斑痣悬茧蜂对受药寄主幼虫的选择性及其后代表现

为探究受到杀虫剂亚致死影响的寄主幼虫对寄生蜂的寄主选择及其子代蜂的影响,以容性寄生蜂斑痣悬茧蜂Meteorus pulchricornis为研究对象,以氯氰菊酯亚致死浓度处理的甜菜夜蛾Spodoptera exigua4龄幼虫为寄主幼虫,进行非选择性和选择性试验。非选择性试验表明,斑痣悬茧蜂成功寄生（完成化蛹）的概率随受药寄主的体重增大而提高,而且受药寄主有效存活的概率亦随其体重增大而提高;与对照寄主相比,寄生蜂对受药寄主的寄生率降低60.2%、子代蜂发育历期显著延长、子代蜂体型（用后足胫节长度表示）显著增大。与来自对照寄主的子代蜂相比,来自受药寄主的子代蜂的寄生能力（用寄生率表示）未受影响,但其后代的结茧率降低10%、发育历期显著缩短、体型显著增大,说明羽化蜂的发育适合度得到了提高。选择性试验结果得出不一致的结论,根据对寄生蜂攻击次数的分析,未发现其在对照与受药寄主之间存在显著偏好;但根据第2次攻击的寄主识别期变量进行的风险分析,受药寄主被寄生风险显著低于对照寄主（低59.7%）,说明寄生蜂偏好攻击对照寄主幼虫。研究结果说明,斑痣悬茧蜂通过偏好体型较大的寄主幼虫,而减轻了受到杀虫剂亚致死效应的间接不良影响。结果表明该寄生蜂具有鉴别出接受亚致死杀虫剂不久的寄主幼虫的能力。     

马拉硫磷亚致死浓度对大豆蚜虫实验种群生理特征和生命表参数的影响

大豆蚜虫是危害大豆的重要害虫,马拉硫磷作为有效防治大豆蚜虫的杀虫剂之一,不仅可以在致死浓度下直接杀死大豆蚜虫,其在亚致死浓度下还会引起大豆蚜虫生理和行为的改变。分析了马拉硫磷3个亚致死浓度(0.05、0.10和0.20 mg/L)对大豆蚜虫生理特征和生命表参数的影响。结果表明:马拉硫磷在0.20 mg/L下处理大豆蚜虫后,其若蚜的发育历期(7.48 d±0.18 d)比对照的(5.78 d±0.30 d)显著延长;同时成蚜的生殖期、寿命和全世代周期也分别比对照的缩短了4、6和4 d。在0.10 mg/L处理下,马拉硫磷可刺激大豆蚜虫生殖功能,单头产蚜总量比对照组提高24%;但当浓度增加到0.20 mg/L时,单头产蚜总量却比对照组降低37%。生命表参数结果显示:0.20 mg/L的马拉硫磷可显著降低大豆蚜虫的净增值率(R0)、内禀增长率(rm)和周限增长率(λ),但显著增加种群倍增时间(Dt);0.10 mg/L的处理情况则相反;0.05 mg/L处理的各项指标与对照间无显著差异。     

Strong resistance to phosphine in the rusty grain beetle,Cryptolestes ferrugineus (Stephens) (Coleoptera: Laemophloeidae): its characterisation,a rapid assay for diagnosis and its distribution in Australia

BACKGROUND: The recent development of very high resistance to phosphine in rusty grain beetle, Cryptolestes ferrugineus (Stephens), seriously threatens stored‐grain biosecurity. The aim was to characterise this resistance, to develop a rapid bioassay for its diagnosis to support pest management and to document the distribution of resistance in Australia in 2007–2011. RESULTS: Bioassays of purified laboratory reference strains and field‐collected samples revealed three phenotypes: susceptible, weakly resistant and strongly resistant. With resistance factors of > 1000 × , resistance to phosphine expressed by the strong resistance phenotype was higher than reported for any stored‐product insect species. The new time‐to‐knockdown assay rapidly and accurately diagnosed each resistance phenotype within 6 h. Although less frequent in western Australia, weak resistance was detected throughout all grain production regions. Strong resistance occurred predominantly in central storages in eastern Australia. CONCLUSION: Resistance to phosphine in the rusty grain beetle is expressed through two identifiable phenotypes: weak and strong. Strong resistance requires urgent changes to current fumigation dosages. The development of a rapid assay for diagnosis of resistance enables the provision of same‐day advice to expedite resistance management decisions. © 2012 Commonwealth of Australia. Published by John Wiley & Sons, Ltd.