斜纹夜蛾在风洞中对性信息素的行为反应及田间诱捕试验

雌蛾腺体内含量最高的组份9,11-14∶Ac（A）在风洞中能引起雄蛾从搜索气迹、定向飞行到撒开味刷企图交尾连续的行为反应,而雌蛾腺体内其它组份单独使用时均不能引起雄蛾上述行为反应。一定量的Z9,E12-14∶Ac（B）对A的活性有增效作用,诱芯中B数量过多,不但失去对A的活性增效作用,还对雄蛾接近诱芯和企图交尾有强烈的抑制作用。9-14∶Ac（C）与11-14∶Ac (D)对雄蛾的定向行为无影响,诱芯中含有50%的C时,反而对雄蛾接近诱芯和企图交尾有抑制作用。A与B在滤纸诱芯中的含量比例与诱芯释放的挥发物比例明显不同,从9∶1（A∶B）诱芯释放的挥发物比例更接近于雌蛾腺体内的天然比例。田间诱捕试验中两组份诱芯的诱捕量随两组份比例不同而变化, 9∶1（A∶B）诱芯的诱捕量最大,1∶1（A∶B）诱芯的诱捕量低于单一的A组份诱芯。     

异丙威·阿维菌素和丙溴磷·阿维菌素两种增效混配制剂对甜菜夜蛾的田间防治效果

24%异丙威·阿维菌素乳油对甜菜夜蛾的田间药效试验结果表明,该混剂药后3天、7天和10天校正防治效果优于异丙威和阿维菌素乳油两个单剂。该混剂用量为50 g/667 m²,药后3天、7天和10天的校正防效分别为82.38%、87.49%和88.90%;用量为37.5 g/667 m²,防效分别为78.21%、83.97%和85.24%。35%丙溴磷·阿维菌素乳油对甜菜夜蛾的田间药效试验结果表明,其对甜菜夜蛾速效性和持效性均佳。该混剂用量为50 g/667 m²,药后3天、7天和10天其校正防效分别为86.15%、91.37%和91.32%;用量为37.5 g/667 m²,防效分别为80.73%、87.40%和88.39%。     

杀菌剂对斜纹夜蛾SL细胞系和幼虫的生物活性

以MTT法筛选了19种杀菌剂对斜纹夜蛾Spodoptera litura SL细胞的毒杀活性,并以该方法研究了三唑类杀菌剂对SL细胞的毒力。结果表明: 福美双、烯唑醇、己唑醇、氟硅唑、苯霜灵、苯醚甲环唑、戊唑醇和腈菌唑等杀菌剂对SL细胞具有优异的毒杀活性。三唑类杀菌剂腈菌唑、烯唑醇、己唑醇和戊唑醇处理SL细胞48 h后,LC₅₀值分别为21.94 μg/mL、 23.80 μg/mL、 33.16 μg/mL和47.63 μg/mL。以考马斯亮蓝G₂₅₀法研究了腈菌唑对SL细胞中蛋白质含量和乳酸脱氢酶(LDH)漏出率的影响, 20 μg/mL腈菌唑处理12 h、24 h、48 h和72 h后,SL细胞中蛋白质含量分别降低8.55%、25.95%、42.95%和67.05%;处理24 h和48 h后,SL细胞的LDH漏出率分别为30.66%和32.05%。以浸叶喂食法处理斜纹夜蛾3龄幼虫,三唑类杀菌剂可显著抑制试虫体重增长。以0.5 μg/头、 1.0 μg/头和2.0 μg/头剂量的腈菌唑注射处理72 h后,斜纹夜蛾4龄幼虫血细胞数量分别降低12.31%、 25.96%和25.73%;腈菌唑注射处理48 h和72 h后,对斜纹夜蛾幼虫的LD₅₀值分别为1.59 μg/头和1.53 μg/头。结果显示以离体培养细胞为对象,从现有杀菌剂中寻找新的杀虫剂先导化合物具有良好的研究潜力。     

Purification and properties of a β-glycosidase purified from midgut cells of Spodoptera frugiperda (Lepidoptera) larvae

Two β-glycosidases (BG) (Mr 47,000 and Mr 50,000) were purified from Spodoptera frugiperda (Lepidoptera: Noctuidae) midguts. These two polypeptides associate or dissociate depending on the medium ionic strength. The Mr 47,000 BG probably has two active sites. One of the putative active sites (cellobiase site) hydrolyses p-nitrophenyl β- -glucoside (NPβGlu) (79% of the total activity in saturated enzyme), cellobiose, amygdalin and probably also cellotriose, cellotetraose and cellopentaose. The cellobiase site has four subsites for glucose residue binding, as can be deduced from cellodextrin cleavage data. The enzymatic activity in this site is abolished after carbodiimide modification at pH 6.0. Since the inactivation is reduced in the presence of cellobiose, the results suggest the presence of a carboxylate as a catalytic group. The other active site of Mr 47,000 BG (galactosidase site) hydrolyses p-nitrophenyl β- -galactoside (NPβGal) better than NPβGlu, cleaves glucosylceramide and lactose and is unable to act on cellobiose, cellodextrins and amygdalin. This active site is not modified by carbodiimide at pH 6.0.The Mr 47,000 BG N-terminal sequence has high identity to plant β-glycosidases and to mammalian lactase–phlorizin hydrolase, and contains the QIEGA motif, characteristic of the family of glycosyl hydrolases. The putative physiological role of this enzyme is the digestion of glycolipids (galactosidase site) and di- and oligosaccharides (cellobiase site) derived from hemicelluloses, thus resembling mammalian lactase–phlorizin hydrolase.     

温度和食料对斜纹夜蛾种群的影响

用正弦模型Ｖ（Ｔ）＝Ａ＋Ｂｓｉｎ（Ｃ０＋Ｃ１ｅ＾Ｃ３Ｔ＋Ｃ２ｅ＾－Ｃ３Ｔ）拟合了斜纹夜蛾（Ｓｐｏｄｏｐｔｅｒａ ｌｉｔｕｒａ）发育与温度的关系,并用直接最优法估算了斜纹夜蛾不同发育阶段的温度阈值和所需热量。根据不同温度下的实验种群生命表资料,拟合了斜纹夜蛾不同发育阶段的存活率与温度关系的模型,卵、低龄幼虫、高龄幼虫、蛹的理论最适温度分别为２６．７、２４．７、２４．９、２５．８℃。本文研究了甘蓝、     

苏云金杆菌对甜菜夜蛾毒性的筛选

测定了 10 0株野生型苏云金芽孢杆菌菌株对夜蛾科甜菜夜蛾幼虫的毒力活性 ,经回归分析 ,2 3株对甜菜夜蛾初孵幼虫的毒力与浓度有高相关性 (R >0 .90 ) ,按LC50 计算 ,CN73活性最强 ,LC50 达 2 .393微升培养液 /克饲料 ( μL/g) ;另有 2 3株进行了不同浓度下校正死亡率的比较 ,得到高毒株 13株 ,CN33在 5μL/g浓度下校正死亡率达到 10 0 %。该结果为进一步研究奠定了基础。     

Age-related cannibalism and horizontal transmission of a nuclear polyhedrosis virus in larval Spodoptera frugiperda

1. Experiments were carried out to investigate the incidence of cannibalism throughout the larval development of the noctuid moth Spodoptera frugiperda, and to examine the risk of infection from consuming conspecifics infected with a nuclear polyhedrosis virus (SfNPV). 2. Cannibalism was observed commonly even when food was not limiting, but occurred more frequently at low food quantities and/or high rearing densities. The sex of the larvae had no effect on the incidence of cannibalistic behaviour, however the probability of cannibalism occurring was affected by larval stage. The frequency of cannibalism was significantly higher among fifth- and sixth-instar larvae than among earlier instars, and larvae were more likely to consume younger conspecifics than larvae of the same stage. 3. Fifth-instar larvae offered fourth-instar victims fed equally on healthy larvae, virus-infected larvae (2 days post-infection), uninfected corpses, and virus-killed corpses (6 days post-infection). Horizontal transmission of SfNPV was only recorded in larvae offered virus-killed corpses, however, and total mortality in this treatment was only 32%. 4. In a similar experiment, fourth-instar larvae avoided cannibalising virus-killed corpses. Horizontal transmission of SfNPV was recorded in fourth-instar larvae that consumed 2-day post-infected larvae. The low incidence of cannibalism observed in fourth-instar larvae, however, suggests that this is unlikely to provide an important route for the transmission of SfNPV.     

斜纹夜蛾天敌作用的评价

通过组建斜纹夜蛾第4代和第8代自然种群生命表,运用排除作用控制指数分析了生物因子对斜纹夜蛾种群的自然控制作用。结果表明,低龄(1～3龄)幼虫的捕食性天敌是影响斜纹夜蛾种群数量动态的重要因子。对第4代和第8代种群的排除作用控制指数分别为13.904和12.946.如果没有捕食性天敌的作用,下代种群数量将分别增长到当代的15.1206和74.678倍。病原微生物是影响第4代斜纹夜蛾种群数量的另一重要因子,其排除作用控制指数为2.4726.     

不同温湿度组合对甜菜夜蛾生长发育及繁殖力的影响

不同温湿组合对甜菜夜蛾各虫态生长发育和繁殖力有明显的影响,适宜该虫生长发育的温湿度为２６℃与ＲＨ８０％或ＲＨ９４％两个组合．在这种条件下,其卵孵化率、１～５龄幼虫存活率、蛹羽化率、雌虫比率、产卵的雌虫比率和平均产卵量分别为８２．６３％～８３．７０％、８１．９０％～８２．４７％、８８．００％～８８．０３％、９０．４０％～９１．００％、９３．３６％～９４．１７％、９５．９７％～９６．２６％、９２．７７％～９４．１６％、０．４２～０．４３、０．９８和６０５～６０６粒／雌,且明显高于其它温湿组合．在温湿度为３２℃与ＲＨ９４％条件下,该虫的内禀增长能力最大（０．２２５）．     

Persistence and Effects of Parasitic Genotypes in a Mixed Population of the Spodoptera exigua Nucleopolyhedrovirus

Spod-X, a commercialized bioinsecticide for the control of the pest Spodoptera exigua, is based on a nucleopolyhedrovirus (NPV) of S. exigua (SeMNPV) isolated in Florida (US2wt). This field isolate is made up of at least seven genotypic variants, of which two (US2C and US2E) have defective genomes and act as parasites, reducing the pathogenicity of the viral population. Upon co-infection of US2wt and a Spanish field isolate of the same virus (SP2wt), persistence of the defective variants (US2C, US2E) in the viral progeny was observed. This persistence diluted the presence of intact, self-infectious genotypes in the progeny, decreasing the pathogenicity of these viral inocula. Further passages of viral occlusion bodies produced after the co-infection revealed that the parasite US2C continued replicating and constituted up to 30% of the viral progeny in some samples. In addition, the presence of US2C within SP2wt significantly decreased the pathogenicity of contaminated inocula by 3.6-fold. The use of foreign virus field isolates containing defective genomes and their possible impact on the biological activity of native NPV populations may be a cause for concern where these viruses are used as agents for biological control.