Population Survey and Control of Chironomidae (Diptera) in Wetlands in Northeast Florida, USA

Abstract

A qualitative and quantitative population survey of immature and adult Chironomidae was conducted for 1 year in a country club wetlands in northeast Florida, USA. Glyptotendipes paripes and Goeldichironomus carus were the 2 predominant chironomid species in the wetlands. Adults of these 2 species emerged at nuisance levels from Apr through Jun, and in Aug and Sep. Polypedilum, Cryptochironomus, Tanytarsini, and Tanypodinae collected in low numbers during the survey were not identified to species. In laboratory bioassays, LC90 values of technical grade temephos against G. paripes and G. carus were 0.01 and 0.009 ppm, respectively. For s-methoprene the LC90 values were 0.082 and 0.055 ppm, and for Bacillus thuringiensis serovariety israelensis (Bti) 1.056 and 0.467 ppm, respectively. In experimental field plots in the wetlands, 5% AI Skeeter Abate® (temephos) pellets at 0.1 kg AI/ha reduced midge larvae by 52-86% and at 0.2 kg/ha by 74-92% during 4 weeks posttreatment. Sand formulated technical powder of Bti at 1,000,000 and 2,000,000 ITU (International Toxic Units) Bti/m2 reduced midge larvae by 47-52% and 82-88%, respectively, during 6 to 20 days posttreatment. STRIKE® pellets (4.25% AI s-methoprene) at 0.14 kg AI/ha suppressed a maximum of 80% total chironomid adult emergence at 7 days posttreatment; this IGR at 0.28 kg AI/ha reduced adult emergence up to 92% during 15 days posttreatment. Temephos and Bti were more cost-effective and provided midge control for relatively longer period than s-methoprene in the field evaluations.

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