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Title: Efficacy of Methoprene Applied at Different Temperatures and Rates to Surface Substrates to Control Eggs and Fifth Instars of Plodia interpunctella

item Arthur, Franklin

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/23/2009
Publication Date: 12/15/2009
Citation: Jenson, E.A., Arthur, F.H., Nechols, J.R. 2009. Efficacy of Methoprene Applied at Different Temperatures and Rates to Surface Substrates to Control Eggs and Fifth Instars of Plodia interpunctella. Journal of Economic Entomology. 102: 1992-2002.

Interpretive Summary: Methoprene is an insecticide that is used in pest management programs for stored grains, and works by inhibiting the molting process of insect larvae. Methoprene is effective on stored-product beetles, but there are comparatively fewer data regarding effectiveness on the Indianmeal moth. We conducted tests by exposing eggs or larvae of the Indianmeal moth on packaging materials or flooring surfaces treated with methoprene. Eggs of the Indianmeal were not susceptible to methoprene. However, depending on the specific packaging material and the time of exposure, larvae were susceptible and most of them did not reach the adult stage after they were exposed to methoprene. An economic analysis showed the risks and benefits associated with methoprene treatment, and results of the tests and the budget analysis show that methoprene could be used in pest management plans to control larvae of the Indianmeal moth.

Technical Abstract: A series of studies was conducted to determine the effects of temperature on toxicity of the insect growth regulator (IGR) methoprene to eggs and larvae of Plodia interpunctella Hübner, the Indianmeal moth. When methoprene was applied on craft paper at the rate of 0.0003 mg active ingredient [AI]/cm2, there was little direct toxicity against eggs of P. interpunctella, and temperature did not affect insecticide efficacy. Similarly, exposure of eggs on a paperboard surface treated with different rates of methoprene resulted in delayed adult emergence, but not a reduction in adult emergence. However, wandering-phase larvae of P.interpuctella were susceptible to methoprene, and exposure of larvae for 0.5, 1 and 2 hours on different packaging materials resulted in reduced adult emergence. There was variation in emergence depending on the specific surface, but temperature had no effect on resulting adult emergence from exposed larvae. A partial budget analysis described treatment costs and reduction of risks associated with control of eggs and larvae of P. interpunctella. Results indicate methoprene could be used in management programs to control larvae of P. interpunctella, but eggs may be able to compensate for exposure to methoprene residues on treated surfaces.