Female Mating Frequency and Reproductive Fitness in the Willow Leaf Beetle (Coleoptera: Chrysomelidae)

Abstract

Multiple mating in females is common in nature but may involve fitness costs. Adult females and males of the beetle Plagiodera versicolora Laicharting can mate multiple times. We studied the effect of mating frequency and mating pattern (time interval between matings) on female reproductive fitness by measuring fecundity, hatching probability, and female longevity. Fecundity and longevity were similar in single- and double-mated (two matings separated by a 7 d interval) females. However, two and three successive matings and three matings separated by two 7 d interval had a significant negative effect on the lifetime fecundity and longevity of females. Multiple mating had a positive effect on egg hatching, and two matings sufficed to fertilize the full egg load. These results indicate that the two matings separated by a 7 d interval are optimum for reproductive fitness in female P. versicolora. Suboptimal mating frequency (successive mating or an excessive number of matings) exacts a physiological cost that shortens the female life span and reduces fecundity.

Effects of Delayed Mating on Mating Performance and Reproductive Fitness of the Willow Leaf Beetle (Coleoptera: Chrysomelidae) under Laboratory Conditions

“…There is often a significant correlation between female fertilization rate and mating duration [ 26 ]. One mating cannot fertilize all of the eggs of female P. versicolora [ 23 ]. Therefore, when the female and male delay mating, the female may lay a similar or greater number of eggs by extending the mating duration and maximizing the reproductive output.…”

“…However, the results of this study showed that delayed mating had no significant effect on fecundity. Successive mating or excessive frequency of mating can shorten the oviposition time of female P. versicolora , which can decrease their fecundity [ 23 ]. However, an increase in adult density significantly prolongs the time in which for females to lay eggs, thereby promoting an increase in female fecundity [ 28 ].…”

“…We determined the sex of each adult by their body weight, and the adults were considered to be females if their body weight was more than 6.5 mg; conversely, the adults were considered to be males if their body weight was less than 6.5 mg. We validated this method of sexing adults by mating behavior, with a success rate of 95%. The lifespan of unmated females is about 50 d, and the pre-oviposition period of females is about 7 d [ 23 ]. Therefore, we assume that female and male adults may be encountered at various ages under field conditions.…”

“…All of the females and males mated successfully within 20 min. Two matings are needed in order to fertilize all of the eggs of female P. versicolora [ 23 ]. To compare the effects of delayed mating on mating performance and reproductive fitness, we permitted females and males to mate only once.…”

Occurrence and impact of the parasitic mite Linobia coccinellae on its host beetle Chrysomela populi: implications for its potential as a biological control agent

“…Those pairs of beetles were kept separately in the climate chamber. Males were added to prevent unintended impact by the mating status, which is known to influence longevity and fecundity of chrysomelid beetles (Zhao et al, 2019). The beetles were checked at 1‐ to 2‐day intervals for the vitality and number of eggs laid.…”