Insecticide Resistance Development in Culex Pipiens Population under Selection Pressures with Temephos

In insects, biochemical mechanisms of insecticide resistance base on increasing of activities of main detoxyfying enzymes – monooxygenases, nonspesific esterases, and glutathion-S-transferases. Currently, the progress of resistance development and the degree of contributing enzymes to resistance in insects have been studied for certain insecticides. The goal of this study was to assess activities of monooxygenase, carboxylesterase, glutathione-S-transferase, and alkaline phosphatase in females and males housefly Musca domestica in the second, fourth, sixth, eighth and tenth generations of the chlorfenapyr-selected strain. Evaluation of chlorfenapyr susceptibility showed that adults M. domestica in tenth generations was tolerating to chlorfenapyr as the resistance ration value was 3.6. In certain generations of chlorfenapyr-selected strain M. domestica, monooxygenase activities in males and females were 1.4-2.1 times more, and alkaline phosphatase activities in females were 2.3-2.7 times more than that in control insects. Glutathione-S-transferase activities had no significant differences in adults M. domestica of control and chlorfenapyr-selected strains. For chlorfenapyr-selected strain M. domestica, activities of monooxygenase, carboxylesterase, and alkaline phosphatase differed in males and females of same generations that suggests that mode and pattern of resistance development might be sex-specific in this specie.

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Effects of Propoxur Exposure on Insecticidal Susceptibility and Developmental Traits in Culex pipiens quinquefasciatus

Insects ◽

10.3390/insects10090288 ◽

2019 ◽

Vol 10 (9) ◽

pp. 288

Author(s):

Xiaolei Zhang ◽

Samuel Karungu ◽

Quanxin Cai ◽

Zhiming Yuan ◽

Xiaomin Hu

Keyword(s):

Culex Pipiens ◽

Constitutive Expression ◽

Adult Survivors ◽

Lethal Concentration ◽

P450 Monooxygenase ◽

Resistance Development ◽

Culex Pipiens Quinquefasciatus ◽

Rate Of Increase ◽

Developmental Traits ◽

Net Reproduction

Propoxur-sel strains of Culex pipiens quinquefasciatus were derived from a lab-bred strain following 16 generations of propoxur exposure under sublethal concentrations of LC25 (lethal concentration of 25%) and LC50 (lethal concentration of 50%), respectively. This resulted in resistance development in F16 with ratios of 8.8× and 6.3×, respectively, compared with F0. The fecundity, longevity, sex ratio (F/M), and hatchability of the propoxur-exposed Cx. quinquefasciatus adult survivors and their offspring were decreased, with no effect on the emergence ratio and pupa survival rate. In addition, the intrinsic rates of increase (r), the net reproduction (R0), and the finite rate of increase (λ) of the Cx. quinquefasciatus offspring generations were also decreased significantly compared to F0. Correspondingly, the mean generation time (T) and the population double time (DT) in propoxur-sels were increased. Enhanced activities of cytochrome P450 monooxygenase and esterase were also observed in propoxur-sels, indicating that a detoxification mechanism might be responsible for resistance development in Cx. quinquefasciatus. Except for the three genes cyp4d42v1, cyp4c52v1, and cyp6aa9 which displayed a coincidence in some degree in different treatments, induction by different doses of propoxur and constitutive expression in different generations of propoxur-sel strains resulted in an inconsistent identification of the P450 genes probably related with resistance.

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