Female multiple matings and male harassment and their effects on fitness of arrhenotokous Thrips tabaci (Thysanoptera: Thripidae).

Xiao-Wei Li,Jozsef Fail,Anthony M. Shelton

doi:10.1007/s00265-015-1970-5

Abstract

Although it is generally assumed that one or a few matings are sufficient to maximize female fitness and that mating is generally assumed to be costly to females, multiple matings of females have been reported across a wide and taxonomically diverse set of animals. Here, we investigated female mating frequency and male harassment rate in arrhenotokous Thrips tabaci. In addition, the cost to females of mating, multiple matings, and male harassment to females was evaluated. We found that T. tabaci females mated multiple times during their lifetime and were subjected to a high rate of male harassment at all the ages we tested. Mating was costly to females in terms of reducing longevity and delaying the initiation of egg laying, although mating did not affect the survivorship and longevity of males. Furthermore, continual exposure to males also resulted in a fitness cost to mated females in terms of delayed egg production and reduced fecundity. Virgin females of arrhenotokous thrips produce only male progeny whereas mated females of arrhenotokous thrips produce males from unfertilized eggs and females from fertilized eggs. However, multiple matings did not allow females to fertilize a larger proportion of their eggs to increase the female offspring ratio. Our study demonstrates the conflicts between the occurrence of multiple matings and the cost of sexual activities. This raises questions about the evolution of multiple matings and polyandry in this species. Furthermore, these findings suggest that such phenomena may occur in other animal species and influence the evolution of their mating systems.

Highlights

Mating frequencies of females vary considerably with different mating systems (Thornhill and Alcock 1983)
The experience of the male did not have a significant model effect on female mating frequencies (Wilks’ Λ=0.923; F(4, 32)= 0.665; p=0.621), and there were no significant differences detected by the follow-up univariate tests in the accumulated mating frequency between females paired with mated and virgin males during the first 10 days (F(1, 35)=0.586; p= 0.449) and the entire 30 days (F(1, 35)=0.001; p=0.971) period (Table 3)
There was no model effect of male harassment frequency (Wilks’ Λ=0.923; F(4, 32)=0.665; p=0.621) between mated males and virgin males, and average male harassment rates were equal between females paired with mated or virgin males during the first 10-day (F(1, 35)=2.713; p= 0.108) and the entire 30-day (F(1, 35)=2.528; p=0.121) period (Table 3)

Summary

Introduction

Mating frequencies of females vary considerably with different mating systems (Thornhill and Alcock 1983). For females, there are fitness costs associated with mating, including energetic and time costs for other activities (Daly 1978; Kotiaho et al 1998b; Watson et al 1998; Franklin et al 2012), the risk of increased predation (Wing 1988; Kotiaho et al 1998a; Magnhagen 1991), physical damage (Parker 1979; Leboeuf and Mesnick 1991; Crudgington and Siva-Jothy 2000), toxic seminal fluid (Chen 1984; Chapman et al 1995), and immunity corruption (Rolff and Siva-Jothy 2002) These costs may decrease a female’s lifespan and egg production rate (Arnqvist and Nilsson 2000). Frequent multiple matings can be explained by the benefits females may gain from re-mating, including

Methods

Results

Conclusion