ARS | Publication request: Oral and Topical Toxicity of Fipronil to Melon Fly and Oriental Fruit Fly (Diptera: Tephritidae)

Submitted to: Journal of Entomological Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 28, 2008
Publication Date: October 1, 2009
Citation: Stark, J., Vargas, R.I., Miller, N.W. 2009. Oral and Topical Toxicity of Fipronil to Melon Fly and Oriental Fruit Fly (Diptera: Tephritidae). Journal of Entomological Science. 44: 308-313.

Interpretive Summary: Tephritid fruit flies are important pests that cause economic damage to many fruits and vegetables throughout much of the subtropical and tropical areas of the world. As such, elaborate measures are taken to control or eradicate these species. A large-scale monitoring program is continually conducted in California to detect introductions of various invasive fruit flies including the Mediterranean fruit fly, oriental fruit fly, and melon fly. Detection of fruit flies results in the implementation of eradication programs which usually consist of a pesticide spray program (bait-spray) and the release of sterilized male flies. Malathion in protein bait spray has been the most commonly used insecticide in eradication programs in California. However, there are negative consequences associated with the wide-spread application of malathion bait sprays. Therefore, more environmentally acceptable pesticides are needed for control and eradication of fruit flies. Fipronil is a fairly new insecticide that is being used to control tephritid fruit flies, particularly in the Pacific Island nations. This study determines the concentrations of fipronil needed to kill melon fly and oriental fruit fly.

Technical Abstract: BACKGROUND: The objective of this study was to develop basic oral and topical toxicity data for Fipronil in Solulys protein bait to wild melon fly, Bactrocera cucurbitae (Coquillett) and the oriental fruit fly, Bactrocera dorsalis (Hendel). RESULTS: For the oral study, both females and males were evaluated, while in the contact study only females were evaluated. The 24 h oral LC50 estimates for female B. cucurbitae and B. dorsalis were 113 and 108 mg ai/l, respectively. Female B. cucurbitae were more susceptible than males, but female and male B. dorsalis were equally susceptible to fipronil after the oral route of exposure. Female B. cucurbitae were significantly less susceptible to the fipronil-bait mixture after topical exposure compared to feeding exposure. However, female B. dorsalis were equally susceptible to either route of exposure. At LC50, B. dorsalis was significantly more susceptible than B. cucurbitae by the topical route of exposure. At LC90, B. dorsalis was significantly more susceptible than B. cucurbitae by both oral and topical routes of exposure. CONCLUSIONS: Results of this study indicate that there are differences in susceptibility between B. cucurbitae and B. dorsalis to fipronil, especially at the LC90. B. dorsalis was more susceptible to fipronil than B. cucurbitae by oral and topical routes of exposure. LC90 estimates were much lower that the 5,333 mg ai/l applied to Amulet Attract and Kill Stations for control of B. cucurbitae and B. dorsalis.