Natural Control Studies of the Melon Leaf Miner, Liriomyza pictella (Thomson)1

Abstract

The results of 2 years study of the natural control of the melon leaf miner, Liriomyza pictella (Thomson), by parasitism are discussed. The melon leaf miner is heavily parasitized in nature. Parasitism was low early in the growing season, but increased as the melon plants approached senescence, until the population level of the parasites exceeded that of the melon leaf miner. A close correlation was noted between the population numbers of the host and its parasite, except during the middle of the growing season, at which time the population of the melon leaf miner greatly exceeded that of its parasites. Evidently some additional limiting factors existed which were acting to reduce in number the melon leaf miner as it approached the peak of its population. The use of DDT and parathion depressed the populations of both the host and its parasites, but had less residual effect on the melon leaf miner, thus permitting it to increase in numbers more rapidly than its parasites. At 19 species of hymenopterous parasites were reared from the larval and pupal stages. The two most numerous species were Solenotus begini (Ashm.) and Halitcoptera aenea (Walk)