Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

The effects of mating on the reproductive fitness of Microplitis rufiventris (Hymenoptera: Braconidae).

Abstract

The synovigenic braconid parasitoid, Microplitis rufiventris Kokujev is a promising wasp for use in augmentative releases against young larvae of some noctuid pests, including Spodoptera littoralis (Boisduval), in Egypt. It also has the potential to control the invasive noctuid Spodoptera frugiperda (J.E. Smith) in Africa. M. rufiventris is monandrous in the wild but is polyandrous under some laboratory rearing conditions. S. littoralis larvae were used as hosts to gain an understanding of the influence of mating on wasp-fitness. Newly emerged females (0-3 h old) of M. rufiventris were assigned to one of six mating schedules: Virgin females mated once (on day 1, 3 or 5) or 3 times during their life or provided daily with fresh virgin males. These mating schedules affected fecundity, reproductive longevity and sex ratio of the progeny. The life time fecundity of wasps mated on day 5 or mated three times was higher than that of other females, but their reproductive longevity was significantly shorter. In most cases, offspring production per female per day decreased with age. Mated M. rufiventris females produced significantly more progeny than virgin females. The progeny of virgin females consisted only of males, females that mated once had strongly male-biased sex ratios, whereas multi-mated females had a more female-biased sex ratio. More sperm was stored in the spermatheca than the number of daughters produced in any of the mating schedules. Age at first mating affected the lifetime fecundity. At death, the ovaries of mated wasps contained significantly more mature eggs than those of virgin wasps, indicating that mating increased egg production. This information can help enhance the efficiency of parasitoid mass-rearing and their use as biocontrol agents of noctuid pests.