Acute-Contact and Chronic-Systemic In Vivo Bioassays: Regional Monitoring of Susceptibility to Thiamethoxam in Soybean Aphid (Hemiptera: Aphididae) Populations From the North Central United States

Authors

Matheus G.P.M. Ribeiro, University of Nebraska-LincolnFollow
Thomas E. Hunt, University of Nebraska-LincolnFollow
Blair Siegfried, University of Nebraska-LincolnFollow

Document Type

Article

Date of this Version

2017

Citation

Ribeiro, M. G. P. de M., Hunt, T., Siegfried, B. D. 2017. Acute-contact and chronic-systemic in-vivo bioassays: regional monitoring of susceptibility to thiamethoxam in soybean aphid (Hemiptera: Aphididae) populations from the North Central United States. Journal of Economic Entomology. https://doi.org/10.1093/jee/tox290

Comments

© The Author(s) 2017. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License.

Abstract

The risks associated with soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), in the North Central soybean systems has fostered the adoption of prophylactic chemical control practices, such as planting seeds treated with neonicotinoid insecticides, especially thiamethoxam. Consequently, there is a concern that increased selection pressure imposed on the arthropod–pest complex by this insecticide may lead to resistance. Therefore, in vivo bioassays were conducted to determine the susceptibility of soybean aphid to thiamethoxam among North Central U.S. populations. Concentration-mortality data were collected using contact glass-vial and detached-leaf systemic bioassays. The results of these experiments indicate that both bioassays were reliable to detect shifts in susceptibility between different soybean aphid clones. The LC50s of field populations of soybean aphid were significantly different when mortality was recorded in contact and systemic exposure assays. Nevertheless, the magnitude of the resistance ratios was consistent in both methods. In addition, a significant increase in the LC₅₀ and EC₅₀ values was observed among field populations tested in detached-leaf systemic bioassays. These results represent the first extensive efforts to identify the variability in susceptibility of soybean aphid to thiamethoxam in the North Central United States Therefore, our results provide a baseline for future assessment and contribute to a better understanding of the applicability of in vivo bioassays for susceptibility monitoring and resistance detection of soybean aphid to thiamethoxam.