Nomia Melanderi Research Articles

SolBeePopecotox: A Population Model for Pesticide Risk Assessments of Solitary Bees.

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, SolBeePopecotox, 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.

SolBeePop: A model of solitary bee populations in agricultural landscapes

Abstract 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 Extraordinary Alkali Bee, Nomia melanderi (Halictidae), the World's Only Intensively Managed Ground-Nesting Bee.

Among the ground-nesting bees are several proven crop pollinators, but only the alkali bee (Nomia melanderi) has been successfully managed. In <80 years, it has become the world's most intensely studied ground-nesting solitary bee. In many ways, the bee seems paradoxical. It nests during the torrid, parched midsummer amid arid valleys and basins of the western United States, yet it wants damp nesting soil. In these basins, extensive monocultures of an irrigated Eurasian crop plant, alfalfa (lucerne), subsidize millions of alkali bees. Elsewhere, its polylectic habits and long foraging range allow it to stray into neighboring crops contaminated with insecticides. Primary wild floral hosts are either non-native or poorly known. Kleptoparasitic bees plague most ground nesters, but not alkali bees, which do, however, host other well-studied parasitoids. Building effective nesting beds requires understanding the hydraulic conductivity of silty nesting soils and its important interplay with specific soil mineral salts. Surprisingly, some isolated populations endure inhospitably cold climates by nesting amid hot springs. Despite the peculiarities and challenges associated with its management, the alkali bee remains the second most valuable managed solitary bee for US agriculture and perhaps the world.

Wild Bee Nutritional Ecology: Integrative Strategies to Assess Foraging Preferences and Nutritional Requirements

Bees depend on flowering plants for their nutrition, and reduced availability of floral resources is a major driver of declines in both managed and wild bee populations. Understanding the nutritional needs of different bee species, and how these needs are met by the varying nutritional resources provided by different flowering plant taxa, can greatly inform land management recommendations to support bee populations and their associated ecosystem services. However, most bee nutrition research has focused on the three most commonly managed and commercially reared bee taxa—honey bees, bumble bees, and mason bees—with fewer studies focused on wild bees and other managed species, such as leafcutting bees, stingless bees, and alkali bees. Thus, we have limited information about the nutritional requirements and foraging preferences of the vast majority of bee species. Here, we discuss the approaches traditionally used to understand bee nutritional ecology: identification of floral visitors of selected focal plant species, evaluation of the foraging preferences of adults in selected focal bee species, evaluation of the nutritional requirements of focal bee species (larvae or adults) in controlled settings, and examine how these methods may be adapted to study a wider range of bee species. We also highlight emerging technologies that have the potential to greatly facilitate studies of the nutritional ecology of wild bee species, as well as evaluate bee nutritional ecology at significantly larger spatio-temporal scales than were previously feasible. While the focus of this review is on bee species, many of these techniques can be applied to other pollinator taxa as well.

Hygroscopic larval provisions of bees absorb soil water vapor and release liquefied nutrients

Larvae of most bee species consume individual provision masses composed of pollen mixed with nectar. For simple metabolic reasons, mature larvae should weigh less than their consumed provision. However, past research reported a remarkable result: mature larvae of three ground-nesting halictid bees weighed 60% more than their original provision masses. This surprising paradox could result from the expected hygroscopic nature of nectar. Sugar solutions absorb water vapor at rates defined by their osmolarity and ambient humidity. Our experiments tested this hypothesis, showing that larval provisions of a ground-nesting bee, Nomia melanderi, are strongly hygroscopic. They consequently absorbed substantial water vapor from this bee’s preferred nesting soil. Mature larvae weighed 65% more than their original provision because hygroscopy had greatly augmented available dietary water. Liquid accumulating around isolated provisions was a sweet nutritious broth that included amino acids leached from the pollen. Hygroscopy was most intense during the egg and early larval stages. However, provision liquefaction (and possible drowning) was partly offset by rapid hydration of cached pollen, whose weight could double after absorbing free water. Larval provisions of two cavity-nesting Osmia species also readily absorbed water vapor from a soil atmosphere. However, at humidities measured within tunnels of their natural deadwood nesting substrates, they gained little weight via hygroscopy. Consequently, their mature larvae weighed less, not more, than the provision that they ate. These new insights explain some nesting traits shared by many ground-nesting bees, such as why females do not waterproof the earthen cell caps of their nest cells, or why many colletids cache liquid provisions. Progressive hygroscopy and resulting sugar dilution may also mediate succession of microbial mutualists and pathogens in provision masses of ground-nesting bees.

Experience, but not age, is associated with volumetric mushroom body expansion in solitary alkali bees.

In social insects, changes in behavior are often accompanied by structural changes in the brain. This neuroplasticity may come with experience (experience-dependent) or age (experience-expectant). Yet, the evolutionary relationship between neuroplasticity and sociality is unclear, because we know little about neuroplasticity in the solitary relatives of social species. We used confocal microscopy to measure brain changes in response to age and experience in a solitary halictid bee (Nomia melanderi). First, we compared the volume of individual brain regions among newly emerged females, laboratory females deprived of reproductive and foraging experience, and free-flying, nesting females. Experience, but not age, led to significant expansion of the mushroom bodies - higher-order processing centers associated with learning and memory. Next, we investigated how social experience influences neuroplasticity by comparing the brains of females kept in the laboratory either alone or paired with another female. Paired females had significantly larger olfactory regions of the mushroom bodies. Together, these experimental results indicate that experience-dependent neuroplasticity is common to both solitary and social taxa, whereas experience-expectant neuroplasticity may be an adaptation to life in a social colony. Further, neuroplasticity in response to social chemical signals may have facilitated the evolution of sociality.

Composition and acquisition of the microbiome in solitary, ground-nesting alkali bees

Increasing evidence suggests the microbiome plays an important role in bee ecology and health. However, the relationship between bees and their bacterial symbionts has only been explored in a handful of species. We characterized the microbiome across the life cycle of solitary, ground-nesting alkali bees (Nomia melanderi). We find that feeding status is a major determinant of microbiome composition. The microbiome of feeding larvae was similar to that of pollen provisions, but the microbiome of post-feeding larvae (pre-pupae) was similar to that of the brood cell walls and newly-emerged females. Feeding larvae and pollen provisions had the lowest beta diversity, suggesting the composition of larval diet is highly uniform. Comparisons between lab-reared, newly-emerged, and nesting adult females suggest that the hindgut bacterial community is largely shaped by the external environment. However, we also identified taxa that are likely acquired in the nest or which increase or decrease in relative abundance with age. Although Lactobacillus micheneri was highly prevalent in pollen provisions, it was only detected in one lab-reared female, suggesting it is primarily acquired from environmental sources. These results provide the foundation for future research on metagenomic function and development of probiotics for these native pollinators.

Richness and diversity of insect pollinators in various habitats around Bogani Nani Wartabone National Park, North Sulawesi, Indonesia

Abstract. Koneri R, Nangoy MJ, Wakhid. 2021. Richness and diversity of insect pollinators in various habitats around Bogani Nani Wartabone National Park, North Sulawesi, Indonesia. Biodiversitas 22: 288-297. The pollination of plants by insects is one of the most important and essential ecosystem services in natural and agricultural landscapes and Insect pollinators play an important role in this process. This is because they help to transfer pollen from the anther to the stigma, which leads to fertilization. This study aims to analyze the richness and diversity of insect pollinators in various habitats around the Bogani Nani Wartabone National Park, Toraut, North Sulawesi. It was carried out from June to August 2020 on three types of habitats around the National Park, namely forest edges, shrubs and agricultural land. For each habitat, four plots with a size of 50 m x 25 m were made with a distance of 100 m between them. The insect pollinator observation technique used was the scan sampling method. Furthermore, data analysis was carried out on abundance, richness index, diversity index, species evenness index, dominance index and the relationship between sampling locations and environmental factors. The results showed that there were 979 insect pollinators caught at the observation point, which consisted of 60 species from 16 families and 4 orders and the most common order was Hymenoptera with 31 species. The species which were found based on their relative abundance indicated that Nomia strigata was the most abundant followed by Nomia melanderi, Apis dorsata, Ropalidia fasciata and Amegilla zonata. Furthermore, the highest abundance of insect pollinators was found in shrub habitats, while the highest species richness and diversity were found at the forest edge. Therefore, it was concluded that different types of habitat affect the richness and diversity of insect pollinator species around the Bogani Nani Wartabone National Park. In addition, this proves that the forest area of Bogani Nani Wartabone National Park generally supports the abundance, richness, and diversity of insect pollinators, which were discovered in the surrounding habitats, namely shrubs and agricultural land.

Daily Activity of Wild Bee Pollinators on Strawberry in Highland Agriculture, Eastern Slope of Mount Slamet, Central Java

Wild bees have a vital role in complementing social bee pollination in an agricultural landscape. Pollination effectiveness of wild bee depends on the daily activity of individual bees visiting flowers. This research aimed to understand the activity of wild bees visiting and pollinating flowers of strawberry. A survey has been done from April to July 2018 using scan sampling in 30 plants of strawberry. The results showed that strawberry flowers were visited by five bee species (Nomia melanderi, Campsomeris fasciata, Ceratina dupla, Amegilla zonata, and Lasioglossum malachurum ). The daily activity of wild bee showed significant differences between species (p<0,05), but all species have the same pattern of pollination activity. The highest activity found between 9.00 and 12.00 pm and tended to decrease at the end of the day. The activity of wild bees to visiting flowers affected by daily temperature (r = 0,86). The conclusion was that wild bee species are highly competitive in food resources at midday. Some species showed ecological separation throughout the day. This research found that wild bee species have an important contribution to cash crop pollination in the agriculture area.

Small Body Size Is Associated with Increased Aggression in the Solitary Sweat Bee Nomia melanderi (Hymenoptera, Halictidae)

Modifying ancestral regulatory mechanisms can be a source of evolutionary novelty. Bees in small-colony, dominance-based societies typically show a link between size and aggression: larger bees are more aggressive. This led to the hypothesis that this size-aggression link is a characteristic of ancestral solitary bees that has acquired a novel function in the evolutionary transition from solitary to social behavior. Here we test the central prediction of this hypothesis, that size is linked to aggression in an ancestrally solitary bee. We use the sweat bee Nomia melanderi (Hymenoptera, Halictidae) in the subfamily Nomiinae, which is sister to the social sweat bees, all of which are in the subfamily Halictinae. We measured aggression using a standardized behavioral assay (circle tube) in which two bees were placed together and allowed to interact. We used three treatments: size matched small bees, size matched large bees, and one large bee paired with one small bee. We found no link between ovary size and aggression, but because we used only reproductively active bees we may not have had sufficient variation to detect such a link. Across treatments, body size negatively correlated with aggression. There were no differences between large and small bees in the matched treatments, but in the mixed treatment, small bees were more aggressive than large bees. This supported our prediction of a size-aggression link, although the link was in the opposite direction seen in social bees. Moreover, our data show that even solitary bees can modulate their aggression in response to social context and highlight the importance of studying related solitary species to understand the evolutionary origins of sociality.

Draft Genome Assembly and Population Genetics of an Agricultural Pollinator, the Solitary Alkali Bee (Halictidae: Nomia melanderi).

Alkali bees (Nomia melanderi) are solitary relatives of the halictine bees, which have become an important model for the evolution of social behavior, but for which few solitary comparisons exist. These ground-nesting bees defend their developing offspring against pathogens and predators, and thus exhibit some of the key traits that preceded insect sociality. Alkali bees are also efficient native pollinators of alfalfa seed, which is a crop of major economic value in the United States. We sequenced, assembled, and annotated a high-quality draft genome of 299.6 Mbp for this species. Repetitive content makes up more than one-third of this genome, and previously uncharacterized transposable elements are the most abundant type of repetitive DNA. We predicted 10,847 protein coding genes, and identify 479 of these undergoing positive directional selection with the use of population genetic analysis based on low-coverage whole genome sequencing of 19 individuals. We found evidence of recent population bottlenecks, but no significant evidence of population structure. We also identify 45 genes enriched for protein translation and folding, transcriptional regulation, and triglyceride metabolism evolving slower in alkali bees compared to other halictid bees. These resources will be useful for future studies of bee comparative genomics and pollinator health research.

Pesticide Exposure Assessment Paradigm for Solitary Bees.

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.

Assessing Transportation Impacts to Alkali Bees (Hymenoptera: Halictidae) and Alfalfa Seed Production in Southeastern Washington State

The Washington State Department of Transportation (WSDOT) is proposing safety improvements to U.S. Highway 12 near the town of Touchet, Washington. The improvements include realignment to the north in order to accommodate a wider roadway. The proposed realignment route is within the Touchet-Lowden-Gardena alfalfa seed-growing district, an area critical to alfalfa seed production. The most effective and efficient pollinator for alfalfa is Nomia melanderi Cockerell, a native ground-dwelling bee that is raised in bee beds by area farmers. Relocation of the highway will bisect several bee beds and alfalfa fields. The alfalfa leafcutting bee, Megachile rotundata F., is also an important pollinator in the area. A study was conducted regarding potential impacts to these bees from the highway improvements. One of the objectives of the study was to determine pollinator flight heights over county roads. The “vehicular bee sweeper” was designed to capture insects at specific heights over the roadway and provided data regarding flight height. The majority of N. melanderi flew at heights below 2.1 meters when no other factors were considered, though most M. rotundata flew at or below 0.9 meters. Environmental conditions such as temperature and wind speed had an effect on flight behavior of both pollinators. Due to the low-flying nature of these solitary bees, vehicle strikes can be expected to cause mortality in bisected populations. WSDOT will be able to understand the impacts of the proposed highway to these important alfalfa pollinators and make recommendations to minimize the road’s effects.

Studies on characters for identification of Apis and non Apis bees on coriander

Coriander is used as a strip crop to attract pollinators in order to facilitate pollination of major crops. This strip crop planting is important in determining the occurrence and abundance of pollinators in a locality. Amongst various insect pollinators, bees accomplish more than 80% of insect pollination. The wild bees including bumble bees, leaf cutting bees, alkali bees and carpenter bees are especially adapted for gathering pollen and nectar from flowers. In the present study insect pollinators were collected by fluorescent pan traps, scan sampling and sweep net during March, 2013–2014. An effort was made to study and develop keys for identification of Apis and non Apis bees. All the samples were identified on the basis of tongue length as long tongue and short tongue bees. The bees collected on coriander bloom represent the family Megachilidae, Halictidae and Apidae were found on coriander bloom. Most of the bees belong to genus Halictus having 3 different species (Family Halictidae), one species of family Megachilidae and two species of family Apidae.

Support for the reproductive ground plan hypothesis in a solitary bee: links between sucrose response and reproductive status.

In social bees, foraging behaviour is correlated with reproductive status and sucrose sensitivity via endocrine pathways. This association led to the hypothesis that division of labour in social insect societies is derived from an ancestral ground plan that functions to synchronize dietary preferences with reproductive needs in solitary insects. However, the relationship between these traits is unknown for solitary bees, which represent the ancestral state of social bees. We used the proboscis extension response assay to measure sucrose response among reproductive females of the solitary alkali bee (Nomia melanderi) as a function of acute juvenile hormone (JH) treatments and reproductive physiology. We also tested long-term effects of JH on reproductive development in newly emerged females. JH did not have short-term effects on reproductive physiology or sucrose response, but did have significant long-term effects on ovary and Dufour's gland development. Dufour's gland size, not ovary development, was a significant predictor of sucrose response. This provides support for the reproductive ground plan hypothesis, because the Dufour's gland has conserved reproductive functions in bees. Differing results from this study and honeybees suggest independent origins of division of labour may have evolved via co-option of different components of a conserved ground plan.

Juvenile hormone, but not nutrition or social cues, affects reproductive maturation in solitary alkali bees (Nomia melanderi).

Eusocial insect colonies are defined by extreme variation in reproductive activity among castes, but the ancestral conditions from which this variation arose are unknown. Investigating the factors that contribute to variation in reproductive physiology among solitary insects that are closely related to social species can help to fill this gap. We experimentally tested the role of nutrition, juvenile hormone (JH) and social cues on reproductive maturation in solitary alkali bees (Halictidae: Nomia melanderi). We found that alkali bee females emerge from overwintering with small Dufour's glands and small ovaries, containing oocytes in the early stages of development. Oocyte maturation occurs rapidly, and is staggered between the two ovaries. Lab-reared females reached reproductive maturity without access to mates or nesting opportunities, and many had resorbed oocytes. Initial activation of these reproductive structures does not depend on pollen consumption, though dietary protein or lipids may be necessary for long-term reproductive activity. JH is likely to be a limiting factor in alkali bee reproductive activation, as females treated with JH were more likely to develop mature oocytes and Dufour's glands. Unlike for related social bees, the effects of JH were not suppressed by the presence of older, reproductive females. These results provide valuable insight into the factors that influence reproductive activity in an important native pollinator, and those that may have been particularly influential in the evolution of reproductive castes.

Impact of Global Climate Change on Pollinator Diversity and Conservation: Current Issues and Future Challenges

Over 75% of the major world crops and 80% of all flowering plant species rely on animal pollinators. Of the hundred or so animal-pollinated crops which make up most of the world's food supply, 15% are pollinated by domestic bees, while at least 80% are pollinated by wild bee species and other wildlife. Most of the 25, 000 to 30, 000 species of bees are effective pollinators, and together with moths, flies, wasps, beetles and butterflies, make up the majority of pollinating species. Vertebrate pollinators include bats, non-flying mammals (several species of monkey, rodents, lemur and tree squirrels etc.) and birds (humming birds, sun birds, honey creepers and some parrot species). Current understanding of pollination process shows that, while an interesting specialized relationship exist between plants and their pollinators, healthy pollination services are best ensured by an abundant diversity of pollinators. Thus, pollinators are essential for diet diversity, biodiversity, and maintenance of natural resources. Pollinators which evolved over million of years, are eroding at a fast rate from the globe. During the past few years, many pollinators especially honey bees have been dying across the globe in unprecedented number and, no one has so far been able to prove beyond a reasonable doubt what the causes may have been. The economic implications of these deaths are immediate because honey bees are integral to the pollination of tens of millions of dollars of cash crops in the world. Despite much of the world's agriculture relying on pollination by honeybees, especially European honeybees, their number across the globe has also declined. Many other pollinators such as digger bees, sweat bees, alkali bees, squash bees, leafcutter bees, carpenter bees, mason bees, and shaggy fuzzy foot bees could also be on decline, but data providing unambiguous documentation of trends are simply not available. Threats to pollinators and the services they provide are perceived to be increasing around the world and are mainly man-made in origin. Climate change could be a major factor in weakening the bees and has affected the pollination of crops in many agricultural areas. An attempt has been made to know the causes behind the decline of pollinators, especially in relation to climate change, their conservation and management and impact of declining pollinator population on horticulture in the changed global scenario.

Timing and size of daily pollen meals eaten by adult females of a solitary bee (Nomia melanderi) (Apiformes: Halictidae)

Pollen feeding by solitary bees has been studied mainly with their larvae, overlooking pollen feeding by adults. To address this knowledge gap, we determined the amounts and temporal (daily and lifetime) schedules of pollen consumption by freely nesting, adult females of the alkali bee (Nomia melanderi, Halictidae). Nesting females of known ages were taken at different hours of the day from nesting aggregations managed for alfalfa pollination in southeastern Washington State (USA). Each dissected bee was visually scored for pollen fill of the crop, midgut, and hindgut; we also quantified the crop’s pollen capacity. Our dissections of 188 bees show that adult females ate pollen daily for at least the first 2 weeks following emergence. Most bees (85 %) had pollen boluses in one or more gut regions, indicating active pollen feeding. Pollen masses were most likely in the midgut; the daily volume consumed usually filled both the crop and midgut at least once. Full crops contained 34,000 alfalfa pollen grains, equivalent to <20 % of a full scopal load and 0.8 % of the pollen in a nest provision. Proportionately more females ate pollen as the day progressed, indicated by pollen masses in the crop. By early evening, crops of all bees were filled with pollen. Our study reveals the dietary importance of regular pollen feeding for nesting adult female solitary bees, and not just their larvae, with implications for bee foraging ecology, dietary physiology, reproduction, toxicology, and pollination ecology.

Manipulation of soil temperatures to influence brood emergence in the alkali bee (Nomia melanderi)

Soils in beds of commercially managed Nomia melanderi were manipulated with surface treatments to reduce or increase temperatures at nest depths of 20 cm. Modifying soil temperatures affected pupation rate and emergence date of N. melanderi. In 2010, white chalk dust delayed peak bee emergence by one week, and clear plastic mulch initiated peak emergence one week earlier, significantly increasing overall bee emergence compared to uncovered areas. In 2011, treatments included white chalk dust and plastic agricultural sheets including clear, red, black, white-on-black, blue, and brown. In 2011, clear plastic sheeting initiated early emergence while white chalk dust and white-on-black plastic plots delayed emergence. Expediting or postponing N. melanderi emergence could potentially allow alfalfa seed producers to extend the bees’ foraging season over a greater time period, subsequently increasing pollination, seed set, and economic returns.

The positive contribution of invertebrates to sustainable agriculture and food security.

Abstract This study focuses on three main groups of organisms: soil invertebrates, biological control agents (BCAs) and pollinators. These groups play key roles in agricultural systems, and have the potential to be used, moved or manipulated for the benefit of agriculture. Soil invertebrates are a key component of agricultural landscapes. They participate in essential soil processes that maintain healthy productive soils in the face of changing environmental conditions. Reducing the diversity of a community of soil invertebrates reduces its beneficial functions and services, with drastic ecological effects such as long-term deterioration of soil fertility and agricultural productive capacity. The introduction of a keystone species may have detrimental or beneficial effects depending on the context. The interaction between soil invertebrates and soil micro-organisms is critical: the activities of soil invertebrates regulate microbial activity in soils, and micro-organisms enter into intimate relationships with soil invertebrates to help them degrade highly complex compounds such as cellulose. Different groups of invertebrates provide biological control of crop pests. In many situations, they form the basis of, and tools for, the integrated pest management (IPM) approach. Given that the losses caused by pre- and post-harvest pests can be very substantial, the potential benefits of using invertebrates as BCAs are vast, but as yet only partially tapped. The potential for soil invertebrates to assist in this function is still largely unknown. Pollination services by animals, especially by insects, are among the most widespread and important processes that structure ecological communities in both natural and agricultural landscapes. An estimated 60-90% of the world's flowering plants - including a range of economically important species - depend on insects for pollination. Crop pollination used to be (and often still is) provided by wild pollinators spilling over from natural and semi-natural habitats close to crop fields. This service has generally been free and therefore has received little attention in agricultural management. If wild pollinators are lacking or additional pollination is required, as is the case in many intensive agricultural production systems, farmers in some developed countries can buy or rent managed honeybees or sometimes other species (e.g. bumblebees, alfalfa leafcutter bees and alkali bees). Both options - i.e. use of wild species and managed bees - have recently come under pressure, a development that is sometimes referred to as the 'pollination crisis'. Of the interactions and overlaps between these key groups, that between soil invertebrates and BCAs is the most important, and further research is needed to evaluate the scope and impact of manipulation of the soil ecosystem to conserve or encourage beneficial BCAs.