| Summary: | 碩士 === 國立中興大學 === 昆蟲學系所 === 106 === The tradeoff of life history trait in the evolution of insecticide resistance is common in insect owing to energy acquisition mainly channels for detoxifying enzyme purposes. In addition, acute exposure of insecticide may also elicit impact on physiology and behavior on survived insects. The rove beetle, Paederus fuscipes Curtis, is a beneficial insect that suppresses agricultural pest populations in agroecosystems. However, as with other agricultural pests, massive input of pesticides may have led to selection of resistance in populations of Paederus beetles. Hence, any change of life history traits of Paederus beetle may disrupt their ecosystem service or facilitate their invasion in human setting. In the study, we determined median lethal time of ten field-collected strains in Taiwan against three insecticides that commonly employed to manage agricultural pests including imidacloprid, cyhalothrin and fenitrothion. We exhibited that the toxicities of cyhalothrin and fenitrothion were similar among strains (1 to 4-fold) but significant difference among tested strains was detected in imidacloprid treatment (1 to 16-fold). The effect of long term exposure of imidacloprid on life history traits of Paederus beetle was limited, in which only egg incubation and adult longevity were significantly compensated in the evolution of insecticide resistance. In particular, the egg incubation period was prolonged and adult longevity was reduced along with increasing of imidacloprid resistance. The sublethal effect of imidacloprid on biological attributes of offspring and adult fecundity was investigated on two strains with different level of imidacloprid resistance. The adult sex ratios were slightly female-biased in most combinations. The quality of offspring, particularly eggs, was significantly decrease when adults of Ji strain were sublethal exposed to imidacloprid. In addition, hormetic effect was apparent in Ji strain as mean fecundity per female increase from 12.80 ± 8.95 (±SE) to 42.70 ± 13.77 (±SE) eggs in comparison with those of control (7.10 ± 1.32 (±SE)). However, the phenomenal was rather inconsistent among strains tested possibly owing to difference in insecticide resistance level as reproductive compensation was absent in the resistant population.
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