Incidence and distribution in sorghum of the spotted stem borer Chilo partellus and associated natural enemies in farmers' fields in Andhra Pradesh and Maharashtra states

A series of surveys was carried out in farmers' fields in two major sorghum-growing states of India (Maharashtra and Andhra Pradesh) during the 1994 and 1995 cropping seasons to determine distribution, abundance, and economic importance of the spotted stem borer Chile partellus Swinhoe and associated parasitoids in sorghum. Stem borer incidence and distribution varied significantly between the two states. In Maharashtra, the highest incidence was recorded in Amravati district (40%), followed by Yavatmal (39%). In Andhra Pradesh, the highest incidence and damage were recorded from Medak (31%), followed by Mahbubnagar (30.3%). The natural enemies recorded in the survey included three larval parasitoids, viz. Cotesia ruficrus (Haliday) and C. flavipes Cameron, and Sturmiopsis inferens Townsend and one pupal parasitoid Xanthopimpla stemmator Thunberg. While species composition did not vary between the two states, species predominance varied considerably, such that Cotesia spp. were predominant in Maharashtra, and S, inferens in Andhra Pradesh.