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ABSTRACT Neonicotinoids (NNIs) are the most commonly used insecticides in the world and clothianidin, a type of NNI, is commonly found in honey bee collected pollen. Clothianidin has several negative effects on honey bee health and behaviour, but whether and how it might impact learning and memory remains unclear. Therefore, we exposed honey bee workers to a field‐realistic oral dose of clothianidin for 7 days to assess their sugar responsiveness, and olfactory learning and memory using the proboscis extension response paradigm. Sugar responsiveness impacts important colony‐level traits, such as onset of foraging, that help maintain colony homeostasis as well as impacts learning and memory. We then measured how clothianidin alters protein expression in the brain in an effort to understand the mechanism(s) of clothianidin's effects. Clothianidin‐exposed bees had impaired sugar responsiveness, but no effect was seen on learning and memory. We identified 5069 protein groups and showed that the exposed bees had fewer detectable proteins. The exposed bees also had fewer mitochondrial respiration proteins, as well as reduced levels of nicotinic acetylcholine receptor α7 (nAChRα7) subunit (one of the targets of clothianidin) and reduced levels of acetylcholinesterase and acetylcholinesterase‐2 levels. In the exposed bees, the levels of nAChRα7 subunit positively correlated with sugar responsiveness, providing evidence for a possible mechanical explanation. [ABSTRACT FROM AUTHOR]

Highbush blueberry pollination depends on managed honey bees (Apis mellifera L.) for adequate fruit sets; however, beekeepers have raised concerns about the poor health of colonies after pollinating this crop. Postulated causes include agrochemical exposure, nutritional deficits, and interactions with parasites and pathogens, particularly Melisococcus plutonius [(ex. White) Bailey and Collins, Lactobacillales: Enterococcaceae], the causal agent of European foulbrood disease, but other pathogens could be involved. To broadly investigate common honey bee pathogens in relation to blueberry pollination, we sampled adult honey bees from colonies at time points corresponding to before (t1), during (t2), at the end (t3), and after (t4) highbush blueberry pollination in British Columbia, Canada, across 2 years (2020 and 2021). Nine viruses, as well as M. plutonius , Vairimorpha ceranae, and V. apis [Tokarev et al. Microsporidia: Nosematidae; formerly Nosema ceranae (Fries et al.) and N. apis (Zander)], were detected by PCR and compared among colonies located near and far from blueberry fields. We found a significant interactive effect of time and blueberry proximity on the multivariate pathogen community, mainly due to differences at t4 (corresponding to ~6 wk after the beginning of the pollination period). Post hoc comparisons of pathogens in near and far groups at t4 showed that detections of sacbrood virus (SBV), which was significantly higher in the near group, not M. plutonius , was the primary driver. Further research is needed to determine if the association of SBV with highbush blueberry pollination is contributing to the health decline that beekeepers observe after pollinating this crop. [ABSTRACT FROM AUTHOR]

Bees are the most important insect pollinators of the crops humans grow, and Apis mellifera, the Western honey bee, is the most commonly managed species for this purpose. In addition to providing agricultural services, the complex biology of honey bees has been the subject of scientific study since the 18th century, and the intricate behaviors of honey bees and ants, fellow hymenopterans, inspired much sociobiological inquest. Unfortunately, honey bees are constantly exposed to parasites, pathogens, and xenobiotics, all of which pose threats to their health. Despite our curiosity about and dependence on honey bees, defining the molecular mechanisms underlying their interactions with biotic and abiotic stressors has been challenging. The very aspects of their physiology and behavior that make them so important to agriculture also make them challenging to study, relative to canonical model organisms. However, because we rely on A. mellifera so much for pollination, we must continue our efforts to understand what ails them. Here, we review major advancements in our knowledge of honey bee physiology, focusing on immunity and detoxification, and highlight some challenges that remain. [ABSTRACT FROM AUTHOR]

Many animals have individual and social mechanisms for combating pathogens. Animals may exhibit short-term physiological tradeoffs between social and individual immunity because the latter is often energetically costly. Genetic tradeoffs between these two traits can also occur if mutations that enhance social immunity diminish individual immunity, or vice versa. Physiological tradeoffs between individual and social immunity have been previously documented in insects, but there has been no study of genetic tradeoffs involving these traits. There is strong evidence that some genes influence both innate immunity and behaviour in social insects – a prerequisite for genetic tradeoffs. Quantifying genetic tradeoffs is critical for understanding the evolution of immunity in social insects and for devising effective strategies for breeding disease-resistant pollinator populations. We conducted two experiments to test the hypothesis of a genetic tradeoff between social and individual immunity in the honey bee, Apis mellifera. First, we estimated the relative contribution of genetics to individual variation in innate immunity of honey bee workers, as only heritable traits can experience genetic tradeoffs. Second, we examined if worker bees with hygienic sisters have reduced individual innate immune response. We genotyped several hundred workers from two colonies and found that patriline genotype does not significantly influence the antimicrobial activity of a worker’s hemolymph. Further, we did not find a negative correlation between hygienic behaviour and the average antimicrobial activity of a worker’s hemolymph across 30 honey bee colonies. Taken together, our work indicates no genetic tradeoffs between hygienic behaviour and innate immunity in honey bees. Our work suggests that using artificial selection to increase hygienic behaviour of honey bee colonies is not expected to concurrently compromise individual innate immunity of worker bees. [ABSTRACT FROM AUTHOR]

Many animals have individual and social mechanisms for combating pathogens. Animals may exhibit short-term physiological tradeoffs between social and individual immunity because the latter is often energetically costly. Genetic tradeoffs between these two traits can also occur if mutations that enhance social immunity diminish individual immunity, or vice versa. Physiological tradeoffs between individual and social immunity have been previously documented in insects, but there has been no study of genetic tradeoffs involving these traits. There is strong evidence that some genes influence both innate immunity and behaviour in social insects – a prerequisite for genetic tradeoffs. Quantifying genetic tradeoffs is critical for understanding the evolution of immunity in social insects and for devising effective strategies for breeding disease-resistant pollinator populations. We conducted two experiments to test the hypothesis of a genetic tradeoff between social and individual immunity in the honey bee, Apis mellifera. First, we estimated the relative contribution of genetics to individual variation in innate immunity of honey bee workers, as only heritable traits can experience genetic tradeoffs. Second, we examined if worker bees with hygienic sisters have reduced individual innate immune response. We genotyped several hundred workers from two colonies and found that patriline genotype does not significantly influence the antimicrobial activity of a worker’s hemolymph. Further, we did not find a negative correlation between hygienic behaviour and the average antimicrobial activity of a worker’s hemolymph across 30 honey bee colonies. Taken together, our work indicates no genetic tradeoffs between hygienic behaviour and innate immunity in honey bees. Our work suggests that using artificial selection to increase hygienic behaviour of honey bee colonies is not expected to concurrently compromise individual innate immunity of worker bees. [ABSTRACT FROM AUTHOR]

New genomic resources and genetic tools of the past few years have advanced the nematode genus Caenorhabditis as a model for comparative biology. However, understanding of natural genetic variation at molecular and phenotypic levels remains rudimentary for most species in this genus, and for C. briggsae in particular. Here we characterize phenotypic variation in C. briggsae's sensitivity to the potentially important and variable environmental toxin, ethanol, for globally diverse strains. We also quantify nucleotide variation in a new sample of 32 strains from four continents, including small islands, and for the closest-known relative of this species (C. sp. 9). We demonstrate that C. briggsae exhibits little heritable variation for the effects of ethanol on the norm of reaction for survival and reproduction. Moreover, C. briggsae does not differ significantly from C. elegans in our assays of its response to this substance that both species likely encounter regularly in habitats of rotting fruit and vegetation. However, we uncover drastically more molecular genetic variation than was known previously for this species, despite most strains, including all island strains, conforming to the broad biogeographic patterns described previously. Using patterns of sequence divergence between populations and between species, we estimate that the self-fertilizing mode of reproduction by hermaphrodites in C. briggsae likely evolved sometime between 0.9 and 10 million generations ago. These insights into C. briggsae's natural history and natural genetic variation greatly expand the potential of this organism as an emerging model for studies in molecular and quantitative genetics, the evolution of development, and ecological genetics.