应用逐步统计判别模型预报麦蚜复合种群动态

本文应用逐步统计判别原理 ,对山东省曲阜地区 1982～ 1994年共 13年麦蚜复合种群动态的系统调查资料进行了统计分析 ,建立了 4个统计判别数学模型 :dy1=0 .1 343x1- 0 .1 472x2 ;　　y2 =0 .740 9x1- 0 .1 1 85x2 ;y3=- 8.391 5x1- 1 .785 6x2 ;　y4=2 .32 40x1- 0 .30 82x2运用所建模型 ,对历史资料进行回代验证 ,其平均历史拟合率在 93%以上 ,并以 1 995年作为独立样本进行试报 ,结果与实际一致。     

麦蚜天敌捕食强度的灰色评判

利用灰色局势决策理论,对两种麦蚜的优势种天敌作了灰色评判。结果表明,从捕食强度来看,小麦的孕穗期至腊熟期阶段,麦长管蚜与麦二叉蚜的优势种天敌依次为：龟纹瓢虫,草间小黑蛛和八斑球腹蛛。     

蚜虫警戒素及其类似物的合成

啬薇长管蚜、豌豆蚜、麦二叉蚜、棉蚜和桃蚜、谷长管蚜等蚜虫的警戒素都是倍半萜类化合物（Ｅ）７,１１二甲基３亚甲基１,６,１０十二碳三烯（Ｅ）βＦａｒｎｅｓｅｎｅ［１,２］．通过合成［３～５］并施放蚜虫警戒素以扰乱蚜虫的信息传递,并集中捕...     

Antifeedant activity of long-chain alcohols,and fungal and plant metabolites against pea aphid (Acyrthosiphon pisum) as potential biocontrol strategy

Aphids are noxious insect pests of major crops including cereals and legumes. Particularly, pea aphid (Acyrthosiphon pisum) causes significant yield and quality loses in pea. Crop protection is largely based on noxious chemical pesticides which have prompted a renewed interest in the discovery of natural products as alternatives to synthetic insecticides. In this study different classes of natural compounds were tested in dual choice bioassays to evaluate their feeding deterrence and mortality effect on pea aphid. High feeding deterrence was produced by some of the compounds, particularly1-hexadecanol, gliotoxin, cyclopaldic acid and seiridin. On the contrary, aphid mortality was low although significant for 1-heptadecanol, cytochalasin A, 1-nonadecanol and gliotoxin. Phytotoxicity assessment showed low or imperceptible plant damaged for cytochalasin A, seiridin and 1-nonadecanol. The results obtained showed the potential of seiridin to be used as an alternative to synthetic insecticides.     

Iridoid Sex Pheromone Biosynthesis in Aphids Mimics Iridoid-Producing Plants

Biosynthesis of (1R,4aS,7S,7aR)-nepetalactol ( 1 ) and (4aS,7S,7aR)-nepetalactone ( 2 ) in plants involves iridoid synthase (ISY), an atypical reductive cyclase that catalyses the reduction of 8-oxogeranial into the reactive enol of (S)-8-oxocitronellal, and cyclization of this enol intermediate, either non-enzymatically or by a nepetalactol-related short chain dehydrogenase enzyme (NEPS) that yields the nepetalactols. In this study, we investigated the biosynthesis in vivo of 1 and 2 in the pea aphid, Acyrthosiphon pisum, using a library of isotopically-labelled monoterpenoids as molecular probes. Topical application of deuterium-labelled probes synthesized from geraniol and nerol resulted in production of ²H₄−lactol 1 and ²H₄−lactone 2 . However, deuterium incorporation was not evident using labelled probes synthesized from (S)-citronellol. These results suggest that iridoid biosynthesis in animals, specifically aphids, may follow a broadly similar route to that characterised for plants.     

转菊芋凝集素基因烟草对桃蚜的抗虫性研究

研究了菊芋凝集素基因(hta)对同翅目害虫的抗性。4个同源的hta基因置于CaMV35S启动子和nos终止子的控制下，通过根癌农杆菌(Agrobacterium tumefaciens)介导法被转入烟草。Southern杂交显示，外源hta被整合到转化烟草的基因组中。Northern杂交表明hta mRNA在转基因烟草中进行了表达。利用桃蚜进行的抗虫试验表明，转基因烟草对桃蚜具有抗性。同对照植株相比，T0代转基因烟草使桃蚜的平均虫头数下降70％．在T0代转基因烟草中，转hta-b和hta-c基因烟草对桃蚜繁殖的抑制率分别为53．0％、64．6％，同时，对桃蚜若虫的发育具有明显的抑制作用。     

Insecticidal Activity of Extracts,Fractions, and Pure Molecules of Cissampelos pareira Linnaeus against Aphid,Aphis craccivora Koch

Aphis craccivora Koch is a polyphagous and major pest of leguminous crops causing significant damage by reducing the yield. Repeated application of synthetic insecticides for the control of aphids has led to development of resistance. Therefore, the present study aimed to screen the insecticidal activity of root/stem extracts/fractions, and pure molecules from Cissampelos pareira Linnaeus against A. craccivora for identification of lead(s). Among root extract/fractions, the n-hexane fraction was found most effective (LC₅₀ = 1828.19 mg/L) against A. craccivora, followed by parent extract (LC₅₀ = 2211.54 mg/L). Among stem extract/fractions, the n-hexane fraction (LC₅₀ = 1246.92 mg/L) was more effective than the water and n-butanol fractions. Based on GC and GC-MS analysis, among different compounds identified in the n-hexane fraction of root and stem, ethyl palmitate (known to possess insecticidal activity) was present in the highest concentration (24.94 to 52.95%) in both the fractions. Among pure molecules, pareirarineformate was found most effective (LC₅₀ = 1491.93 mg/L) against A. craccivora, followed by cissamine (LC₅₀ = 1556.31 mg/L). Parent extract and fractions of C. pareira possess promising activity against aphid. Further, field bio-efficacy studies are necessary to validate the current findings for the development of botanical formulation.     

Quercetin and Rutin as Modifiers of Aphid Probing Behavior

Rutin and its aglycone quercetin occur in the fruits, leaves, seeds, and grains of many plant species and are involved in plant herbivore interactions. We studied the effect of the exogenous application of rutin and quercetin on the probing behavior (= stylet penetration activities in plant tissues) of Acyrthosiphon pisum on Pisum sativum, Myzus persicae on Brassica rapa ssp. pekinensis, and Rhopalosiphum padi on Avena sativa using the electrical penetration graph technique (EPG = electropenetrography). The reaction of aphids to quercetin and rutin and the potency of the effect depended on aphid species, the flavonol, and flavonol concentration. Quercetin promoted probing activities of A. pisum within non-phloem and phloem tissues, which was demonstrated in the longer duration of probes and a trend toward longer duration of sap ingestion, respectively. M. persicae reached phloem in a shorter time on quercetin-treated B. rapa than on the control. Rutin caused a delay in reaching sieve elements by A. pisum and deterred probing activities of M. persicae within non-phloem tissues. Probing of R. padi was not affected by quercetin or rutin. The potency of behavioral effects increased as the applied concentrations of flavonols increased. The prospects of using quercetin and rutin in plant protection are discussed.     

Predicting the probability of wheat aphid occurrence using satellite remote sensing and meteorological data

The occurrence and prevalence of wheat aphid has severe impact on wheat quality and bring about wheat yield loss. Infestation models commonly based on in situ meteorological data can be effective, but are usually lacking spatialized information, which could be provided using multispectral remote sensing datasets. The purpose of this study was to develop a prediction model for aphid occurrence probability by combining remote sensing images and meteorological data in a logistic regression based framework. In such framework, the predictor variables are: land surface temperature (LST), normalized difference vegetation index (NDVI) and perpendicular drought index (PDI) derived from satellite remote sensing image and temperature, precipitation and wind speed coming from meteorological stations. Logistic regression estimated predictor coefficients showed that LST was the most important factor inducing aphid occurrence, followed by NDVI, temperature, precipitation, wind speed and PDI. The prediction accuracy of the model was evaluated by calculating receiver operating characteristics (ROC) against reference data, scoring a value of area under the ROC curve of 0.993, and resulting in an overall predicted accuracy of 94.4% for the estimated subset. In addition, the results suggested that the probability of aphid occurrence obtained by the logistic regression model had a positive correlation with aphid damage level from field data. Based on the validation subset, it was observed that there were lower omission error with 23.68 and commission error with 23.81% and higher overall accuracy with 75.61% when the cut-off probability (p) value was 0.45. The model developed can be a useful tool to predict aphid occurrence and incidence over winter wheat with some advance, and it could be effective in protecting winter wheat from aphid infestation.