【作者】 杨捷；

【导师】 刘树生；

【作者基本信息】 浙江大学 ， 农业昆虫与害虫防治， 2004， 硕士

【摘要】 小菜蛾分布广，在热带和亚热带地区世代重叠严重，繁殖力高，对杀虫剂易产生抗性，已成为十字花科蔬菜上的一种主要害虫。多杀菌素是近年来新开发的大环内酯类杀虫剂，对鳞翅目、双翅目和缨翅目害虫有极好的灭杀效果。经过几年大田应用，已有美国夏威夷、中国浙江温州等地区的小菜蛾表现出对多杀菌素较高的抗性。本文选用温州地区抗性虫源进行了室内筛选，得到了遗传背景一致的敏感SS和抗性RR品系，在低温、适温和高温下比较了SS和RR品系的发育、存活和生殖情况，以探讨其对多杀菌素的抗性是否伴有适合度的变化，以及适合度变化与温度的关系。 比较测定了SS和RR品系的卵冷藏在6℃下0-28天、蛹冷藏在6℃下0-28天和-5℃下0-21天后在适温下发育的多项生物学指标。结果表明，(1)不经低温时，RR与SS之间差异不显著或幅度很小；(2)卵经6℃处理后，RR与SS品系相比，卵孵化率和幼虫化蛹率显著下降、发育历期显著延长；(3)蛹经历6℃处理后，RR品系子代卵孵化率较SS的显著低；(4)蛹经-5℃处理后，RR与SS品系相比，蛹的发育历期显著延长、子代卵孵化率显著下降。 在低温自然变温条件下、适温和高温模拟自然变温条件下，比较观察了SS和RR品系的发育、存活和生殖情况。(1)在低温下，SS品系初始卵数752粒，孵化639粒，发育到蛹15头；RR品系初始卵数823粒，孵化470粒，最终仅有1头发育至蛹。RR品系的孵化率(57％)、幼虫化蛹率(0.2％)比SS品系的孵化率(85％)、幼虫化蛹率(2.4％)均显著要低。(2)在适温下，虽然SS与RR品系之间在一些特性上存在显著差异，但总的说来差异不大，经生命生殖力表综合分析，SS和RR品系所表现的内禀增长率分别为0.2138(?)／(?)／天和0.2112(?)／(?)／天，基本一致；(3)在高温下，RR品系的幼虫化蛹率(12.4％)比SS品系的(21.2％)显著要低；蛹重(平均3.77mg)也比SS品系的(平均4.25mg)显著要低，其它多项指标差异未达显著水平，经生命生殖力表综合分析，RR品系的内禀增长率为0.0793(?)／(?)／天，SS品系的为0.1153(?)／(?)／天。显然，RR品系的内禀增长率比SS品系的要低。 综合以上两部分试验结果可见，小菜蛾对多杀菌素的抗性在耐低温能力方面有显著的适合度代价，在耐高温(＞32℃)能力上也有一定的适合度代价，而在适温条件下则未表现出显著的适合度代价。依据这些结果推论，在冬季有持续6℃以下低温、及夏季有持续32℃以上高温的地区，气温的自然变化有利于敏感基因的维持，延缓抗性的发展；而在气温较高而又没有极端低温和高温的地区，则有利于小菜蛾对多杀菌素抗性的发展。在这些地区应尽早实施减少施药量、轮换用药、生态调控和生物防治等综合措施，延缓和治理小菜蛾对多杀菌素的抗性。更多还原

【Abstract】 The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), has become a major pest on vegetable crucifers due to its overlapping generations, high reproductive rate and high ability to develop resistance to insecticides, especially hi tropical and subtropical regions. Spinosad is a recently developed macrolide that has high efficacy hi killing Lepidoptera, Diptera, and Thysanoptera. However, field populations of the diamondback moth resistant to Spinosad were found in Hawaii, USA, and Wenzhou, China only after two to three years of large-scale application of this insecticide, hi this study, homozygotes of the diamondback moth with similar genetic background, susceptible (SS) or highly resistant (RR) to Spinosad, were obtained by crossing and selection using a susceptible strain originally collected from Wuhan, China hi 1989 and a field resistant strain originally collected from Wenzhou, China in 2001. Development, survival and reproduction were compared between the SS and RR strains at low, moderate, and high temperatures. Our objective was to investigate whether resistance to Spinosad is associated with fitness changes, and whether fitness changes are temperature-dependent.Eggs or pupae of SS and RR strains were kept at 6℃ for 0-28 days, or pupae of the two strains were kept -5℃ for 0-21 days. These low-temperature treated eggs or pupae were then moved to 25℃ to observe their subsequent development, survival or reproduction at this moderate temperature. The results showed that: (1) there was no or little difference between the two strains when they were not exposed to the low temperatures; (2) when eggs were kept at 6℃ for various periods of time, the subsequent percent hatch of eggs and percent pupation of larvae of RR strain were significantly lower, and development time of eggs of RR strain was significantly longer, compared to those of SS strain; (3) when pupae were kept at 6癈 for various periods of time, percent hatch of eggs in progeny of RR strain was significantly lower than that of SS strain; and (4) when pupae were kept at -5℃ for various periods of tune, the subsequent development time of pupae of RR strain was significantly longer and percent hatch of eggs in progeny of RR strain was significantly lower, compared to those of the SS strain.The development, survival and reproduction were also compared between RR and SSstrains at natural fluctuating low temperature regimes as well as at simulated natural fluctuating moderate and high temperature regimes. The results showed that: (1) at low temperature, in the 752 eggs of the SS strain initially inoculated 639 of them hatched and 15 of them developed to the pupal stage, while in the 823 eggs of the RR strain initially inoculated only 470 hatched and 1 of them developed to the pupal stage. Percent hatch of eggs (57%) and percent pupation of larvae (0.2%) of the RR strain were significantly lower than those (85% egg hatch, 2.4% pupation) of SS strain; (2) at moderate temperature, the two strains showed limited differences though statistically significant differences existed for some traits. Analysis using life and fertility tables showed that the intrinsic rate of increase was 0.2138 $/$/day for SS and 0.2112 day for RR, very similar between the two strains; and (3) at high temperature, percent pupation of larvae (12.4%) of RR strain was significantly lower than that of SS (21.2%), and mean pupae weight (3.77 mg) of RR was significantly lower than that of SS (4.25 mg). There were no significant differences in other traits. Life and fertility table analysis showed that the intrinsic rate of increase of RR (0.0793 day) was lower than that of SS (0.1153 day).It is concluded from these results that resistance to spinosad of the diamondback moth is associated with significant fitness costs in low temperature tolerance as well as some fitness costs in heat (>32) tolerance, but little or no fitness costs at moderate temperatures. In regions with a cold-winter (temperature frequently goes below<6) and a hot summ更多还原