DEVELOPMENT OF PESTICIDE-TREATED SPHERES FOR CONTROLLING APPLE MAGGOTFLIES (DIPTERA, TEPHRITIDAE) - PESTICIDES AND RESIDUE-EXTENDING AGENTS

Dimethoate, azinphosmethyl, methomyl, tralomethrin, malathion, fenvale rate, and carbaryl were evaluated in the laboratory for contact toxici ty to apple maggot flies, Rhagoletis pomonella (Walsh), with or withou t a feeding stimulant (sucrose) during a 10-min exposure period. Addit ion of sucrose decreased LC(50)s and LC(90)s of all insecticides teste d but had no effect on toxicity relationships among insecticides. In c ombination with sucrose, dimethoate was most toxic; azinphosmethyl, tr alomethrin, and methomyl were more toxic than malathion and fenvalerat e; and carbaryl was least toxic. At a concentration of insecticide equ al to five times the LC(90) value established in laboratory tests, all insecticides tested in field cages, except dimethoate and malathion, reduced tile duration of fly visitation and feeding on sucrose-coated, insecticide-treated red spheres. Spheres treated with a mixture conta ining 1.05% (AI) dimethoate or methomyl, 58.95% corn syrup, and 40% la tex paint as a residue-extending agent killed 76-87% and 50-62%, respe ctively, of alighting flies at 0 residual days (before exposure to wea ther). However, the spheres were ineffective after exposure to 6.6 mm rainfall. Effectiveness of pesticide-treated spheres in killing visiti ng flies was limited more by loss of feeding stimulant as a result of washoff by rainfall than by degradation of insecticide. Retreating wea ther-exposed (up to 35 d) dimethoate-treated spheres with 16% sucrose restored effectiveness in killing alighting flies. Neither dinethoate nor methomyl in combination with latex paint and corn syrup had a nega tive effect on the attraction of flies to treated spheres.