Cage study of spinosad-based bait efficacy on bactrocera cucurbitae, dacus ciliatus, and dacus demmerezi (diptera: Tephritidae) in reunion Island

Abstract

On Reunion Island, Bactrocera cucurbitae (Coquillett), Dacus ciliatus (Loew), and Dacus demmerezi (Bezzi) cause severe damage to Cucurbit crops. The aim of the study was to test in field cages the effectiveness of Synis-appt (Dow AgroSciences), a spinosad-based bait (0.02% of spinosad) on both attraction and mortality of young adults (69 d old) of these three species. The effects of gender were also evaluated for all species whereas the effects of protein deprivation were tested with B. cucurbitae only. For the first 15 min after application, significantly more B. cucurbitae adults (21.7 ± 1.8%) were attracted to the bait than D. demmerezi (7.6 ± 2.4%) and D. ciliatus (2.7 ± 1.4%); the subsequent response (3075 min after bait application) of D. demmerezi was statistically similar to that recorded for B. cucurbitae; whereas the response of D. ciliatus to the bait was consistently significantly lower. Adult mortality was significantly higher for B. cucurbitae (94.6 ± 0.7%) than for D. demmerezi (85.7 ± 2.1%), and was significantly higher for the latter than for D. ciliatus (60.4 ± 4.4%). Sex had no significant effect on the mortality rate for each species. The efficiency of the bait was the same for B. cucurbitae adults regardless whether or not the diet included proteins. Overall, Synisappt appears to be more effective against B. cucurbitae and B. demmerezi than against D. ciliatus. In Reunion Island, this bait could constitute a useful component in the framework of Integrated Pest Management. © 2012 Entomological Society of America.