A preliminary survey reveals that common viruses are found at low titers in a wild population of honey bees (Apis mellifera).

A major threat to honey bee (Apis mellifera Linnaeus, Hymenoptera: Apidae) health continues to be parasitism by the mite Varroa destructor, which has been linked to high colony losses worldwide. Besides feeding on developing and adult bees, Varroa is also a prolific vector of honey bee-associated viruses. Because they live in unmanaged conditions, wild honey bee colonies are not treated against Varroa, which has enabled the natural selection of more mite-tolerant bees. To date, few studies have explored the prevalence of viruses in unmanaged colonies. The Welder Wildlife Refuge (WWR) in Texas is a unique site to study the viral landscape of unmanaged honey bees in the United States. The goals of this study were to identify and quantify viruses in wild colonies at the WWR, to examine changes in the prevalence of viruses in these colonies over time, and to compare the presence and titers of viruses between wild colonies at the WWR and those from the nearest managed apiary. We collected bees from colonies at the WWR in 2013, 2016, and 2021, and analyzed selected viruses for their presence and titers via quantitative polymerase chain reaction. In 2021, we also sampled bees from the nearest managed apiary for comparison. We found low average virus titers in all wild colonies sampled, and no difference in virus titers between colonies at the WWR and those from the managed apiary. Our study indicates that virus titers in wild colonies at the WWR are similar to those found in nearby colonies, and that these titers fluctuate over time.

Transcriptomic analysis of the honey bee (Apis mellifera) queen brain reveals that gene expression is affected by pesticide exposure during development.

Honey bees (Apis mellifera) play a pivotal role in agricultural production worldwide, primarily through the provision of pollination services. But despite their importance, honey bee health continues to be threatened by many factors, including parasitization by the mite Varroa destructor, poor queen quality, and pesticide exposure. Accumulation of pesticides in the hive's comb matrix over time inevitably leads to the exposure of developing brood, including queens, to wax contaminated with multiple compounds. Here, we characterized the brain transcriptome of queens that were reared in wax contaminated with pesticides commonly found in commercial beekeeping operations including either (a) a combination of 204,000 ppb of tau-fluvalinate and 91,900 ppb of coumaphos ("FC" group), (b) a combination of 9,800 ppb of chlorpyrifos and 53,700 ppb of chlorothalonil ("CC" group), or (c) 43,000 ppb of amitraz ("A" group). Control queens were reared in pesticide-free wax. Adult queens were allowed to mate naturally before being dissected. RNA isolated from brain tissue from three individuals per treatment group was sequenced using three technical replicates per queen. Using a cutoff log2 fold-change value of 1.5, we identified 247 differentially expressed genes (DEGs) in the FC group, 244 in the CC treatment group, and 668 in the A group, when comparing each group to the control. This is the first study to examine the sublethal effects of pesticides commonly found in wax (particularly amitraz) on the queen's brain transcriptome. Future studies should further explore the relationship between our molecular findings and the queen's behavior and physiology.

(Not) far from home: No sex bias in dispersal, but limited genetic patch size, in an endangered species, the Spotted Turtle (Clemmys guttata).

Sex-biased dispersal is common in many animals, with male-biased dispersal often found in studies of mammals and reptiles, including interpretations of spatial genetic structure, ostensibly as a result of male-male competition and a lack of male parental care. Few studies of sex-biased dispersal have been conducted in turtles, but a handful of studies, in saltwater turtles and in terrestrial turtles, have detected male-biased dispersal as expected. We tested for sex-biased dispersal in the endangered freshwater turtle, the spotted turtle (Clemmys guttata) by investigating fine-scale genetic spatial structure of males and females. We found significant spatial genetic structure in both sexes, but the patterns mimicked each other. Both males and females typically had higher than expected relatedness at distances <25 km, and in many distance classes greater than 25 km, less than expected relatedness. Similar patterns were apparent whether we used only loci in Hardy-Weinberg equilibrium (n = 7) or also included loci with potential null alleles (n = 5). We conclude that, contrary to expectations, sex-biased dispersal is not occurring in this species, possibly related to the reverse sexual dimorphism in this species, with females having brighter colors. We did, however, detect significant spatial genetic structure in males and females, separate and combined, showing philopatry within a genetic patch size of <25 km in C. guttata, which is concerning for an endangered species whose populations are often separated by distances greater than the genetic patch size.