Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/12/2003
Publication Date: 11/1/2003
Citation: BROWN, M.W., SCHMITT, J.J., ABRAHAM, B.J. SEASONAL AND DIURNAL DYNAMICS OF SPIDERS (ARANEAE) IN WEST VIRGINIA ORCHARDS AND THE EFFECT OF ORCHARD MANAGEMENT ON SPIDER COMMUNITIES. ENVIRONMENTAL ENTOMOLOGY. 2003. Vol. 32(4)P 830-839. Interpretive Summary: The public and government regulatory agencies are demanding less use of pesticides in the production of our food. Increasing biological control of insect pests is one approach that is being used to reduce the reliance on chemical pesticides. In this paper we investigated the impact of spiders in controlling insect pests of apple orchards with both field experiments and a survey of the world literature on spiders in orchards. A large variety of spiders were found in high abundances in both unmanaged and pesticide-treated orchards. Data from around the world show that anywhere apples are grown, spiders are abundant and can contribute significantly to pest control. Spiders in orchards have a large potential to control many pests in orchards, and better management of spiders can contribute to reducing pesticides. The information in this paper will be used by researchers in insect pest management and biological control in research projects to increase biological control in orchards and other farming systems.
Technical Abstract: Four apple orchards under different management (unmanaged; horticultural management only; horticultural management with apple, peach, and cherry trees interplanted; and standard commercial management) were sampled for spider abundance. Sampling was done with limb jarring at four times during the season, with samples taken hourly over a 24-hour period. A total of 1926 spiders from 15 families was collected, and 44% of all spiders were Salticidae. More spiders were collected in August (37%) than earlier months, but the highest diversity of spider families was in July. Older, more structurally diverse apple trees had the greatest diversity of spiders. The family Oxyopidae was most abundant in the commercially managed orchard. Spiders in the families Anyphaenidae, Philodromidae and Thomisidae were significantly more abundant during night samples than during the day. Philodromids were also significantly more abundant on peach and cherry trees than on apple, possibly being attracted to extrafloral nectaries. Comparisons with other published data sets found that regional differences were more important determinants of spider community structure in apple than insecticide use. Northern and Western European apple orchards were found to be dominated by web-building spiders, and North American (except for sprayed Quebec orchards) and Israeli orchards were dominated by hunting spiders. Abundance and diversity of the spider community in orchards suggests that spiders could be major contributors to biological control of many insect pests.