Meteorus gyrator (Thunberg) (Hymenoptera: Braconidae) In Egypt: Geographical Distribution and Mass-production

Abstract

Background: The larval internal parasitoids in the genus Meteorus attack certain lepidopterous larvae in different Egyptian fields. Two species, M. rubens and M. gyrator were the most abundant species reared from several lepidopterous larval species, which feed on different host plants in the two selected Governorates in Egypt throughout two successive years.
 Aim: This work presents a method specifically designed to improve the abundance and the parasitizing potential of M. gyrator in open fields to parasitize and develop on a broad range of noctuid’s pests by releasing considerable number of the parasitoid adults. Also it deals with some aspects of the basic biology of M. gyrator parasitizing Spodoptera littoralis and Autugrapha ni, as mass-rearing hosts.
 Methodology: 1- Population Dynamics
 Biweekly samples of lepidopterous larvae were collected from different host plants in the fields of Giza and Faiyum Governorates, for two successive years (November, 2017 to October, 2019). Collected larvae were confined individually under constant conditions until pupation or the emergence of the internal parasitoid’s larvae for pupation.
 2- Laboratory Rearing
 Cultures of some insect larvae, Heliothis armigera, Spodoptera exigua, Agrotis ipsilon, Sesamia cretica, S. littoralis and Autographa ni were reared in laboratory under constant conditions to act as hosts for mass-production of the parasitoid, M. gyrator.
 Results: Obtained results reveal that A. ipsilon was the main host of M. rubens, it was more abundant in both years and localities of the survey. Meteorus gyrator was recorded at fewer numbers; it was reared from S. littoralis, S. exigua, S. critica, Heliothis spp. and Autographa spp. The parasitism percentage by M. rubens averaged 23.10% at Giza. While in the case of M. gyrator it averaged 3.25%. In Faiyum, the corresponding figure averaged 12.96% parasitism for M. rubens; while it averaged 6.93%, for M. gyrator. To increase the efficacy of M. gyrator, mass production experiments were carried out, suggesting that Autographa ni was the most suitable for mass-rearing than S. littoralis.
 Conclusion: To increase the efficacy of M. gyrator as an endoparasitoid, its numbers in the field should be increased by releasing a considerable number of adults, to control lepidopterous larval pests.