Department of Entomology, Cornell University, Ithaca, NY 14853, USA.
J Med Entomol. 2010 Mar;47(2):188-98. doi: 10.1603/me09131.
Insecticide resistance in populations of mosquitoes is an escalating problem that can directly affect disease prevalence. Determining the fitness associated with an insecticide resistance mechanism (allele) will provide for greater understanding of the evolution of resistance, and help inform effective vector management programs. Previously, a population cage experiment in which the alleles of two highly related strains of Culex pipiens quinquefasciatus (Say) SLAB (susceptible) and ISOP450 (permethrin resistant because of cytochrome P450-mediated detoxification) were placed in direct competition in the absence of insecticide revealed that the P450 resistance allele frequency decreased over time. In the current study, SLAB and ISOP450 development, mortality and energetic resources derived from glycogen, other sugars and lipids were measured to identify biological parameters that might explain the previously observed fitness cost. SLAB exhibited shorter egg-to-adult female development time and larger body size when reared in groups when compared with ISOP450. ISOP450 female adults provided 20% sugar water lived longer than 20% sugar water fed females of the SLAB strain. No significant differences in larval development time, larval mortality, pupal stage duration time, pupal mortality, longevity of male and female adults provided with distilled water and males provided sugar water were found between the strains. The caloric content from glycogen and lipids were significantly higher in SLAB relative to ISOP450 in adults. The slower female emergence time and smaller body size when reared in groups combined with lower energy reserves (glycogen and lipids) associated with the resistance allele (in ISOP450) are likely fitness costs associated with the resistance allele of P450-mediated detoxification.
蚊虫种群对杀虫剂的抗药性是一个日益严重的问题，它会直接影响疾病的流行程度。确定与杀虫剂抗性机制（等位基因）相关的适合度，将有助于更好地了解抗性的进化，并为有效的病媒管理计划提供信息。此前，在一个种群笼实验中，将两种高度相关的库蚊（Culex pipiens quinquefasciatus （Say）SLAB （敏感）和 ISOP450 （因细胞色素 P450 介导的解毒而对拟除虫菊酯具有抗性）的等位基因直接放在没有杀虫剂的情况下进行竞争，结果显示 P450 抗性等位基因的频率随着时间的推移而降低。在目前的研究中，测量了 SLAB 和 ISOP450 的发育、死亡率以及来自糖原、其他糖和脂类的能量资源，以确定可能解释之前观察到的适合度成本的生物学参数。与 ISOP450 相比，SLAB 以群体形式饲养时，雌性从卵到成虫的发育时间更短，体型更大。当以 20%的糖水喂养时，ISOP450 雌性成虫的寿命比 SLAB 菌株的 20%糖水喂养的雌性成虫长 20%。在幼虫发育时间、幼虫死亡率、蛹期持续时间、蛹死亡率、提供蒸馏水的雌雄成虫寿命以及提供糖水的雄性成虫之间，没有发现两种菌株之间的显著差异。成年 SLAB 相对于 ISOP450 的糖原和脂类的热量含量显著更高。当以群体形式饲养时，雌性成虫的出现时间较慢，体型较小，而与抗性等位基因（在 ISOP450 中）相关的能量储备（糖原和脂类）较低，这可能是与 P450 介导的解毒抗性等位基因相关的适合度成本。
