary bees is smaller and too scattered to be able to draw robust conclusions. Nevertheless,it issufficient to be able to define a plausible range of background daily mortality rates, and to provide some indications of differences among species.
Many of our most valuable crops require an insect, usually a bee, for pollination. Bees pollinate some 400 crops worldwide and 130 in the United States. In addition, agriculture is becoming more dependent on the services of bees because the proportion of crops that require insect pollination has increased in recent years. When a managed pollinator is provided, most often it is the familiar honey bee, Apis mellifera L., which is employed to do the job. For centuries, the honey bee was cultured for its production of honey and wax, and, more recently, intensive monoculture crop cultivation has made providing bees for a pollination fee an important aspect of beekeeping. Europeans brought the honey bee everywhere they settled, and it is now employed as a crop pollinator on every continent except Antarctica. But the ubiquitous honey bee is just one of about 16,000 described species of bees in 1200 genera worldwide. North America alone has 3800 species, of which 21 are introduced. Bees are most diverse in the warm-temperate, drier parts of the world; for example, California has 1985 species. The bees range from specialists that visit only one species of plant to generalists like the honey bee, and from solitary to eusocial, again like the honey bee. They are grouped into seven major families. The most familiar are the Halictidae (sweat bees), Megachilidae (leafcutting bees and mason bees), and Apidae (carpenter bees, bumble bees, and honey bees). Many of the solitary species visit crop plants, and some are now managed for their pollination services. The value of insect-pollinated crops in the United States was estimated to be 3.4 billion of which was attributed to non-Apis bees.
We investigated nutrition as a potential mechanism underlying the link between floral diversity/composition and wild bee performance. The health, resilience, and fitness of bees may be limited by a lack of nutritionally balanced larval food (pollen), influencing the entire population, even if adults are not limited nutritionally by the availability and quality of their food (mainly nectar). We hypothesized that the nutritional quality of bee larval food is indirectly connected to the species diversity of pollen provisions and is directly driven by the pollen species composition. Therefore, the accessibility of specific, nutritionally desirable key plant species for larvae might promote bee populations. Using a fully controlled feeding experiment, we simulated different pollen resources that could be available to bees in various environments, reflecting potential changes in floral species diversity and composition that could be caused by landscape changes. Suboptimal concentrations of certain nutrients in pollen produced by specific plant species resulted in reduced bee fitness. The negative effects were alleviated when scarce nutrients were added to these pollen diets. The scarcity of specific nutrients was associated with certain plant species but not with plant diversity. Thus, one of the mechanisms underlying the decreased fitness of wild bees in homogenous landscapes may be nutritional imbalance, i.e., the scarcity of specific nutrients associated with the presence of certain plant species and not with species diversity in pollen provisions eaten by larvae. Accordingly, we provide a conceptual representation of how the floral species composition and diversity can impact bee populations by affecting fitness-related life history traits. Additionally, we suggest that mixes of 'bee-friendly' plants used to improve the nutritional base for wild bees should be composed considering the local flora to supplement bees with vital nutrients that are scarce in the considered environment.
Current pesticide risk assessment for bees relies on a single (social) species, the western honey bee, Apis mellifera L. (Hymenoptera: Apidae). However, most of the >20,000 bee species worldwide are solitary. Differences in life history traits between solitary bees (SB) and honey bees (HB) are likely to determine differences in routes and levels of pesticide exposure. The objectives of this review are to: 1) compare SB and HB life history traits relevant for risk assessment; 2) summarize current knowledge about levels of pesticide exposure for SB and HB; 3) identify knowledge gaps and research needs; 4) evaluate whether current HB risk assessment schemes cover routes and levels of exposure of SB; and 5) identify potential SB model species for risk assessment. Most SB exposure routes seem well covered by current HB risk assessment schemes. Exceptions to this are exposure routes related to nesting substrates and nesting materials used by SB. Exposure via soil is of particular concern because most SB species nest underground. Six SB species (Hymenoptera: Megachilidae-Osmia bicornis L., O. cornifrons Radoszkowski, O. cornuta Latreille, O. lignaria Say, Megachile rotundata F., and Halictidae-Nomia melanderi Cockerell) are commercially available and could be used in risk assessment. Of these, only N. melanderi nests underground, and the rest are cavity-nesters. However, the three Osmia species collect soil to build their nests. Life history traits of cavity-nesting species make them particularly suitable for semifield and, to a lesser extent, field tests. Future studies should address basic biology, rearing methods and levels of exposure of ground-nesting SB species.
Our growing human population will be increasingly dependent on bees and other pollinators that provide the essential delivery of pollen to crop flowers during bloom. Within the context of challenges to crop pollinators and crop production, farm managers require strategies that can reliably provide sufficient pollination to ensure maximum economic return from their pollinator-dependent crops. There are unexploited opportunities to increase yields by managing insect pollination, especially for crops that are dependent on insect pollination for fruit set. We introduce the concept of Integrated Crop Pollination as a unifying theme under which various strategies supporting crop pollination can be developed, coordinated, and delivered to growers and their advisors. We emphasize combining tactics that are appropriate for the crop’s dependence on insect-mediated pollination, including the use of wild and managed bee species, and enhancing the farm environment for these insects through directed habitat management and pesticide stewardship. This should be done within the economic constraints of the specific farm situation, and so we highlight the need for flexible strategies that can help growers make economically-based ICP decisions using support tools that consider crop value, yield benefits from adoption of ICP components, and the cost of the practices. Finally, education and technology transfer programs will be essential for helping land managers decide on the most efficient way to apply ICP to their unique situations. Building on experiences in North America and beyond, we aim to provide a broad framework for how crop pollination can help secure future food production and support society’s increasing need for nutritious diets.
The present work examines the richness, abundance of nests, and annual activity of bee species nesting in trap-nests at acerola orchards in a semiarid region near Feira de San tana, Bahia State, Brazil. Collections using trap-nests were made in three orchards, between October 2008 and September 2009. Centris analis Fabricius, Centris tarsata Smith and Tetrapedia diversipes Klug used the trap-nests. Two-hundred and fifty four nests were obtained, mostly made by C. analis (n=213). All three species used the 5 and the 10 cm long trap-nest tubes and nesting was more frequent in the largest (n= 189) than in the smaller (n=65) tubes. Most nesting activities occurred from December 2008 through April 2009. C. analis is considered to have significant potential for the management of pollination in acerola orchards of the semiarid region in Bahia State, due to the high abundance of its nests.
Pollination is a prerequisite for fruit and seed set. As fruits and/or seeds are the economic products of most of our crop species, pollination plays a vital role in realizing optimal yield. Except cereals which are wind pollinated, most of our crop species are pollinated by animals, largely insects. Historically pollination of crop plants was dependent on wild native pollinators present on and around the crop fields. Due to a number of reasons, particularly habitat degradation and monoculture cropping system, wild pollinators have not been able to provide adequate pollination services to crop plants. Various approaches are now available to sustain pollination in crop species. The most effective approach is to use managed pollinators; they are being used routinely in developed countries for over 15 major crops and has developed into a well-organized industry. Managed pollinators include honeybees, particularly Apis mellifera, bumblebees and recently a few solitary bees such as species of Osmia, Nomia and Megachile. Greenhouse-grown tomatoes are pollinated exclusively by managed bumblebees. Techniques have also been developed to carry out supplementary pollinations through pollen sprays to overcome pollination constraints in self-incompatible species and also during inclement weather conditions under which bee activity gets reduced. Hand pollination is also followed for production of hybrid seeds in some vegetable crops. Recent trend has been towards integrated use of managed pollinators along with wild pollinators by maintaining pollinator-friendly habitats and agricultural practices. The technology of using managed pollinators to overcome pollination constraints is yet to be exploited in developing countries, largely due to lack of awareness amongst the farmers, insufficient data on crop pollinators and limitation of research backup on the management of pollination services.
Recent populations of the red sunflower seed weevil, Smicronyx fulvus LeConte (Coleoptera: Curculionidae), have been inconsistent or declining, particularly in North Dakota. Consequently, research on weevil biology, including development of resistant germplasm, has been limited. To determine whether cold storage of diapausing larvae could be improved, nonconstant temperature treatments (fluctuating thermal regime [FTR] and thermoperiod [TP]) were tested versus a constant 6°C for storage up to 365 d. Both alternate temperature treatments produced more adult weevils than constant 6°C for short (42, 91 d) storage, while all temperature treatments were good (≥60% adult emergence) at moderate term (182 d) cold storage, and FTR was best for long (365 d) periods. Excluding the 14-d storage period, which produced too few weevils for comparison, each doubling of cold storage time (e.g., from 42 to 91 d, 91 to 182 d), usually decreased the number of days to 50% relative emergence by ∼10 d. After 365 d of larval storage, emerged S. fulvus adults successfully infested sunflowers in a plant growth chamber, with damage per female similar to that observed in field trials. Compared with previous efforts to store weevil larvae, the method of collection and FTR storage is either more effective (greater adult emergence and reduced parasitism) or more time-efficient, and should permit year-round research using S. fulvus adults. Because successful emergence under FTR was >75% after 365 d, additional research would be required to determine the maximum effective duration of cold storage for S. fulvus .
The PPR Panel was asked to deliver a scientific opinion on the science behind the development of a risk assessment of plant protection products on bees (Apis mellifera, Bombus spp. and solitary bees). Specific protection goals options were suggested based on the ecosystem services approach. The different routes of exposure were analysed in detail for different categories of bees. The existing test guidelines were evaluated and suggestions for improvement and further research needs were listed. A simple prioritisation tool to assess cumulative effects of single pesticides using mortality data is suggested. Effects from repeated and simultanous exposure and synergism are discussed. Proposals for separate risk assessment schemes, one for honey bees and one for bumble bees and solitary bees, were developed.
We studied the oxygen consumption of two megachilid bees (Hymenoptera: Megachilidae), Megachile rotundata (F.) and Osmia lignaria Say, at selected, biologically relevant intervals throughout their respective life cycles. The U-shaped oxygen consumption curve and the static weights of wintering (nonfeeding) prepupae that we observed during the life cycle of M. rotundata support previous arguments for a winter diapause similar to that observed in other Hymenoptera. For O. lignaria, which overwinters as an adult, we found stepwise increases in oxygen consumption and continuous weight loss throughout the wintering period. However, our observations on adult O. lignaria wintering requirements are consistent with the previously published results for overwintering M. rotundata prepupae and reveal sharply increasing survival rates when wintered for a minimum of 3 mo. We interpret the greatly reduced survival in both M. rotundata and O. lignaria, as an indication that a critical biological process, diapause, is disrupted among individuals wintered for <3 mo. In the continued development of these two species as commercial scale pollinators on an ever-increasing list of target crops, any similarities or contrasts observed between the "summer bee," M. rotundata, and the "spring bee," O. lignaria, although of interest from a biological perspective, will probably have important implications in the continued development of sustainable population management protocols.
Poor pollination is a common cause of low fruit set in cherry orchards, and a high population of pollinators is therefore required. Osmia lignaria, the blue orchard bee, has been used successfully in Utah as an alternative to honey bees.
The foraging behavior and pollinating efficacy of Osmia cornuta (Latreille) and Apis mellifera L. were studied in an orchard of ‘Delicious’ apple, Malus domestica Borkh, in northeastern Spain. Yields after one single visit were more than five times higher in flowers visited by O. cornuta than in those visited by A. mellifera nectar gatherers. This is attributed to the lower rate of stigma contact in A. mellifera visits, rather than to insufficient deposition of compatible pollen when the stigmas are contacted. A. mellifera pollen collectors had very high rates of stigma contact, but they were very scarce (3%) on ‘Delicious’ flowers despite the presence of abundant brood in their hives. One single visit per flower by O. cornuta produced commercial fruit set (27.4%) and fruit size (>70 mm diameter). Based on cell production, average number of trips required to provision a male and a female cell, and flower visiting rates, it is estimated that a mean of 22,252 apple flower visits per female O. cornuta were made during the 15-d flowering period. This result indicates that 530 nesting O. cornuta females per hectare are enough to provide adequate apple pollination.
Comparative results were obtained on in-nest biology, late embryogenesis,
and immature development of two leafcutting bee species (Megachile rotundata (Fabricius)
and Megachile apicalis Spinola) to determine how these closely related species are parti
tioned. M. apicalis applied nectar to the nest tube prior to constructing each leaf cell and
also added nectar to the lip of the cell prior to cell capping whereas M. rotundata did not.
M. apicalis also constructed cells with fewer leaf pieces (6-10 versus 14 in M. rotundata)
but used fewer leaf pieces per cell (6-8) near the end of the nesting cycle while M. rotundata
utilized the same number of leaves throughout nesting periods. The embryos of both species
actively twisted in rotating 180? on their long axis which is similar to rotation methods
observed by us in other megachilid taxa but different from other families (i.e., Colletidae).
Both species developed through 5 instars even though M. apicalis eclosed from the chorion
as a second instar and M. rotundata eclosed as a first or second instar. We conclude that
Apoidea undergoes four larval molts and 5 instars and suggest that one or more instars
were missed in previous studies reporting fewer than 5 instars. Variability in embryonic
and larval developmental rates at constant temperatures indicate genetic plasticity. How
ever, developmental rates were not found to be correlated with diapause induction with
either species.
Cocoons of the potential orchard pollinator Osmia comuta were exposed to different over-wintering and incubation temperatures to see if adult emergence could be manipulated and bees could be induced to emerge in synchrony with almond bloom. Bees over-wintered in a warehouse in an almond-growing area emerged over a period of time longer than the blooming period of commercial almond orchards. Conversely, bees over-wintered in refrigerators completed emergence in less than a week. Longer over-wintering periods yielded shorter emergence periods, but lower over-wintering temperatures did not. Incubation of over-wintered cocoons for 24 h failed to consistently accelerate emergence. The shortest emergence periods were obtained when bees were over-wintered at 3 degrees C for 120 d.
To estimate Osmia cornuta densities required for pollination of 'Braeburn' apple, trees were caged and supplied with different bee densities in 2000 and 2001. The following pollination treatments were compared: (1) one O. cornuta pair per five trees: 5 adjacent trees, 2 'Braeburn', 1 'Granny Smith' (pollenizer) and 2 'Braeburn', caged with 1 female and 1 male O. cornuta; (2) one O. cornuta pair per tree: 5 trees as above, caged with 5 female and 5 male O. cornuta; (3) open pollination: 5 trees as above, uncaged; (4) no pollinators: 5 trees as above, caged without pollinating insects. Fruitlet-set (fruitlets retained on the tree before June drop), misshapen fruit-percentages (percent fruits with at least one empty carpel), and seed-set (number of seeds per fruit) were measured. Cages with no pollinators had the lowest fruitlet-set (2000: 11.5%; 2001: 7.7%) and seed-set (2000: 1.6; 2001: 1.9), and the highest proportion of misshapen fruits (2000: 96.8%; 2001: 96.3%) in both years. Values obtained in cages with one O. cornuta pair per five trees were not significantly different from those obtained in open-pollinated trees. Cages with one O. cornuta pair per tree had fruitlet-set (2000: 37.9%; 2001: 20.4%) similar to cages with one pair per five trees (2000: 33.0%; 2001: 18.6%) or to open-pollinated trees (2000: 31.0%; 2001: 21.7%), but had significantly higher seed-set (2000: 7.5 vs. 5.7 and 6.0, respectively; 2001: 5.6 vs. 4.3 and 4.0, respectively) and lower misshapen fruit incidence (2000: 27.5% vs. 54.0% and 56.5%, respectively; 2001: 54.8% vs. 71.5% and 76.1%, respectively) in both years. One O. cornuta pair per five trees can provide commercially acceptable fruitlet-set, whereas one O. cornuta pair per tree can ensure maximum seed-set and thus high-quality yields on 'Braeburn'.
The effects of pollinator density on the seed set of a male-sterile ( MS) and a male-fertile (MF) line of winter oilseed rape ( Brassica napus) were studied in 24 isolation cages ( 7.5 m(2)). Pollinator treatments comprised of high pollinator density ( a small honeybee colony and 10 mason bees, Osmia rufa), and a gradient of increasing O. rufa densities from zero ( control) up to 100 bees per cage. High pollinator densities increased the seed weight per plant from 6.5 g to 56.9 g for the MS line. However seed weight did not differ between high pollinator densities and controls for the MF line. Increasing densities of O. rufa had a significant effect on almost all yield components of the MS line, but only marginal effects on the MF line. The number of seeds per pod, the seed weight per plant and the harvest index ( seed weight/plant dry weight) of the MS line showed a significantly steeper increase with increasing bee density than that of the MF line. The results suggest that solitary bees could be used successfully to replace honeybees as pollinators of MS oilseed rape in isolation cages.
To investigate the possibility of pollinating 'Abate Fetel' and 'Max Red Bartlett' pears with O. cornuta, different pollination treatments were compared in 1998 and 1999: ( 1) trees caged with O. cornuta bees; ( 2) open pollination - uncaged trees located at various distances from O. cornuta nesting shelters; ( 3) trees caged without bees. O. cornuta was the most abundant pollinator species in the orchard (97.6% of the observed insects). Caged trees pollinated by O. cornuta set significantly more fruitlets and matured more fruits than caged trees without pollinators. The fruitlet- and fruit-set in open-pollinated trees was intermediate between caged trees with O. cornuta and caged trees without bees in 'Abate Fetel' in 1998 and 'Max Red Bartlett' in 1999, but did not differ from fruitlet- set in non-pollinated trees in the other two variety-years. Open-pollinated trees had seed-sets comparable to caged trees with O. cornuta. The pollen provisions stored in O. cornuta nests were almost exclusively composed of Pyrus pollen. As evidenced by traces of Prunus pollen some O. cornuta foraged 400 m away from the nesting shelters.
Osmia cornuta was tested as a pollinator of caged hybrid red rape for seed production in comparison to A. mellifera. Nine screen cages were set up, each to enclose ten plants of red rape. Four cages were provided with 40 O. cornuta (10 females and 30 males). In each of other four cages a small nucleus (ca. 400 workers) of A. mellifera was introduced. To estimate seed yields without pollinators, no bees were introduced in the ninth cage. After bloom, seed yield, seed germination percentages after 5 and 7 days, and seed weight were measured. Osmia cornuta readily visited red rape flowers, and pollinated them successfully. The O. cornuta cages produced a 1.5-fold increase in seed yield compared to A. mellifera cages. Seed quality was similar in O. cornuta and A. mellifera cages. The "no pollinator" cage produced few seeds, and of low quality. Red rape seems to be a suitable plant on which to rear O. cornuta, since the O. cornuta population released was increased by 1.2-fold.
Megachile rotundata (F.), a gregarious, cavity-nesting, leaf-cutting bee, is used throughout North America for the pollination of alfalfa, Medicago sativa L., seed crops. We examined the influence of various temperature regimes on development, survival, emergence, and longevity in both nondiapausing and diapausing forms of this species. In general, development rates increased with increasing constant temperatures used in this study (18, 22, 26, and 29°C), but the 26 and 29°C treatments were clearly superior as rearing temperatures for immatures. In diapausing individuals, a variable temperature treatment 14:27°C (8:16 h daily cycle, mean 22°C) reduced the length of prepupal and pupal development stages following incubation in the early summer when compared with individuals reared under the constant 22°C treatment. We discuss the importance of differing temperature regimes on M. rotundata development, survival, and longevity over the entire life cycle. We also discuss the importance of making a connection between immature development and sufficient wintering conditions to postdiapause development, a topic that has received much more attention in the literature.
Cladistic analysis is used to study the evolution of 29 biological characters related to nesting behavior, nest provisioning, oviposition, cocoon spinning, defecation, and life cycle (nest characters) in 11 species of Osmia bees (Hymenoptera: Megachilidae) and two outgroup genera. A molecular phylogeny based on 38 allozyme loci-as-characters and a combined character phylogeny are produced to compare with the nest character phylogeny. All phylogenetic trees support the monophyly of the genus Osmia and the subgenus Osmia (Osmia) with Osmia ribifloris Cockerell basal to the other species in this subgenus. The subgenus Helicosmia (=Chalcosmia) is resolved as a sister clade to O. (Osmia) in the molecular tree and as sister to the subgenus Cephalosmia in the nest character and combined trees. Incomplete biological information from additional species of all three subgenera is provided to support the consistency of nest characters at the subgeneric level and their use in the establishment of subgeneric phylogenies in the family Megachilidae.
The objective of this study was to find one or more rearing methods that would allow us to release Osmia lignaria Say populations from natal nests to pollinate February-flowering almonds, Prunus amygdalus Batsch, in California’s Central Valley. We exposed three phenologically distinct O. lignaria populations (early-, mid-, and late-flying) to different temperature treatments through development and wintering for a total of nine rearing treatments. These treatments combined three approaches to obtain early bee emergence: (1) exposing bees to warmer or fluctuating temperatures, or both, during development; (2) exposing bees to warmer wintering temperatures; and (3) using early-flying bee populations from Central Valley California latitudes. Extended periods of high prewintering temperatures resulted in apparent fat body consumption of prewintering adults and reductions in springtime adult longevity. In general, temperature treatments that promoted rapid immature development, and thus longer wintering periods, resulted in earlier spring emergence patterns of bees well timed with bloom period of almonds. Warmer wintering periods also resulted in earlier emergence. In addition to providing good bee-bloom synchrony, several treatments also yielded vigorous emerging populations, rapid establishment and nesting, and population increases. The potential importance of our results to anticipated increases in the demand for pollination services in California’s Central Valley almonds is discussed.
A leaf-cutter bee, Osmia coerulescens, was able to increase its population when solely on red clover, and so pollinate this important crop plant. Seed yields from Osmia-pollinated plants averaged 440 kg/ha. Data on the sex ratio and the average number of cells produced are given. Mortality of overwintering adults was high.
A population ofthe orchard pollinator Osmia cornuta (Latreille 1805) was released in an almond orchard in NE' Spain to test fue attractiveness of 4 diff.erent man-made nesting materials. Wood blocks are found most attractive, followed by grooved boards, reed sections, and milk-carton nesting units. Bamboo reeds are much more attractive than Phragmites or Arundo reeds. No significant differences in fue number of cells built per nest or in mortality mies are found between nesting materials. On fue other hand, fue sex ratio (MM / FF» of progeny differs between nesting materials, and tends to be higher in fue least attractive ones. The highest cell production and female cell production is obtained in wood blocks, and therefore, fuese are considered fue most suitable nesting materials for pollination operations with O. cornuta.
Three Osmia cornuta Latr. populations were released in each of three almond orchards near Reus (NE Spain). In each orchard, bees were offered the same choice of paper straws of tour different lengths (12, 15, 18, and 21 cm) inserted in milk-carton nesting materlals. Releasing methods used differed between orchards: bees of orchard A were released within their natal straws; bees of orchard B were released by inserting individual cocoons in new straws; bees of orchard C were mass-released in emergence boxes. Nesting bees at each orchard were counted, and the results showed that significancly more females dispersed in orchard C (79.10 %), than in orchard B (51.04 %) or orchard A (28.34 %). Females preferred to nest in longer straws (15 to 21 cm) than in 12 cm straws in the three orchards. In general, the number of cells built per nest increased, and sex ratio (males/females) of progeny decreased with straw length. Previously occupied straws were preferred to previously unoccupied straws in both orchards A and B. Comparison of these results with results obtained in other studies indicates that O. cornuta females select new holes when attractive nesting materials are offered, and previously occupied holes when less attractive nesting materials are available.
Survival and development of prepupae of the alfalfa leafcutter bee, Megachile rolundata (F.), for 4 locations in Alberta, Canada, were investigated during incubation of cocoons at eight constant temperatures in the laboratory. Good survival was observed for incubation temperatures of 20–32°C and there was no significant interaction in postoverwintering mortality between males and females. In some cases, prepupae held at 35 or 37°C went through a state of arrested development for 2–3 weeks, which may be a form of aestivation. Development times at seven constant temperatures by location and sex are provided. There were no significant differences among locations in mean development time and a common linear regression equation for development versus temperature was determined. Threshold temperature for prepupal development was estimated to be 15·7°C and 295 accumulated ‘degree-days’ were required for 50% completion of adult emergence. This information was used for successful prediction of adult emergence when leafcutter bee cocoons were placed in a commercial incubator. The duration and temperature of cold storage for cocoons prior to incubation must be standardized to allow homologous comparisons of research results.
Until 1997, honey bees, Apis mellifera L., were used to pollinate Brassicaceae grown in field cages at the North Central Regional Plant Introduction Station (NCRPIS), at Ames, IA. At this time, a solitary bee, Osmia cornifrons (Radoszkowski), was first employed to pollinate the crop in field cages; however, a native bee species, Osmia lignaria subsp. lignaria Say, out-competes O. cornifrons in central Iowa for artificial nesting sites erected for rearing. The purpose of this study was to investigate the efficacy of these two solitary bee species for producing Brassica napus, B. rapa, and Sinapis alba seed in field cages. There was no difference in seed production for the S. alba accession, PI 209022, or the B. rapa accession, PI 278766, between the two species of Osmia. But, the B. rapa accession, PI 392025, and the B. napus accession, PI 469944, produced significantly more seed when pollinated by O. lignaria subsp. lignaria than by O. cornifrons. Because the native bee is easier to rear and maintain, it will be the pollinator of choice for control pollinating collections of Brassicaceae species maintained at NCRPIS. The commercial use of O. lignaria subsp. lignaria or the related subspecies, O. lignaria subsp. propinqua, should be investigated for improving the production of canola and rapeseed.
Papilio canadensis encounters shorter, cooler summers in interior Alaska than in northern Michigan: average thermal sums are 583 vs. 985 Celsius degree-days (10@?C base); mean daily temperature is 14.4 vs. 18.8@?. The temperature physiology of P. canadensis could be evolutionarily conserved, or the species may be a composite of regionally adapted populations. We evaluated these hypotheses by comparing the developmental physiology of P. canadensis from Alaska and Michigan across a range of temperatures in the laboratory and field. Higher temperatures generally resulted in more rapid larval development, but the effects varied with insect population and host. At low temperatures (12@?), Alaskan larvae grew faster than Michigan larvae (fifth instars doubled their fresh mass in 5.8 vs. 9.1 d), primarily due to 40% higher consumption rates. At high temperatures (30@?), Alaskan larvae grew slower, faster, or the same as Michigan larvae, depending upon host. Effects of host quality were greatest at high temperatures. Elevated respiratory expenses in Alaskan larvae (35% higher than Michigan larvae) made them especially sensitive to host quality at high temperatures. Dry matter digestibility and nitrogen use efficiency differed across hosts, but not between populations or across temperatures. Molting accounted for 35-51% of development time. Alaskan larvae completed their fifth molt faster than Michigan larvae at 12@? (11.8 vs. 17.8 d), but not at 30@? (3.1 vs. 2.9 d). In both populations, molt was more temperature sensitive than growth at low temperatures (Q"1"0 of 5.65 vs. 3.04 from 12 to 18@?), but less temperature sensitive at high temperatures (Q"1"0 of 1.60 vs. 2.06 from 18 to 30@?). Survival differed across temperatures, but not between populations. Under ideal basking conditions, larvae in the field were able to elevate body temperatures @?10@? above ambient, but such conditions were rare in Alaska and larvae were usually near ambient temperature. Alaskan larvae were no better than Michigan larvae at selecting high radiation microsites or converting solar radiation into heat. Growth rates of Alaskan larvae were the same in the field and laboratory when fed the same foliage and exposed to the same mean daily air temperature. We incorporated P. canadensis temperature responses into a life history development model, then used a 48-yr climatic record to evaluate the fitness contributions of apparent adaptations to Alaskan summers. On a good host, at Alaskan temperatures, Alaskan P. canadensis had an estimated fitness 3.0 times greater than Michigan P. canadensis. Furthermore, the Michigan population was predicted to go extinct in 31 of 48 yr at Alaskan temperatures. Changes in growth temperature responses made the greatest contribution to enhanced fitness in Alaska, followed by increased mass of neonates, enhanced molting abilities at low temperatures, and a reduced size threshold for pupation. Analysis of fitness trade-offs suggested that extreme summers have been more important than average summers in shaping adaptive responses. Regional adaptation to climate allows P. canadensis to maintain a broader geographic distribution than would otherwise be possible, but northern distribution limits are probably still constrained by summer temperatures.
Two species of bees native to China, Osmia excavata Alfken and Osmia jacoti Cockerell, were released in 1991–1993 to observe life-history characteristics and assess pollination efficiency. Osmia excavata successfully established in both coastal (Shandong Province) and interior (Hebei Province) habitats, whereas O. jacoti was only able to establish in the coastal habitat. Sex ratios (female:male) ranged from 1:1.05 for O. jacoti to 1:2.46 for O. excavata. Apple, Malus domestica Borkh (Rosaceae), pollination was enhanced following the release of either species in orchards in Shandong. Fruit diameter increased following the release of either Osmia species in 'Red Delicious' blocks compared with control blocks where no pollination treatment was applied. The number of seeds per fruit was also increased relative to controls, and the percentage of asymmetrical fruit decreased. Release of O. excavata produced the best results for this cultivar. For 'Ralls Janet', the number of seeds per fruit increased following the release of either species and the percentage of asymmetrical apples decreased. Effects on fruit diameter were confounded by poor cultural practices (i.e., lack of adequate fruit thinning) in these 'Ralls Janet' blocks. Fruit set increased relative to controls following release of either Osmia species for both apple cultivars. Release of O. excavata also produced higher fruit set relative to blocks that received hand pollination treatment; release of O. jacoti was better than hand pollination only for 'Red Delicious'. Observations on the behaviour of individuals showed that O. excavata averaged 49.6 foraging trips per day and set an estimated 3108 fruit on 'Ralls Janet'; O. jacoti made fewer foraging trips (average of 31.2) per day and set 1831 fruit. Both species were more efficient pollinators than Apis mellifera. Osmia excavata would