Field evaluation of Spalangia endius Walker in controlling Zeugodacus cucurbitae (Coquillett)

Abstract

We designed a series of semifield experiments and two types of nylon cages to evaluate the control efficacy of Spalangia endius Walker in the field and to verify the possibility of using S. endius for the control of Zeugodacus cucurbitae (Coquillett) pupae. More hosts were killed by S. endius at higher parasitoid–host ratios. The effectiveness of S. endius was highest at a parasitoid–host ratio of 1:10, which caused 50.33% and 33% mortality in enclosed and semiopen conditions, respectively. The adult parasitoids supplemented with honey solution or water survived to 7 or 5 days at most, respectively. S. endius showed a low control efficacy for Z. cucurbitae pupae in the field. However, combined with the natural mortality of pupae and the effects of other natural enemies, the mortality of Z. cucurbitae pupae exceeded 85%. Thus, S. endius may help control Z. cucurbitae pupae in the field, but other control strategies need to be applied to kill the pupae in the soil which S. endius cannot reach and to control any remaining adult Z. cucurbitae.