Widespread antibiotic usage in apiculture contributes substantially to the global dissemination of antimicrobial resistance and has the potential to negatively influence bacterial symbionts of honey bees (Apis mellifera). Here, we show that routine antibiotic administration with oxytetracycline selectively increased tetB (efflux pump resistance gene) abundance in the gut microbiota of adult workers while concurrently depleting several key symbionts known to regulate immune function and nutrient metabolism such as Frischella perrera and Lactobacillus Firm-5 strains.
The highly organized societies of the Western honey bee Apis mellifera feature a highly reproductive queen at the center of attention and a large cohort of daughters that suppress their own reproduction to help rear more sisters, some of whom become queens themselves. This reproductive altruism is peculiar because in theory it evolves via indirect selection on genes for altruism that are expressed in the sterile workers but not in the reproductive queens. In this study we attempt to situate lists of genes previously implicated in queenright worker sterility into a broader regulatory framework.
The process of caste differentiation is central to understanding insect sociality, because it is task specialization that enables division of labor within eusocial colonies. Selection presumably favors colonies that can adjust their division of labor in response to changing environmental demands, and for many taxa genetic and epigenetic factors are an important part of this equation. In this entry, we provide a framework for understanding genetic and epigenetic effects on caste.
American foulbrood (AFB) is a highly virulent disease afflicting honey bees (Apis mellifera). The causative organism, Paenibacillus larvae, attacks honey bee brood and renders entire hives dysfunctional during active disease states, but more commonly resides in hives asymptomatically as inactive spores that elude even vigilant beekeepers. The mechanism of this pathogenic transition is not fully understood, and no cure exists for AFB. Here, we evaluated how hive supplementation with probiotic lactobacilli (delivered through a nutrient patty; BioPatty) affected colony resistance towards a naturally occurring AFB outbreak.
The study of social breeding systems is often gene focused, and the field of insect sociobiology has been successful at assimilating tools and techniques from molecular biology. One common output from sociogenomic studies is a gene list. Here, we promote a view that is relatively common to molecular systems biology, where gene lists are converted into gene networks that better describe the functional connections that regulate behavioral traits. We present a narrative related to honeybee worker sterility to show how network analysis can be used to reprioritize candidate genes based on connectivity rather than their freestanding expression values. We argue that because network analyses are not restricted to “genes” as nodes, their implementation can potentially connect multiple levels of biological organization into a single, progressively complex study system.
Caste-biased genes in a subterranean termite are taxonomically restricted: implications for novel gene recruitment during termite caste evolution
The caste system of social insects presents a classic polyphenism in which widely divergent reproductive and non-reproductive phenotypes are expressed from the same genome. In termites, the sterile soldier caste is particularly divergent in phenotype and presumably evolved under selection for defensiveness. In this study, we use genomic phylostratigraphy to show that genes with soldier- and other caste-biased expression from the Eastern subterranean termite Reticulitermes flavipes are more taxonomically restricted on the tree of life than genes with no caste-biased expression.
In a termite colony, reproduction is monopolized by a small number of sexuals that are supported by an army of reproductively altruistic soldiers and workers. A recent RNA sequencing analysis of the Eastern subterranean termite revealed that most of the identified (78%) caste-biased genes exhibit a distinct soldier-specific pattern. Paradoxically, despite a shared developmental program with workers, this defensively specialized caste is well-differentiated from both the reproductive (nymph) and the other non-reproductive caste (worker) of this species. The soldier biased pattern suggests novel use of genes specifically implicated in this caste’s defensive role.
No Genetic Tradeoffs between Hygienic Behaviour and Individual Innate Immunity in the Honey Bee, Apis Mellifera
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. 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.