W. Joe Lewis, Philip B. Haney,and Sbarad Phatak CONTlNUED STUDIES OF INSECT POPULATION DYNAMICS IN CRIMSON CLOVER & REFUGIA /COTTON SYSTEMS. PART 1: SWEEP & WHOLE PLANT SAMPLING 1996 Beltwide Cotton Conf.1108-1114.

Abstract

Sweep, shake and whole plant sarnpling rnelhods were used to monitor a compare the seasonal abundance of plant-dwelling beneficials and pests three cotton fields in Dooly and Tift county, in the Coastal Plain region of south Georgia. The two Dooly county sampling sites wete a 20 ha conservation-tilled (Crimson clover) field and a nearby 20 ha conventions tilled (fallow) field. Sarnples in Tift county were taken from a 10 ha conventional-tilled field interspersed with six permanent 3-row refugia strips comprised of Crimson clover and annual weeds. Beneficial arthropod monitored included the striped lynx spider, Oxyopes salticus, Crab spiders (Thomisidae), two big-eyed bugs, Geocoris punctipes and G. uliginosis, fire ants, Solenopsis invicta, the minute pirate bug, Orius insidiosus, an Anthicid (ant-like flower beetle), Notoxus monodon, three Coccinellids; Hippodarnia convergens, Coccinella seplempunctara, and Harmonia axyridis, a Nabid (Damsel bug) and a Chrysopid (Green lacewing). Pests monitored included the cotton aphid, Aphis gossypii, budworms, Heliothis virescens, bollworms, Helicoverpa zea, cabbage and soybean loopers, Trichoplusia ni and Pseudoplusia includens, thrips and the tarnished plant bug. Lygus linceolaris

In Dooly county, the dominant generalist predators taken in Crimson clover sweep samples were O. insidiosus, spiders, Geocoris, and a Nabid. Crimson clover also harbors a diverse aphidophagous complex, including Coccinellids.several parasitoids, Syrphids and Chrysopids. Weather had a profound
influence on beneficial and pest populations. 1995 was much drier than 1994, and overall densities of spiders, S. invicta, Coccinellids lacewings, lepidopterous larvae, thrips and plant bugs were all significantly lower in both fields in 1995 than in 1994. Cotton aphid densities were seven times higher;
Geocoris and Anthicid densities were not significantly different. Ratios of beneficials to lepidopterous larvae were significantly higher (p < 0.05) in the clover field. S. invicta was the only beneficial with significantly higher densities in the clover field dusing both seasons. S. invicra significantly reduced densities of Geocoris, Anthicids, Coccinellids and lacewings in the clover, but did significantly effect spiders.

In Tift county, seasonal densities of spiders, S. invicta, Geocoris and Coccinellids were signifiicanty higher in cotton strips lying between or adjacent to the refugia strips than in cotton strips Iying farthest from the
refugia Density and distribution of beneficials in the entire rft county field remained high throughout the entire season.

A total of four foliar insecticide treatments were applied to the conservation-tilled field in Dooly county in 1994-95, vs. eight in the conventional-tilled field. No foliar insecticide treatments were applied in the Tift county cotton/refugia field.