Compatibility of entomopathogenic nematodes (Nematoda: Rhabditida) with registered insecticides for Spodoptera frugiperda (Smith, 1797) (Lepidoptera: Noctuidae) under laboratory conditions

The fall armyworm, Spodoptera frugiperda (Smith, 1797) (Lepidoptera: Noctuidae) is considered the main key pest of corn crops in Brazil. Entomopathogenic nematodes (EPNs) may be used to control this pest, applied together with other different entomopathogen agents or phytosanity products in the spraying mixture. Thus, the objective of work was to evaluate the compatibility of EPNs with different insecticides used of S. frugiperda control in laboratory conditions. Three species of EPNs (Heterorhabditis indica, Steinernema carpocapsae and Steinernema glaseri) and 18 insecticides registered to control of S. frugiperda in corn crops were tested. Compatibility of the insecticides with EPNs was evaluated by observing mortality and infectivity of infecting juveniles (IJs) 48 h after immersion in solution of the insecticide formulations. Among all insecticides tested, Lorsban™ (chlorpyrifos), Decis™ (deltamethrin), Match™ (lufenuron), Deltaphos™ (deltramethrin + triazophos), Dimilin™ (diflubenzuron), Stallion™ (gamacyhalothrin), Karate Zeon™ (lambdacyhalothrin) Tracer™ (spinosad), Vexter™ (chlorpyrifos), Galgotrin™ (cypermethrin), Certero™ (triflumuron), and Talcord™ (permethrin) were compatible (class 1) with the three nematode species tested under laboratory conditions.     

Evaluation of entomopathogenic nematodes for biocontrol of the european corn borer,Ostrinia nubilalis, on sweet corn in Israel

The potential of entomopathogenic nematodes for biological control of the European corn borer (ECB),Ostrinia nubilalis (Hübner), was evaluated under laboratory, screenhouse and field conditions. The ‘All’ and ‘Mexican’ strains ofSteinernema carpocapsae (Weiser) and the ‘HP88’ strain ofHeterorhabditis bacteriophora Poinar were compared in both dose response assays (5, 50 and 500 infective juveniles [IJ] per petri dish containing five 5th-instar ECB eggs; 72 h of incubation) and exposure time assays (3, 6 and 9 h of incubation). In the dose response assays the highest rates of ECB killing resulted from infestation with the Mexican strain ofS. carpocapsae. In the exposure time assays there were no significant differences between the killing rates of the three nematode strains. Sweet corn plants(Zea mays var.saccharata) grown in a screenhouse, were infested with ECB neonates and 4 days later sprayed with a suspension of the Mexican strain ofS. carpocapsae (50,000 IJ per plant). The number of ECB larvae found on treated corn plants after one week was significantly (P=0.05) lower (3- to 5-fold) than the number found on untreated plants. Similar treatment in the field significantly reduced the rate of economic ear damage from 20% to 5%. Contribution from the Agricultural Research Organization. No. 2260-E, 1997 series     

甘肃省昆虫病原线虫区系研究

为查明甘肃省昆虫病原线虫的种类及区系分布,通过大蜡螟诱捕法对甘肃省昆虫病原线虫资源进行了调查,分离得到昆虫病原线虫种群51个,分属于8个种：斯氏线虫属（Steinernema）5种,异小杆线虫属（Heterorhabditis）3种。其中斯氏属3个种A,B,C和异小杆1个种D属于国内新记录种。调查表明：甘肃省昆虫病原线虫的优势种为Steinernema feltiae,昆虫病原线虫的分布与土壤类型及植被类型关系密切,沙壤土和壤土中线虫检出率分别为12.2%和8.8%,较粘土5.3%的检出率高,且在果园、菜地和大田中的线虫检出率分别为10.4%,9.2%和5.2%,较未耕地3.3%的检出率高,说明沙壤土和壤土适于昆虫病原线虫的种群建立,且在有农事活动的地块中昆虫病原线虫分布较多。     

水稻二化螟病原线虫N-Yz1的分离鉴定及其感染特性

【目的】二化螟是危害水稻的重要害虫,其钻蛀为害,防治困难,严重威胁水稻生产。本研究对感染二化螟昆虫病原线虫的分离筛选和感染特性进行研究,期望为水稻钻蛀害虫危害的防治提供新的途径和方法。【方法】自越冬代二化螟幼虫体内通过组织分离筛选,获得野外感染二化螟的昆虫病原线虫,室内接种实验分析分离昆虫病原线虫对二化螟的感染活性和作用特性。【结果】自然罹死二化螟幼虫体内分离获得野外感染的昆虫病原线虫N-Yz1,接种4龄二化螟幼虫导致感染并死亡,后期虫体内产生大量形态一致的侵染期线虫(IJ)。形态学观察结合r DNA-ITS序列分析,鉴定分离昆虫病原线虫隶属于斯氏线虫属,与已鉴定种小卷蛾斯氏线虫同源性达99.87%。昆虫病原线虫N-Yz1对不同龄期二化螟幼虫都有较高感染致死作用,40头(IJ)的线虫接种剂量,对低龄(2～3龄)二化螟致死速度快、致死率高,接种24h就出现感染致死个体,48h后幼虫全部死亡。高龄幼虫(4～6龄)感染致死速度较慢,死亡高峰发生在接种线虫后的48 h。N-Yz1接种剂量与二化螟死亡率呈显著正相关,剂量超过30IJs/头时,4龄二化螟感染死亡率达90%以上。N-Yz1对二化螟幼...     

夜蛾斯氏线虫对菜青虫几种保护酶活力的影响

为探索昆虫病原线虫对菜青虫保护酶活力的影响,分别用10、50、100头夜蛾斯氏线虫（Steinernema feltiae）侵染4龄菜青虫（Pieris rapae）,对侵染后菜青虫体内超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）的活力变化进行了研究。结果表明,接入线虫后,菜青虫的SOD活力显著上升。16 h时各处理的SOD活力均达到最大值,10、50、100头线虫处理的菜青虫SOD活力分别为44.266 7、49.866 7、68.033 3 U/g,均显著高于对照的35.033 3 U/g（p<0.01或p<0.05）,3种线虫剂量处理之间也存在显著差异（p<0.01或p<0.05）。POD的活性在接虫后8 h各处理均显著高于对照（p<0.05）,酶活性随侵染线虫数量的增加而增大,到24 h以后酶的活性开始显著下降,线虫剂量越大下降越快。CAT活力在处理后均显著上升,16~32 h各处理均维持在较高的水平,32 h以后开始显著下降。这反映出菜青虫在昆虫病原线虫侵染初期防御能力增强,16~32 h以后防御能力显著下降。     

利用吸附性物质贮存昆虫病原线虫

昆虫病原线虫制剂产业化需要有效的贮存方法。本试验利用国产硅藻土和高分子凝胶,比较硅藻土和凝胶不同比例、不同温度及添加防霉剂,对线虫存活率、霉菌控制和线虫毒力的影响。线虫在10℃下24周后存活率仍达90．5％,线虫对大蜡螟幼虫的感染率仅下降19．5％。23℃下贮存8周时,存活率高于93％,但16周后几乎全部死亡;对测定昆虫的感染率8周后下降了26．8％。加入的食品抗霉剂对线虫存活率和感染率无明显影响,但防霉效果仅维持2周。结果表明,利用国产硅藻土可贮存Steinernema carpocapsae线虫。     

Susceptibility of the taro beetle,Papuana uninodis,to entomopathogenic nematodes

Six strains of entomopathogenic nematodes, Steinernema glaseri (Steiner) (Biosys #326, nc 34, gb), S. feltiae = bibionis (Filipjev) (Biosys #349), S. carpocapsae Weiser (Biosys #25) and Heterorhabditis zealandica Poinar, were evaluated in laboratory tests against taro beetles, Papuana uninodis Prell. Larvae of this species and adult Papuana Arrow spp. were found to be susceptible to entomopathogenic nematodes. The best results were obtained with S. glaseri #326 in larval and adult P. uninodis . The dose causing 50% mortality (LD ) for third instar P. uninodis larvae in Petri dish assays ranged from almost 7000 nematodes/larva for 1 days exposure to less than 250 nematodes/larva for 6 days; in pot assays the concentration causing 50% mortality (LC ) in 2 weeks was 1.4 106 nematodes/m2. For 50 adults in Petri dishes with soil, the LD was ca 20 000 nematodes/ 50 adult for 1 weeks exposure and ca 6000 nematodes/adult for 3 weeks. In pot assays the LC was 2.5 106 nematodes/m2 in 3 weeks. 50 Preliminary tests showed that P. huebneri (Fairmaire) and P. woodlarkiana laevipennis Arrow adults were also most susceptible to S. glaseri #326. A field test on adults Papuana uninodis did not result in damage reduction but served to illustrate the practical difficulties of applying nematodes in remote areas. 50