Lhb. Kanga et Fw. Plapp, DEVELOPMENT OF A TECHNIQUE TO MONITOR RESISTANCE TO BIODEGRADABLE INSECTICIDES IN-FIELD POPULATIONS OF TOBACCO BUDWORM (LEPIDOPTERA, NOCTUIDAE), Journal of economic entomology, 88(3), 1995, pp. 487-494
A procedure involving the use of glass vials containing insecticide wa
s developed to monitor for resistance to biodegradable insecticides am
ong field populations of adult tobacco budworms, Heliothis virescens (
F.). These insecticides are replacing pyrethroids for the tobacco budw
orm control in areas where pyethroid resistance is a problem. Residues
of profenofos, chlorpyrifos, methomyl, and endosulfan in glass vials
were depleted in 2 d when they were held either in daylight or in the
dark at room temperature. Residues of these compounds remained much lo
nger (>70 d) in vials held in the freezer. The loss of toxicity was sh
own to be mainly caused by hydrolytic degradation of the insecticide r
ather than to the volatilization. The addition of mineral oil or ethyl
ene glycol did not increase the persistence of insecticide residues in
glass vials; however, addition of an organic acid (benzoic or decanoi
c) to the vials significantly extended stability of insecticide residu
es. Based on these results, treating vials with combinations of insect
icides plus benzoic acid and storing them in a freezer is the preferre
d technique if they are held for extended periods before use. The usef
ulness of this technique was confirmed by gas-liquid chromatographic a
nalysis of insecticide residues and by field monitoring data.