植物性杀虫剂印楝对同翅目害虫的防治研究

近年来,由于人们对农药使用引起的害虫抗药性、农药残留和环境毒性等问题的认识,植物性杀虫剂的研究越来越受到重视,是传统农药的理想替代品之一。本以植物性杀虫剂印楝为研究对象,综述了其对同翅目叶蝉、蚜虫、飞虱和粉虱等主要类群中,农业重要害虫的防治作用研究结果,展望了印楝应用于害虫综合防治中的前景。     

印楝愈伤组织形成及其印楝素含量测定

取印楝（AzadirachtaindicaA．Juss）不同器官作外植体,研究培养基和继代次数对愈伤组织生长及其印楝素（Azadirachtin）生物合成的影响．印楝的不同器官（根、叶、茎及皮）均能诱导出愈伤组织,这些愈伤组织均有合成印楝素的能力．其中以叶诱导的愈伤组织生长速率及印楝素含量为最高．含有较低按盐的B5培养基有利于细胞生长,含有较高铵盐的MS培养基有利于印楝素积累,不含铰盐的White培养基对两者均不利．愈伤组织继代2—3代,有利于愈伤组织生长和印楝素合成。     

印楝素A和印楝素B对棉铃虫生长发育的影响

为了明确印楝素A和印楝素B生物活性的差异,选用印楝素A和印楝素B对棉铃虫生长发育的影响进行了比较研究。结果表明:印楝素A和印楝素B对棉铃虫3龄幼虫具有良好的拒食活性,5μg/mL处理48 h对棉铃虫3龄幼虫的拒食率分别为85.17%和69.02%。分别用含有药剂(1μg/mL)的饲料饲喂棉铃虫5龄幼虫,结果表明:印楝素A和印楝素B能够明显抑制棉铃虫5龄幼虫的体重增长,处理14 d后幼虫的体重分别下降50.28%和43.08%,仅有少量个体化蛹,化蛹率分别为26.67%和13.33%。进一步的羽化结果表明:经印楝素A和印楝素B处理的虫蛹均未能完成羽化。综合各阶段试验结果来看,印楝素A和印楝素B的生物活性存在差异,印楝素B对棉铃虫生长发育的抑制作用高于印楝素A。     

印楝愈伤组织的培养条件及对印楝素含量的影响

由于印楝（ＡｚａｄｉｒａｃｈｔａｉｎｄｉｃａＡ．Ｌｕｓｓ）提取物对农业、仓库和卫生害虫具有明显的拒食、抑制生长发育、忌避、毒杀、内吸和不育等活性,并有高效、低毒、无环境污染、不易引起昆虫抗药性等优点〔１〕,受到人们的关注。但是,它的自然分布有限,我国...     

植物杀虫剂印楝对同翅目害虫的防治研究

近年来,由于人们对农药使用引起的害虫抗药性、农药残留和环境毒性等问题的认识,植物性杀虫剂的研究越来越受到重视,是传统农芭的理想替代品之一.本文以植物性杀虫剂印楝为研究对象,综述了其对同翅目叶蝉、蚜虫、飞虱和粉虱等主要类群中,农业重要害虫的防治作用研究结果,展望了印楝应用于害虫综合防治中的前景.     

印楝素A与印楝素B对粉纹夜蛾BTI-Tn-5B1-4的细胞毒性

为了明确印楝素A和B活性差异的机理,本研究比较了印楝素A和印楝素B对粉纹夜蛾Trichoplusia ni离体培养胚胎细胞系BTI-Tn-5B1-4的毒性。结果表明：印楝素A与印楝素B对BTI-Tn-5B1-4细胞具有良好的增殖抑制活性,处理后3 d,其IC₅₀值分别为2.9 μg/mL和9.85 μg/mL,印楝素A的细胞毒力显著高于印楝素B。倒置显微镜观察发现,印楝素A和印楝素B处理可导致细胞变形,贴壁能力下降,并出现明显空泡,印楝素A的影响明显高于印楝素B。流式细胞仪检测结果表明,印楝素可导致BTI-Tn-5B1-4细胞体积显著膨大,印楝素A处理细胞体积增大程度显著高于印楝素B;印楝素可以明显影响BTI-Tn-5B1-4细胞膜电位,1.25 μg/mL印楝素A和印楝素B处理后3 d,细胞DiBAC4（3）荧光强度分别增加88.12%和55.37%,印楝素A的影响显著高于印楝素B。荧光显微镜观察发现,印楝素对BTI-Tn-5B1-4细胞核具有明显影响,印楝素B的影响明显高于印楝素A,印楝素B处理后,细胞核受损细胞数更多,受损程度更严重。结果显示印楝素A和印楝素B的细胞作用机理存在差异,本研究从细胞学水平解释了印楝素的生长发育抑制作用机理。     

印楝素对亚洲玉米螟幼虫生长发育的影响

本文报道印楝素对亚洲玉米螟Ostrinia furnacalis Guene幼虫生长发育的抑制作用和引起幼虫各器官的病变症状。用含20ppm印楝素的人工饲料饲喂亚洲玉米螟3—4龄幼虫2天,然后换入正常饲料,可使幼虫期显著延长,最后不能化蛹而死亡。印楝素对幼虫的作用是缓慢的,虫体受药后还可发育一个龄期。处理幼虫的行为失常,取食动作逐渐消失,主要靠消耗体内的水分和脂肪来维持生命。幼虫的胸足变黑,胸部出现褐色斑,这些部位的表皮分层不正常,真皮细胞坏死或自溶。处理幼虫的大脑萎缩,生殖器官和前胸腺肿大,前胸腺细胞膜厚而松散,血淋巴中β-蜕皮酮含量显著降低。从整个中毒症状来看,印楝素可能作用于亚洲玉米螟幼虫的神经和内分泌系统,从而逐渐引起各器官的病变。     

一株印楝植物内生真菌Epicoccumsp．次生代谢产物的研究

从印楝植物内生真菌Epicoccum sp.的发酵液中分离得到6个化合物,经波谱数据分析分别鉴定为苔黑酚(1)、4-甲基苔黑酚(2)、苔色酸(3)、对羟基苯乙酸(4)、邻苯二甲酸正丁异丁酯(5)、乙基-β-D-葡萄糖苷(6).以上化合物均为首次从该属真菌中分离得到.     

印楝植物内生真菌Phomopsis sp.的代谢产物研究

从印楝植物内生真菌Phomopsis sp．的菌丝体提取物中分离得到4个化合物,通过波谱技术分别鉴定为水苏碱（1）、甲基-β-D-葡萄糖苷（2）、过氧化麦角甾醇（3）、腺嘌呤核苷（4）,这些化合物均为首次从该属真菌中分离得到。     

Entomopathogenic fungi as biological insecticides to control malaria

Malaria is arguably the most serious vector-borne disease worldwide. The already-alarming number of deaths caused by malaria is increasing, caused in part by the increase in mosquito resistance to chemical insecticides. In two recent articles, the use of an approach was reported that could open a new front in the fight against malaria. Laboratory and field studies demonstrate that entomopathogenic fungi can efficiently kill adult anopheline mosquitoes, the females of which are the obligatory vectors for malaria parasites.     

Selectivity evaluation of insecticides used to control tomato pests to Trichogramma pretiosum

The effects of the insecticides abamectin, acetamiprid, cartap and chlorpyrifos on larvae, pupae (within the host egg) and adults of the egg parasitoid Trichogramma pretiosum Riley (Hym.: Trichogrammatidae) were evaluated under laboratory conditions, using three standard tests described by IOBC. When sprayed on the immature stages of this parasitoid, cartap and chlorpyrifos proved to be the most harmful insecticides, affecting both the emergence success and parasitism capacity of this parasitoid, whereas abamectin and acetamiprid were selective. Abamectin was harmful to adults (residue test on glass plates), slightly harmful to larvae, and moderately harmful to pupae (sprayed on the immature stages within host eggs Anagasta kuehniella (Zeller)); acetamiprid was moderately harmful to adults, harmless to larvae, and slightly harmful to pupae; cartap was harmful to adults, moderately harmful to larvae and harmful to pupae; chlorpyrifos to adults, harmless to larvae and harmful to pupae.     

Field tests with insecticides and insect growth regulators to control insect pests of cowpea and its effects on certain beneficial insects

A small‐plot tests were conducted on cowpea, Vigna ungiculata (L.) Walp, to determine the effectiveness of 14 selected insecticides representing four insecticide classes (organophosphates, carbamates, pyrethroids, and insect growth regulators, IGRs), and four insecticide/IGR mixtures on cowpea insect pests and its effects on certain beneficial insects. By day 3 after treatement, the insecticides phenthoate, isoxathion, cyanophos, carbaryl, and cypermethrin used at sub‐recommended rates reduced the leafhopper, Empoasca spp., populations by >83% than those in the control. On that day, all insecticide treatments significantly reduced the cowpea aphid, Aphis craccivora, numbers below that of the control. The prothiofos, isoxathion, pirimicarb, and fenpropathrin treatments provided continuing control to both leafhoppers and aphids through day 21 after spraying. It seems that most insecticide treatments were not effective in whitefly, Bemisia tabaci, control. The best control of the whitefly immatures was obtained by day 3 after spraying in plots received thiodicarb (76%) and fenpropathrin (60%). All selected insecticides and rates used had very low residual effect against B. tabaci immatures. By day 3 posttreatment, the carbaryl (2.02 kg/ha) caused completely protection for cowpea pods frMw blue pea butterfly, Lampides boeticus, larvae. The IGRs, flufenoxuron and Dowco‐439, applied alone and those applied in mixtures with insecticides, carbaryl/teflubenzuron, chlorpyrifos/XRD‐473, and methomyl/ flufenoxuron, exhibited satisfactory control (>81%) to butterfly larvae on day 7 posttreatment. All treatments did not exhibit a considerable residual activity against L. boeticus larvae through 2–3 weeks followed spray. Most insecticides applied at the higher rates used significantly reduced the numbers of limabean pod borer, Etiella zinckenella, larvae found in cowpea pods collected on day 7 after application. The IGRs, flufenoxuron and Dowco‐439, applied alone, at 0.119 kg/ha, or in mixtures, methomyl/flufenoxuron (0.167 kg/ha) and chlorpyrifos/Dowco‐439 (0.911 kg/ha) caused >73% control of E. zinckenella larvae through day 21 posttreatment. The best control of cowpea weevil, Callosobru‐chus spp., adults (>83%), on day 3 after spraying, was obtained in treatments of cyanophos (1.19 kg/ha), prothiofos (1.43 kg/ha), flufenoxuron (0.119 kg/ha), and chlorpyrifos/Dowco‐439 (0.911 kg/ha). The IGR flufenoxuron applied alone or in mixture, methomyl/flufenoxuron (0.164 kg/ ha) exhibited satisfactory residual activity against Callosobruchus adults through day 21 posttreatment. Percentage seed damage by the larvae of cowpea weevils was significantly lower in most treatments than that of control. Populations of insect predators found in all treated plots were extremely reduced than those found in untreated plots. By day 21 after spraying, the IGRs flufenoxuron, XRD‐473, and Dowco‐439, applied at the low rate of 0.071 kg/ha, seemed to be less effect against insect predators than other insecticides used.     

Frequency of occurrence of fungi on wood in Malaysian mangroves

Over one hundred fungi have been reported on mangrove wood (Hyde and Jones, 1988; Jones and Kuthubutheen, 1989; Hyde and Jones, unpublished) from tropical and subtropical locations. A variety of factors affect the frequency of occurrence of these fungi, e.g . salinity, length of exposure of substrate, wood species and location within the mangrove. Two aspects are addressed in this paper: a) Comparison of the fungi present at three mangroves in Malaysia (Morib, Kuala Selangor, Port Dickson); and b) The fungi colonising specific mangrove wood, e.g. Avecennia marina, Bruguiera gymnorrhiza. Species diversity was greatest at Port Dickson with 63 fungi recorded while species composition varied from site to site. Common fungi at Morib and Kuala Selangor were Halocyphina villosa and Leptosphaeria australiensis along with Kallichroma tethys and Lulworthia grandispora at the latter site. None of these were common at Port Dickson, the dominant species at this site were Hypoxylon oceanicum and Massarina ramunculicola. A comparison of the fungi occurring on Avicennia marina and Bruguiera gymnorrhiza indicated that Halocyphina villosa was common on both timbers. Species diversity and abundance were greatest on Avicennia with the following fungi listed as common: Eutypa sp., Kallichroma tethys, Marinosphaera mangrovei, Phoma sp. and Julelia avicenniae.     

Comparative efficacy assessment of fungi,nematodes and insecticides to control western corn rootworm larvae in maize

All three larval instars of Diabrotica virgifera virgifera LeConte (western corn rootworm, Coleoptera: Chrysomelidae) feed on the roots of maize, Zea mays (L.). We assessed the efficacies of the following four agents in controlling these larvae: (1) the entomopathogenic fungus Metarhizium anisopliae (Metsch.) Sorokin (Hypocreales: Clavicipitaceae), (2) the nematode Heterorhabditis bacteriophora Poinar (Nematoda: Rhabditida), (3) a tefluthrin-based soil insecticide and (4) clothianidin-coated seeds. The agents were applied in field plot experiments in southern Hungary in 2006 and 2007. Efficacy was assessed by comparing the number of emerging D. v. virgifera adults and corresponding root damage among treatments and untreated controls. All agents significantly reduced D. v. virgifera numbers and root damage, but the relative success of each treatment was variable. On average across fields and years, the nematode and the two insecticides reduced D. v. virgifera by 65 ± 34% SD, while the fungus reduced D. v. virgifera by 31 ± 7%. According to the node injury scale, the agents prevented 23–95% of potential root damage. Large-scale commercialisation of these biological agents could offer viable and practical control options against D. v. virgifera.     

3种农药对黑荆树主要食叶害虫的林间防治

选用3种农药对黑荆树主要食叶害虫柑橘卷叶蛾、大袋蛾、黑荆大造桥虫进行林间防治试验。结果表明,以10％氯氰菊酯1：2000、90％敌百虫晶体1：600、80％敌敌畏1：800防治效果最佳,与各药剂的最低浓度间存在显著差异。3种药剂总体防治效果无显著差异。因此,在生产性防治时可任选其中一种药剂。     

Invaders' control on post-disturbance succession in coastal mangroves

Aims In recent years, coastal mangroves have been frequently affected by large disturbances (cyclones, hurricanes, flooding and tsunamis) and post-disturbance vegetation is often dominated by small stature mangrove, mangrove-associate and non-mangrove species potentially affecting ecosystem functioning. Knowledge on the processes of mangrove vegetation development and recovery (succession) following normal and large disturbances will benefit practitioners in designing robust ecosystem management/restoration plans. Here we propose a conceptual model of disturbance-mediated succession in mangroves.Methods Based on field observations and species' life history traits, we develop conceptual models of mangrove succession under normal disturbance regime and recently experienced increased frequency of large disturbances. We evaluate our conceptual models by conducting a scenario testing experiment.Important findings We suggest two predominant processes affecting mangrove succession after disturbance: propagule limitation due to damage of seed producing mature trees and dispersal barrier resulting from biological invasion associated with large disturbance. We argue that large disturbances affect mature trees more than the small-stature non-tree (shrubs, herbs and climbers) species creating a larger propagule shortage for mangrove tree species than non-tree species. Secondly, large disturbances facilitate invasion of free-floating aquatics, which may interfere with the flow-facilitated propagule dispersal and seedling establishment of mangrove species. In a scenario testing experiment, we have shown that similar levels of disturbance impact vegetation development and recovery differently depending on the presence or absence of invasive species. We conclude that since biological invasion is one of the major drivers of post-disturbance mangrove succession, the dimension of biological invasion should be included in prediction, management and restoration of mangrove forests.