A review of area-wide management of Helicoverpa and Heliothis (Lepidoptera: Noctuidae) with pathogens (1987-1997)

Research to develop improved methods of managing serious insect pests of Mi ssissippi Delta crops, specifically cotton, by use of natural insect pathog ens was begun in 1987 at the USDA, ARS, Southern Insect Management Research Unit (SIMRU) in Stoneville, MS. Previous research had shown that non-crop plants, particularly early-season weeds, were hosts for the tobacco budworm , Heliothis virescens (F.), and cotton bollworm, Helicoverpa tea (Boddie), prior to the presence of crop hosts. It was theorized that tobacco budworm and cotton bollworm populations could be managed by either controlling the insects on the weeds using insecticides, or by controlling the early season hosts themselves via herbicides or mowing. Since entomopathogens (microbia l insecticides) are considered to be among the safest methods of insect con trol, research was begun to investigate their use in a management scheme. P ositive results of small field and cage tests (prior to 1990) led to large area studies, beginning with a 25,900-ha test in 1990, and culminating in 8 1,000-ha tests in 1994 and 1995. Tests over smaller areas in 1996 and 1997 were designed to (1) evaluate the effectiveness of a commercially-prepared formulation of the virus sprayed twice at weekly intervals (1996) and (2) d etermine efficacy of a half-rate of the new virus formulation in an attempt to reduce costs (1997). Collective results of this 11-yr study indicate th at virus application can be accomplished at a reasonable cost, and that suc h treatment consistently reduced the number of moths emerging from weed hos ts by >70%. Herein, we present brief results of the long-term study that le d to the present question of what the future holds for this project.