Fipronil toxicity to Diaprepes abbreviatus l. (coleoptera: curculionidae) larvae

H. N. Nigg, S. E. Simpson, H. E. Anderson, L. K. Yang


Citrus seedlings of Citrus obovoidea were potted in soil containing 25 ppm bifenthrin and 2.5, 5, 10, 15, 20, or 25 ppm fipronil. Plants were monitored for trunk growth, root wet and dry weight, and Diaprepes abbreviatus larvae at intervals for 2 yr. Larvae were recovered from inoculated controls at each sampling interval, including an adult female at 720 days. No larvae were recovered from fipronil treatments. Larvae were recovered from the bifenthrin treatment at 720 days, but not at other sampling intervals. At 720 days there were no differences in percent trunk growth. The control with larvae had less wet and dry root weights compared to treatments of fipronil above 2.5 ppm, but these differences were not statistically different among pesticide treatments. C. obovoidea seedlings tolerated 10 neonate larvae every 30 days (total : 240 larvae) over a 2-yr period.


diaprepes; quarantine control; resistance

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Proc. Fla. State Hort. Soc.     ISSN 0886-7283