Effects of an Entomopathogenic Nematode and a Nuclear Polyhedrosis Virus on Emergence of Heliothis virescens (Lepidoptera: Noctuidae)

Abstract

Cage tests were conducted during the 1993 growing season to determine the effect of incorporating an entomopathogenic nematode (Steinernema riobravis) in soil under cotton on subsequent emergence of tobacco budworm, Heliothis virescens (L.). When soil under seedling cotton was treated with 240K nematodes per m2 on 13 May, the number of moths emerging in cages was reduced by an average of 66%, compared to the untreated control, for at least 21 days following application. When a similar rate was applied on soil under mature cotton on 12 July, the number of moths emerging in treated cages after developing as larvae on the plants was 57% less over a 39 d period compared to the untreated control. In another cage study, application of the nematodes on wild geranium, Geranium dissectum L., an early-season host of tobacco budworms and cotton bollworms, Helicoverpa zea (Boddie), reduced adult emergence by 36% compared to untreated areas, whereas a single application of baculovirus from the celery looper (600 billion polyhedra per ha) reduced the emergence by 56%. In this latter test, adult emergence was further reduced (73% less than control) when a whitening agent was added to the virus application. These studies indicate than an entomopathogenic nematode, and the use of a whitening agent with baculovirus, might be useful in tobacco budworm management programs.