I. Dacus dorsalis Hendel bba 3 Dacus zonatus (Saunders)' Toxicity Tests of Some Insecticides against Fruit Flies I. Dacus dorsalis Hendel and Dacus zonatus (Saunders)

Abstract

Comparative toxicity tests of ten insecticides were made against Dacus zonutus (Saunders) and Dacus dorsalis Hendel (Tephritidae, Diptera). In the feeding method, it reveals that the susceptibility of both species to trichlorfon and malathion was increased as the age of adult flies increased from 1,7,14,21 and 24 days respectively. Results from this study also showed that D. zonatus was 2.5 and 1.5 times respectively higher resistant to trichlorfon and malathion than D. dorsalis. The species also demonstrated higher tolerance to the following insecticides when they were tested at two days old age through the following methods: isoprocarb, methyl parathion, and BHC by vaccuum dusting; DDT, trichlorfon, carbaryl, and malathion by toxicity deposit; and malathion by topical application. However, the results were reversed when the topical application was employed in testing with trichlorfon, carbaryl, methomyl, dimethoate, and cypermethyl. The insects showed no significant difference in their susceptibility when trichlorfon, malathion, and cabaryl were injected directly into their blood stream. Malathion and trichlorfon are normally recommended for bait sprays in combination with an attractant such as the yeast protein hydrolysate. Since D. zonatus is comparatively higher resistant to both insecticides, it may need higher dosages for the bait sprays in the field in order to obtain satisfactory results of simultaneous controls of both species.