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Effects of Karate® Insecticide on Beneficial Arthropods in Bollgard® Cotton

J.F.H. Cole, E.D. Pilling, R. Boykin and J.R. Ruberson


 
ABSTRACT

The effects of the pyrethroid insecticide lambda-cyhalothrin (Karate®) on beneficial arthropods in Bollgard® cotton were investigated in Georgia during the 1996 cotton season. Two applications (mid-June and late July) of lambda-cyhalothrin were made on large (>3 acres) replicated plots, and effects were compared to control and methyl-parathion treated plots. Populations of natural enemies and pests were assessed throughout the season in the crop canopy by sweep-net and shake-cloth sampling, and on the ground using pit-fall traps. A comparison of final yield between the treated plots and the control was made at the end of the season. Over 30 species of beneficial arthropods were identified during the study, including big-eyed bugs, pirate bugs, lady beetles, lacewings, spiders, parasitoid wasps and ground beetles. Results showed the first lambda-cyhalothrin spray was applied before the beneficial population had built up and therefore had little effect. The second application caused a transient reduction in the natural enemy population, numbers however recovered within 10 days. Applications of methyl-parathion had a longer duration of effect on some important natural enemy groups, principally big-eyed bugs (Geocoris spp.). Effects of insecticide applications were primarily confined to arthropods in the crop canopy, with little impact on ground dwelling species. Good pest control was demonstrated following applications of lambda-cyhalothrin, in particular of fleahoppers, stink bugs and plant bugs. By direct comparison of total natural enemy and pest populations numbers, lambda-cyhalothrin was shown to cause no significant disruption of season-long predator to pest ratios. Finally, a 12% increase in yield was evident following the application of lambda-cyhalothrin compared to control plots. In summary, lambda-cyhalothrin provided good pest control whilst maintaining beneficial populations, providing additional natural control. No significant disruption in the balance between predators and pests was caused, and overspraying Bollgard® cotton with lambda-cyhalothrin significantly increased yield.



Reprinted from Proceedings of the 1997 Beltwide Cotton Conferences pp. 1118 - 1120
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998