Interaction between the larval endoparasitoid Campoletis sonorensis (Hymenoptera : Ichneumonidae) and its host the tobacco budworm (Lepidoptera : Noctuidae)

Studies on growth and development of Campoletis sonorensis (Cameron) in var ious instar Heliothis virescens (F.) larvae were conducted. The behavior an d morphological changes of the parasitized host was also evaluated. The res ults indicate that the host's age at the time of parasitism apparently infl uenced the development and subsequent fitness of the parasitoid. When initi ating development in 3rd or 4th instar hosts, the parasitoid developed sign ificantly slower. than when initiating in Ist instar hosts. Furthermore, wh en developing in 3rd or 4th instar hosts, the parasitoid developed signific antly faster during embryonic and Ist instar stages, and significantly slow er during the 2nd, 3rd, and dth instar stages than those developing in Ist instar hosts. In younger hosts, parasitoids also produced a significantly r educed body length, weight, longevity, and egg production estimate. Parasit ism of H. virescens larvae by C. sonorensis changed host's morphology and b ehavior allowing easy identification of parasitized individuals and estimat ion of the age of the developing parasitoid within its host.