Interspecific interactions between twoTuta absoluta(Lepidoptera: Gelechiidae) larval parasitoids with contrasting life histories

Abstract

AbstractInterspecific interactions between two larval parasitoids ofTuta absoluta(Meyrick) with partially overlapping host niches were studied: the idiobiont ectoparasitoidDineulophus phthorimaeaeDe Santis, and the koinobiont endoparasitoidPseudapanteles dignus(Muesebeck).T. absolutais an important pest of tomato crops worldwide, and its management could be improved by understanding the competitive interactions and potential coexistence between these two parasitoids. Firstly, a 15-min fixed time laboratory test evaluated the host-searching ability of adultD. phthorimaeaeandP. dignuswasps onT. absolutalarvae. Secondly,D. phthorimaeaehost discrimination against endoparasitized and non-endoparasitized hosts byP. dignus, at different adult female ages, was experimentally examined.D. phthorimaeaewasps spent significantly more time in general searching in the presence of its competitor than in its absence, but, parasitism was only effective byP. dignus. OlderD. phthorimaeaewasps discriminated significantly less than young wasps betweenT. absolutalarvae parasitized and unparasitized byP. dignus, and an interaction took place by non-concurrent host-feeding. Intra-guild predation ofP. dignuslarvae byD. phthorimaeaefemale feeding behaviour might have a minor effect in this system. Results are discussed in the context of literature supporting diverse evidence of coexistence in other parasitoid-host systems, with implications forT. absolutabiological control.