Drosophila Control in Tomato Fields1

Abstract

Insecticidal sprays were tested for the field control of Drosophila oviposition—principally that of Drosophila melanogaster Meig—in tomato fruits during 1955 and 1957. Diazinon® ( O,O -diethyl O -(2-isopropyl-4-methyl-6-pyrimidinyl) phosphorothioate) applied at the rate of one-half pound per acre gave a satisfactory reduction of Drosophila activity. Wettable powder, emulsifiable concentrate and a granular formulation of Diazinon were compared and found to be equally effective at the rate of one-half pound per acre. The granular formulation exhibited long residual action and there appeared to be some cumulative effect from repeated applications. Malathion applied to small plots and in commercial plantings was only effective for 2 to 3 days and was followed by a very rapid fly buildup. Phosdrin® (1-methoxycarbonyl-1-propen-2-yl dimethyl phosphate) had somewhat the same weakness as malathion—short residual action. Ronnel and Dibrom®(1,2-dibromo-2,2-dichloroethyl dimethyl phosphate) were tested during 1957 only and compared favorably with Diazinon. Hydrolyzed yeast did not prove to be an added attractant to the flies when used alone.