Suppression of Populations of Drosophila melanogaster in Tomato Field Plots with Chemosterilant Baits

In 1963, gallon jars containing fermented bait, sprayed on the inside and outside glass surfaces with a 2% (w/v) aqueous solution of apholate and distributed at the rate of 16 jars per acre, gave a maximum of 63% suppression of Drosophila melanogaster Meigen in ¼-acre field plots of tomatoes at Beltsville, Maryland. Hampers of tomatoes sprayed with a 2% (w/v) aqueous solution of apholate and distributed at the same intervals were less effective. Diazinon granules applied at a rate of 1 lb of actual ingredient per acre gave a maximum of 93% control. Seven weekly applications were made of all treatments. In 1964, interplot movement of Drosophila flies was apparently too great in small tomato plots spaced 50 ft apart for chemosterilant treatments to produce statistically significant differences in suppression of this insect. However, the eggs laid by females collected from the plots produced 50% fewer adult progeny than did those laid by females collected from untreated tomatoes growing 1½ miles away. Maximum sterilities of females collected in 1963 and 1964 from chemosterilant-treated plots were 94 and 81%, respectively.