Mating triggers immediate upregulation of the heat shock response but downregulation of immune activity in the female reproductive tract of moths

Abstract

• Mating induced upregulation in genes related to reproduction in S. litura females. • Mating triggered immediate upregulation of stress response. • Mating triggered immediate downregulation in immune activity. • Mating induced tissue-specific transcriptional changes. Mating induces female changes, and how females respond to male manipulation through ejaculates, especially at the molecular level, is currently a key topic of sexual conflict and coevolution in insects. Here, we show that mating induced significant transcriptional changes both in the reproductive tract (RT) and head of Spodoptera litura females, with all those genes that are directly related to fecundity, such as yolk protein and vitellogenin , being upregulated after mating, suggesting that mating promoted egg production. The most interesting changes are the upregulation of the heat shock response and the downregulation of immunity soon after mating in the RT. An increased heat shock response after mating may contribute to the formation of a favorable microenvironment for the interaction between gametes. The downregulation of immune activities may be due to males suppressing female immunity directly to promote sperm storage and fertilization in females. Another interesting finding is that mating results in the downregulation of five circadian regulation genes (including two clock core genes) in the RT. Moreover, mating also induced significant changes in other gene families, such as neuropeptides and cytochrome p450, suggesting that some of them may play important functions in mating responses and postmating physiological and behavioral switches. In addition, a prominent change in the head was found in which many olfactory-related genes were upregulated after mating. S. litura females usually start to lay eggs at night soon after mating, and thus, an increased olfactory function after mating is beneficial for host location by females during the night.