Plastic films for polytunnels can prolong the effective residual life of cypermethrin to over 6 months

van Emden, H. F. and Hadley, P. (2011) Plastic films for polytunnels can prolong the effective residual life of cypermethrin to over 6 months. Journal of Horticultural Science & Biotechnology, 86 (2). pp. 196-200. ISSN 1462-0316 doi: 10.1080/14620316.2011.11512747

Abstract/Summary

Synthetic pyrethroid insecticides are degraded almost entirely by ultraviolet (UV)-catalysed oxidation. A bioassay using the beetle Tribolium confusum duVal caged on bandages soaked in 0.04% a.i. cypermethrin showed large differences in residual insecticide-life under three plastic films available for cladding polytunnels. Cypermethrin exposed to a UV film that transmitted 70% of UVB and 80% of UVA killed all beetles for 8 weeks, compared to only 3 weeks for cypermethrin exposed in a clear plastic envelope. Cypermethrin under a UV-absorbing film that reduced the transmission of UVB and UVA to 14% and 50%, respectively, gave a complete kill for 17 weeks. Reducing the transmission of UVB to virtually zero, and that of UVA to only 3%, using a UV-opaque film prolonged the effective life of the cypermethrin residue to 26 weeks, and some beetles were still killed for a further 11 weeks. Even after this time, beetles exposed to cypermethrin from the UV-opaque treatment were still affected by the insecticide, and only showed near-normal mobility after 24 months of pesticide exposure to the UV-opaque film. These results have implications for the recommended intervals between cypermethrin treatment and crop harvest, and on the time of introduction of insect-based biological control agents, when UV-opaque films are used in commercial horticulture.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/19592
Item Type	Article
Refereed	Yes
Divisions	Life Sciences > School of Biological Sciences > Ecology and Evolutionary Biology
Publisher	Taylor & Francis
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