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Title: Effects of methoprene and synergized pyrethrin aerosol applications on Tribolium castaneum (Herbst) populations

item TUCKER, ANGELA - Kansas State University
item Campbell, James - Jim
item Arthur, Franklin
item ZHU, KUN YAN - Kansas State University

Submitted to: Journal of Stored Products Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/11/2014
Publication Date: 10/1/2015
Publication URL:
Citation: Tucker, A.M., Campbell, J.F., Arthur, F.H., Zhu, K. 2015. Effects of methoprene and synergized pyrethrin aerosol applications on Tribolium castaneum (Herbst) populations. Journal of Stored Products Research. 64B:168-174. doi: 10.1016/j.jsrp.2014.09.007.

Interpretive Summary: Aerosol insecticides are often used as part of management programs for the red flour beetle inside mills and warehouses, and these aerosols generally target the adult stage. However, there is little information on if the presence of treated adults affects the overall population. We treated adult beetles with single and multiple applications of pyrethrin insecticide, pyrethrin with the insect growth regulator methoprene, or just the oil carrier that was in the pyrethrin formulation. After treatment the adults were put into various arenas with established populations to see if the presence of these treated adults affected the population. When a refugial food source was present, single applications of the insecticides did not affect the overall number of adults or the population growth rate. Multiple applications did result in some reduction of total numbers and the growth rate, especially when pyrethrin was combined with methoprene. However, this effect was mitigated by the population numbers. Results show that effects of a single insecticide application may be limited and multiple applications of an insecticide may be necessary to affect resident populations.

Technical Abstract: Experiments were performed to investigate the effects of horizontal transfer of the insect growth regulator (IGR) methoprene on confined populations of Tribolium castaneum (Herbst) either with or without hidden refugia. Multiple applications were made with the IGR alone or combined with synergized pyrethrin, and compared to untreated controls which received no spray applications or were treated with the carrier Isopar M used for formulating the insecticides. The total number of living beetles from colonies which received adults that were treated with Isopar M or no adults (control) was significantly greater than those that received synergized pyrethrin (P<0.05) or methoprene. There was no difference in the number of living individual and instantaneous rate of increase (ri) in established populations treated with insecticides and containing a hidden refugia compared to those which received the pyrethrin applications (P=0.05). Sanitation levels nested inside the treatment groups also had no effects (P=0.05), suggesting that populations in hidden refugia can persist even with multiple applications of methoprene and synergized pyrethrin. Populations with an accessible hidden refugia that were exposed to synergized pyrethrin and methoprene had a s lower number of living adult and a lower ri value than populations that were exposed to synergized pyrethrin alone (P<0.001). Additionally, populations which received one, two, or three aerosol applications had similar numbers of living adults and ri but were significantly different from populations which received four aerosol applications. This suggests that the combinations of methoprene and synergized pyrethrin could be more effective than synergized pyrethrin when multiple aerosol applications are performed and cumulative effects on populations could occur.