# Polyandry and sperm competition in two traumatically inseminating species of Strepsiptera (Insecta)

## TL;DR

This study shows that some female insects in the order Strepsiptera mate with multiple males, leading to offspring with multiple fathers.

## Contribution

The study provides evidence of polyandry and sperm competition in two traumatically inseminating Strepsiptera species.

## Key findings

- Offspring of a single female can have multiple fathers in two Strepsiptera species.
- In S. ovinae, the first male contributes more offspring than subsequent males.
- X. vesparum shows no significant link between mating duration and offspring contribution.

## Abstract

Polyandry, the practice of females mating with multiple males, is a strategy found in many insect groups. Whether it increases the likelihood of receiving beneficial genes from male partners and other potential benefits for females is controversial. Strepsiptera are generally considered monandrous, but in a few species females have been observed copulating serially with multiple males. Here we show that the offspring of a single female can have multiple fathers in two Strepsiptera species: Stylops ovinae (Stylopidae) and Xenos vesparum (Xenidae). We studied female polyandry in natural populations of these two species by analysis of polymorphic microsatellite loci. Our results showed that several fathers can be involved in both species, in some cases up to four. Mating experiments with S. ovinae have shown that the first male to mates with a given female contributes to a higher percentage of the offspring than subsequent males. In X. vesparum, however, we found no significant correlation between mating duration and offspring contribution. The prolonged copulation observed in S. ovinae may have the advantage of reducing competition with sperm from other males. Our results show that monandry may not be the general pattern of reproduction in the insect order Strepsiptera.