|RASHID, TAHIR - Alcorn State University|
|FENG, GUOLEI - Alcorn State University|
Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/31/2014
Publication Date: 11/19/2014
Citation: Chen, J., Rashid, T., Feng, G. 2014. Esterase in imported fire ants, Solenopsis invicata and S. richteri (Hymenoptera: Formicidae): activity, kinetics and variation. Scientific Reports. 4(7112):1-9. doi: 10.1038/srep07112.
Interpretive Summary: Red imported fire ant is one of the most successful invasive species with tremendous economic and ecological impact. The black imported fire ants are very similar to the red imported fire ant in their biology and behavior; however, red imported fire ant is a more successful invader than black imported fire ant. Toxic tolerance has been found to be important to the success of some invasive species. Esterases play an important role in insect toxic tolerance. In this study, we investigated toxic tolerance and esterase activity in both red imported fire ant and black imported fire ant and found red imported fire ant is significantly more toxic tolerant than the black imported fire ant and esterase activities in red imported fire ant were more than three times higher than those in black imported fire ant. Toxic tolerance may contribute to the invasion success of red imported fire ant. This study provided a justification to develop species specific chemical control technolgies for control of these two pest ants.
Technical Abstract: Black imported fire ant, Solenopsis richteri, is closely related to the notorious red imported fire ant, Solenopsis invicta. Despite being very similar in biology and behavior, S. invicta is a much more successful invader. In contrast to S. invicta that has invaded numberous countries and regions, S. richteri has been established only in the southern United States outside its native range. Toxic tolerance has been found to be important to the success of some invasive species. We hypothesized that S. invicta is more tolerant to toxins than S. richteri. Toxicity of 6 toxins was measured for both species, including five insecticides, acephate, dieldrin, deltamethrin, heptachlor and malathion and one common component of ant defensive secretion, 2-tridecanone. The result strongly supported our hypothesis. S. invicta was more tolerant to each tested toxin than S. richteri. Since esterases play an important role in insect detoxification process, we further hypothesized that S. invicta has higher esterase activity than S. richetri. This hypothesis is also supported. For both substrates, a-naphthyl acetate (a -NA and B-naphtyhl acetate (B-NA), esterase activities in S. invicta were more than three times higher than those in S. richteri. Esterases in both S. invicta and S. richetri were inhibited by malaoxon, indicating that esterases were B-type in both species. Esterases were sensitive to the inhibition by eserine, indicating cholinesterases and/or cholinesterase-like esterases may be important components of esterases in both species. 2-tridecanone showed a significantly greater inhibition to esterases in S. richteri than those in S. invicta. This may explain why 2-tridecanone is more toxic to S. richteri than S. invicta.