Effect of host age, parasitoid age and temperature on interspecific competition between Chelonus insularis Cresson, Cotesia marginiventris Cresson and Microplitis manilae Ashmead
Rajapaske, R.H.S. | Waddill, H. van | Ashley, T.R. (University of Florida, Gainsville (USA). Dept. of Entomology and Nematology)
The effects of host age, age of Cotesia marginiventris Cresson adults and temperature on interspecific competition between fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith), larval parasitoids C. marginiventris, Microplitis manilae Ashm. and the egg-larval parasitoid, Chelonus insularis Cresson were studied. All parasitization results for C. marginiventris and M. manilae were from FAW larvae parasitized as eggs by C. insularis. The maximum reproductive potential for C. marginiventris was achieved in hosts initially parasitized by C. insularis and were 36 to 48 hours old and at a temperature of 25 deg C. No host discrimination was found for C. marginiventris between larvae containing a developing C. insularis and non-parasitized larvae. The optimum parasitoid age for C.marginiventris during the host exposure period was 48 to 96 hr. Younger or older parasitoids were not able compete as successfully against C.insularis. A sex ratio of approximately 65 males was present in C. marginiventris progeny produced from parents ranging in age from 24 to 108 hr old. Egg to adult development times at 25 deg C were 17 and 26 days for C. marginiventris and C.insularis, respectively. In multiple parasitized larvae, C. marginiventris appeared to physically attack and destroy the larvae of C. insularis. However, M. manilae larvae died after 6 days without appearing to have been physically attacked in hosts containing C. insularis
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