|RASHID, TAHIR - Alcorn State University|
|FENG, GUOLEI - Alcorn State University|
Submitted to: Open Biological Sciences Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/19/2016
Publication Date: 1/31/2017
Citation: Chen, J., Rashid, T., Feng, G., Jin, X. 2017. Toxicity of polyoxyethylene tridecyl ether surfactants to Solenopsis invicta workers in relation to their HLB numbers. Open Biological Sciences Journal . 3:1-8.
Interpretive Summary: The red imported fire ants cause more than 6 billion dollars annual economic losses in the United States. Synthetic insecticides are frequently used in the red imported fire ant management, which is an important source of contamination in the environment. Surfactants are commonly used in insecticide formulations as inert or less toxic adjuvants to enhance the performance of the insecticides. USDA-ARS scientists at the National Biological Control Laboratory (Stoneville, MS) have conducted toxicity bioassay on six polyoxyethylene tridecyl ether (Ethal TDA) surfactants. It was found that Ethal TDA surfactants have their intrinsic toxicities against S. invicta workers. Their contact toxicity was reversely correlated to their HLB numbers. Ethal TDA with HLB number 8 may be useful as an active ingredient in controlling fire ants. If Ethal TDAs are adequate surfactants for formulating a fire ant control product, effort should be made to use Ethal TDAs with smaller HLB numbers. These results may help us reduce the use of synthetic insecticides in the fire ant management.
Technical Abstract: Surfactants are commonly used in insecticide formulations as adjuvants to enhance the performance of the insecticidal active ingredients. However, surfactants may have their own intrinsic detrimental effect on insects. In this study, the responses of red imported fire ants, Solenopsis invicta Buren, to 6 polyoxyethylene tridecyl ether surfactants (Ethal TDA) and their relationships to the hydrophilic-lipophilic balance (HLB) numbers were investigated in topical, glass-vial and immersing bioassays. In topical and glass-vial bioassays, significant linear dependence of ant mortality on HLB number was detected and the mortality was negatively related to HLB number. In immersing bioassay, a fast immobilizing effect was observed; however, the time needed to immobilize ants was not related to HLB number in most cases. In conclusion, Ethal TDA surfactants have intrinsic toxicity against S. invicta workers and ant mortality in both topical and glass-vial bioassays was negatively related to their HLB numbers.