Paternity skew in seven species of honeybees (Hymenoptera: Apidae: Apis)

Honeybees (Apis) show an extremely polyandrous mating system. In general honeybee queens mate with at least ten drones. The reproductive success of the drones is usually biased giving rise to speculations of a first or last male advantage. Especially for A. andreniformis and A. florea a first male advantage was hypothesized due to the peculiar anatomy of their male genitalia. We reanalyzed data from the literature by using a sample size calibration method to survey the differences and similarities in paternity skew among species in the genus Apis. The paternity skew among seven honeybee species differed significantly, particularly due to the rare patrilines. The sorting algorithm, i.e. the ranking of the patrilines, had, however, a considerable effect on the paternity skew pattern. The frequent patrilines appeared to be similarly distributed in all tested species. As a consequence the proposed first male advantage in the dwarf honeybees is not supported by empirical data

Genetic underpinnings of division of labor in the honeybee (Apis mellifera)

Honeybees have been studied for centuries, starting with Aristotle, who wrote the first book about bee breeding. More than 2000 years later, the honeybee entered the genomic era as the first social insect whose genome was sequenced, leading to significant insight into the molecular mechanisms underlying social behavior. In addition, gene expression studies and knockdown using RNAi have extended the understanding of social interactions. Much of the work has focused on caste determination – the mechanism that results in reproductive division of labor, division of labor within the worker caste, and worker reproduction – an essential process underlying eusociality. Here we review the molecular factors involved in caste determination and the differential regulation of caste-specific genes. Recent findings suggest that division of labor is influenced by a small number of loci showing high levels of pleiotropy, suggesting that changes in a small number of genes lead to large changes in the phenotype.German Research Foundation DFG (grants Mo 373/26-2 and Mo 373/30-1) to R.F.A.M. and the Federal Ministry for Education and Research BMBF (FKZ: 0315126) to H.M.G.L.http://www.journals.elsevier.com/trends-in-geneticshb201

Comparative analyses of the major royal jelly protein gene cluster in three Apis species with long amplicon sequencing

The western honeybee, Apis mellifera is a prominent model organism in the field of sociogenomics and a recent upgrade substantially improved annotations of the reference genome. Nevertheless, genome assemblies based on short-sequencing reads suffer from problems in regions comprising e.g. multi-copy genes. We used single-molecule nanopore-based sequencing with extensive read-lengths to reconstruct the organization of the major royal jelly protein (mrjp) region in three species of the genus Apis. Long-amplicon sequencing provides evidence for lineage-specific evolutionary fates of Apis mrjps. Whereas the most basal species, A. florea, seems to encode ten mrjps, different patterns of gene loss and retention were observed for A. mellifera and A. dorsata. Furthermore, we show that a previously reported pseudogene in A. mellifera, mrjp2-like, is an assembly artefact arising from short read sequencing.The German Research Foundation (Deutsche Forschungsgemeinschaft - DFG, Grant MO 373/32-1 to RFAM).http://dnaresearch.oxfordjournals.orgam2017Zoology and Entomolog

A selective sweep in a Varroa destructor resistant honeybee (Apis mellifera) population

The mite Varroa destructor is one of the most dangerous parasites of the Western honeybee (Apis mellifera) causing enormous colony losses worldwide. Various chemical treatments for the control of the Varroa mite are currently in use, which, however, lead to residues in bee products and often to resistance in mites. This facilitated the exploration of alternative treatment methods and breeding for mite resistant honeybees has been in focus for breeders in many parts of the world with variable results. Another approach has been applied to a honeybee population on Gotland (Sweden) that was exposed to natural selection and survived Varroa-infestation for more than 10 years without treatment. Eventually this population became resistant to the parasite by suppressing the reproduction of the mite. A previous QTL mapping study had identified a region on chromosome 7 with major loci contributing to the mite resistance. Here, a microsatellite scan of the significant candidate QTL regions was used to investigate potential footprints of selection in the original population by comparing the study population on Gotland before (2000) and after selection (2007). Genetic drift had caused an extreme loss of genetic diversity in the 2007 population for all genetic markers tested. In addition to this overall reduction of heterozygosity, two loci on chromosome 7 showed an even stronger and significant reduction in diversity than expected from genetic drift alone. Within the selective sweep eleven genes are annotated, one of them being a putative candidate to interfere with reduced mite reproduction. A glucose-methanol-choline oxidoreductase (GMCOX18) might be involved in changing volatiles emitted by bee larvae that might be essential to trigger oogenesis in Varroa.BEEDOC research network (EU FP7 to RFAM and IF, EU contract number: FP7-KBBE-2009-3 244956 CP-FP).http://www.elsevier.com/locate/meegidhb201

A selective sweep in a microsporidian parasite Nosema-tolerant honeybee population, Apis mellifera

Nosema is a microsporidian parasite of the honeybee, which infects the epithelial cells of the gut. In Denmark, honeybee colonies have been selectively bred for the absence of Nosema over decades, resulting in a breeding line that is tolerant toward Nosema infections. As the tolerance toward the Nosema infection is a result of artificial selection, we screened chromosome 14 for a selective sweep with microsatellite markers, where a major quantitative trait locus (QTL) had been identified to be involved in the reduction in Nosema spores in the honeybees. By comparing the genetic variability of 10 colonies of the selected honeybee strain with a population sample from 22 unselected colonies, a selective sweep was revealed within the previously identified QTL region. The genetic variability of the swept loci was not only reduced in relation to the flanking markers on chromosome 14 within the selected strain but also significantly reduced compared with the same region in the unselected honeybees. This confirmed the results of the previous QTL mapping for reduced Nosema infections. The success of the selective breeding may have driven the selective sweep found in our study.European Union’s Seventh Framework Program BeeDoc, Deutsche Forschungsgemeinschaft project DFG SPP 1399 (MO 373/26-1), Romanian Centre for Bee Biotechnology (RoBeeTech) and China Scholarship Council.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1365-2052hb201

Reproductive Biology of the Cape Honeybee: A Critique of Beekman et al: A critique of "Asexually Produced Cape Honeybee Queens (Apis mellifera capensis) Reproduce Sexually,” authors: Madeleine Beekman, Michael H. Allsopp, Julianne Lim, Frances Goudie, and Benjamin P. Oldroyd. Journal of Heredity. 2011:102(5):562-566

Laying workers of the Cape honeybee parthenogenetically produce female offspring, whereas queens typically produce males. Beekman et al. confirm this observation, which has repeatedly been reported over the last 100 years including the notion that natural selection should favor asexual reproduction in Apis mellifera capensis. They attempt to support their arguments with an exceptionally surprising finding that A. m. capensis queens can parthenogenetically produce diploid homozygous queen offspring (homozygous diploid individuals develop into diploid males in the honeybee). Beekman et al. suggest that these homozygous queens are not viable because they did not find any homozygous individuals beyond the third larval instar. Even if this were true, such a lethal trait should be quickly eliminated by natural selection. The identification of sex (both with molecular and morphological markers) is possible but notoriously difficult in honeybees at the early larval stages. Ploidy is however a reliable indicator, and we therefore suggest that these "homozygous” larvae found in queen cells are actually drones reared from unfertilized eggs, a phenomenon well known by honeybee queen breeder

Interactions between integrated pest management, pollinator introduction, and landscape context on avocado Persea americana productivity

Pest management and insect pollination are important services that support crop production but are most often studied in isolation in cropping systems. Avocado Persea americana Mill. is an economically important crop in East Africa, which suffers from pest threats and potential drawbacks of the global pollinator crisis. The integration of pest and pollinator management is a growing research trend as a potential solution for sustainable crop production with minimum adverse effects on the environment and biodiversity. This study assessed potential interactions between landscape context, honeybee Apis mellifera L. introduction and integrated pest management (IPM) on avocado pests Bactrocera dorsalis (Hendel) and Thaumatotibia leucotreta (Meyrick), pollinators, and productivity in Kenya. Results showed an interaction between honeybee introduction and IPM on A. mellifera, with the highest mean abundance on the farms with both honeybee colonies and IPM. The abundance and diversity of non-Apis flower visitors were not affected by IPM and honeybee introduction across the landscapes. Pollinator introduction and IPM implementation resulted in a 941% fruit set increase and up to 97% fruit abscission within the high vegetation productivity class. Pest abundance significantly decreased on the farms with IPM, resulting in a 6% increase of final fruit weight compared with the farms without IPM. Overall, integration of pest and pollinator management did not synergistically increase the final avocado yield but represented a potential strategy to reduce pest densities while preserving wild visitors and benefiting from secondary products of honeybee colonies.The German Federal Ministry for Economic Cooperation and Development (BMZ) commissioned and administered through the Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) Fund for International Agricultural Research (FIA) and Norwegian Agency for Development Cooperation, the Section for research, innovation, and higher education, UK’s Foreign, Commonwealth and Development Office (FCDO), Swedish International Development Cooperation Agency (Sida), the Swiss Agency for Development and Cooperation (SDC), the German Academic Exchange Services (DAAD), Federal Democratic Republic of Ethiopia, and the Kenyan Government.https://www.schweizerbart.de/journals/entomologiadm2022Zoology and Entomolog

Floral turnover and climate drive seasonal bee diversity along a tropical elevation gradient

The contribution of seasonality in species communities to elevational diversity of tropical insects remains poorly understood. We here assessed seasonal patterns and drivers of bee diversity in the Eastern Afromontane Biodiversity Hotspot, Kenya, to understand the contribution of seasonality to elevational biodiversity patterns. Bee species and plant species visited by bees were recorded on 50 study plots in regrowth vegetation across four major seasons along two elevation gradients from 525 to 2530 m above sea level. Bees were sampled by transect walks using sweep nets and aspirators. We examined how local species richness (α-diversity) and seasonal changes in local species communities (β-diversity) contribute to species richness across seasons (γ-diversity) along elevation gradients. Using a multimodel inference framework, we identified the contribution of climate and floral seasonality to elevational patterns in bee diversity. We found that both α- and γ-diversity decreased with elevation. Seasonal β-diversity decreased with elevation and the high turnover of species across seasons contributed to a considerably higher γ- than α-diversity on study plots. A combination of seasonality in climate and the seasonal turnover of floral resources best explained the seasonality in bee species communities (seasonal β-diversity). We, therefore, conclude that, despite the more stable, and favorable climatic conditions in the tropics (in comparison to temperate regions), climatic seasonality and its influence on bees’ floral resources largely determined seasonal patterns of bee species diversity along elevation gradients on tropical mountains.JRS Biodiversity Foundation (grant number: 60610), UK’s Foreign, Commonwealth & Development Office (FCDO), the Swedish International Development Cooperation Agency (Sida), the Swiss Agency for Development and Cooperation (SDC), the Federal Democratic Republic of Ethiopia, and the Government of the Republic of Kenya.https://onlinelibrary.wiley.com/r/ecs2am2023Zoology and Entomolog

Detection of the spotted wing drosophila, Drosophila suzukii, in continental sub-Saharan Africa

The spotted wing drosophila, Drosophila suzukii Matsumura, is an insect pest of soft-skinned fruit, native to Eastern Asia. Since 2008, a world-wide dispersal of D. suzukii is seen, characterized by the establishment of the pest in many Asian, American and European countries. While the potential for invasion of continental Africa by D. suzukii has been predicted, its presence has only been shown for Morocco in Northern Africa. Knowledge about a possible establishment in other parts of the continent is needed as a basis for pest management. In 2019, we carried out a first survey in three counties in Kenya to monitor for the presence of D. suzukii using traps baited with a blend of apple cider vinegar and red wine. A total of 389 D. suzukii flies were captured in a fruit farm at Nakuru county, with more female flies being trapped than males. We confirmed the morphological identification of D. suzukii using DNA barcoding. In 2020, we performed a follow-up survey at 14 locations in six counties to delimit the distribution of D. suzukii in the main berry growing zones in Kenya. The survey indicated that so far D. suzukii is restricted to Nakuru county where it was initially detected. This is the first study to provide empirical evidence of D. suzukii in continental sub-Saharan Africa, confirming that the pest is expanding its geographic range intercontinentally. Given the high dispersal potential of D. suzukii, a concerted effort to develop management strategies is a necessity for containment of the pest

Reproductive Biology of the Cape Honeybee: A Critique of Beekman et al.

A critique of “Asexually Produced Cape Honeybee Queens (Apis mellifera capensis) Reproduce Sexually”: Laying workers of the Cape honeybee parthenogenetically produce female offspring whereas queens typically produce males. Beekman et al. confirm this observation, which has repeatedly been reported over the last 100 years including the notion that natural selection should favor asexual reproduction in A. m. capensis. They attempt to support their arguments with an exceptionally surprising finding that A. m. capensis queens can parthenogenetically produce diploid homozygous queen offspring (homozygous diploid individuals develop into diploid males in the honeybee). Beekman et al. suggest that these homozygous queens are not viable because they did not find any homozygous individuals beyond the third larval instar. Even if this were true, such a lethal trait should be quickly eliminated by natural selection. The identification of sex (both with molecular and morphological markers) is possible but notoriously difficult in honeybees at the early larval stages. Ploidy is however a reliable indicator and we therefore suggest that these “homozygous” larvae found in queen cells are actually drones reared from unfertilized eggs, a phenomenon well known by honeybee queen breeders.http://www.ncbi.nlm.nih.gov/pubmed/22581844ab201