Effect of different temperatures on Trichogramma chilonis (Hymenoptera: Trichogrammatidae) parasitizing the eggs of Corcyra cephalonica and Helicoverpa armigera

Abstract

The experiment was carried out to evaluate the temperatures requirements for the proper storage of trichocards parasitized by Trichogramma chilonis (Ishii) prepared from two host eggs i.e. Corcyra cephalonica (Stainton) (Lepidoptera: Pyralidae) and Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae). The effect of different temperatures treatment on the biological parameters like parasitization capacity, emergence percentage, adult longevity, sex ratio of T. chilonis, on the eggs of C. cephalonica and H. armigera were investigated. Parasitized trichocards were kept at 90, 110, 130, 150, 170, 190, 210, 230, 250 and 27 0C. Storage temperature of 15 0C showed the highest per cent parasitism (89.33% on C. cephalonica & 88.33% for H. armigera eggs) which was declining with increase in temperature, per cent adult emergence was 94 & 96% on C. cephalonica and H. armigera eggs respectively and total fecundity (99.33 & 103.67% on C. cephalonica and H. armigera eggs respectively) also followed the similar trend. Storage temperature of 90 recorded the highest longevity of T. chilonis (11.50 & 11.17 days, respectively on C. cephalonica and H. armigera eggs). Treatment with storage temperature of 13 0C recorded the highest sex ratio of female to male, 5:1 on C. cephalonica eggs and 4:1 on H. armigera eggs. In general the treatment with 15 0C was most effective overall recording the highest in three parameters and can be considered as the best treatment. The results suggested that the most suitable temperature for the storage of trichocards can be 130 to 15 0C.