Attack Biology and Egg Maturation Strategy of Two Tachinid Parasitoids of Leafroller (Lepidoptera: Tortricidae) Pests in Tree Fruit

Abstract

Abstract Reproductive biology, including mode of attack and egg maturation, has not been described for the leafroller (Lepidoptera: Tortricidae) parasitoids Nemorilla pyste (Coquillett) and Nilea erecta (Walker) (Diptera: Tachinidae). Mode of host attack is an important character for understanding evolutionary relationships in Tachinidae, and is an important consideration for biological control. In parasitic Hymenoptera, egg maturation strategy is predictive of many life-history variables, but these predictions have not been tested in other parasitoid groups. In this article, observations on the mode of attack of N. erecta and N. pyste that were acquired through the rearing of these species in the laboratory are described. The study also used dissections to examine internal reproductive physiology and obtain fecundity data for flies of different ages. Fecundity data from the dissections and from cage experiments were used to estimate the ovigeny index of the two species. N. pyste was found to be a highly synovigenic oviparous species, whereas N. erecta was found to be moderately synovigenic and ovolarviparous. Life-history associations of hymenopteran parasitoids with egg maturation strategy appeared not to apply to these tachinids.