Do male seminal donations shape female post-mating receptivity in a usually monandrous moth?

Post-Mating Responses in Insects Induced by Seminal Fluid Proteins and Octopamine

Following insect mating, females often exhibit a series of physiological, behavioral, and gene expression changes. These post-mating responses (PMRs) are induced by seminal fluid components other than sperm, which not only form network proteins to assist sperm localization, supplement female-specific protein requirements, and facilitate the formation of specialized functional structures, but also activate neuronal signaling pathways in insects. This review primarily discusses the roles of seminal fluid proteins (SFPs) and octopamine (OA) in various PMRs in insects. It explores the regulatory mechanisms and mediation conditions by which they trigger PMRs, along with the series of gene expression differences they induce. Insect PMRs involve a transition from protein signaling to neuronal signaling, ultimately manifested through neural regulation and gene expression. The intricate signaling network formed as a result significantly influences female behavior and organ function, contributing to both successful reproduction and the outcomes of sexual conflict.

The female Euscepes postfasciatus refractory period is induced by the male but length is determined by the female

Females of many animals mate multiple times during their lives (i.e., polyandry). The period between matings (mating interval) is called the refractory period (RP). In the West Indian sweet potato weevil (Euscepes postfasciatus), males use the ejaculate to induce the RP in females to prevent re-mating. By measuring the RP, a large variation of 1-49 days was observed. This variation may be due to the males (ejaculate quantity and quality) and females (ejaculate sensitivity/degradation ability and body size) and their interactions, but the exact mechanisms are currently unclear. Here, we investigated a tendency towards a particular female RP duration and the associated traits of males and females to test the following three factors responsible for variation in the length of the RP: male manipulation of ejaculate volume, individual differences in male ejaculation substances, and ejaculate sensitivity/degradation ability in females. We prepared virgin males and females to create mating pairs. The following day, another mate was introduced to the females, and the first RP was measured. The same procedure was used for measuring the second RP. The males were also provided with another female (second female), mated, and then the RP of the second female was measured. In addition, the relationship between the length of the RP and female fitness was investigated. The results showed that there was a significant positive correlation between the first and second RP in the focal females, while no significant correlation was observed between the RP of the first and second females induced by the same male. It was also found that the length of the RP did not affect female fitness. This indicated that the males did not adaptively manipulate ejaculation volume depending on the quality of the females, and variance in the length of the RP may be explained by variation in the female physiological ability against ejaculate.