Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 28, 2005
Publication Date: December 19, 2005
Citation: Thomas, D.B., Mangan, R.L. 2005. Non-target impact of spinosad GF-120 bait-sprays for control of the Mexican fruit fly (Diptera: Tephritidae) in Texas citrus. Journal of Economic Entomology. 98(6):1950-1956.
Interpretive Summary: The organic insecticide Spinosad was tested in Texas citrus orchards to study the effects on pests and their natural enemies. If the insecticide, targeting fruit flies, were to also kill other insects, unintended effects could result. For example, many citrus feeding insects are controlled naturally by wasps, spiders, or other predators. Killing off of the natural enemies by the insecticide might result in loss of natural controls and induce damaging population levels of citrus pests. Of the ten pest insects studied, eight decreased, one remained the same, and one increased modestly, but not to economically damaging levels. The sprays did not have a noticeable effect on the beneficial insects.
Bait sprays containing the toxicant Spinosad (GF-120), were applied in citrus groves where the Mexican fruit fly was detected in surveillance traps. Reduction in sterile fly captures in the treated groves was 47-63% compared to control groves. There were no detectable effects on specific indicator species of beneficial insects, nor in numbers of parasitoids and predators in general in the treated groves. Eight of ten secondary pest populations declined in the test groves subsequent to spray applications, as they did in the controls. Citrus whitefly populations increased modestly and Citrus black fly populations remained unchanged compared to pre-treatment levels. No outbreaks of secondary pests occurred in the treated groves.