ISHS Acta Horticulturae 591: III International Symposium on Pistachios and Almonds
TOLERANCE OF PEACH TWIG BORER, ANARSIA LINEATELLA ZELLER, TO ORGANOPHOSPHATE AND PYRETHROID INSECTICIDES |
| Authors: | F.G. Zalom, D.B. Walsh, W. Krueger, J. Connell |
| Keywords: | diazinon, esfenvalerate, resistance, almond, California, dormant sprays |
| Abstract:
The peach twig borer, Anarsia lineatella Zeller, is one of the most important Lepidoptera species to attack almonds. In addition to feeding on shoots which can result in deformation of young trees, A. lineatella larvae also feed on new crop nuts. Organophosphate and mineral oil sprays applied during dormancy have proven to be an effective method of control for many years. During the 1990s, the use of organophosphate sprays during dormancy declined substantially, and is being replaced by several alternative management approaches. One common practice is the substitution of a pyrethroid insecticide, either esfenvalerate or permethrin, for the organophosphate. The susceptibility of overwintered A. lineatella larval populations from several California growing regions to the organophosphate diazinon and the pyrethroid esfenvalerate was studied each spring from 1997 through 1999. All of the A. lineatella populations sampled were susceptible to diazinon, with LD50 values ranging from less than 200 ppm (Arbuckle and Williams) to around 500 ppm in the Kern Co. orchards. Most of the A. lineatella populations sampled were susceptible to esfenvalerate, with LD50 values ranging from 0.15 to 12.43 ppm. Sites near the Sacramento River in Glenn and Butte Counties had significantly higher LD50 values than those observed at the other sites, indicating tolerance has developed to this pesticide. The Sacramento Valley sites where tolerance is suspected have had a history of continued use of pyrethroids as a spray during dormancy for the previous 5 to 7 years. | |
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