|WIJAYARATNE, L.K.W. - University Of Manitoba|
|FIELDS, P.G. - Agriculture And Agri-Food Canada|
Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/31/2011
Publication Date: 2/1/2012
Citation: Wijayaratne, L., Fields, P., Arthur, F.H. 2012. Effect of methoprene on the progeny production of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae). Pest Management Science. 68(2): 217-224. doi: http://dx.doi.org/10.1002/ps.2247.
Interpretive Summary: Insect growth regulators (IGRs) affect growth and development of immature insects, and may also produce sub-lethal effects such as a reduction in number of eggs laid by adults. In this test, larvae and adults of the red flour beetle, a major pest of stored products, were exposed on wheat treated with the IGR methoprene. Exposure of adults produced little effect on subsequent reproduction of those adults. However, male larvae that were exposed to the treated wheat were more susceptible than female larvae with generally lower adult emergence in exposed male larvae compared to exposed female larvae. In addition, males that survived to the adult stage and paired with unexposed females generally produced fewer offspring than unexposed males paired with unexposed females. Results show that sub-lethal effects caused by an IGR could contribute to overall population reductions from insecticidal treatments.
Technical Abstract: Tribolium castaneum is a serious insect pest of stored-products around the world. Current control measures for this species have several limitations; loss of registration, insecticide resistance, and consumer concerns about chemical residues in food. The objective of this study was to determine if methoprene affects progeny production of T. castaneum. Late instar larvae or young adults were exposed to methoprene-treated wheat and progeny production determined. The pairing of male and female adults was performed as untreated x untreated, treated x untreated, or treated x treated to study sex-based effects. There were three outcomes to late instar larvae held on methoprene-treated wheat kernels (0.001 and 0.0165 ppm): 1. failure to emerge as an adult, 2. emergence as an adult and almost no offspring produced, or 3. emergence as an adult and normal production of offspring. Male larvae were more susceptible to methoprene than female larvae. In contrast, the young adults exposed to methoprene (1.67 to 66.6 ppm) showed no reduction in offspring production. Methoprene concentrations will decline with time following its application. However, this research indicates that methoprene can still reduce populations of T. castaneum by affecting their progeny production, even if adults emerge.