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Effect of Malathion on Beneficial Insects

P. G. Tillman and J. E. Mulrooney


 
ABSTRACT

Susceptibility of four natural enemies, Geocoris punctipes (Say), Cotesia marginiventris (Cresson), Bracon mellitor Say, and Cardiochiles nigriceps Vierick, to several insecticides was determined. In topical toxicity tests, malathion ultra-low-volume (ULV) (95 %) was applied undiluted at 1.36 and at 1.02 kg (AI)/ha with cottonseed oil in a total volume of 1.17 liter/ha. Fipronil and cyfluthrin were applied at 0.043 and 0.037 kg (AI)/ha, respectively, plus cottonseed oil in a total volume of 1.17 liter/ha. Emulsifiable concentrate (EC) formulations of malathion and fipronil at 1.12 and 0.043 kg (AI)/ha, respectively, also were applied with water in a total volume of 93.5 liter/ha. All of the insecticides were highly toxic to all five insect species when applied topically. In insecticide residue tests, undiluted malathion ULV at 1.36 kg (AI)/ha, and fipronil and cyfluthrin at 0.028 and 0.022 kg (AI)/ha, respectively, plus Orchex® 796 was applied in a total volume of 1.17 liter/ha. Toxicity of residues of these insecticides to the five insect species was determined at 0, 24, and 48 h after treatment. Residues of malathion ULV were highly toxic to all five insects 48 h after treatment except for C. nigriceps which was affected only slightly less by this insecticide than the other four species at 48 h after treatment. Residues of fipronil were less toxic to C. nigriceps than to the other natural enemies 0 to 48 h after treatment. Residues of cyfluthrin were less toxic to all insects than the other two insecticide treatments for each time regime. In a rate residual test conducted in the same manner as the above residue test, malathion ULV (95 %) was applied at 1.36 and 0.85 kg (AI)/ha plus cottonseed oil in a total volume of 1.17 liter/ha. Residues of undiluted malathion ULV were highly toxic to the insects through 48 h after treatment except for C. nigriceps while residues of malathion ULV with cottonseed oil were highly toxic to only B. mellitor and C. marginiventris at 48 h after treatment.



Reprinted from Proceedings of the 2000 Beltwide Cotton Conferences pg. 1064
©National Cotton Council, Memphis TN

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Document last modified Saturday, Jun 17 2000