ABSTRACT
Background & objectives: Due to ever growing insecticide resistance in mosquitoes to commonly used insecticides in many parts of the globe, there is always a need for introduction of new insecticides for the control of resistant vector mosquitoes. In this study, larvicidal and adulticidal efficacies of three neonicotinoids (imidacloprid, thiacloprid and thiamethoxam) were tested against resistant and susceptible populations of Anopheles stephensi Liston 1901, Aedes (Stegomyia) aegypti Linnaeus, and Culex quinquefasciatus Say (Diptera: Culicidae). Methods: Laboratory-reared mosquito species were used. Insecticide susceptibility tests were done using standard WHO procedures and using diagnostic dosages of insecticide test papers and larvicides. Adulticidal efficacy of candidate insecticides was assessed using topical application method and larval bioassays were conducted using standard WHO procedure. Results: The results of topical application on 3-5 day old female mosquitoes indicated that resistant strain of An. stephensi registered lower LC50 values than the susceptible strain. Among the three insecticides tested, thiacloprid was found more effective than the other two insecticides. Culex quinquefasciatus registered lowest LC50 for imidacloprid than the other two mosquito species tested. In larval bioassays, the LC50 values registered for imidacloprid were in the order of Cx. quinquefasciatus <An. stephensi (SS) <An. stephensi (RR) <Ae. aegypti. In case of thiacloprid, the order of efficacy (LC50) was Cx. quinquefasciatus <An. stephensi (SS) <An. stephensi (RR), whereas in case of thiamethoxam, the larvicidal efficacy was in the order of An. stephensi (RR) <An. stephensi (SS) <Cx. quinquefasciatus. Interpretation & conclusions: The present study indicated that insecticide resistant strains of mosquito species tested showed more susceptibility to the three neonicotinoids tested, and the possibility of using neonicotinoids for the control of resistant mosquitoes should be explored.
ABSTRACT
A molecularly imprinted polymer (MIP) for the selective solid phase extraction of imidacloprid, imidaclothiz, thiacloprid was synthesized by polymerization for 24 h using thiacloprid as template. Dynamic adsorption and selective adsorption test showed that the MIP could quickly adsorb the imidacloprid, imidaclothiz, thiacloprid, with good selectivity for targets. The maximum static adsorption capacity of MIP was 31. 7, 36. 7 and 45. 3 mg / g, respectively. A molecularly imprinted solid phase extraction (MIP-SPE) was developed to separate, clean up and enrich the thiacloprid, imidacloprid and imidaclothiz residue in paddy water, soil, rice, tomato, cucumber. The average recoveries were 80. 2% -98. 8% , with relative standard deviation of 1. 4% -4. 5% . The MIP-SPE was used to analyses the real samples, the result was satisfied.