Effects of oviposition in a non‐host species on foraging behaviour of the parasitoid Cotesia glomerata

Abstract

Parasitoids lay their eggs in or on a host, usually another insect. During foraging, parasitoids can encounter insects that differ in terms of host suitability and quality. At one extreme end of this spectrum are non‐hosts that are unsuitable for offspring development. Non‐hosts are generally ignored but parasitization does occur and occasionally also results in egg deposition. Here, the authors investigate how oviposition in a non‐host influences subsequent foraging behaviour of a parasitoid and whether this is mediated by learning. The study system consists of the endoparasitoid Cotesia glomerata and the presumed non‐host caterpillar Mamestra brassicae. In the presence of Pieris brassicae hosts and/or their traces (frass), C. glomerata inserted its ovipositor into M. brassicae caterpillars. Eggs were deposited, but all eggs disappeared within 96 h, confirming the non‐host status of M. brassicae. In contrast to the expectation, there was no memory retention after oviposition in a non‐host and parasitoids did not alter their behaviour with respect to non‐host contacts and ovipositions. Instead, C. glomerata became more motivated to forage on a non‐host infested leaf. The authors propose that egg deposition in non‐hosts by C. glomerata might be due to their high egg load, which is thought to make parasitoids less selective on host quality, especially when they have few reproductive opportunities. In such cases, fitness costs to individual females are low. Egg deposition in non‐hosts might ultimately lead to host range expansion if parasitoids overcome the defence response of non‐hosts over evolutionary time.

En route to resources: Foraging strategies of plant‐associated insects to identify resources in complex dynamic environments

“…This reduction in time spent on examining non-resources might be the result of habituation or increased discrimination abilities. Interestingly, oviposition in non-host caterpillars had the opposite effect and increased the motivation of the parasitoid C. glomerata to forage on a non-host-infested leaf but did not result in associative learning of the presented odour (de Bruijn et al, 2022;Vosteen et al, 2019).…”

“…Illustration credits: Yavanna Aartsma, Dani Lucas-Barbosa, Paula Peeters-Pollinator Link, Quint Rusman.Results show that confusion occurs across functional groups, despite a research focus on different foraging steps in herbivores as compared to pollinators and parasitoids. Future work should reduce this asymmetry by clarifying the incidence of confusion in early foraging steps of herbivores and the extent to which it reduces foraging efficiency, while non-host utilization in pollinators and parasitoids has received little attention so far (but seede Bruijn et al, 2022;Vosteen et al, 2019Vosteen et al, , 2020.…”

Strength of enemy release from parasitoids is context-dependent in the invasive African Fig Fly,Zaprionus indianus

“…Invasive species lack this coevolutionary relationship, which raises questions about how they interact with parasitoids of established drosophilids (Kraaijeveld et al 1998). Leptopilina heterotoma is a generalist parasitoid wasp found in North America that parasitizes larvae of numerous drosophilid species due to its low selection threshold (Quicray et al 2023, de Bruijn et al 2022). Although L. heterotoma is a generalist, not all hosts are suitable for parasitoid development (Quicray et al 2023).…”