A novel gene from the takeout family involved in termite trail-following behavior.

This study investigated physiological and behavioral functions of a novel gene identified from the termite Reticulitermes flavipes. The gene, named deviate, encodes an apparent ligand binding protein from the takeout-homologous family. Initial studies were conducted to investigate deviate mRNA expression among termite castes and body regions, and changes in response to light-dark conditions, starvation, temperature, and juvenile hormone (JH). Deviate has ubiquitous caste and tissue expression, including antennal expression. Consistent with characteristics of other takeout family members, deviate expression is responsive to photophase conditions (p<0.1), and feeding, temperature, and JH (p<0.05). Using RNA-interference (RNAi) techniques, short-interfering RNAs (siRNAs) homologous to the deviate gene were synthesized and injected into worker termites, which were then subjected to bioassays designed to (1) induce caste differentiation or (2) measure various behavioral aspects of foraging and trail following. No impacts on JH-dependent caste differentiation were observable. However, trail following accuracy was significantly reduced in termites that received deviate siRNA injections, and this pattern generally mirrored deviate mRNA attenuation and recovery after RNAi. In a subsequent distance foraging bioassay, deviate-silenced termites exhibited equal feeding levels to controls, suggesting the deviate gene is not linked to general vigor or the ability/motivation of termites to move and forage. These findings are among the first linking the expression of a termite gene with eusocial behavior; they illustrate the connection between deviate expression and trailing behavior, which is a key evolutionary adaptation vital to subterranean social insects such as termites and ants.

Application of RNA interference in functional genomics studies of a social insect.

Social insects represent a group of organisms that have dual importance from perspectives relating to both basic and applied science. From a basic perspective, social insects serve as excellent model systems for studying social organization, behavioral ecology, neurobiology, and phenotypic plasticity. From applied perspectives, social insects play important roles in the pollination of agricultural crops, in the damage of human structures and commodities, and in cellulose processing in natural ecosystems. With the advent of insect sociogenomics research (and the ability to identify dozens or hundreds of relevant candidate genes from a single experiment) has come a great demand for functional genomics tools for application in gene characterization. To date, RNAi is one of the most powerful tools to have become available for such functional characterizations, and it has broad relevance across a range of insect sociobiology research topics.