Toxicity of Different Dilutions of Spinosad Bait against Two Fruit-fly Species (Diptera: Tephritidae)

Abstract

Toxic bait is an alternative to manage fruit flies (Tephritidae) in orchards and in wide-area programmes. The mortality caused by different dilutions of spinosad baits on adults of Ceratitis capitata (Wied.) and Anastrepha grandis (Macquart) (Tephritidae) were compared with a hydrolysed protein (BioAnastrepha) and water in laboratory. Females and males of C. capitata and A. grandis were exposed to Success® 0.02CB (GF-120 NF Naturalyte fruit-fly, 0.02% spinosad) diluted in distilled water (v/v) at 1:1.5; 1:4.5; 1:9.0 and 1:18.0. Spinosad dilutions at 1: 1.5 and 1: 4.5 showed similar effects and provided 100% adult mortality 24 hours after exposure to the baits. Anastrepha grandis was more susceptible to spinosad baits than C. capitata. Females of C. capitata were less susceptible to spinosad diluted at 1: 1.5, 1: 4.5 and 1: 90, than C. capitata males and both sexes of A. grandis. The values of lethal times (LT50) varied for the different dilutions of spinosad for both fruit-fly species; however, with different patterns for each species. The LT50 values of the two highest concentrations (1: 1.5, 1: 4.5) of spinosad bait were similar for fruit flies of both sexes of each species, but a significant difference was observed between species, with higher LT50 values for C. capitata. In general, the cumulative mortalities of spinosad baits increased at 240, 360, 480 minutes and 24 hours after exposure. BioAnastrepha was shown to be toxic to both species, especially for A. grandis, killing 82% of females and 72% of males at 24 hours after exposure. Spinosad bait may be used in different dilutions to manage C. capitata and A. grandis, with similar toxicity for the two highest spinosad concentrations.