Influence of socio-environmental conditions on gene expression in R. flavipes termites

Strict regulation of the caste differentiation process is important to maintain the appropriate proportions of castes in social insect colonies. Previously, a number of extrinsic and intrinsic factors have been shown to modulate caste composition in termites. For example, one important factor in caste differentiation is the influence of nestmates, in particular, soldier termites have been shown to influence nestmate caste differentiation. Here, we investigated the impact of juvenile hormone-III (JHIII), soldier head extracts (SHE), JHIII+SHE, and live soldiers on phenotypic differentiation and gene expression profiles of Reticulitermes flavipes workers. Using quantitative-real-time PCR we determined the expression patterns of 49 genes in response to the different socio-environmental and semiochemical treatments, at three different days (1,5, and 10). Four main groups of genes were identified to be significantly differentially expressed between the treatments. Cytochrome P450, mevalonate pathway, hemolymph protein, and developmental genes were differentially expressed between treatments. JHIII and live soldier treatments had an impact on caste differentiation and had a significant impact on a number of genes homologus to genes responsible for JH biosynthesis/degradation and development, supporting that live soldiers are indeed regulating the caste differentiation of other nestmates. Interestingly, SHE did not have the same effect as the live soldier treatment on caste differentiation and gene expression. Overall this research sheds completely new light on the impact different socio-environmental factors play on termite gene expression and caste differentiation. By understanding how these factors affect termite development, we can better understand termite sociality and developmental biology.