印楝素乳油x对-小菜蛾种群的控制作用

通过室内外系统试验探讨了印楝素乳油对小菜蛾Plutella xylostella种群的控制作用.结果表明,其控制作用主要表现在对成虫产卵的显著忌避作用、对幼虫的拒食作用以及对生长发育的影响和减少幼虫危害力等方面.印楝素乳油0.005 mL/L处理对成虫的忌避率为78.3%,对幼虫的选择性和非选择性拒食率分别为71.8%和62.9%,幼虫总取食量是对照的59.0%,使小菜蛾种群趋势指数(I值)降为2.4,干扰作用控制指数(1lpc)为0.1079.采用状态空间分析法就印楝素乳油施用后小菜蛾种群数量动态的模拟分析亦表明,其显著的控制作用表现在种群发展初期对成虫的忌避作用.     

印楝素乳油对小菜蛾种群的控制作用模拟

应用害虫种群系统控制控制的状态空间方程和作用因子添加分析法,模拟1％印楝素乳油对小菜蛾种群的控制作用,结果表明,印楝素浮油对小菜蛾种群的控制机理,主要是对小菜蛾成虫的显忌避作用,尤其是在种群发展的初期,由于其显的忌避作用,降低田间卵量,使其种群数量明显降低下来,有效控制其为害。     

印楝素乳油对荔枝蒂蛀虫种群的控制作用

利用生命表的方法和干扰作用控制指数评价了印楝素乳油对荔枝蒂蛀虫Conopomorpha sinensisBradley种群的控制作用,结果表明:0.3%印楝素乳油对荔枝蒂蛀虫成虫显著的产卵忌避作用是其对该种群控制的主要机理。在室内,0.3%印楝素乳油在6 mL/L和3 mL/L的浓度处理下,对荔枝蒂蛀虫成虫产卵的忌避率分别为89.3%和86.3%。田间的试验结果表明,在印楝素乳油浓度为6 mL/L和和3 mL/L的处理区中,荔枝蒂蛀虫的种群趋势指数分别为1.23和1.45,显著低于对照区的种群趋势指数11.60,干扰作用控制指数分别为0.106和0.112。这2个浓度的印楝素乳油对荔枝蒂蛀虫种群的控制效果分别可达89.4%和87.5%。     

印楝素乳油对黄曲条跳甲种群控制作用评价

在生命表方法分析的基础上。建立了害虫累积为害量指标,用以描述和比较某一时间段内害虫动态持续为害力大小．应用该指标分析印楝素乳油对黄曲条跳甲(Phyllotreta striolata(F.))种群控制作用,结果表明,对成虫显著的忌避作用是其对种群控制的主要机理．印楝素0．50ml·L^-1对成虫的忌避率为83．75％,种群趋势指数I值降为0．3354,干扰作用控制指数为0．0863．采用田间试验获得的结果,避免了室内测定的空间限制,因而是评价异源植物次生化合物对害虫忌避作用的主要依据．该指标在以害虫控制为目标的动态研究中具有较好的应用前景．     

植物保护剂保卫德对小菜蛾种群控制效应评价

室内外试验表明,植物保护剂保卫德（BIOACT－T35）对小菜蛾种群具有较好的控制效应,其显的控制机理主要表现在对成虫产卵的忌避作用和对幼虫的拒食作用。保卫德10．00ml／L处理对成虫的忌避率为81．43％,对幼虫的选择和非选择性拒食率为96．32％和93．17％,小菜蛾种群趋势指数I值由对照的18．2840降为1．9492,干扰作用控制指数为0．1066。     

印楝素乳油对斜纹夜蛾的生物活性及田间防效研究

在室内测定了印楝素乳油对斜纹夜蛾(Spodopteralitura)的生物活性,并进行了田间防治试验.结果表明,印楝素乳油对斜纹夜蛾具有多种生物活性,主要表现在对幼虫的拒食作用、生长发育的抑制作用和一定的毒杀活性,以及对成虫产卵的忌避作用.经印楝素处理后,幼虫平均发育历期延长、幼虫体重、蛹重、化蛹率和蛹羽化率显著低于对照,印楝素乳油12μl·L^-1浓度处理3龄幼虫5和7d后的体重分别是对照组的36.8%和14.5%,而幼虫平均发育历期比对照组延长6d左右,化蛹率和蛹羽化率分别是27.79%和37.23%,显著低于对照组85.66%和82.11%.印楝素对低龄幼虫有一定的毒杀活性,而对高龄幼虫活性则很低.田间防治试验表明,印楝素乳油对斜纹夜蛾种群有良好的控制作用,施药7d后其防治效果要优于化学农药10%除尽悬浮剂.     

苦皮藤乳油对小菜蛾种群控制效应评价

在室内外试验的基础上 ,应用生命表技术评价 1%苦皮藤 (CelastrusangulatusMaxim .)乳油对小菜蛾 (PlutellaxylostellaL .)种群的控制作用 ,结果表明 ,其控制作用主要表现在对成虫产卵的忌避作用和对幼虫的拒食作用。浓度 10 .0 0mL/L的苦皮藤液效果最佳 ,对成虫的忌避率为 73 2 % ,对幼虫的选择性和非选择性拒食率分别为 94 7%和 93 5 % ,小菜蛾种群趋势指数I值由对照的 2 1 6 140降为 0 6 6 84,干扰作用控制指数为 0 0 30 8。     

植物提取物和药剂对蔬菜蚜虫实验和自然种群的联合控制作用

研究白蝴蝶（Syngonium podophyllum ）乙醇提取物、苍耳（Xanthium sibiricum ）乙醇提取物、机油乳剂和0.3%印楝素乳油对桃蚜（Myzus persicae）和萝卜蚜（Lipaphis erysimi）的控制效果.室内四因子（1/2实施）二次正交回归旋转组合设计测试对有翅蚜的忌避作用,结果表明,对有翅桃蚜的主要忌避作用物为苍耳乙醇提取物,当苍耳提取物与白蝴蝶乙醇提取物混用,以及机油乳剂和印楝素混用时,对桃蚜有翅蚜的忌避效果提高;而对萝卜蚜有翅蚜的忌避作用主要受苍耳提取物和白蝴蝶提取物的影响.这些干扰作用均是非线性的.田间试验结果,单独使用白蝴蝶提取物对有翅成蚜有较强的驱避作用;对萝卜蚜自然种群的干扰控制作用以4种植物提取物和药剂混配效果最好,达95.7%;对桃蚜自然种群干扰控制效果最好的则是白蝴蝶提取物,控制效果达87%;同时,白蝴蝶提取物与印楝素乳油混配以及苍耳提取物与印楝素乳油混配,对两种蚜虫的控制效果均达80%以上.     

植物提取物和药剂对蔬菜蚜虫种群的联合控制作用

研究白蝴蝶(Syngonium podophyllum)乙醇提取物、苍耳(Xanthium sibiricum)乙醇提取物、机油乳剂和0.3%印楝素乳油对桃蚜(Myzus persicae)和萝卜蚜(Lipaphis erysimi)的控制效果.室内四因子(1/2实施)二次正交回归旋转组合设计测试对有翅蚜的忌避作用,结果表明,对有翅桃蚜的主要忌避作用物为苍耳乙醇提取物,当苍耳提取物与白蝴蝶乙醇提取物混用,以及机油乳剂和印楝素混用时,对桃蚜有翅蚜的忌避效果提高;而对萝卜蚜有翅蚜的忌避作用主要受苍耳提取物和白蝴蝶提取物的影响.这些干扰作用均是非线性的.田间试验结果,单独使用白蝴蝶提取物对有翅成蚜有较强的驱避作用;对萝卜蚜自然种群的干扰控制作用以4种植物提取物和药剂混配效果最好,达95.7%;对桃蚜自然种群干扰控制效果最好的则是白蝴蝶提取物,控制效果达87%;同时,白蝴蝶提取物与印楝素乳油混配以及苍耳提取物与印楝素乳油混配,对两种蚜虫的控制效果均达80%以上.     

番茄抽提物对小菜蛾的忌避,拒食及抑制产卵作用

在自然变温条件下,研究了番茄抽提物对小菜蛾成虫的忌避、幼虫的拒食作用及成虫繁殖力的影响。试验表明：番茄抽提物对小菜蛾成虫具有很强的忌避作用;用番茄抽提物处理过的包菜叶饲喂小菜蛾幼虫,其拒食率达５３％;番茄提物对小菜蛾成虫产卵也有明显抑制作用,产卵量下降６０％;番茄与包菜间种能明显地抑制小菜蛾种群数量的增长。其种群可下降５０％以上。     

亚致死剂量阿维菌素和氟虫睛处理小菜蛾对寄生蜂菜蛾绒茧蜂生长发育的影响

分别在小菜蛾体内的菜蛾绒茧蜂处于卵期、早期幼虫和中期幼虫时,饲喂小菜蛾2龄幼虫亚致死剂量（＝LC₁₀）的阿维菌素和氟虫睛,研究上述杀虫剂处理对寄主体内菜蛾绒茧蜂结茧率和羽化率的影响。结果表明： 在菜蛾绒茧蜂处于卵期、早期幼虫和中期幼虫时,饲喂小菜蛾LC₁₀剂量阿维菌素处理的菜叶后,菜蛾绒茧蜂的结茧率分别下降26.6%,22.8%和5.8%,饲喂小菜蛾LC₁₀剂量氟虫睛处理的菜叶后,菜蛾绒茧蜂的结茧率分别下降76.9%,42.5%和18.5%。上述阿维菌素处理对菜蛾绒茧蜂成虫羽化率影响不显著,但上述氟虫睛处理可显著抑制菜蛾绒茧蜂成虫羽化率,在菜蛾绒茧蜂处于卵期、早期幼虫和中期幼虫时,饲喂小菜蛾LC₁₀ 剂量氟虫睛处理的菜叶可导致菜蛾绒茧蜂成虫羽化率分别下降53.1%,36.1%和47.8%。结果显示,即便是对寄主小菜蛾幼虫很低的剂量（LC₁₀剂量）也会显著危害小菜蛾幼虫体内的菜蛾绒茧蜂的生长发育。此外,饲喂小菜蛾幼虫亚致死剂量杀虫剂对菜蛾绒茧蜂生长发育的影响与杀虫剂种类及蛾绒茧蜂发育阶段有关。     

An Evidence to Use Cotes/a plutellae (Kurdjumov) (Hymenoptera: Braconidae) as a Field Control Agent against Diamondback Moth,Plutella xylostella L (Lepidoptera: Plutellidae)

The parasitic effectiveness of Cotesia plutellae Kurdjumov for the control of diamondback moth (DBM), Plutella xylostella L., was investigated without spraying pesticides in the greenhouse, and the damage degrees of Brassica rapa cv. Pakchoi grown in parasitoid-applied plot and control plot were evaluated. Among the 961 fourth instar DBM larvae collected in the common cabbage fields at Kwanshan region in Taiwan, 336 cocoons of C. plutellae were harvested from DBM larvae, which showed a parasitism rate of 35.0%. A total of 650 DBM adults and 600 C. plutellae adults were released according to the releasing scheme in the experiment plot. As a result, 56.7% of the DBM larvae were parasitized by C. plutellae adults 12 days before harvest, and the parasitism reached 80.8% at six days before harvest. At the harvest time, a population density of C. plutellae cocoons in the experiment plot was 2.2/plant, and that of normal DBM larvae was 0.5/plant. The density of DBM in the control plot was much higher than in the parasitoid-released plot by 7.7/plant. In the first survey, the density of DBM larvae on a Pakchoi plant was quite low, 0.3 ∼ 0.8 larvae. However, the DBM population increased dramatically after six days later, 5.7-10.1 larvae/plant. The population density of DBM larvae showed clear difference between the parasitoid-released plot and control plot. The parasitism increased to nearly two fold within a week after the release of DBM adults. As a further study, a combining use of two or more species para-sitoids could be considered to improve a parasitism against DBM in the fields.     

Initiation of fungal epizootics in diamondback moth populations within a large field cage: proof of concept for auto-dissemination

Adult diamondback moths (DBM), Plutella xylostella L. (Lepidoptera: Plutellidae), inoculated with the fungus Zoophthora radicans, were released within a large field cage containing DBM‐infested potted broccoli plants. Larvae and pupae on exposed and caged control plants were examined on five occasions over the next 48 days for evidence of Z. radicans infection. Infected larvae were first detected on exposed plants 4 days after the initial release of adults, and after 48 days the infection level reached 79%. Aerially borne conidia were a factor in transmission of the fungus. Infection had no effect on possible losses of larval and adult cadavers due to scavengers in field crops. In a trial to measure the influence of infection on dispersal, twice as many non‐infected as infected males were recaptured in pheromone traps, although the difference in cumulative catch only became significant 3 days after release of the males. In a separate experiment, when adult moths were inoculated with Beauveria bassiana conidia and released into the field cage, DBM larvae collected from 37 of 96 plants sampled 4 days later subsequently died from B. bassiana infection. The distribution of plants from which the infected larvae were collected was random, but the distribution of infected larvae was clustered within the cage. These findings suggest that the auto‐dissemination of fungal pathogens may be a feasible strategy for DBM control, provided that epizootics can be established and maintained when DBM population densities are low.     

Testing of selected insecticides to assess the viability of the integrated pest management of the Eucalyptus snout-beetle Gonipterus scutellatus in north-west Spain

Abstract:  We investigated, by means of topical, residual and field assays, the toxicity of four insecticides ( Bacillus thuringiensis , azadirachtin, flufenoxuron and ethofenprox) to adult, larvae and eggs of the Eucalyptus snout-beetle Gonipterus scutellatus and their side-effects on the adults of the solitary egg parasitoid Anaphes nitens , its natural enemy. In the topical toxicity experiment, both flufenoxuron and ethofenprox severely affected G. scutellatus , causing 100% adult mortality after 7 days, and 75 and 100% larval mortality, respectively. Ethofenprox also caused 93% larval pre-eclosion mortality and 100% parasitoid mortality. In the residual experiment, azadirachtin acted as an effective larvicide when ingested (73% mortality after 7 days). Ethofenprox showed the highest toxicity, with 100% mortality of adults and larvae of G. scutellatus after 24 h. On the day 7 of observation, flufenoxuron resulted in 93% adult mortality and 100% larval mortality. After contact with residuals, only ethofenprox and flufenoxuron had adversely affected A. nitens (98% mortality after 48 h). Bacillus thuringiensis exhibited only a slight activity against the pest or the parasitoid. The field experiment was carried out on three localities, with a preliminary sampling, and three samplings after the applications of the products, on days 7, 14 and 30. We evaluated the parasitism rate, parasitoid sex ratio, parasitoid pre-eclosion mortality, the abundance of G. scutellatus adults, larvae and egg capsules, the pre-eclosion mortality rate of weevil eggs and larvae and the foliar damage. Only fluenoxuron and ethofenprox reduced the pest population and the foliar damages, but ethofenprox also significantly decreased the rate of parasitism (17%) after 7 days. Given our experimental results, we suggest that flufenoxuron and azadirachtin could be used in association with the natural enemy.