Action of insecticides on forest pest insects. V. Effectiveness of insecticides against forest sawfly (Diprionidae) larvae.
The activity of insecticides from the group of pyrethroids (alphamethrin [alpha-cypermethrin], bifenthrin, deltamethrin, esfenvalerate, lambda-cyhalothrin, zeta-cypermethrin) arylpropylethers (etofenprox), and acylureas (diflubenzuron, flufenoxuron, novaluron, teflubenzuron, triflumuron), used in commercial or experimental formulations against Diprionidae larvae was evaluated in laboratory experiments during 1991-93. Two methods of application were used: topical application, and exposure of insects to treated pine needles. Pyrethroid insecticides and etofenprox showed very good effectiveness against the larvae: alpha-cypermethrin, zeta-cypermethrin and lambda-cyhalothrin showed similar activity, and esfenvalerate and bifenthrin demonstrated slightly lower activity. Deltamethrin was the most effective when topical application was used, but this insecticide showed lower activity (similar to esfenvalerate) when insects were exposed to treated pine needles. This may be due to a change in diprionid sensitivity to contact and stomachal activity of deltamethrin as a result of 14 years of application of this insecticide in forestry. The effectiveness of etofenprox was lower than that of pyrethroids, especially when the topical application method was used, but this insecticide is effective at higher doses than used for pyrethroids. The acylureas showed differences in efficacy: experiments with exposure of the larvae to treated pine needles demonstrated that flufenoxuron, novaluron and teflubenzuron were more active than diflubenzuron and triflumuron.