Esterase-mediated tolerance to a formulation of the organophosphate insecticide monocrotophos in the entomopathogenic fungus, Beauveria bassiana (Balsamo) Vuill: a promising biopesticide

The use of biopesticides compatible with chemical pesticides is recommended in pest management as an effective and ecologically sound strategy. The entomopathogenic fungus Beauveria bassiana (Balsamo) Vuill, which is used as a biopesticide, was found to exhibit and lose tolerance to two organophosphorus insecticides widely used in Indian fields. The pattern of response is similar to the esterase-mediated organophosphate tolerance in aphids achieved through esterase gene duplication. Therefore the role of esterase in the tolerance exhibited by isolates of B. bassiana to the organophosphate, monocrotophos, was studied. Both the total soluble protein content and esterase activity were found to increase significantly in B. bassiana cultures that were able to grow in the presence of monocrotophos. With the hitherto established linkage between esterase overproduction and organophosphate tolerance in insects and the observed similarity in response of the insects and B. bassiana to the chemical, it is concluded that tolerance to monocrotophos in B. bassiana may be due to a mechanism similar to that operating in insects. Habituation of the fungus to monocrotophos to initiate expression of esterase gene may help in achieving compatibility between the two.     

Assessment of the suitability of Tinopal as an enhancing adjuvant in formulations of the insect pathogenic fungus Beauveria bassiana (Bals.) Vuillemin

BACKGROUND: Biopesticides based on Beauveria bassiana (Bals.) Vuillemin hold great promise for the management of a wide range of insect pests. The conidia in the biopesticide formulation require an adjuvant to protect them from photoinactivation by sunlight. The suitability of Tinopal, an optical brightener used as sunscreen for baculovirus formulations, for use with B. bassiana was assessed. The aim was to study the effect of Tinopal on the growth and photoprotection of B. bassiana, and its effect on the susceptibility of insects to B. bassiana. RESULTS: Tinopal was found to have no adverse effect on the growth of B. bassiana. It was found to confer total protection (approximately 95% conidial germination at 10 g Tinopal L(-1)) from sunlight up to 3 h of exposure, and a better survival rate than controls even up to 4 h. Helicoverpa armigera Hübner larvae fed on diet with 5 g kg(-1) Tinopal were found to have reduced growth. The duration of the larval stage increased by 3-4 days in 1 and 5 g kg(-1) Tinopal treatments. Among the moths that emerged from larvae fed on diet with 5 g kg(-1) Tinopal, a significantly high number were malformed compared with controls. The larvae that were fed diet with Tinopal showed quicker and higher mortality and required a lower effective lethal dose (LC(50)) than the controls. Tinopal was found to have a synergistic effect with B. bassiana in causing insect mortality. CONCLUSIONS: Tinopal was found to be a suitable adjuvant for B. bassiana-based biopesticide formulations. It conferred tolerance to sunlight and caused stress in the insect, leading to a synergistic effect with B. bassiana.     

球孢白僵菌对马铃薯块茎蛾的毒力及其与常用农药的生物相容性测定

室内测定了从云南分离的7株球孢白僵菌对马铃薯块茎蛾幼虫的毒力,结果表明,在接菌孢子浓度为10⁵个/mL和10⁷个/mL下,接种后7d马铃薯块茎蛾幼虫累积死亡率分别为23.3%～70.0%和33.3%～86.7%,添加吐温80的清水对照死亡率仅为3.3%。筛选出毒力较高的Bb7001、Bb7004、Bb8001 3个菌株,其中菌株Bb8001对马铃薯块茎蛾幼虫的毒力最高,在孢子浓度1×10⁵、1×10⁷个/mL下,第7天的累计死亡率分别为70.0%和86.7%,其毒力回归方程Y=0.366X+3.409(R=0.956),剂量效应LC₅₀=2.24×10⁴个/mL,孢子浓度10⁷个/mL下的LT₅₀为4.3d。测定了毒力较高的菌株与12种农药的生物相容性,结果表明在供试农药推荐用量及其101、00倍稀释液下,球孢白僵菌Bb7001、Bb7004、Bb8001的3个菌株孢子在含所选农药的营养液中生物相容性良好的农药有:苏云金芽孢杆菌可湿性粉剂(Bt)、10%吡虫啉可湿性粉剂、2.5%菜喜悬浮剂及松毛虫病毒可湿粉剂,可配伍使用;而阿维菌素、农安、卡死克、抑太保对球孢白僵菌有很强的抑制作用,应避免配伍使用。     

玉米根际球孢白僵菌群体遗传多样性的ISSR分析

为了明确玉米根际球孢白僵菌的遗传分化情况及亲缘关系,通过ISSR-PCR分子标记技术对分离自玉米根际的球孢白僵菌的遗传多样性进行了研究。从40个引物中共筛选出11个多态性高、稳定性好的引物用于正式的扩增分析,在37个菌株中共扩增出83条谱带,其中多态性条带占69条,多态性百分率为83.13%。平均每引物扩增条带在7.5条。群体的多态位点百分率(PPL)为83.13%,Nei基因多样性指数(H)为0.316 9,Shannon信息指数(I)为0.465 7。结果表明,分离自安徽省涡阳、萧县、蒙城三个地区的球孢白僵菌具有较高的遗传多样性。研究结果对进一步探讨玉米根际球孢白僵菌不同菌株的生防效果具有重要意义。     

球孢白僵菌对葱地种蝇成虫的毒力及繁殖力的影响

本文采用浸虫法测定了4株球孢白僵菌对1日龄葱地种蝇（本文称葱蝇）成虫的毒力,筛选出高致病力的菌株,描述了感染症状,测定了其亚致死剂量LC₂₀和LC₅₀对存活1日龄葱蝇成虫生物学参数和繁殖力的影响,并比较了5.8×10³和5.7×10⁵孢子/mL对1日龄和10日龄葱蝇成虫死亡率和单雌产卵量的差异。结果表明菌株Bb01对葱蝇成虫的致病力最强,其LC₅₀为1.76×10⁶孢子/mL,其次为菌株Bb03和Bb02,其LC₅₀分别为4.05×10⁶和1.86×10⁷孢子/mL。与对照相比,菌株Bb01亚致死剂量处理1日龄成虫后,明显延迟了葱蝇成虫的产卵前期,降低了单雌产卵量,LC₂₀浓度处理时单雌产卵量比对照下降了51.9%,LC₅₀处理下降92.2%,明显缩短了雌成虫寿命,但卵孵化率没有明显影响。虽然菌株Bb01对1日龄成虫造成的死亡率较高,但在5.7×10⁵孢子/mL下,10日龄成虫单雌产卵量比对照下降了82.5%,对种群控制效果仍较强。     

球孢白僵菌对斜纹夜蛾高毒菌株筛选与制剂的研发

斜纹夜蛾Spodoptera litura是一种危害极大的农业害虫,为了探索1条可持续、无污染的新型防治方法,我们通过标准喷塔法从12株球孢白僵菌Beauveria bassiana中筛选出1株对斜纹夜蛾2龄幼虫高毒力的菌株--球孢白僵菌Bb2860菌株.在喷雾浓度为(2592±275)孢子·mm-2的高浓度下,菌株Bb2860对斜纹夜蛾2龄幼虫在第7d的校正死亡率达82.43%±6.03%.不同制剂的室内生测试验表明,孢子水悬液和2种油剂(分别为不含稳定剂和含有稳定剂)在中浓度319～529孢子·mm-2的喷雾浓度下,7d后对斜纹夜蛾2龄幼虫的累计死亡率分别为54.8%、70.0%和76.7%;菌药协同作用为86.8%.另外,于2009年9月在安徽马鞍山进行自然条件下对花椰菜叶上斜纹夜蛾幼虫的田间小区药效试验.处理9d后,纯菌剂的相对防效为77.64%;低剂量和常规用量5%氟啶脲(抑太保)的相对防效分别为49.02%和89.70%;菌药混用的相对防效为91.13%.本研究显示出利用球孢白僵菌制剂及其与低剂量抑太保混用防治斜纹夜蛾的良好应用前景.     

吉林省球孢白僵菌遗传多样性与亚洲玉米螟化性相关性分析

利用ITS序列分析和ISSR分子标记对吉林省玉米主产区的49株寄生亚洲玉米螟的球孢白僵菌进行了遗传多样性分析。ITS序列分析表明,各菌株间的亲缘关系与其地理来源无关。分别根据9个采集地,以及寄主化性类型划分供试菌株类群,利用ISSR分子标记技术进一步分析表明,不同地理类群中榆树地区的遗传多样性最高,双辽地区最低;双辽和通化地区间的遗传分化系数最高,梨树和通化地区间的遗传距离最大。根据寄主化性类型划分类群得出一代玉米螟分离菌株遗传多样性指数最高,一代兼二代区最低;一代兼二代区菌株遗传分化系数最高,而一代区和二代区的遗传距离最大。由此可见,吉林省球孢白僵菌遗传多样性水平较高,种群的异质性较强,遗传多样性同地理位置无关,与寄主化性类型存在相关性。     

Entomopathogens (Beauveria bassiana and Steinernema carpocapsae) for biological control of bark-feeding moth Indarbela dea on field-infested litchi trees

BACKGROUND: The bark-feeding moth Indarbela dea (Swinhoe) is one of the major pests of litchi (Litchi chinensis Sonn.) in Asia. Effects on larval mortality and web production were tested by repeated, single and combined tree trunk applications of the entomopathogenic fungus Beauveria bassiana (Bals.) Vuill. and the entomopathogenic nematode Steinernema carpocapsae (Weiser). Two separate application trials were conducted in different seasons on young and older larvae respectively. RESULTS: In both trials, complete or nearly complete mortality (100% and 95%) of the larvae was achieved 3 weeks after application of S. carpocapsae alone and 2 weeks after the combined application of B. bassiana and S. carpocapsae (100% in both trials). However, in the combined application, all larvae were killed by one treatment, while the application of S. carpocapsae alone needed to be repeated to reach the same result. The effectiveness of the combined entomopathogen application and of the application of S. carpocapsae alone was not influenced by the age of the larvae. However, the single applications of B. bassiana were only effective on young larvae. In both trials, web production of surviving larvae was very significantly reduced by the application of S. carpocapsae in single and combined treatments. CONCLUSIONS: As the results show, only one application is necessary in the combined application of the two entomopathogens to control I. dea, which implies that such treatment is probably the economically most relevant solution.     

球孢白僵菌对二斑叶螨的致病性和对天敌智利小植绥螨的间接影响

二斑叶螨是世界性害螨,为害多种经济作物和蔬菜.为明确球孢白僵菌和捕食螨联合应用防控二斑叶螨的可行性,本文测定了不同浓度球孢白僵菌GZGY-1-3孢子悬浮液对二斑叶螨的致病力,并用喷施球孢白僵菌16h、24h、36h和48h后的二斑叶螨分别饲喂智利小植绥螨,测定智利小植绥螨连续两代的致死率、生长发育及繁殖力变化.结果表明...     

葫芦科作物种传病毒及其检疫重要性

本文全面介绍了葫芦科作物病毒及种传病毒的种类,并对种传病毒进行风险分析。截止2011年5月,危害葫芦科作物的病毒种类已达86种(其中暂定种17种、类病毒1种),种传病毒11种。重要性分析表明,葫芦科种传病毒具有重要的检疫重要性。     

Formulation of vegetable fat pellets with pheromone and Beauveria bassiana to control the larger grain borer,Prostephanus truncatus (Horn)

The use of hydrogenated rapeseed oil as a carrier for conidia of the entomopathogenic fungus Beauveria bassiana (Bals) Vuill was investigated as part of a research programme on the control of the larger grain borer, Prostephanus truncatus (Horn). Melting the oil, which is solid at temperatures below 32 °C, allows the incorporation of materials such as aggregation pheromones and conidia; sudden cooling produces solid fat pellets. In attraction tests conducted with pellets containing P truncatus aggregation pheromone, significantly higher numbers of beetles were attracted to pellets containing pheromone at a concentration of 4 ml litre⁻¹ compared to control pellets for at least four weeks when held in Petri dishes in the laboratory and for at least six weeks when pellets held in insect traps were exposed to outside conditions. The attraction was retained over a period of storage in glass bottles; pellets stored in the freezer or incubator (at −10 °C or 27 °C) attracted beetles according to the pheromone level for the duration of the work (14 and 13 months respectively). When pheromones and conidia were incorporated into the same pellets they could be stored in a freezer or refrigerator retaining over 80% viability after 51 weeks; those stored in an incubator at 27 °C showed significantly lower germination at 20.7–27.2% after the same time. There was an indication that the pheromone caused a slight reduction in the viability of conidia, although this may have been just a slight delay in the speed of germination. Rapid dose transfer from pellets with conidia with and without the addition of pheromone was demonstrated. Insects were exposed to pellets for 24 hours and 96–100% mortality was observed in treatments containing conidia within six days of exposure. © 1999 Society of Chemical Industry     

葱蝇成虫防御类酶和血细胞对球孢白僵菌的防御作用

测定了葱蝇成虫被球孢白僵菌侵染后,虫体超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、谷胱甘肽-S-转移酶(GSTs)、羧酸酯酶(CarE)和乙酰胆碱酯酶(AChE)的活性变化,并对侵染后血细胞的变化进行拍照观察。结果表明,虫体内SOD、CAT、POD、GSTs和AChE的比活力呈先上升后下降的趋势;处理组虫体内的Car E比活力和对照组的变化趋势相同,但始终低于对照组。侵染36~48 h后,大量的血细胞在菌丝体周围集结、包囊,阻碍和抑制菌丝的增殖。侵染54 h后,菌丝开始突破包囊块,在血淋巴中大量增殖,血细胞免疫被破坏。综上所述,球孢白僵菌侵染初期会触发葱蝇成虫的免疫系统,但由于菌丝的大量增殖,后期免疫系统崩溃,导致成虫死亡。为揭示球孢白僵菌的致病机理及葱蝇对真菌侵染的免疫防御提供理论依据。     

小麦籽粒营养物质和次生物质含量与其对玉米象抗性的关系

为明确生产栽培小麦品种对玉米象Sitophilus zeamais(Motschulsky)的抗性机制,采用选择性和非选择性试验法系统评估了9个小麦品种对玉米象的抗性,并分析了小麦籽粒营养物质和次生物质含量与其抗性的关系。结果显示,不同小麦品种对玉米象的抗性存在显著差异,其中陕麦139和西农88的不选择性和抗生性较弱,小偃22、周麦16和周麦11较强;玉米象成虫对西农165选择性最强,虫口数为152.00头,而卵至子代成虫发育历期最长,为35.06 d,子代成虫数、重量损失率和敏感系数均较低,分别为19.67头、5.37%和8.30;对周麦18选择性最差,敏感性居中。玉米象成虫对不同小麦品种的选择性与各物质含量,以及总酚、蛋白质含量与各抗性指标均无显著相关性,但阿魏酸含量与子代成虫数、敏感系数及重量损失率显著负相关;可溶性糖含量与子代成虫数、敏感系数及重量损失率显著正相关,与卵至子代成虫发育历期显著负相关。表明小麦品种对玉米象的抗生性与其籽粒中阿魏酸和可溶性糖含量相关,阿魏酸含量越高、可溶性糖含量越低,小麦对玉米象的抗性越强。     

新疆准噶尔盆地东南部狼(Canis lupus)的生境选择及其季相变化

采用痕迹样方和对照样方分析卡拉麦里山有蹄类自然保护区狼(Canis lupus)的生境选择及其季相变化。结果表明:春季,狼选择海拔900~1 000 m的山坡和山顶,距离水源2~4 km,道路0.5~1 km,居民点2~4 km及隐蔽级高(0.9~1)的区域;夏季,选择山坡和山沟、海拔900~1 000 m、与水源距离≤2 km、距离道路1.5~3 km、与居民点的距离4~6 km;以及隐蔽级高(0.9~1)的地域;冬季,选择山坡和沙丘、海拔≤800 m、与水源距离≤2 km、与道路的距离1.5~3 km、与居民点的距离2~4 km、隐蔽级在0.5~0.9的区域。主成分分析表明,春季狼生境选择主要受人为干扰的影响,夏季主要受水源因子干扰的影响,冬季主要受食物干扰的影响。     

Field trial measuring the compatibility of methoxyfenozide and flonicamid with Orius laevigatus Fieber (Hemiptera: Anthocoridae) and Amblyseius swirskii (Athias-Henriot) (Acari: Phytoseiidae) in a commercial pepper greenhouse

BACKGROUND: Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) and Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) are among the most serious pests of sweet peppers in greenhouses. Chemical control is difficult because of their high reproductive rates and insecticide resistance, and seasonal inoculative releases of Orius laevigatus (Fieber) and Amblyseius swirskii (Athias‐Henriot) are commonly used to reduce their populations. As chemical treatments are often needed in the crop against other pests, the side effects of methoxyfenozide (an insect growth regulator against lepidopteran pests) and flonicamid (a selective feeding inhibitor against sucking insects) were studied in both beneficial organisms in a commercial greenhouse. RESULTS: Orius laevigatus and A. swirskii were released at commercial rates (4–5 and 100 m^?2), and a strong establishment and a very homogeneous distribution were reached. One pesticide treatment with the maximum field recommended concentration of methoxyfenozide and flonicamid (96 and 100 mg AI L^?1) was done when they were well established, and their population levels were not affected either immediately or up to 30 days after treatment. CONCLUSION: The results are indicative of no impact of methoxyfenozide and flonicamid on the two natural enemies in the field, and both can be considered as potential alternatives to be included in IPM programmes in sweet pepper. Copyright © 2011 Society of Chemical Industry