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Title: Influence of temperature and artificially-created physical barriers on the efficacy of synergized pyrethrin aerosol

item KHAREL, KABITA - Kansas State University
item Arthur, Franklin
item ZHU, KUN YAN - Kansas State University
item Campbell, James - Jim
item SUBRAMANYAM, BHADRIRAJU - Kansas State University

Submitted to: Journal of Stored Products Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/7/2014
Publication Date: 1/2/2015
Publication URL:
Citation: Kharel, K., Arthur, F.H., Zhu, K., Campbell, J.F., Subramanyam, B. 2015. Influence of temperature and artificially-created physical barriers on the efficacy of synergized pyrethrin aerosol. Journal of Stored Products Research. 60:36-42. DOI:

Interpretive Summary: Aerosol insecticides are being used to control flour beetles inside mills and warehouses but there is little information regarding aerosol dispersal underneath structural barriers. We built wooden boxes of different heights that were closed at one end and on the top and sides, and conducted studies by placing confused flour beetles in dishes set in the open and at different positions underneath the boxes. Survival increased as box height decreased and as distance from the front of the box increased, indicating little dispersion of the aerosol underneath the opening. Complete mortality was achieved only when insects were exposed in the open. Results show how barriers and obstructions inside a storage facility may inhibit aerosol dispersal and thus lead to reduced insect control.

Technical Abstract: Flour mills in the United States are utilizing synergized pyrethrin aerosol for management of stored product insects. However, the dispersal of the aerosol within a facility may be hampered by barriers created from machinery and other equipment that block dispersion. Additionally, seasonal temperature variations may influence the dispersion and toxicity of synergized pyrethrin. A study was conducted to evaluate the influence of barriers and temperatures on the efficacy of synergized pyrethrin aerosol against adults and pupae of Tribolium confusum. Insects were exposed to pyrethrin aerosol inside experimental sheds maintained at target temperatures of 22, 27, and 32 °C. Wooden boxes (1 m in length, 20 cm in width, and 5, 10, or 20 cm in height) were used for creating different open and concealed areas for exposing insects. Results showed that exposing adults of T. confusum in the open produced more moribund adults (those knocked down and unable to move except for reflex twitching or unable to respond when touched with a probe) at all test temperatures, while survival increased with increasing distance from the front to the back of the boxes. Similarly, less than 2% of pupae exposed in the open areas emerged as adults, but as the distance increased from the front to the back of the box adult emergence increased. The recovery of moribund adults increased as the distance increased underneath the boxes. More aerosol apparently dispersed under the box height of 20 cm compared to 5 and 10 cm. Results show pyrethrin aerosol can provide good control of T confusum and may not be affected by seasonal temperature variations, but aerosol dispersion into obstructed or concealed areas may be limited inside flour mills.