Efficacy of Methoprene Applied at Different Temperatures and Rates on Surface Substrates to Control Eggs and Fifth Instars of <I>Plodia interpunctella</I>

Abstract

A series of studies was conducted to determine the effects of temperature on toxicity of the insect growth regulator methoprene to eggs and larvae of Plodia interpunctella (Hübner), the Indianmeal moth. When methoprene was applied to Kraft paper at the rate of 0.0003 mg of 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 ofP. interpuctella were susceptible to methoprene, and exposure of larvae for 0.5, 1, and 2 h 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.

Economic Feasibility of Methoprene Applied as a Surface Treatment and as an Aerosol Alone and in Combination With Two Other Insecticides

“…These treatments were simulated across six temperatures (21, 24, 27, 30, 32, and 35ЊC) on wheat diet and raisins. Survivorship estimates for insecticide treatments were modeled based on results from studies by Jenson et al (2009Jenson et al ( , 2010a; calculated for use in population simulations in Fontenot et al (2012a,b); and this study. Mortality levels in this economic model are calculated by subtracting total population at 180 d for each treatment from total population survival at 180 d where there was no treatment.…”

“…These models were based on four main components; time required for the complete life cycle, male longevity, female longevity, and fecundity. Survivorship values for these models were calculated using data from Jenson et al (2009), speciÞcally for mortality when insecticides were applied to eggs. Adjustment of survivorship was only applied to immatures because there are no data to support the assertion that methoprene kills adult Lepidoptera and mortality was simulated to occur at noon on the day of insecticide treatment for all immatures that are in that stage at that time.…”

“…Adjustment of survivorship was only applied to immatures because there are no data to support the assertion that methoprene kills adult Lepidoptera and mortality was simulated to occur at noon on the day of insecticide treatment for all immatures that are in that stage at that time. Survivorship values were calculated using the mortality data for Indianmeal moth eggs exposed to the label rates for surface or aerosol application of each insecticide reared on the corresponding diet from Jenson et al (2009Jenson et al ( , 2010a as these are the most likely scenario for egg mortality in Þeld situations. For a more detailed discussion of model components, please refer to Fontenot et al (2012a,b).…”

“…Survival was estimated as 5.4%, which was the lowest survivorship used in the simulations. Though there is no interaction or relationship between temperature and methoprene in survival or mortality of Indianmeal moth between 20 and 32ЊC, (Jenson et al 2009), there is a strong relationship between temperature and total development time from egg to adult. Beginning populations were standardized to 100 eggs and no adult moths.…”

“…Currently, in facilities where aerosol fogging systems are installed, pest managers are using conventional insecticides alone and in combination with IGRs. One IGR, methoprene, which is a juvenile hormone analog, has been evaluated alone and in combination with esfenvalerate and 1% synergized pyrethrin for control of eggs of the Indianmeal moth (Plodia interpunctella Hü bner) (Jenson et al 2009(Jenson et al , 2010a. Comparison can also be made between the use of methoprene as an aerosol and as a contact surface treatment in food storage and processing facilities.…”