Bumblebee Bombus Research Articles

Functional impact of subunit composition and compensation on Drosophila melanogaster nicotinic receptors-targets of neonicotinoids.

Neonicotinoid insecticides target insect nicotinic acetylcholine receptors (nAChRs) and their adverse effects on non-target insects are of serious concern. We recently found that cofactor TMX3 enables robust functional expression of insect nAChRs in Xenopus laevis oocytes and showed that neonicotinoids (imidacloprid, thiacloprid, and clothianidin) exhibited agonist actions on some nAChRs of the fruit fly (Drosophila melanogaster), honeybee (Apis mellifera) and bumblebee (Bombus terrestris) with more potent actions on the pollinator nAChRs. However, other subunits from the nAChR family remain to be explored. We show that the Dα3 subunit co-exists with Dα1, Dα2, Dβ1, and Dβ2 subunits in the same neurons of adult D. melanogaster, thereby expanding the possible nAChR subtypes in these cells alone from 4 to 12. The presence of Dα1 and Dα2 subunits reduced the affinity of imidacloprid, thiacloprid, and clothianidin for nAChRs expressed in Xenopus laevis oocytes, whereas the Dα3 subunit enhanced it. RNAi targeting Dα1, Dα2 or Dα3 in adults reduced expression of targeted subunits but commonly enhanced Dβ3 expression. Also, Dα1 RNAi enhanced Dα7 expression, Dα2 RNAi reduced Dα1, Dα6, and Dα7 expression and Dα3 RNAi reduced Dα1 expression while enhancing Dα2 expression, respectively. In most cases, RNAi treatment of either Dα1 or Dα2 reduced neonicotinoid toxicity in larvae, but Dα2 RNAi enhanced neonicotinoid sensitivity in adults reflecting the affinity-reducing effect of Dα2. Substituting each of Dα1, Dα2, and Dα3 subunits by Dα4 or Dβ3 subunit mostly increased neonicotinoid affinity and reduced efficacy. These results are important because they indicate that neonicotinoid actions involve the integrated activity of multiple nAChR subunit combinations and counsel caution in interpreting neonicotinoid actions simply in terms of toxicity.

Responses in honeybee and bumblebee activity to changes in weather conditions

Insect pollination, and in particular pollination by bees, is a highly valued ecosystem service that ensures plant reproduction and the production of high-quality crops. Bee activity is known to be influenced by the weather, and as the global climate continues to change, the flying frequency and foraging behaviour of bees may also change. To maximise the benefits of pollination in a changing world, we must first understand how current weather conditions influence the activity of different bee species. This is of particular interest in a country such as Ireland where inclement weather conditions are nominally sub-optimal for foraging. We observed honeybee (Apis mellifera) and buff-tailed bumblebee (Bombus terrestris) activity across a variety of weather conditions at seven apple orchards to determine how four weather variables (temperature, relative humidity, solar radiation, wind) influenced the flight activity of each species. Each orchard contained three honeybee and three bumblebee colonies, and so we were able to observe a colony of each species concurrently in the same weather conditions. Overall, honeybees were more sensitive to changes in weather than bumblebees and could be more predisposed to future changes in within-day weather conditions. Our results indicate bumblebees could compensate for low honeybee activity in inclement conditions, which supports the theory that pollinator diversity provides resilience. This may be particularly important in management of pollinators in crops that flower in the spring when weather is more variable, and to allow varied responses to global climate change.

Commercial Bombus impatiens colonies function as ecological traps for wild queens

Abstract In response to anthropogenic environmental change, the cues that animals use throughout their lifecycle to optimize fitness may become unreliable, resulting in an ecological trap. Here we investigated whether commercial bumble bee Bombus impatiens colonies managed for early spring crop pollination act as ecological traps for wild nest‐searching Bombus queens by subverting their natural nest usurpation behaviour. An average of 10 dead wild queens were recovered from each standard colony during the 2‐week period of the experiment, but colonies with queen excluders were successful in preventing wild queen deaths. The use of queen excluders did not impact colony performance in terms of resident queen survival, colony reproduction, colony weight gain or worker body size. Sites where wild nest‐searching queens were small had higher rates of failed usurpation, suggesting smaller‐sized queens are disproportionately at risk from failed usurpation. Furthermore, sites where commercial colonies without queen excluders were introduced for spring crop pollination had fewer bumble bee visits to a later‐blooming crop compared to sites without commercial colonies. Synthesis and applications. Our findings reveal a novel mechanism by which commercial colonies can negatively impact wild bumble bee populations and their pollination services. At the same time, we demonstrate a simple and inexpensive risk mitigation tool—a queen excluder—was 100% effective at eliminating this risk without compromising colony performance. Commercial colonies used outdoors during the bumble bee nest‐searching period should be fit with queen excluders to prevent negative impacts on wild pollinator communities and their services.

Higher floral richness promotes rarer bee communities across remnant and reconstructed tallgrass prairies, though remnants contain higher abundances of a threatened bumble bee (Bombus Latreille)

Managing and restoring tallgrass prairie ecosystem is an important form of pollinator conservation in the Midwestern United States. Prairie reconstruction has been found to enhance native bee diversity and abundance, but it is less clear if prairie reconstruction conserves species thought to be at-risk. We reanalyze a previously published dataset on the bee communities of reconstructed and remnant prairie in the US state of Minnesota to investigate how the abundance of at-risk species respond to local factors, such as floral diversity and prairie type (reconstructed or remnant), and landscape factors, in the form of surrounding agricultural production. We defined at-risk species in two ways. For bumble bees, we used the IUCN red list of bumble bees for North America. As other species in the bee community have not been systematically evaluated, we used an independent data set to calculate a community-level measure of rarity as a proxy for species risk. We calculated community rarity metrics using a Species Weighted Mean (SWM) approach, with species level rarity (relative abundance and site occurrence) derived from a regional dataset comprised of over 30,000 specimens from across the US state of Minnesota. We found that the declining bumble bee Bombus fervidus had higher abundances in remnant rather than reconstructed prairies. Floral richness was associated with rarer bee communities (lower SWM values) across remnant and reconstructed prairies. We show that planting and managing prairies for floral diversity promotes bee communities with rarer species, but that remnants better support some at-risk species such as Bombus fervidus.

Bumblebee cognitive abilities are robust to changes in colony size

Eusocial insect colonies act as a superorganism, which can improve their ability to buffer the negative impact of some anthropogenic stressors. However, this buffering effect can be affected by anthropogenic factors that reduce their colony size. A reduction in colony size is known to negatively affect several parameters like brood maintenance or thermoregulation, but the effects on behaviour and cognition have been largely overlooked. It remains unclear how a sudden change in group size, such as that which might be caused by anthropogenic stressors, affects individual behaviour within a colony. In this study, the bumblebee Bombus terrestris was used to study the effect of social group size on behaviour by comparing the associative learning capabilities of individuals from colonies that were unmanipulated, reduced to a normal size (a colony of 100 workers) or reduced to a critically low but functional size (a colony of 20 workers). The results demonstrated that workers from the different treatments performed equally well in associative learning tasks, which also included no significant differences in the learning capacity of workers that had fully developed after the colony size manipulation. Furthermore, we found that the size of workers had no impact on associative learning ability. The learning abilities of bumblebee workers were thus resilient to the colony reduction they encountered. Our study is a first step towards understanding how eusocial insect cognition can be impacted by drastic reductions in colony size.Significance statementWhile anthropogenic stressors can reduce the colony size of eusocial insects, the impact of this reduction is poorly studied, particularly among bumblebees. We hypothesised that colony size reduction would affect the cognitive capacity of worker bumblebees as a result of fewer social interactions or potential undernourishment. Using differential conditioning, we showed that drastic reductions in colony size have no effect on the associative learning capabilities of the bumblebee Bombus terrestris and that this was the same for individuals that were tested just after the colony reduction and individuals that fully developed under the colony size reduction. We also showed that body size did not affect learning capabilities. This resilience could be an efficient buffer against the ongoing impacts of global change.

Whole genome demographic models indicate divergent effective population size histories shape contemporary genetic diversity gradients in a montane bumble bee.

Understanding historical range shifts and population size variation provides an important context for interpreting contemporary genetic diversity. Methods to predict changes in species distributions and model changes in effective population size (N e) using whole genomes make it feasible to examine how temporal dynamics influence diversity across populations. We investigate N e variation and climate-associated range shifts to examine the origins of a previously observed latitudinal heterozygosity gradient in the bumble bee Bombus vancouverensis Cresson (Hymenoptera: Apidae: Bombus Latreille) in western North America. We analyze whole genomes from a latitude-elevation cline using sequentially Markovian coalescent models of N e through time to test whether relatively low diversity in southern high-elevation populations is a result of long-term differences in N e. We use Maxent models of the species range over the last 130,000 years to evaluate range shifts and stability. N e fluctuates with climate across populations, but more genetically diverse northern populations have maintained greater N e over the late Pleistocene and experienced larger expansions with climatically favorable time periods. Northern populations also experienced larger bottlenecks during the last glacial period, which matched the loss of range area near these sites; however, bottlenecks were not sufficient to erode diversity maintained during periods of large N e. A genome sampled from an island population indicated a severe postglacial bottleneck, indicating that large recent postglacial declines are detectable if they have occurred. Genetic diversity was not related to niche stability or glacial-period bottleneck size. Instead, spatial expansions and increased connectivity during favorable climates likely maintain diversity in the north while restriction to high elevations maintains relatively low diversity despite greater stability in southern regions. Results suggest genetic diversity gradients reflect long-term differences in N e dynamics and also emphasize the unique effects of isolation on insular habitats for bumble bees. Patterns are discussed in the context of conservation under climate change.

DNA methylation is associated with codon degeneracy in a species of bumblebee

Social insects display extreme phenotypic differences between sexes and castes even though the underlying genome can be almost identical. Epigenetic processes have been proposed as a possible mechanism for mediating these phenotypic differences. Using whole genome bisulfite sequencing of queens, males, and reproductive female workers we have characterised the sex- and caste-specific methylome of the bumblebee Bombus terrestris. We have identified a potential role for DNA methylation in histone modification processes which may influence sex and caste phenotypic differences. We also find differentially methylated genes generally show low levels of DNA methylation which may suggest a separate function for lowly methylated genes in mediating transcriptional plasticity, unlike highly methylated genes which are usually involved in housekeeping functions. We also examined the relationship between the underlying genome and the methylome using whole genome re-sequencing of the same queens and males. We find DNA methylation is enriched at zero-fold degenerate sites. We suggest DNA methylation may be acting as a targeted mutagen at these sites, providing substrate for selection via non-synonymous changes in the underlying genome. However, we did not see any relationship between DNA methylation and rates of positive selection in our samples. In order to fully assess a possible role for DNA methylation in adaptive processes a specifically designed study using natural population data is needed.

Flower patterns improve foraging efficiency in bumblebees by guiding approach flight and landing

Abstract Colourful patterns on flowers are thought to benefit both pollinators and the plants they visit, by increasing the plants' pollination success via an increased foraging efficiency of the pollinators. This increased efficiency is assumed to result from a guidance effect of the flower patterns, correspondingly termed ‘nectar guides’, which indicate the position of the nectary to visiting pollinators, thus reducing their flower handling time. Although it is well established that flower patterns play an important role in flower choice, the mechanisms by which they improve the foraging efficiency of flower‐visiting insects remain poorly understood. In this study, we quantified the contributions of patterns to all phases of flower interaction in the buff‐tailed bumblebee Bombus terrestris. We analysed the bees' flight paths, as well as landing positions and walking tracks on artificial flowers with different pattern types. We reveal that flower patterns reduced the overall flower handling time of the bees by up to 30%, by guiding their approach flight, landing positions and departure decisions. Surprisingly, we observed no improvement in nectary discovery time after the bees landed on the flower. Since we tested experienced foragers, which represent the majority of insect pollinators active in nature, the newly described nectary‐independent guidance effects of flower patterns are of high ecological relevance. Read the free Plain Language Summary for this article on the Journal blog.

Biogeography, climate, and land use create a mosaic of parasite risk in native bumble bees

Host-parasite interactions are crucial to the regulation of host population growth, as they often impact both long-term population stability and ecological functioning. Animal hosts navigate a number of environmental conditions, including local climate, anthropogenic land use, and varying degrees of spatial isolation, all of which can mediate parasitism exposure. Despite this, we know little about the potential for these environmental conditions to impact pathogen prevalence at biogeographic scales, especially for key ecosystem service-providing animals. Bees are essential pollination providers that may be particularly sensitive to biogeography, climate, and land-use as these factors are known to limit bee dispersal and contribute to underlying population genetic variation, which may also impact host-parasite interactions. Importantly, many native bumble bee species have recently shown geographic range contractions, reduced genetic diversity, and increased parasitism rates, highlighting the potential importance of interacting and synergistic stressors. In this study, we incorporate spatially explicit environmental, biogeographic, and land-use data in combination with genetically derived host population data to conduct a large-scale epidemiological assessment of the drivers of pathogen prevalence across >1000 km for a keystone western US pollinator, the bumble bee Bombus vosnesenskii. We found high rates of infection from Crithidia bombi and C. expoekii, which show strong spatial autocorrelation and which were more prevalent in northern latitudes. We also show that land use barriers best explained differences in parasite prevalence and parasite community composition, while precipitation, elevation, and B. vosnesenskii nesting density were important drivers of parasite prevalence. Overall, our results demonstrate that human land use can impact critical host-parasite interactions for native bees at massive spatial scales. Further, our work indicates that disease-related survey and conservation measures should take into account the independent and interacting influences of climate, biogeography, land use, and local population dynamics.

Resilience of bumblebee foraging behavior despite colony size reduction.

Foraging behavior is driven by diverse factors, notably life history traits. Foraging strategies are particularly complex among eusocial species such as bumblebees, because they depend primarily on the needs of the colony, rather than on individual's needs. Colony size, i.e. the number of workers in a colony vary a lot among eusocial insects. While a large colony can be adaptive, several drivers can strongly decrease colony size, like pesticides or high temperatures. In this study, we used the bumblebee Bombus terrestris to assess if workers adapted their foraging behavior to such rapid decreases in colony size. We conducted the foraging experiments with two plant species commonly used by bumblebees: Borago officinalis and Echium plantagineum. Several foraging parameters were measured: foraging time, number of foraging trips, number of workers foraging, handling time and visiting rate. Despite a drastic reduction in colony size, nearly all the foraging behavior parameters were unaffected by the colony size reduction. Colonies that were subject to a large decrease in workers instead displayed high resilience and behavioral plasticity by quickly increasing the proportion of foragers. Ultimately, further research should assess if this consistency in foraging behavior also allows bumblebee colonies to maintain both the efficiency of the resources collection and pollination.

Field-realistic acute exposure to glyphosate-based herbicide impairs fine-color discrimination in bumblebees.

Pollinator decline is a grave challenge worldwide. One of the main culprits for this decline is the widespread use of, and pollinators' chronic exposure to, agrochemicals. Here, we examined the effect of a field-realistic dose of the world's most commonly used pesticide, glyphosate-based herbicide (GBH), on bumblebee cognition. We experimentally tested bumblebee (Bombus terrestris) color and scent discrimination using acute GBH exposure, approximating a field-realistic dose from a day's foraging in a patch recently sprayed with GBH. In a 10-color discrimination experiment with five learning bouts, GBH treated bumblebees' learning rate fell to zero by third learning bout, whereas the control bees increased their performance in the last two bouts. In the memory test, the GBH treated bumblebees performed to near chance level, indicating that they had lost everything they had learned during the learning bouts, while the control bees were performing close to the level in their last learning bout. However, GBH did not affect bees' learning in a 2-color or 10-odor discrimination experiment, which suggests that the impact is limited to fine color learning and does not necessarily generalize to less specific tasks or other modalities. These results indicate that the widely used pesticide damages bumblebees' fine-color discrimination, which is essential to the pollinator's individual success and to colony fitness in complex foraging environments. Hence, our study suggests that acute sublethal exposure to GBH poses a greater threat to pollination-based ecosystem services than previously thought, and that tests for learning and memory should be integrated into pesticide risk assessment.

Morphological Variation in Bumblebees (Bombus terrestris) (Hymenoptera: Apidae) After Three Decades of an Island Invasion.

Introduced social insects can be highly invasive outside of their native range. Around the world, the introduction and establishment of the eusocial bumblebee Bombus terrestris (L. 1758) (Hymenoptera: Apidae) has negatively impacted native pollinators and ecosystems. Understanding how morphological variation is linked to environmental variation across invasive ranges can indicate how rapidly species may be diverging or adapting across novel ranges and may assist with predicting future establishment and spread. Here we investigate whether B. terrestris shows morphological variation related to environmental variation across the island of Tasmania (Australia) where it was introduced three decades ago. We collected 169 workers from 16 sites across Tasmania and related relative abundance and morphology to landscape-wide climate, land use, and vegetation structure. We found weak morphological divergence related to environmental conditions across Tasmania. Body size of B. terrestris was positively associated with the percentage of urban land cover, a relationship largely driven by a single site, possibly reflecting high resource availability in urban areas. Proboscis length showed a significant negative relationship with the percentage of pasture. Wing loading and local abundance were not related to the environmental conditions within sites. Our results reflect the highly adaptable nature of B. terrestris and its ability to thrive in different environments, which may have facilitated the bumblebee's successful invasion across Tasmania.

Bombus haemorrhoidalis Abundance in Comparison with other Insect Pollinators from Rawalakot, Azad Jammu and Kashmir Pakistan

Bumblebees are important pollinators in both wild and managed cropping system and from the last few decades these bees are using as commercial pollinators to enhance the yield in greenhouse and glasshouse crops like tomato, cucumber and bell pepper. Indigenous bumblebee Bombus haemorrhoidalis, is an important pollinator of Northern Pakistan and plays key role in wild pollination. Present study was conducted to explore the relative abundance of B. haemorrhoidalis in comparison with other common insect pollinators. Monthly surveys were conducted from March, 2017 to February, 2018 to record the abundance of different pollinators. Hymenopteran pollinators were found as most abundant insect order with six species following by Lepidopteran pollinators with five species. B. haemorrhoidalis recorded with maximum abundance and Syrphus spp were recorded with second highest abundance. Maximum diversity of pollinators was observed at Banjosa and Paniola areas. Such ecological information about pollinators is important for possible conservation program in this region and it is also will be helpful in conservation program of Bumblebees in future

Structure of the Flight Muscle Thick Filament from the Bumble Bee, Bombus ignitus, at 6 Å Resolution.

Four insect orders have flight muscles that are both asynchronous and indirect; they are asynchronous in that the wingbeat frequency is decoupled from the frequency of nervous stimulation and indirect in that the muscles attach to the thoracic exoskeleton instead of directly to the wing. Flight muscle thick filaments from two orders, Hemiptera and Diptera, have been imaged at a subnanometer resolution, both of which revealed a myosin tail arrangement referred to as “curved molecular crystalline layers”. Here, we report a thick filament structure from the indirect flight muscles of a third insect order, Hymenoptera, the Asian bumble bee Bombus ignitus. The myosin tails are in general agreement with previous determinations from Lethocerus indicus and Drosophila melanogaster. The Skip 2 region has the same unusual structure as found in Lethocerus indicus thick filaments, an α-helix discontinuity is also seen at Skip 4, but the orientation of the Skip 1 region on the surface of the backbone is less angled with respect to the filament axis than in the other two species. The heads are disordered as in Drosophila, but we observe no non-myosin proteins on the backbone surface that might prohibit the ordering of myosin heads onto the thick filament backbone. There are strong structural similarities among the three species in their non-myosin proteins within the backbone that suggest how one previously unassigned density in Lethocerus might be assigned. Overall, the structure conforms to the previously observed pattern of high similarity in the myosin tail arrangement, but differences in the non-myosin proteins.

Investigating the effects of glyphosate on the bumblebee proteome and microbiota

Glyphosate is one of the most widely used herbicides globally. It acts by inhibiting an enzyme in an aromatic amino acid synthesis pathway specific to plants and microbes, leading to the view that it poses no risk to other organisms. However, there is growing concern that glyphosate is associated with health effects in humans and an ever-increasing body of evidence that suggests potential deleterious effects on other animals including pollinating insects such as bees. Although pesticides have long been considered a factor in the decline of wild bee populations, most research on bees has focussed on demonstrating and understanding the effects of insecticides. To assess whether glyphosate poses a risk to bees, we characterised changes in survival, behaviour, sucrose solution consumption, the digestive tract proteome, and the microbiota in the bumblebee Bombus terrestris after chronic exposure to field relevant doses of technical grade glyphosate or the glyphosate-based formulation, RoundUp Optima+®. Regardless of source, there were changes in response to glyphosate exposure in important cellular and physiological processes in the digestive tract of B. terrestris, with proteins associated with oxidative stress regulation, metabolism, cellular adhesion, the extracellular matrix, and various signalling pathways altered. Interestingly, proteins associated with endocytosis, oxidative phosphorylation, the TCA cycle, and carbohydrate, lipid, and amino acid metabolism were differentially altered depending on whether the exposure source was glyphosate alone or RoundUp Optima+®. In addition, there were alterations to the digestive tract microbiota of bees depending on the glyphosate source No impacts on survival, behaviour, or food consumption were observed. Our research provides insights into the potential mode of action and consequences of glyphosate exposure at the molecular, cellular and organismal level in bumblebees and highlights issues with the current honeybee-centric risk assessment of pesticides and their formulations, where the impact of co-formulants on non-target organisms are generally overlooked.

The diversity, evolution, and development of setal morphologies in bumble bees (Hymenoptera: Apidae: Bombus spp.).

Bumble bees are characterized by their thick setal pile that imparts aposematic color patterns often used for species-level identification. Like all bees, the single-celled setae of bumble bees are branched, an innovation thought important for pollen collection. To date no studies have quantified the types of setal morphologies and their distribution on these bees, information that can facilitate understanding of their adaptive ecological function. This study defines several major setal morphotypes in the common eastern bumble bee Bombus impatiens Cresson, revealing these setal types differ by location across the body. The positions of these types of setae are similar across individuals, castes, and sexes within species. We analyzed the distribution of the two most common setal types (plumose and spinulate) across the body dorsum of half of the described bumble bee species. This revealed consistently high density of plumose (long-branched) setae across bumble bees on the head and mesosoma, but considerable variation in the amount of metasomal plumosity. Variation on the metasoma shows strong phylogenetic signal at subgeneric and smaller group levels, making it a useful trait for species delimitation research, and plumosity has increased from early Bombus ancestors. The distribution of these setal types suggests these setae may serve several functions, including pollen-collecting and thermoregulatory roles, and probable mechanosensory functions. This study further examines how and when setae of the pile develop, evidence for mechanosensory function, and the timing of pigmentation as a foundation for future genetic and developmental research in these bees.

Bumblebees under pollution pressure of pesticides in urban and agrarian landscapes

Pesticides are used in anthropogenically influenced bumblebee habitats, such as agricultural fields and gardens. During their foraging flights, pollinators come into direct contact with these pollutants via e.g. contaminated food sources. There is growing proof that bees are regularly exposed to mixtures of agrochemicals, but most research has been focused on honey bees (Apis mellifera), whereas little is known about bees not belonging to the Apis genus (non-Apis). Aim of our study was to investigate the pesticide load of foraging bumblebees (Bombus terrestris) in agricultural and urban areas. We placed commercial bumblebee hives at three urban and three agrarian locations. Foragers were analysed for 24 target pesticides with focus on fungicides. In 184 out of 220 analysed field samples, residues of 15 pesticides were found. Concentrations ranged from 0.03 to 978.17 ng/g bumblebee. Most often detected pesticides were prosulfocarb (36.4% of foragers) and flutolanil (15.9%), both never documented in bumblebees before. The pesticide load was significantly different between land-uses in spring. The study highlights the importance of considering pesticide mixtures under field conditions for toxicity studies and risk assessment. The described biomonitoring approach is cheap, easy to perform and could be used to improve monitoring programs on a global scale.

Using Image Deep Learning to Measure Flight Speeds and Patterns of Honeybees (Apis mellifera) and Bumblebees (Bombus terrestris) near Their Hives

Using Image Deep Learning to Measure Flight Speeds and Patterns of Honeybees (Apis mellifera) and Bumblebees (Bombus terrestris) near Their Hives

Genetic variation and microbiota in bumble bees cross-infected by different strains of C. bombi.

The bumblebee Bombus terrestris is commonly infected by a trypanosomatid gut parasite Crithidia bombi. This system shows a striking degree of genetic specificity where host genotypes are susceptible to different genotypes of parasite. To a degree, variation in host gene expression underlies these differences, however, the effects of standing genetic variation has not yet been explored. Here we report on an extensive experiment where workers of twenty colonies of B. terrestris were each infected by one of twenty strains of C. bombi. To elucidate the host's genetic bases of susceptibility to infection (measured as infection intensity), we used a low-coverage (~2 x) genome-wide association study (GWAS), based on angsd, and a standard high-coverage (~15x) GWAS (with a reduced set from a 8 x 8 interaction matrix, selected from the full set of twenty). The results from the low-coverage approach remained ambiguous. The high-coverage approach suggested potentially relevant genetic variation in cell surface and adhesion processes. In particular, mucin, a surface mucoglycoprotein, potentially affecting parasite binding to the host gut epithelia, emerged as a candidate. Sequencing the gut microbial community of the same bees showed that the abundance of bacterial taxa, such as Gilliamella, Snodgrassella, or Lactobacillus, differed between 'susceptible' and 'resistant' microbiota, in line with earlier studies. Our study suggests that the constitutive microbiota and binding processes at the cell surface are candidates to affect infection intensity after the first response (captured by gene expression) has run its course. We also note that a low-coverage approach may not be powerful enough to analyse such complex traits. Furthermore, testing large interactions matrices (as with the full 20 x 20 combinations) for the effect of interaction terms on infection intensity seems to blur the specific host x parasite interaction effects, likely because the outcome of an infection is a highly non-linear process dominated by variation in individually different pathways of host defence (immune) responses.

Foraging discrepancy of Bombus species with native versus non–native flora in Chitwan Annapurna landscape, Nepal

We compared the foraging frequency of bumblebee ( Bombus spp) with native versus non-native flowring plants in Chitwan Annapurna Landscape (CHAL). Specimens were collected using a sweeping net along the altitudinal gradients following an accessible walking trail between 600 to 3500 m asl. The random sampling was carried in different habitat types (agriculture, forest, grassland and home garden) along the transects. The relative frequency of Bombus species was significantly vary with the flowering plant(Native types and non native cultivated, non native naturalized and invasive) in sampling rout along the altitudinal gradients. some Bombus species were found to be foraged only to the specific flowers within the study sites indicating that the specific flowering preference of certain bumblebees in the study area. The overall result indicated, the differential foraging choice of Bombus species with native and non-native plant communities in the study area.