Evaluation of a commercially available beneficial insect habitat for management of lepidoptera pests.

A field study was conducted in 2003 and 2004 at the Center for Environmental Farming Systems in Goldsboro, NC, to evaluate the effectiveness of a commercially available beneficial insect habitat in decreasing pest caterpillar populations in organically managed tomato, Lycopersicon esculentum Mill., plots. Six pairs of tomato plots were established and a commercial beneficial insect habitat seed mix (Peaceful Valley's Good Bug Blend) transplanted around the perimeter of treatment plots, whereas a brown-top millet, Brachiaria ramose (L.) Stapf., border was planted around control plots. Egg predation, egg parasitism by trichogrammatid wasps, and larval parasitism by braconid wasps was monitored throughout the growing season to determine whether habitat increased their activity. In both years of this study, the density of Helicoverpa zea (Boddie) and Manduca spp. eggs was not significantly different between treatment and control plots. Although parasitism was the most important component of egg mortality (19-49%), parasitism was not significantly different between habitat types. Identifiable predation was a minor component (3-9%) of egg fate; it is possible that unidentified predation may be part of the approximately 35-52% of eggs that met unknown fates. Larval parasitism levels ranged from approximately 10 to 90% but was not significantly influenced by the presence of beneficial insect habitat in either year of the study. These results demonstrate that natural enemy activity in organic tomatoes was not amplified, and pest populations were not reduced by the presence of a commercially available beneficial insect habitat.