Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/16/2016
Publication Date: 7/7/2016
Publication URL: http://handle.nal.usda.gov/10113/63267
Citation: Arthur, F.H. 2016. Methodology for evaluating the insect growth regulator (IGR) methoprene incorporated into packaging films. Insects. 7(3). doi: 10.3390/insects7030033.
Interpretive Summary: Methoprene is an insecticide that is impregnated onto packaging films to protect bagged processed grain products from insect infestation, but there are no tests evaluating the actual effectiveness of methoprene used in this manner. Results of experimental tests using red flour beetle and confused flour beetle larvae and eggs and different types of packaging films generally show that larvae of the red flour beetle were more susceptible to methoprene impregnated packaging than larvae of the confused flour beetle, but when the eggs were exposed there was little development of either species to the adult stage. Methoprene inhibited adult emergence of larval red flour beetle on a wide variety of different packing films and construction material evaluated in the current study. Only one test involved evaluations on the inside surface of the packaging material, with noticeable loss of efficacy on the inside surface, especially with confused flour beetle. There is a need to examine in more detail the susceptibility of other stored product insect species to the packaging materials that have incorporated methoprene, but our results show that methoprene impregnated packaging could be utilized to reduce infestation by flour beetles.
Technical Abstract: The insect growth regulator methoprene has been impregnated onto various packaging materials to control stored product insects, and is labeled for use in this manner in the United States. Different methodologies were utilized to evaluate efficacy towards Tribolium castaneum (Herbst), the red flour beetle, and T. confusum Jacquelin duVal, the confused flour beetle. Tests were conducted by creating arenas in which larvae were exposed on the packaging surface along with a flour food source, or adults were exposed and assessments were done on emerged progeny adults resulting from eggs laid by parental females. In tests with larvae exposed on impregnated birdseed bags, the outside surface had more activity compared to the inside surface, especially on T. confusum. In other studies with different materials, there was generally 100% inhibition of adult emergence of exposed larvae or of progeny adults. The best technique for evaluation was to expose late-stage larvae as the test life stage. Results show the potential of using methoprene-impregnated packaging for bagged storage of processed grains and grain products.