No evidence for an up-regulation of female immune function in response to elevated risk of sexual conflict

TL;DR

The study found no evidence that female seed beetles boost their immune response when exposed to higher risks of sexual conflict.

Contribution

This study is novel in experimentally testing female immune plasticity in response to perceived sexual conflict cues.

Findings

Female seed beetles did not show increased phenoloxidase (PO) capacity when exposed to cues of higher sexual conflict.

PO capacity remained unchanged across different larval and adult social treatments.

Results suggest females may not adjust immunocompetence in response to perceived mating risks.

Abstract

Sexual conflict is widespread among sexually reproducing organisms. Phenotypic plasticity in female resistance traits has the potential to moderate the harm imposed by males during mating, yet female plasticity has rarely been explored. In this experiment, we investigated whether female seed beetles invest more in immunocompetence, measured as phenoloxidase (PO) capacity, when exposed to cues signalling a greater risk of sexual conflict. Risk perception was manipulated by housing focal individuals alone or with a companion as developing larvae, followed by exposure to a mating-free male- or female-biased social environment when adults. We predicted that females exposed to cues of increased sexual conflict would have increased PO capacity. However, PO capacity did not differ between either larval or adult social treatments. Our results suggest that females may not perceive a risk to their fitness on the basis of increased male presence or are unable to adjust this aspect of their phenotype in response to that risk.

Figures