Role of Mating Receptivity Peptides in Helicoverpa armigera: Molecular and Evolutionary Perspectives

Previous studies have implicated the role of peptides/proteins in male accessory glands (MAGs), responsible for the induction of behavioral and reproductive changes in Helicoverpa armigera females. Our and several other studies have seen the MAG showed post-mating behaviors such as accelerated unreceptivity to re-mating and other post-mating traits. We have reported several peptides responsible for reduced mating receptivity, including a putative 4.9 kDa, a novel peptide with various functions in female post-copulatory reproductive behavior (PMR). In this study, we report a detailed analysis of the proteins from a biochemical, physiological, molecular and evolutionary perspective. 5 major classes of multigene family proteins were detected after protein database searches. All proteins were found to bind nucleic acids, possess signal peptides, and undergo posttranslational modification by seminal fluid proteins (SFPs). The Porphobilinogen synthetase protein (PBGS) was unique to the lepidopteran order. Our molecular studies support the observation that the molecular weight of MAG proteins varies significantly across species, suggesting the existence of different target sites or faster evolution of SFP. MAG proteins not only ensure male reproductive fitness by constantly evolving under postcopulatory sexual selection (PCSS), but also maintain species-specific barriers to fertilization thus potentially contribute to the formation of new species and mediate reproductive conflicts between the sexes.