Social Apoptosis in Varroa Mite Resistant Western Honey Bees (Apis mellifera).

Honey bees are eusocial animals that exhibit both individual and social immune responses, which influence colony health. This is especially well-studied regarding the mite Varroa destructor Anderson and Trueman (Parasitiformes: Varroidae), a parasite of honey bee brood and disease vector. Varroa was introduced relatively recently to Apis mellifera L.

Artificial selection reveals the role of transcriptional constraints in the maintenance of life history variation.

The trade-off between reproduction and self-maintenance is a cornerstone of life history theory, yet its proximate underpinnings are elusive. Here, we used an artificial selection approach to create replicated lines of Japanese quail () that differ genetically in their reproductive investment. Whole transcriptome sequencing revealed that females from lines selected for high reproductive output show a consistent upregulation of genes associated with reproduction but a simultaneous downregulation of immune genes.

Insulin Receptor Substrate Gene Knockdown Accelerates Behavioural Maturation and Shortens Lifespan in Honeybee Workers.

In animals, dietary restriction or suppression of genes involved in nutrient sensing tends to increase lifespan. In contrast, food restriction in honeybees ( ) shortens lifespan by accelerating a behavioural maturation program that culminates in leaving the nest as a forager. Foraging is metabolically demanding and risky, and foragers experience increased rates of aging and mortality.

Increased prenatal maternal investment reduces inbreeding depression in offspring.

Inbreeding depression refers to the reduction of fitness that results from matings between relatives. Evidence for reduced fitness in inbred individuals is widespread, but the strength of inbreeding depression varies widely both within and among taxa. Environmental conditions can mediate this variation in the strength of inbreeding depression, with environmental stress exacerbating the negative consequences of inbreeding.

Vitellogenin in the honey bee brain: Atypical localization of a reproductive protein that promotes longevity.

In comparative gerontology, highly social insects such as honey bees (Apis mellifera) receive much attention due to very different and flexible aging patterns among closely related siblings. While experimental strategies that manipulate socio-environmental factors suggest a causative link between aging and social signals and behaviors, the molecular underpinnings of this linkage are less well understood. Here we study the atypical localization of the egg-yolk protein vitellogenin (Vg) in the brain of the honey bee.

Genomic correlates of recombination rate and its variability across eight recombination maps in the western honey bee (Apis mellifera L.).

Background: Meiotic recombination has traditionally been explained based on the structural requirement to stabilize homologous chromosome pairs to ensure their proper meiotic segregation. Competing hypotheses seek to explain the emerging findings of significant heterogeneity in recombination rates within and between genomes, but intraspecific comparisons of genome-wide recombination patterns are rare. The honey bee (Apis mellifera) exhibits the highest rate of genomic recombination among multicellular animals with about five cross-over events per chromatid.

Genetic architecture of a hormonal response to gene knockdown in honey bees.

Variation in endocrine signaling is proposed to underlie the evolution and regulation of social life histories, but the genetic architecture of endocrine signaling is still poorly understood. An excellent example of a hormonally influenced set of social traits is found in the honey bee (Apis mellifera): a dynamic and mutually suppressive relationship between juvenile hormone (JH) and the yolk precursor protein vitellogenin (Vg) regulates behavioral maturation and foraging of workers. Several other traits cosegregate with these behavioral phenotypes, comprising the pollen hoarding syndrome (PHS) one of the best-described animal behavioral syndromes.

Genotype effect on lifespan following vitellogenin knockdown.

Honey bee workers display remarkable flexibility in the aging process. This plasticity is closely tied to behavioral maturation. Workers who initiate foraging behavior at earlier ages have shorter lifespans, and much of the variation in total lifespan can be explained by differences in pre-foraging lifespan.

Insulin-like peptide response to nutritional input in honey bee workers.

The rise in metabolic disorders in the past decades has heightened focus on achieving a healthy dietary balance in humans. This is also an increasingly important issue in the management of honey bees (Apis mellifera) where poor nutrition has negative effects on health and productivity in agriculture, and nutrition is suggested as a contributing factor in the recent global declines in honey bee populations. As in other organisms, the insulin/insulin-like signaling (IIS) pathway is likely involved in maintaining nutrient homeostasis in honey bees.

The gene vitellogenin affects microRNA regulation in honey bee (Apis mellifera) fat body and brain.

In honey bees, vitellogenin (Vg) is hypothesized to be a major factor affecting hormone signaling, food-related behavior, immunity, stress resistance and lifespan. MicroRNAs, which play important roles in post-transcriptional gene regulation, likewise affect many biological processes. The actions of microRNAs and Vg are known to intersect in the context of reproduction; however, the role of these associations on social behavior is unknown.

Physiological variation as a mechanism for developmental caste-biasing in a facultatively eusocial sweat bee.

Social castes of eusocial insects may have arisen through an evolutionary modification of an ancestral reproductive ground plan, such that some adults emerge from development physiologically primed to specialize on reproduction (queens) and others on maternal care expressed as allo-maternal behaviour (workers). This hypothesis predicts that variation in reproductive physiology should emerge from ontogeny and underlie division of labour. To test these predictions, we identified physiological links to division of labour in a facultatively eusocial sweat bee, Megalopta genalis.

Insulin-like peptide genes in honey bee fat body respond differently to manipulation of social behavioral physiology.

Nutrient sensitive insulin-like peptides (ILPs) have profound effects on invertebrate metabolism, nutrient storage, fertility and aging. Many insects transcribe ILPs in specialized neurosecretory cells at changing levels correlated with life history. However, the major site of insect metabolism and nutrient storage is not the brain, but rather the fat body, where functions of ILP expression are rarely studied and poorly understood.

Genotype effect on regulation of behaviour by vitellogenin supports reproductive origin of honeybee foraging bias.

In honeybee colonies, food collection is performed by a group of mostly sterile females called workers. After an initial nest phase, workers begin foraging for nectar and pollen, but tend to bias their collection towards one or the other. The foraging choice of honeybees is influenced by vitellogenin (vg), an egg-yolk precursor protein that is expressed although workers typically do not lay eggs.

Down-regulation of honey bee IRS gene biases behavior toward food rich in protein.

Food choice and eating behavior affect health and longevity. Large-scale research efforts aim to understand the molecular and social/behavioral mechanisms of energy homeostasis, body weight, and food intake. Honey bees (Apis mellifera) could provide a model for these studies since individuals vary in food-related behavior and social factors can be controlled.

The gene vitellogenin has multiple coordinating effects on social organization.

Temporal division of labor and foraging specialization are key characteristics of honeybee social organization. Worker honeybees (Apis mellifera) initiate foraging for food around their third week of life and often specialize in collecting pollen or nectar before they die. Variation in these fundamental social traits correlates with variation in worker reproductive physiology.