Development and evaluation of techniques for using Chrysopa carnea Stephens to control Heliothis spp. on cotton

Abstract

A series of laboratory, greenhouse and field studies were conducted to assess the feasibility of using Chrysopa carnea Stephens for controlling populations of the bollworm, Heliothis zea (Boddie), and the tobacco budworm, Heliothis virescens (F.) on cotton. Included were studies of the effects of extended laboratory culture on different biological attributes of C. carnea; the development of a practical method of rearing and distributing C. carnea larvae; and the determination of the numbers of C. carnea larvae required to control populations of Heliothis spp. on cotton. Studies of the effects of extended laboratory culturing on populations of C. carnea demonstrated that insects reared in conditions of continuous light, temperature and relative humidity were different from those collected in the field. Differences were found in adult longevity and fecundity, larval development time, and larval searching ability. There was a progressive decline in the adult longevity and fecundity and larval searching ability and the larval development time increased as the length of time in laboratory culture increased. Studies designed to develop methods of rearing large numbers of C. carnea for field release demonstrated that C. carnea larvae could be reared on non-viable eggs of Sitotroga cerealella (Oliver). The eggs of these species could be mixed with the sawdust to rear C. carnea larvae in a medium that was suitable for field release..