Parasitism and optimization of Hyposoter didymator (Hymenoptera: Ichneumonidae) rearing on Spodoptera littoralis and Helicoverpa armigera (Lepidoptera: Noctuidae)

This study investigated the growth and the development of the parasite H. didymator on the 1^st, 2^nd and 3^rd instars of Spodoptera littoralis and Helicoverpa armigera under laboratory conditions. The S. littoralis was a better rearing host than H. armigera for the growing of H. didymator. The parasite development on the 2^nd instar larvae of both hosts was faster than on the 1^st and 3^th instars larvae. The development time of the parasite from egg to adult was similar in both insects. The development time of the 2^nd instar was 17.05 ± 0.87 days in S. littoralis and 17.24 ± 0.84 days in H. armigera. The parasite life cycle on both hosts was affected significantly, for example the age of the parasite females has a high influence on the pupae death rate and the females number in the offspring. The female percentage in the offspring was 51.8 % in four cohorts after 36 hours of copulation, and was 30% after 24 hours of copulation in the first and two cohorts only. Moreover, there was no effect on the parasite mating percentage or the existence of males with females during the oviposition period.