Response of blueberry maggot fly (Diptera: Tephritidae) to imidacloprid-treated spheres and selected insecticides
AbstractImidacloprid-treated spheres and several classes of insecticides were evaluated in field and laboratory experiments to determine their effects on Rhagoletis mendax Curran adult behavioural activity and larval infestation in highbush blueberries, Vaccinium corymbosum L. (Ericaceae). In field tests, three treatments representing an attract-and-kill system (imidacloprid-treated spheres) and two classes of insecticides, including a naturalyte spinosad (SpinTor 2 SC) and organophosphates (Imidan®/Malathion), were evaluated against an untreated control. Significantly more blueberry maggot puparia were collected from untreated (control) plots than from other treatments evaluated. There were no significant differences in larval infestation of berries collected from plots treated with imidacloprid-treated spheres, SpinTor 2 SC, and Imidan®/Malathion. Less than 1% of the berries collected from imidacloprid-treated sphere plots and SpinTor 2 SC treated plots contained blueberry maggot larvae. In toxicity and fruit-injury studies, SpinTor 2 SC as well as additional compounds from various classes were evaluated, including a botanical [azadiractin (Ecozin 3%)], a particle film [kaolin clay (SurroundTM WP)], and three neonicotinoids [imidacloprid (Provado 1.6 F), thiocloprid (Calypso 480 SC), and thiamethoxam (PlatinumTM 2 SC and ActaraTM 25 WG)]. SpinTor 2 SC exhibited a time lag (18 h) in reducing R. mendax activity. Ecozin 3% and SurroundTM WP were ineffective in suppressing R. mendax adult activity, but numbers of larvae in SurroundTM WP treated fruit were significantly reduced. The effectiveness of neonicotinoid insecticides varied initially but resulted in equivalent levels of mortality after 48 h compared with our conventional organophosphate treatment of Guthion 50 WP. Oviposition scars on Provado 1.6 F treated plots were significantly more numerous than on plots treated with SpinTor 2 SC, Calypso 480 SC, Actara 25 WG, and Guthion 50 WP.