红火蚁对辛硫磷敏感性及其乙酰胆碱酯酶活性的研究

用点滴法测定了辛硫磷对红火蚁不同品级的毒力，并用乙酰硫代胆碱-二硫双对硝基苯甲酸法（ASCh-DTNB法）测定了各品级乙酰胆碱酯酶(acetyl cholinesterase，AChE)的活性，以探明蚁群中不同品级个体对辛硫磷的敏感性差异及其与靶标酶的关系。毒力测定结果表明，处理后24h，辛硫磷对工蚁、兵蚁、有翅雄蚁、有翅雌蚁和蚁后的毒力（LC50值）分别为1.04、2.06、7.38、9.39和7.81 ug/ml，显示不同品级红火蚁对辛硫磷的敏感性差异非常大，其中工蚁最敏感，而有翅雌蚁蚁后敏感性最低。靶标酶活性测定结果表明，红火蚁不同品级个体中乙酰胆碱酯酶的活性存在极大差异，其中以有翅雄蚁的总活性最低，为0.0469 nmol/min?头，而以有翅雌蚁的最高，为14.8929 nmol/min?头。不同品级红火蚁对辛硫磷的敏感性与其乙酰胆碱酯酶活性不存在显著相关性（r=0.7456）。

Susceptibility to Phoxim and Acetyl Cholinesterase Activity of The Red Imported Fire Ant (Solenopsis invicta Buren)

The toxicities of the different castes of the red imported fire ant （Solenopsis invicta Buren） against phoxim were measured by topical application and their individual activities of acetyl cholinesterase were determined by ASCh-DTNB method, to prove the susceptibility to phoxim and its relationship with the target enzyme. The results of toxicity showed that the LC50 after 24 h treatment for worker ants, soldier ants, male winged ants, female winged ants and queens were 1.04, 2.06, 7.38, 9.39 and 7.81 μg/ml, respectively. It revealed that the susceptibility of different castes to phoxim varied significantly. Worker ants were highly susceptible, while the female winged ants and queens were highly tolerate compared with worker ants. The results of acetyl cholinesterase activity showed that extreme difference occurred among castes. The lowest individual acetyl cholinesterase activity of 0.0469 nmol/min per ant was found in male winged ants, while the highest of 14.8929 nmol/ min per ant in female winged ants. Correlationship analysis indicated that the susceptibility of different caste ants to phoxim was not significantly correlated with the individual activity of their acetyl cholinesterase at a r-value of 0.7456.