BIOLOGY OF COTESIA (= APANTELES) TELENGAI (HYMENOPTERA, BRACONIDAE) ON ITS NATURAL HOST AGROTIS-SEGETUM (LEPIDOPTERA, NOCTUIDAE)

The host suitability of Agrotis segetum Denis and Schiff., A. ipsilon Hufn., Spodoptera littoralis Boisd., S. exigua Hub., Mythimna loreyi D uponchel and Mamestra oleracea L. for the gregarious braconid Cotesia (= Apanteles) telengai Tobias was determined under laboratory conditio ns. The parasitoid only completed its development in larvae of A. sege tum. The percentage of successfully parasitized larvae and the mean du ration of C. telengai egg-larval period were inversely related to the age of the host ol host instar at parasitization. The mean number of p arasitoids which emerged per parasitized larva was positively correlat ed with the larval age. The sex ratio was consistently high (ca. eight males to one female), independent of the host instar parasitized, as compared to 1:1 as observed frequently in field populations of this wa sp. The females of C. telengai were active and produced offspring at t emperatures of 15, 20, 25 and 30 degrees C. However, the mean percenta ge of parasitized larvae increased from 13.1 to 72% and the mean proge ny per parasitoid female increased from 14.7 to 129.4 parasitoids, bot h significant, when the experimental temperature was raised from 15 to 30 degrees C, while their mean development time decreased fr om 75.5 to 19.2 days. Ar 25 degrees C, the virgin and mated females continued oviposition until days 16 and 17, with a lifetime total of progeny of 397.6 (SD +/- 224.7) and 611.1 (SD +/- 128.8) parasitoids respectively , reaching a maximum of 64.3 and 99.2 on day 2 respectively.