Horatio C. Mason

Suppression of Drosophila melanogaster in Commercial Tomato Fields by Area and Direct Field Releases of Tepa-sterilized Adults

In 1967, ca. 41.5 million unsexed adult Drosophila melanogaster Meigen were reared, sterilized with tepa, marked with fluorescent dye, and distributed weekly June 8–Sept. 13 in a 25 mile2 area in New Jersey for suppression of this insect in commercial tomato fields. The 1st 9 releases (ca. 24.6 million flies) distributed over the 25-mile2 area failed to suppress development of D. melanogaster in 125 acres of tomatoes near the center of the test area. The last 6 releases (ca. 16.8 million flies) concentrated on the 125 acres of tomatoes near the center of the area, reduced the native fly population 61% (maximum) and oviposition in ripe tomatoes 78% (maximum) in the release fields in September compared with the check area; these differences were statistically significant at the 1% level of probability. Females isolated from field collections taken in the release area after Aug. 15 were significantly less prolific than those from the check area. Flies treated with tepa or dye or both appeared slightly weaker or less active than untreated flies.

Experiments with Insecticides for the Control of Drosophila Breeding

In experiments under field conditions at Beltsville, Maryland, one application of the following insecticides gave good control of drosophila breeding in piles of cull tomatoes: aldrin, dieldrin, ethion, heptachlor, clilordane, methoxychlor, ronnel (Dow ET-57), malathion, dicapthon, Diazinon° ( 0,0 -diethyl 0 -(2-isopropyl-4-methyl-6-pyrirnidinyl)phosphorothioate), and Dipterex ° ( 0,0 -dimethyl 2,2,2-trichloro-1-hydroxyethylphosphonate). Malathion, the only insecticide tested under commercial conditions, also gave good control of drosophila breeding in tomato skin piles on the Eastern Shore of Maryland.