Effects of production system on vegetable arthropods and their natural enemies

Populations of foliar insect pests and natural enemies were monitored in vegetable production systems incorporating varying degrees of sustainable practices in Fletcher, NC, USA. Two types of tillage (conventional plow and disk, strip-tillage), two input approaches (chemically-based, biologically-based) and two cropping schedules (continuous tomato (Lycopersicon esculentum Mill.), 3-year rotation of corn (Zea mays L.), cucumber (Cucumis sativus L.) and tomato) were employed from 1995 to 1998. Tomato pest pressure was relatively low in all years, resulting in a limited impact of production systems on potato aphid, Macrosiphum euphorbiae (Thomas) (Homoptera: Aphididae), and its associated parasitoids and predators. Thrips (Frankliniella spp. (Thysanoptera)) populations were significantly higher in the biological input treatments in 3 of 4 years. Lepidopterous (primarily Helicoverpa zea Boddie (Lepidoptera: Noctuidae)) damage on tomato was significantly higher in biological treatments in all years, damage by thrips and pentatomids (Hemiptera: Pentatomidae) increasing each year in the continuous tomato crop schedule. Most insect populations were significantly influenced by type of insecticide input or ground cover. Few population measurements were affected by tillage type. Foliar insect problems in commercial vegetable production may be associated predominantly with insecticide input (i.e. more damage with biologically based insecticides) and use of intercropping (i.e. more damage in systems with living mulch); however, the long term effects of tillage and crop rotation remain to be seen.