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| Research: cyfluthrin; temperature |
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The effects of temperature on residual efficacy of cyfluthrin wettable powder
Dr. Frank Arthur
Introduction: |
The toxicity of most organophosphate insecticides generally increases as temperatures
increase. In contrast, toxicity of pyrethroids often decreases as temperatures increase,
although results can vary depending on chemical structure, the target species, the
specific insecticide, and the temperature range. The objectives of this test were to
determine: 1) the effect of temperature on knockdown and survival of red flour beetles
exposed on concrete treated with 9.5 mg per ft2 20% [AI] cyfluthrin wettable
powder (WP), and 2) effects associated with residue aging. |
Methods: |
Adult red flour beetles were exposed for 0.5, 1, or 2 hours on concrete treated with
cyfluthrin in incubators set at 68, 77, 86, or 95 °F. After exposure, beetles were
removed from the treated surface and classified as either knocked down or running. Beetles
were put in Petri dishes and returned to the same incubators in which they were exposed,
and after one week the beetles that were upright and running after one week were
considered to have survived exposure to cyfluthrin. Tests were repeated on the same
treated dishes with new beetles every two weeks for eight weeks.
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Results: |
There was no difference in knockdown of red flour beetles among the temperatures.
Knockdown generally increased as exposure interval increased and decreased as residues
aged (Figure 1). There was no difference in survival at the three exposure intervals, but
survival increased as temperature increased and as residues aged (Figure 2). By week 6
survival at 77, 86, or 95° was > 90%. There was considerably less survival at 68°
compared to the other temperatures.
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Conclusions: |
Indoor environmental temperature could affect the residual efficacy of cyfluthrin WP. As
temperature increases, red flour beetles can apparently recover from knockdown. The
toxicity of cyfluthrin appears to be negatively correlated with temperature. |
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(Figure 1) |
(Figure 2) |
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Last Modified: 03/31/2009
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