为了明确七星瓢虫对吡虫啉的抗性发展动态,在室内选用吡虫啉逐代筛选,选育抗吡虫啉的七星瓢虫品系。发现七星瓢虫对吡虫啉的抗性整体呈上升趋势,但抗性不稳定,选育20代后抗性为63.1519倍。同时为了明确七星瓢虫对吡虫啉产生抗性后对其生物学特性的影响,将抗性选育13代的七星瓢虫品系与敏感七星瓢虫品系、野外七星瓢虫种群进行生物学特性的比较,结果表明,从幼虫的整个发育历期来观察,抗性品系幼虫的发育历期为12.36 d,野外种群为9.88 d,敏感品系为10.62 d,3者之间差异显著;蛹发育历期3者之间没有差异;4龄老熟幼虫、蛹、初羽化雌成虫、初羽化雄成虫平均体重3组间有一定的差异;七星瓢虫抗性品系、敏感品系、野外种群前期的卵孵化率分别为63.0%、62.4%和66.3%,中期的卵孵化率分别为64.8%、58.7%和75.6%,后期的卵孵化率分别为69.3%、57.4%和75.5%,3组之间无显著差异;抗性品系雌成虫的平均产卵量为1043.3粒,敏感品系为1100.2粒,野外种群雌成虫为1250.1粒,3者之间没有显著差异。综上所述,抗药性对七星瓢虫的生物适合度有一定程度的影响,但是,由于抗性倍数较低,影响尚不明显。
A field population of seven-spot ladybird, Coccinella Septempunctata Linnaeus, was selected for imidacloprid resistance under laboratory condition to explore the resistant developmental dynamics. After 20 generations, the selected population showed resistance increase of 63.1519 folds compared with that of a susceptible strain. Biological characteristics were also investigated in three groups of C. septempunctata, the resistant strain (R), the susceptible strain (S) and a field population (F). Significant difference was observed in the larval duration among the three groups, larval stage of R, S, and F were 12.36 days, 10.62 days and 9.88 days, respectively. No differences were found in pupal duration. There was slight difference among the three groups in body weights of the 4th instar larvae as well as pupae and male adults. Egg hatching rates were 63.0%, 62.4%, and 66.3% in the prophase, respectively; 64.8%, 58.7%, and 75.6% in the midphase, respectively; and 69.3%, 57.4%, and 75.5%
