菊叶香藜精油的提取及对昆虫活力抑制的研究

[目的]探讨菊叶香藜精油的最佳提取方式,初步研究精油对昆虫的活力抑制.[方法]利用水蒸气蒸馏的方法,对不同形式、不同部位及不同条件下菊叶香藜的精油进行提取,并用提取的精油设计不同的精油剂量梯度进行玉米象的活力抑制试验.[结果]不同形式、不同部位及不同条件下菊叶香藜的精油提取量均有较明显的差异.微波处理10 min、料液比1∶15时,回流4h,菊叶香藜的精油量达最大值;菊叶香藜的花部位的精油含量最大,在4h的回流时间下可以获得8.4 md/kg的精油量;菊叶香藜精油对玉米象活力有一定抑制作用,且随精油浓度增加抑制程度增加.[结论]该研究为菊叶香藜精油向杀虫剂方面发展提供理论依据.     

三种植物精油对玉米象成虫的控制作用

以无水乙醇为溶剂提取苍耳、枫杨和苦楝三种植物精油,研究其对玉米象成虫的控制作用.结果表明:苍耳、枫杨和苦楝精油对玉米象成虫均具有较强的驱避、熏蒸和触杀作用.其中苦楝和枫杨精油的驱避效果较好,处理120 h后,对玉米象的驱避率达到Ⅳ级;苦楝的熏蒸作用最好,处理72 h后,熏蒸校正死亡率达到91.1%;枫杨精油的触杀效果最好,处理96 h后,触杀的校正死亡率达到100%.研究表明:枫杨、苦楝和苍耳精油具有作为储粮防护剂的开发潜力.     

Variation in resistance of Mexican landraces of maize to maize weevil Sitophilus zeamais,in relation to taxonomic and biochemical parameters

Summary Accessions representing twenty eight landraces of maize were assessed for susceptibility to the maize weevil, Sitophilus zeamais in standardized resistance tests. Susceptibility parameters such as weight loss of grain, number of insect progeny produced, the Dobie index of susceptibility, and oviposition on grain were found to vary significantly by genotype, with exceptional resistance found in accessions representing the Naltel, Chapalote and Palomero landraces. As in improved genotypes, susceptibility was negatively correlated to phenolic and protein content of the variety tested but positively correlated to moisture content. A detailed analysis of the phenolics revealed the presence of diferulate which may contribute to mechanical resistance of the seed by cross-linking of cell wall hemicelluloses. A canonical discriminant analysis of the resistance data suggests that most of the five landrace groupings are significantly different. The ancient indigenous and prehistoric mestisos groupings are sources of resistant genotypes.     

Composition and toxic, repellent and feeding deterrent activity of essential oils against the stored-grain pests Tribolium castaneum (Coleoptera: Tenebrionidae) and Sitophilus oryzae (Coleoptera: Curculionidae)

BACKGROUND: The composition and bioactivity of essential oils from Tagetes terniflora Kunth, Cymbopogon citratus Stapf. and Elyonurus muticus (Spreng) Kuntz were evaluated against stored‐grain pests. RESULTS: Fumigant and contact toxicities were observed with T. terniflora on adults of both pests. In contact toxicity, this oil was less toxic to Tribolium castaneum (Herbst). Essential oils from C. citratus and E. muticus showed contact toxicity on S. oryzae. All essential oils produced: (a) repellency on larvae and adults of T. castaneum and adults of Sitophilus oryzae (L.); (b) post‐ingestive toxicity on T. castaneum larvae and S. oryzae adults and alteration of nutritional index on T. castaneum and S. oryzae adults. Cymbopogon citratus reduced the relative growth rate and the efficiency of conversion of ingested food in T. castaneum larvae. Tagetes terniflora produced a feeding stimulant effect in T. castaneum adults. In addition, they had a feeding deterrent action against S. oryzae adults. The composition of essential oils from C. citratus and E. muticus varied only in one component. CONCLUSION: These results showed that the essential oils from T. terniflora, C. citratus and E. muticus should be studied further for their use in integrated pest management programmes for T. castaneum and S. oryzae control. Copyright © 2011 Society of Chemical Industry     

雅脊金小蜂长翅型雌蜂繁殖和搜索能力研究

本文就雅脊金小蜂Theocolax elegans(Westwood,1874)的繁殖能力和对米象幼虫的搜索能力进行了研究。结果发现,温度和繁殖方式都会影响雅脊金小蜂的产卵能力,包括产卵期、单雌产卵量和子代性比;在小麦粒中,雅脊金小蜂的垂直搜索能力可达30 cm以下。     

苏云金素对几种农林卫生害虫的杀虫活性

在室内用加毒饲料或沾毒叶片喂饲等感染方法，分别测定了苏云金素对鞘翅目、鳞翅目、双翅目和同翅目等１４种农林卫生害虫的毒力。结果表明苏云金素对所试昆虫的幼虫均有一定的毒杀或抑制作用，其ＬＣ＿（５０）值从０．６３８μｇ／ｍｌ至６０３．２２μｇ／ｍｌ不等，因试虫种类、虫龄而异。苏云金素对玉米象和前２８星瓢虫成虫毒力较低，对玉米象的ＬＣ＿（５０）为４１０．５２μｇ／ｍｌ；以５０～４５０μｇ／ｍｌ浓度感染２８星瓢虫成虫，死亡率仅４～３２％，其产卵量明显低于对照组，但对卵的孵化率没有影响。     

米象对甲酸乙酯的抗性风险评估

应用数量遗传学中的阈性状分析法,计算米象对甲酸乙酯的抗性现实遗传力,并对米象的抗药性风险进行了评估。结果表明,在平均死亡率为57.4%的选择压力下,米象对甲酸乙酯的抗性现实遗传力(h2)为0.0646,在此选择压力下要使米象对甲酸乙酯产生10倍的抗药性,共需要选育179代。     

不同温度下玉米象与谷蠹种内和种间竞争研究

参照Giga的方法在28℃和33℃下研究玉米象与谷蠹的种内和种间竞争,结果表明单独饲养下玉米象与谷蠹的生殖曲线均为抛物线型,属于资源利用竞争型,种内竞争强度取决于初始虫口密度。玉米象与谷蠹混合饲养的种群数量均明显小于单独饲养的种群数量,两物种为争夺有限的资源产生竞争,种间竞争强度取决于初始虫口密度和温度条件。在28℃下玉米象生殖曲线为凸型,是强竞争者,将长期占据统治地位;在33℃下谷蠹的竞争能力增强,生殖曲线由28℃下的凹型转变为33℃下的凸型,将有可能占据决定地位,但玉米象在较高虫口密度下生殖曲线仍为凸型,竞争结果最终可能会导致两物种共存。     

雅脊金小蜂长翅型雌蜂对米象种群的控制作用

雅脊金小蜂Theocolax elegans（West．）是我国南方重要仓储害虫米象Sitophilus oryzae（L．）的优势天敌。为了更好地保护和利用该蜂，采用单因子方差分析和ISD多重比较，在实验室内研究了雅脊金小蜂和米象的种群数量动态，以及该蜂长翅型雌蜂对米象种群的控制作用。结果显示，在温度25℃、相对湿度65％的条件下，雅脊金小蜂和米象的世代发育历期分别约为25天和40天。按照每盒1、2、4、8、16、32、64和128头接入的寄生蜂均可定殖，并对米象种群起着控制作用。其中，接蜂64头时，即寄生蜂与米象数量比为1：6时，控制效果最好，在放蜂后第10-50天内，控制效果迭89．11％-96．47％，与其它几组试验差异显著。试验结果表明，雅脊金小蜂可以有效地控制米象的发生与危害。     

Persistence of insect growth regulators against the rice weevil,sitophilus oryzae,in grain commodities

Ten insect growth regulators (IGRs): four juvenile hormone analogs (JHAs) — fenoxycarb, MV-678, R-20458 and dofenapyn, and six molt inhibitors (MIs) — triflumuron, chlorfluazuron, hexaflumuron, teflubenzuron, Dowco 439 and flufenoxuron; and the organophosphate malathion, were evaluated for residual activity in stored grain for 2 years against the rice weevil,Sitophilus oryzae (L.). Triflumuron, flufenoxuron, teflubenzuron, chlorfluazuron, hexaflumuron and fenoxycarb, each at a concentration as low as 1 ppm a.i., were superior to 10 ppm malathion throughout the experiment. The six MIs, each tested at 50 and 100 ppm a.i., gave complete control for 2 years. Moreover, a concentration as low as 1 ppm a.i. of triflumuron, teflubenzuron, flufenoxuron and chlorfluazuron had good residual activity for 1 year post-treatment and provided almost complete grain protection during this period. Among the JHAs, fenoxycarb had the best residual activity. It gave almost complete control (96.6%) ofS. oryzae at 10 ppm for 18 months post-treatment. The other JHAs at the four test concentrations failed to produce this level of control. The viability of the wheat grain was not affected by any of the insecticidal treatments, with 90% germination recorded in treated and control, grains at all intervals tested.