New uses for old chemistry - chlorpyrifos-methyl for the control of pyrethroid resistant Meligethes (pollen beetle) in oilseed rape

摘要

With the loss of many active ingredients as a result of the European re-registration process, the range of insecticides available for resistance management has been reduced. There is widespread resistance in Meligethes aeneus (pollen or blossom beetle) populations in Northern Europe to pyrethroid insecticides. With little other chemistry available for the control of pyrethroid resistant pollen beetle, chlorpyrifos-methyl (Reldan), is being developed for use in oilseed rape for the control of this pest. Chlopyrifos-methyl is one of the few organophosphate insecticides to obtain an Annex I listing under 91/414. This insecticide can be used to control pollen beetle populations that are currently resistant to pyrethroids or as a management tool to prevent the build up of pyrethroid resistance in susceptible populations. Rates between 338 - 450 g a.i./ha give -80% control of the pest beetle. No cross-resistance between chlorpyrifos-methyl and the pyrethroid lambda-cyhalothrin was detected in field collected populations of M aeneus. As pollen beetle applications are made close to or at flowering, safety to honeybees (Apis melliferd) is an important factor. However, cage studies in oilseed rape have shown no effect on honey bees when not sprayed directly onto bees even when applied at full flowering. Residues were not toxic to foraging bees and bee foraging intensity was not affected.