Survey of Ground-Dwelling Predaceous and Parasitic Arthropods in Cabbage Fields in Upstate New York 1 A. M. SHELTON, J. T. ANDALORO,' AND C. W. HOY Department of Entomology, New York State Agricultural Experiment Station, Cornell University, Geneva, New York 14456 Environ.Entornol.12:1026-1030(1983) ABSTRACT During ]979 and 1981, populations of ground-dwelling predators and parasites in re- search and commercial cabbage fields in upstate New York were assessed by pitfall trapping tn determine species composition, abundance, phenology, and the impact of insecticides on them. Staphylinidae, Phalangida, Carabidae, and Araneida were consistently the most abundant predaceous taxa. Carabids and Staphylinids together comprised 75.9 and 74.1% of all predaceous or parasitic insects in commercial fields during 1979 and 1981, respectively. One of the 32 species of Carabidae captured, Pterostichus melanarius (Il1iger), accounted for >50% of the total number of Carabidae. Total number of predators and parasites tended to decline from July through September in both treated and untreated fields, but this decline was hastened by the use of broad-spectrum insecticides. Ground-dwelling predators can be important control agents of insect pests of brassica crops. In studies con- ducted in England, Hughes (1959) concluded that two genera of carabids (Bembidion and Trechus) destroyed >90% of the cabbage maggot, Hylemya brassicae Bouche, eggs. In another study Wright ct a!. (1960) demonstrated an inverse relationship between the num- ber of ground predators and survival of cabbage maggots in brassiea. Further studies by Coaker and Williams (1963) utilized precipitin tests to identify several carabid and staphylinid predators of the immature stages of the cab- bage maggot. In Canada, Wisharf et al. (1956) reported carabids as the most abundant group of predators on cabbage maggot eggs, and within this group Bembidion quadrimaculatum oppositum Say and B. nitidum (Kby.) were the most important. Furthermore, a survival model developed by Mukerji (1971) for cabbage maggot in- dicated the importance of pupal parasitism by a staphy- linid, Aleochara bilineata Gyll., as a stabilizing factor in maggot populations. Predation by ground-dwelling arthropods on other cabbage insect pests has been re- ported (Pimental 1961, Oatman and Platner 1969, Weires and Chiang 1973), but their importance in controlling pest populations has not been established. Because we lack information on existing natural con- trol agents, present management of insect pests in most commercial cabbage fields in New York relies solely on the use of insecticides for pest suppression. However, this strategy can substantially reduce the effectiveness of predators and parasites on pests like cabbage maggots (Pitre and Chapman 1964, Coaker 1966, Chapman and Eckenrode 1973). Therefore, a documentation of the ground-dwelling parasite-predator complex and its phe- nology in New York cabbage fields and information on the effects of insecticides on them is required for the implementation of sound control practices. This infor- mation is not currently availablc in the literature. In this study we surveyed this complex in several upstate New 'Approvedby the Director.N.Y.StaleAgric.Exp.Stn.. forpub- licationas JournalPaperNo. 3438.Receivedfor publication13May 1982:accepted2 February1983. '1PMPrograms,CornellUniversity. Geneva.NY 14456. York cabbage fields to identify possible biological con- trol agents, observe their phenology, and assess the im- pact of insecticides on them. Materials and Methods This survey was conducted in commercial and n.:- search cabbage fields in Ontario County, New York. Three 4- to 5-ha commercial fields and one I-ha un- treated research field were surveyed during the 1979 cropping season. Two of the commercial fields wcre divided in half, and each half received a different in- secticide treatment regime, either based on the recom- mendations of Cornell's Processing Cabhage Integrated Pest Management (IPM) Program (side A) or the grow- er's judgment (side B). During 1981, one 2-ha com- mercial field was surveyed. This field was divided into thirds, each treated with a different insecticide regime based on a low, moderate, or high action threshold for lepidopterous pests. All insecticide applications were re- corded. Arthropods were collected in pitfall traps (450-011plastic cups) placed within the rows between cabbage plants. Traps were filled with a mixture of water, detergent, and alcohol. From 25 to 50 traps were placed in each field for 3- to 7-day intervals. Arthropods were identi- fied and enumerated, and the data were summarized by field, date, and mean per trap per 3 days. Results and Discussion In the untreated field during 1979, the most abundant predator-parasite taxa were Staphylinidae (27.3%). Phalangida (24.9%). Araneida (14.5%), and Carabidac (12.5%), and together they comprised ca. 80% of pre- daceous or parasitic arthropods captured (Table I). Ca- rabidae and Staphylinidae together comprised 66% of the predaceous or parasitic insect complex. In the com- mercial fields for both years, these four taxa were again the most abundant. Staphylinidae and Carabidae to- gether comprised 75.9 and 74. I% of the insect predator- parasite complex in commercial fields during 1979 and 1981, respectively (Fig. I and 2). Thirty-two species of Carabidae were identified from fields sampled during the 2 test years. More than half 1026