Field Parasitism and Biological Characteristics of Potent Larval Endoparasitiods of Spilosoma obliqua Walker in Jammu and Kashmir, India

Abstract

Three species of braconid parasitoids viz, Glyptapanteles agamemnonis Wilkinson, Meteorus sp. and Cotesia ruficrus (Haliday) were recovered from the field collected larvae of Spilosoma obliqua Walker feeding on cultivated Vigna mungo and wild weeds, Xanthium strumarium and Parthenium hysterophorus during kharif 2002 and 2003 in Jammu (J & K). Besides, the prevalence of one ichneumonid parasitoid Agathis sp. and viral disease (Nucleopolyhedrovirus) was also noticed. Meteorus sp. Was considered as most promising parasitoid of this pest with a maximum parasitizatiou of 77.0 percent. Nevertheless, G. agamemuonsis is reported for the first time on S. obliqua in India. While, G agamemuonsis was recovered from the larvae feeding on all the three hosts viz Vigna mungo, Parthenium hysterophorus and Xanthium strumarium, Meteorus sp. was never recovered from P. hysterophorus. However, both these parasitoid co-existed in nature and found together attacking 3-4^th instar larvae from September to October (37-43 SW) with a peak activity within a minimum temperature range of 14.0 to 18.0°C. The natural parasitism by these parasitoids did not reveal significant correlation with aboitic factors, but the relationship between their respective K-valucs and larval density fit into density dependent model K = aN^b. However, C. ruficrus and Agathis sp. were noticed in later season when the mean minimum temperature reached below 10°C. The behaviour and developmental biology of all the three braconid parasitoids of S. obliqua is described.