The molecular response to mating and nuptial gifts in female decorated crickets

Nuptial food gifts are offered at copulation by males in a wide variety of insects, and males might use these gifts to manipulate female physiology. In decorated crickets (Gryllodes sigillatus), nuptial food gifts take the form of a spermatophylax, a gelatinous mass forming part of the male spermatophore and consumed by the female after mating, but before she removes the sperm-containing ampulla. Using RNA sequencing, we compared gene expression in two different tissues between five different groups of females: (1) virgin females, (2) mated females allowed to feed on the spermatophylax, (3) mated females not allowed to feed on the spermatophylax, (4) virgin females that fed on a spermatophylax, and (5) mated females that fed on a pectin gel. In the gut tissue, we found that the act of mating reduces the expression of gut enzymes, but that this effect is reversed when females feed on the spermatophylax. In addition, we found that there are only low numbers of differentially expressed genes in the head tissue, the majority of which are involved in regulatory functions. Finally, we used WGCNA (weighted gene co-expression network analysis) to find three modules of co-expressed genes that are either correlated to mating or to spermatophylax feeding.