Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 1, 2001
Publication Date: N/A
Interpretive Summary: To successfully reduce the dependence on chemical pesticides, we must begin to rely on natural biological controls in agricultural production. To be able to rely on biological control we must have a complete knowledge of what species of beneficial insects are present and the ecology of these organisms. This study was designed to study the biological control species sin apple orchards over the course of the day and throughout the seasons, and to evaluate the effects of some orchard management practices on these species. It was found that two little known species (a lady bird beetle and a relative of lacewings) are very abundant in the orchard and may be contributing to the control of pests without our knowledge. Several groups of insect predators and parasites, including mite-feeding insects, are more abundant at night than during the day and their role in orchard biological control may be underestimated. It was also found that the extra floral nectaries on peaches attract a large number of biological control species and may be a useful addition to apple orchards for enhancing biological control. These results will be used by orchard researchers in evaluating biological control of orchard pests and designing orchards to rely more on biological and less on chemical control.
Technical Abstract: Limb jarring samples were taken in 4 experimental apple orchards at hourly intervals over a 24-hour period at four times during the growing season of 1991. A total of 1176 individual predators were collected belonging to seven orders and 22 families. The most abundant species was Coniopteryx sp. (Coniopteryigidae:Neuroptera) and the most abundant family was Coccinellidae (Coleoptera). A total of 396 adult parasitoids were collected from 26 families of Hymenoptera and one Diptera family, Encyrtidae was the most abundant family of parasitoids. All other individuals were classified as potential food items and were identified only to order and some common families, 5812 potential food items were collected. Diversity of predators and parasitoids was greatest in May and June. Diversity of predators was highest on apple that was inter-planted with peach and cherry trees, diversity of parasitoids was greatest on peach trees and in the insecticide treated orchard. Chrysopids (Neuroptera), clerids (Coleoptera) and Leptothrips mali (Fitch) (Phlaeothripidae:Thysanpotgera) were most commonly collected at dawn or during the night, suggesting that their role in orchards may be under- estimated by sampling only during daylight hours. All parasitoids except Scelionidae and Platygastridae (Hymenoptera) were most commonly collected during the night. Results indicate that peach trees are attractive to both predators and parasitoids and therefore may be a valuable addition to apple orchards to enhance the abundance of biological control species.