Toxicity of some biorational and conventional insecticides to cotton bollworm, Helicoverpa armigera (Lepidoptera: Noctuidae) and its ectoparasitoid, Habrobracon hebetor (Hymenoptera: Braconidae)

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Abstract

Insect growth regulators and spinosyns which are physiologically and ecologically selective, respectively, have been investigated as replacements or complements to non-selective conventional insecticides. The effects of diflubenzuron, hexaflumuron, profenofos, spinosad and thiodicarb were assessed on the 1st instars of cotton bollworm, Helicoverpa armigera (Hübner) using dietary and leaf disc bioassay methods. Based on modes of action of the insecticides tested, the mortalities were recorded after 24 h in profenofos, thiodicarb and spinosad experiments and after 120 h in hexaflumuron and diflubenzuron treatments. The LC50 values for diflubenzuron, hexaflumuron, profenofos, spinosad and thiodicarb in dietary method were 595.05, 0.31, 3.69, 0.13 and 11.2 mg ai/L; and in leaf disc method, they were >2000, 0.46, 9.55, 0.2 and 15.52 mg ai/L, respectively. The effects of these insecticides on adult Habrobracon hebetor Say, an ectoparasitoid of cotton bollworm were tested using residual method. The mortalities were recorded after 24 h in all treatments. The LC50 values for diflubenzuron, hexaflumuron, profenofos, spinosad and thiodicarb for females were >2000, >2000, 12.44, 15.64 and 81.04 mg ai/L, respectively and for males, they were >2000, >2000, 6.91, 11.73 and 40.39 mg ai/L, respectively. In this study spinosad and hexaflumuron seemed to be more useful than the other insecticides due to their higher toxicity to H. armigera and lower toxicity to H. hebetor.

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Journal of Entomological Society of Iran
Volume 28, Issue 1
September 2008
Pages 27-37

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