Competitive interaction between Campoletis chlorideae (Uchida) and Eriborus argenteopilosus (Cameron), solitary parasitoids of Helicoverpa armigera (Hubner)

摘要

C. chlorideae and E. argenteopilosus are the predominant parasitoids attacking H. armigera larvae. Competitive interaction between these two solitary parasitoids of H. armigera was studied in the laboratory. C. chlorideae and E. argenteopilosus individually parasitized 58% and 54% H. armigera larvae, respectively, the combination of the two parasitoids gave 71-76% parasitism. C. chlorideae was found to dominate (51%) when the H. armigera larva was first parasitized by C. chlorideae and then by E. argenteopilosus (20%). Similarly, E. argenteopilosus dominated (54%) when the H. armigera was first parasitized by E. argenteopilosus and then by C. chlorideae (22%). The parasitoids when released together parasitized 81% H. armigera larvae. The developmental period in C. chlorideae ranged from 13 to 16 days and in E. argenteopilosus from 18 to 21 days in different treatments. Sex ratio (male:female) in the case of C. chlorideae varied from 2.14:1 to 2.7:1 and in E. argenteopilosus 1.68:1 to 1.83:1. No difference in developmental time was achieved irrespective of parasitoid sequence. C. chlorideae and E. argeneopilosus were able to parasitize and develop on H. armigera irrespective of the sequence of parasitism.