Toxicity, horizontal transfer, physiological and behavioral effects of cycloxaprid against Solenopsis invicta (Hymenoptera: Formicidae)

Authors: ZHANG, LANG - South China Agricultural Univerisity; WANG, LEI - South China Agricultural Univerisity; Chen, Jian; ZHANG, JIANLONG - South China Agricultural Univerisity; HE, YINGHAO - South China Agricultural Univerisity; LU, YONGYUE - South China Agricultural Univerisity; CAI, JIACHENG - Salisbury University; CHEN, YUAN - Salisbury University; WEN, XUEJUN - South China Agricultural Univerisity; XU, ZHIPING - East China University Of Science And Technology; WANG, CAI - South China Agricultural Univerisity

Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/22/2022
Publication Date: 3/7/2022
Citation: Zhang, L., Wang, L., Chen, J., Zhang, J., He, Y., Lu, Y., Cai, J., Chen, Y., Wen, X., Xu, Z., Wang, C. 2022. Toxicity, horizontal transfer, physiological and behavioral effects of cycloxaprid against Solenopsis invicta (Hymenoptera: Formicidae). Pest Management Science. 78:2228-2239. https://doi.org/10.1002/ps.6847.
DOI: https://doi.org/10.1002/ps.6847

Interpretive Summary: The red imported fire ant is a significant urban, agricultural, and medical pest with a wide distribution. Contact insecticide is commonly used in controlling fire ants. A significant problem using contact insecticides in managing fire ants is that some ants can escape the contact with insecticide after its application, due to the repellant property of the insecticide. A non-repellant and relatively slow acting insecticide may improve the control efficacy by facilitating the contact between ants and the insecticide. In this study, cycloxaprid, a newly discovered neonicotinoid insecticide, was evaluated for controlling fire ants and compared to imidacloprid and bifenthrin, which are two insecticides commonly used in controlling fire ants. The results showed that surfaces or sand treated with cycloxaprid, imidacloprid, or bifenthrin all caused high mortality of fire ant workers, but the action of cycloxaprid and imidacloprid was slower than bifenthrin. Like imidacloprid and bifenthrin, cycloxaprid can be horizontally transferred from corpses and between living ants and its contact and horizontal toxicities are slightly higher than imidacloprid. In addition, although contact with cycloxaprid and imidacloprid-treated surfaces significantly induced the activities of various detoxification enzymes in ants, they had no significant effect on the foraging behaviors of fire ant workers before the onset of the toxicity. Also, sand treated at lethal concentrations of cycloxaprid or imidacloprid did not stop the digging activities of ants before the toxicity was manifested. Interestingly, fire ant workers excavated significantly more sand containing 0.01 ppm cycloxaprid than untreated sand in the no-choice digging bioassays. In addition, extensive nesting activities (sand excavation and stacking) were observed in the flowerpots containing untreated sand or sand treated with cycloxaprid or imidacloprid. On the contrary, bifenthrin significantly reduced the foraging, digging, and nesting activities of fire ant workers, due to its fast-acting property. In conclusion, due to its slow-acting and non-repellent properties and excellent contact and horizontal toxicity, cycloxaprid has a great potential to be used in fire ant management.

Technical Abstract: BACKGROUND: The red imported fire ant, Solenopsis invicta Buren, is a significant urban, agricultural, and medical pest with a wide distribution in the world. Surface or mound treatment using contact-based insecticide is one of the main methods to control S. invicta. In the present study, cycloxaprid, a newly-discovered neonicotinoid insecticide, was evaluated for S. invicta control and compared with two referent insecticides, imidacloprid and bifenthrin. RESULTS: Surfaces or sand treated with cycloxaprid, imidacloprid, or bifenthrin caused high mortality of S. invicta workers, and the action of cycloxaprid or imidacloprid was slower than bifenthrin. Like imidacloprid and bifenthrin, cycloxaprid can be horizontally transferred from corpses or live donor ants to recipient ants. In addition, cycloxaprid- or imidacloprid-treated surfaces significantly induced the activities of various detoxification enzymes; nevertheless, they had no significant effect on the foraging behaviors of S. invicta workers. Also, sand treated with cycloxaprid or imidacloprid did not negatively affect the digging activities of ants. Interestingly, S. invicta workers excavated significantly more sand containing 0.01 ppm cycloxaprid than untreated sand in the no-choice digging bioassays. In addition, extensive nesting activities (sand excavation and stacking) were observed in the flowerpots containing untreated sand or sand treated with cycloxaprid or imidacloprid. On the contrary, bifenthrin significantly reduced the foraging, digging, and nesting activities of S. invicta workers. CONCLUSION: Cycloxaprid is a slow-acting and non-repellent insecticide against S. invicta workers, and its contact and horizontal toxicities are slightly higher than imidacloprid.