An expression system for Gustatory receptors - and why it failed

Genome of the small hive beetle (Aethina tumida, Coleoptera: Nitidulidae), a worldwide parasite of social bee colonies, provides insights into detoxification and herbivory

Background

The small hive beetle (Aethina tumida; ATUMI) is an invasive parasite of bee colonies. ATUMI feeds on both fruits and bee nest products, facilitating its spread and increasing its impact on honey bees and other pollinators. We have sequenced and annotated the ATUMI genome, providing the first genomic resources for this species and for the Nitidulidae, a beetle family that is closely related to the extraordinarily species-rich clade of beetles known as the Phytophaga. ATUMI thus provides a contrasting view as a neighbor for one of the most successful known animal groups.

Results

We present a robust genome assembly and a gene set possessing 97.5% of the core proteins known from the holometabolous insects. The ATUMI genome encodes fewer enzymes for plant digestion than the genomes of wood-feeding beetles but nonetheless shows signs of broad metabolic plasticity. Gustatory receptors are few in number compared to other beetles, especially receptors with known sensitivity (in other beetles) to bitter substances. In contrast, several gene families implicated in detoxification of insecticides and adaptation to diverse dietary resources show increased copy numbers. The presence and diversity of homologs involved in detoxification differ substantially from the bee hosts of ATUMI.

Conclusions

Our results provide new insights into the genomic basis for local adaption and invasiveness in ATUMI and a blueprint for control strategies that target this pest without harming their honey bee hosts. A minimal set of gustatory receptors is consistent with the observation that, once a host colony is invaded, food resources are predictable. Unique detoxification pathways and pathway members can help identify which treatments might control this species even in the presence of honey bees, which are notoriously sensitive to pesticides.

The neurobiology of gustation in insect disease vectors: progress and potential

For insect vectors of human diseases, mealtimes are a key moment of infection. Understanding how and when such species decide on what to feed is both an interesting problem in sensory neurobiology and a source of information for intervention of these behaviors to control spread of infectious agents. Here I review the current knowledge of the molecular and cellular mechanisms of gustation in insect disease vectors, covering blood-feeders as well as scavengers that spread pathogens indirectly. I also consider how these behaviors are modulated over short and long timescales, and describe efforts to artificially modulate them. Though a relatively nascent field, gustatory neurobiology in insect vectors has much promise for future fundamental discoveries and practical applications.