Pesticide applications on Java potato fields are ineffective in controlling leafminers, and have antagonistic effects on natural enemies of leafminers

In Indonesia a range of insecticides is routinely applied to control agromyzid leafminers. Insecticide applications can reduce parasitism by indigenous parasitoid wasps and also decrease numbers of the predatory muscid fly, Coenosia humilis, and these effects reduce control of leafminers. In replicated field trials, repeated applications of Profenofos were ineffective in controlling L. huidobrensis numbers on potatoes. Applications of Profenofos and Carbosulfan decreased rates of parasitism by Hemiptarsenus varicornis and Opius chromatomyiae, and reduced numbers of C. humilis. These detrimental effects of the pesticides observed may have contributed to the increased damage and decreased yield in the pesticide-treated fields. An alternative control strategy involving the applications of Abamectin led to a reduction in leafminers without harmful effects on parasitoids and predators. Abamectin applications provide one potential component of an effective Liriomyza control strategy for Indonesian potato farmers.