Biology of Cardiochiles nigricollis Cameron, a Larval Endo-parasitoid of Cnaphalocrocis medinalis (Guen.) and Marasmia exigua Butler
The parasitoid Cardiochiles nigricollis Cameron usually parasitize the fourth instar larvae of Cnaphalocrocis medinalis and Marasmia exigua. Four instars were identified during the development of the parasitoid. The first instar larva is un-segmented and slightly curved. In the second instar segmentation appeared and tracheal system could be observed faintly. In the third instar head was well demarcated and the larva further grew in size. Six to eight days after egg laying the full grown larva came out of the host. The average pupal period lasted for 5.3 days in females and 6.7 days in males in the laboratory. Average incubation period, larval duration and pupal duration were 1.2 days, 10 days and 6.7 days respectively. C. nigricollis entered diapause at pupal stage and it started from the end of August and increased steadily till the first week of December when the entire population entered diapause. This phenomenon was observed only during wet season. On an average male emerged after 213 days and females after 224 days from the diapausing pupae. The gradual increase in the number of C. nigricollis entering diapause in the field population could possibly be due to occurrence of a heterogenous population of C. nigricollis in the field which responded gradually to fall in atmospheric temperature. Brachymeria sp., Orgilus sp., Trichomalopsis (Eupteromalus) parnarae Gahan and Elasmus sp. were reared as hyper-parasitoids on pupae of C. nigricollis.
Cardiochiles nigrocollis, Cnaphlocrocis medinalis, Marasmia exigua, Biology, Rice.
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