Susceptibility of selected stored product insects to a combination treatment of pyriproxyfen and novaluron

Authors: Arthur, Franklin; HARTZER, KRIS - Former ARS Employee

Submitted to: Journal of Pest Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/24/2017
Publication Date: 3/1/2018
Citation: Arthur, F.H., Hartzer, K.L. 2018. Susceptibility of selected stored product insects to a combination treatment of pyriproxyfen and novaluron. Journal of Pest Science. 91(2):699-705. https://doi.org/10.1007/s10340-017-0914-4.
DOI: https://doi.org/10.1007/s10340-017-0914-4

Interpretive Summary: Residual surface treatments with insect growth regulators, which prevent immature insects from developing to the adult stage, can be applied to flooring surfaces to control stored product insects in flour mills, food warehouses, and retail stores. There is a new product on the market with the trade name Tekko, which is a combination of two different growth regulators. However, there is no information on the effectiveness of this product. On concrete surfaces treated at the label rate there was no development of red flour beetle eggs or larvae to the adult stage for up to 16 weeks, indicating complete inhibition of population growth. However, warehouse beetle larvae were less susceptible, and by the end of the test many of the exposed eggs and larvae of the warehouse beetle were able to successfully complete development to the adult stage. Tests with the hide beetle were inconclusive because of extensive cannibalization. An index was also developed to track and assess development of eggs and larvae to subsequent life stages. Results show that this Tekko could be used to control red flour beetles, but more frequent applications may be necessary to control the warehouse beetle. Mill and warehouse managers can use these results to better utilize insect growth regulators in their management programs, while taking into account differential susceptible among pest insect species.

Technical Abstract: A series of tests was conducted to evaluate susceptibility of Tribolium castaneum (Herbst), the red flour beetle, Trogoderma variabile (Ballion), the warehouse beetle, and Dermestes maculatus (DeGeer), the hide beetle, to a new insecticide (Tekko®) which contained the IGR pyreproxyfen and the chitenase-inhibitor novaluron as the active ingredients. Efficacy was assessed by adult emergence of exposed immatures, an index based on development of those exposed immatures, and progeny production of exposed adults. Concrete exposure arenas were treated with the label rate of the insecticide, and bioassays were conducted at 0, 2, 4, 8, 12, and 16 weeks post-treatment. No exposed T. castaneum eggs or larvae reached the adult stage at any time during the test, and the index values for exposed eggs and larvae remained near the minimum. No progeny adults were produced from exposure of parental adults on the treated surface. Adult emergence of T. variable from eggs or larvae did not exceed 25% for the first eight weeks of the test, but at the end of the test at 16 weeks adult emergence was 44% and 71%, respectively. There was a corresponding increase in the developmental index values as well as the weeks progressed. Progeny production from exposed parental adults was lower for the first four weeks of the test but by week 8 progeny production in the treatments was so extensive that this portion of the test was discontinued. No eggs or larvae of D. maculatus emerged as adults, nor were any progeny produced from the parental exposures, but excessive cannibalization in untreated controls occurred throughout the test. Results show that exposure of eggs and larvae of either species provided a more accurate assessment residual efficacy of Tekko® compared to exposing parental adults, but T. variable was much more tolerant to the residues compared to T. castaneum. Evaluations regarding D. maculatus will require more refined testing methodologies than those utilized in this study to avoid the effects of cannibalization.