灰葡萄孢(Botrytis cinerea)对氟啶胺的敏感基线及对不同杀菌剂的交互抗性

为了明确灰葡萄孢对新型杀菌剂氟啶胺的敏感性分布和该药剂是否与其它杀菌剂存在交互抗性,本试验采用菌丝生长速率法,测定了采自河北省和山东省不同地区的99株灰葡萄孢对氟啶胺的敏感性及其中48株灰葡萄孢对氟啶胺、嘧霉胺、多菌灵、异菌脲、乙霉威和啶酰菌胺的敏感性.结果表明,氟啶胺对从未使用过氟啶胺的地区采集的灰葡萄孢99个野生菌...     

Toxicity and binding analyses of Bacillus thuringiensis toxin Vip3A in Cry1Ac-resistant and-susceptible strains of Helicoverpa armigera(Hübner)

The Bacillus thuringiensis vegetative insecticidal protein, Vip3 A, represents a new family of Bt toxin and is currently applied to commercial transgenic cotton. To determine whether the Cry1Ac-resistant Helicoverpa armigera is cross-resistant to Vip3 Aa protein, insecticidal activities, proteolytic activations and binding properties of Vip3 Aa toxin were investigated using Cry1Ac-susceptible(96S) and Cry1Ac-resistant H. armigera strain(Cry1Ac-R). The toxicity of Vip3 Aa in Cry1Ac-R slightly reduced compared with 96 S, the resistance ratio was only 1.7-fold. The digestion rate of full-length Vip3 Aa by gut juice extracts from 96 S was little faster than that from Cry1Ac-R. Surface plasmon resonance(SPR) showed there was no significant difference between the binding affinity of Vip3 Aa and BBMVs between 96 S and Cry1Ac-R strains, and there was no significant competitive binding between Vip3 Aa and Cry1 Ac in susceptible or resistant strains. So there had little cross-resistance between Vip3 Aa and Cry1 Ac,Vip3A+Cry proteins maybe the suitable pyramid strategy to control H. armigera in China in the future.     

萝卜蚜对氰戊菊酯的抗药性汰选及其交互抗性

将田间采回的萝卜蚜种群分成两部分,一部分用氰戊菊酯连续汰选13次,另一部分不用药汰选,连续饲养作对照。汰选前及每汰选3～4次测定1次氰戊菊酯对两种群的毒力。结果表明,对照种群对氰戊菊酯的敏感性增加3.76倍,而汰选种群对该农药的抗药性与汰选前比较增长了163.25倍,与同期饲养对照种群比较,抗性已达613.62。该汰选种群对不含氟的溴氰菊酯和氯氰菊酯存在明显的交互抗性(分别达360.7和53.9倍),对含氟的三氟氯氰菊酯、氟氰菊酯和氟胺氰菊酯也存在交互抗性,但只有7倍左右;而对马拉硫磷、氧化乐果、杀螟松、久效磷和灭多威及菊马混剂没有表现出交互抗性,为进一步探讨萝卜蚜的抗药性治理措施提供了试验依据。     

小菜蛾对阿维菌素B_1抗药性选育及交互抗性

用阿维菌素B_1(abamectin)对小菜蛾敏感种群在室内进行抗性品系选育。经过25代连续汰选,获得抗性种群Laba-R,与选育前比较,抗性提高100倍。Laba-R种群在不接触任何药剂条件下饲养20代,抗性逐渐下降,很难恢复到选育前的敏感状态。抗性汰选前后分别测定10种药剂的剂量-死亡率毒力回归线,发现Laba-R抗性种群对乙酰甲胺磷、锐劲特、灭多威、敌敌畏不存在交互抗性;对溴氰菊酯、氯氰菊酯、杀虫双、巴丹和Bt的敏感性略有下降,但无明显交互抗性。活体增效剂试验表明,增效醚(PBO)和磷酸三苯酯(TPP)对阿维菌素B_1均有明显的增效作用,其中PBO的增效活性尤为显著,它能使对阿维菌素B_1产生100多倍抗药性的小菜蛾完全恢复其敏感性。说明多功能氧化酶解毒代谢增强可能是小菜蛾对阿维菌素B_1产生抗性的主导因素之一。     

小菜蛾对阿维菌素的抗性选育及交互抗性研究

用阿维菌素对小菜蛾进行室内抗性汰选,选择压为约杀死种群70％的剂量。连续施药7～8次即表现抗性趋势,汰选至11代,获得抗性指数为80.71的抗性种群(ABM-R)。ABM-R种群对所测试的有机磷杀虫剂乙酰甲胺磷、有机氯类的硫丹、沙蚕毒素类的杀螟丹、氨基甲酸酯类的灭多威、微生物杀虫剂Bt、磺胺脲类衍生物丁醚脲、芳基取代的吡咯杂环化合物虫螨腈和昆虫生长调节剂定虫隆、虫酰肼无交互抗性(R/S为0.73～1.19),而对苯基吡唑类氟虫腈的敏感性却有所上升(R/S为0.22)。增效剂试验显示,PB和唧对ABM-S种群无增效作用,而对ABM-R种群增效作用显著,增效比分别为24.57和13.61,表明多功能氧化酶和羧酸酯酶在抗性机制中可能起重要作用。     

抗吡虫啉桃蚜种群的选育及其交互抗性研究

采用浸渍法,在室内用吡虫啉对桃蚜敏感种群进行抗性选育,经过15代的连续汰选,获得抗性指数为14.34倍的抗吡虫啉桃蚜种群。对9种常用杀虫剂的交互抗性测定结果表明,该种群对拟除虫菊酯类如高效氯氟氰菊酯(抗性指数12.76倍)和溴氰菊酯(10.24倍),有机磷类如氧乐果(7.95倍)、辛硫磷(5.44倍)和甲胺磷(5.32倍)以及吡虫啉·高效氯氰菊酯混剂(8.90倍)均产生了不同程度的交互抗性,而对氨基甲酸酯类如灭多威(3.15倍)、有机氯类如硫丹(1.64倍)以及阿维菌素·辛硫磷混剂(2.31倍)等无明显的交互抗性。     

Target site insensitivity and mutational analysis of acetylcholinesterase from a carbofuran-resistant population of Colorado potato beetle, Leptinotarsa decemlineata (Say)

The BERTS strain of Colorado potato beetle (CPB) was found to be highly resistant to N-methyl carbofuran but relatively susceptible to azinphosmethyl. N-Methyl carbofuran resistance was found to correlate well with acetylcholinesterase (AChE) insensitivity. In becoming resistant to N-methyl carbofuran, the AChE of the BERTS strain became more sensitive to N-propyl carbofuran inhibition. This negative cross-insensitivity correlated well to the increased relative toxicity of the BERTS strain to N-propyl carbofuran compared to the susceptible SS strain. BERTS beetles were sorted into BERTS-R and BERTS-S substrains using their AChE activity profiles. Sequence comparisons of AChE cDNAs from the two substrains revealed the presence of the point mutation that results in the S291G substitution previously found in the AChE of the azinphosmethyl-resistant AZ-R strain of CPB. A novel mutation present only in BERTS-S CPB, however, resulted in an additional I392T substitution in the AChE and apparently reverses the resistance conferring properties of the S291G substitution.     

小菜蛾对丁烯氟虫腈的抗性选育及生物适合度

用丁烯氟虫腈对小菜蛾敏感品系在室内经7代次药剂汰选,获得了抗性品系(R),与敏感品系(S)比较其抗性指数为77.58倍。抗性汰选前后,采用点滴法测定的结果表明,小菜蛾对阿维菌素、毒死蜱、灭多威、杀虫单和高效氯氰菊酯的敏感性并无明显变化,其抗性指数为0.80~1.36,均不存在交互抗性。通过构建种群生命表,观察比较了小菜蛾抗丁烯氟虫腈品系和敏感品系的一系列生长发育和繁殖特征。结果表明,抗丁烯氟虫腈品系较敏感品系幼虫期和蛹历期延长,低龄幼虫龄期转换时的虫口死亡率增加,蛹重减轻,化蛹率和羽化率降低;在繁殖上表现为产卵量增加,而孵化率和雌雄比降低,雌成虫的数量、寿命减少。抗丁烯氟虫腈种群相对于敏感种群的相对适合度为0.84,抗性种群在繁殖能力上存在明显的生存劣势。     

Sensitivity of<Emphasis Type="Italic">Botrytis cinerea</Emphasis> from greenhouse vegetables to DMIs and fenhexamid

Two hundred isolates ofBotrytis cinerea were collected from greenhouse vegetables between 2003 and 2006 to determine their baseline sensitivity to triadimefone, penconazole, tebuconazole and fenhexamid. Mean values of 50% effective concentrations (EC₅₀) of inhibiting growth were 4.853±5.102, 0.41±0.215, 0.19±0.099 and 0.36±0.891 mgl ⁻¹, respectively (mean±SD). Individuals ofB. cinerea in the population differed by a factor (EC₅₀ of the least sensitive isolate/EC₅₀ of the most sensitive isolate) of 6625, 20, 603 and 1800, respectively. Naturally fenhexamid-resistant isolates were detected with an unexpected high frequency of 10% although the pathogen population had never been exposed to this fungicide. The resistance level (mean EC₅₀ of resistant isolates / mean EC₅₀ of sensitive isolates) was 19.5. These naturally resistant isolates also were resistantin vivo, and there was no significant difference in growth rate, conidial production or pathogenicity ability between naturally resistant and wild sensitive isolates. These results indicated that there was a potential risk of practical resistance if fenhexamid was applied alone. Negative cross-resistance was observed between fenhexamid and tebuconazole in 90% of the naturally resistant isolates. Moreover, an obvious synergism of the antifungal activity of fenhexamid by tebuconazole was demonstrated in some of the naturally fenhexamid-resistant isolates. http://www.phytoparasitica.org posting May 9, 2007.     

橘小实蝇对甲氨基阿维菌素苯甲酸盐的抗性机制及对其他药剂的交互抗性

入侵害虫橘小实蝇严重为害蔬菜、花卉、水果等经济作物,目前在田间常使用杀虫剂进行防治。为探索甲氨基阿维菌素苯甲酸盐(甲维盐)防控橘小实蝇的抗性风险,采用药膜法测定了橘小实蝇抗甲维盐种群(EB)对8种杀虫剂的交互抗性水平,并测定了橘小实蝇EB种群、金华田间种群(JH)和敏感种群(S)的解毒酶活性。历经33代筛选,橘小实蝇EB种群对甲维盐产生了43.4倍的中等水平抗性,对阿维菌素存在中等水平交互抗性,对吡虫啉、辛硫磷、马拉硫磷存在低水平交互抗性,对噻虫胺、高效氯氟氰菊酯、多杀霉素和虫螨腈未表现出交互抗性。胡椒基丁醚(PBO)、磷酸三苯酯(TPP)和顺丁烯二酸二乙酯(DEM)均可显著提高甲维盐对橘小实蝇EB种群、JH种群和S种群的室内毒力。橘小实蝇EB种群细胞色素P450(3.9倍)和b₅含量(3.3倍)、O-脱甲基酶活性(4.2倍)、谷胱甘肽S-转移酶活性(2.7倍)、羧酸酯酶活性(3.2倍)显著高于S种群。多功能氧化酶、谷胱甘肽S-转移酶、羧酸酯酶活性显著增强可能是橘小实蝇对甲维盐产生高水平抗性的重要机制。