Natural occurrence of Beauveria bassiana on adults of the invasive mango seed weevil Sternochetus mangiferae (Coleoptera: Curculionidae) in Brazil

Journal of Plant Diseases and Protection - The mango seed weevil Sternochetus mangiferae (Fabricius) (Coleoptera: Curculionidae) was detected in Brazil in 2014, becoming a potential threat to mango...     

In planta detection of Macrophomina phaseolina from jute (Corchorus olitorius) by a sodium acetate-based direct PCR method

Macrophomina phaseolina (Tassi) Goid. is the most important pathogen of jute and primarily causes seedling blight, leaf spot and stem rot. The pathogen was detected from field samples by a simple method of direct PCR (dPCR) which obviates the steps of DNA extraction. The leaf bits were treated with a lysis buffer at 65°C for 25 min, whereas the stem pieces were initially incubated at 65°C for 5 min followed by incubation at 60°C for 25 min and the lysate was used as PCR template. Based on the type of tissue, the composition and concentration of lysis buffer systems were optimized. For leaf samples the optimized buffer system composed of 20 mmol l ^-1 tris (hydroxymethyl aminomethane (Tris)-Cl (pH 8.0), 1.5 mmol l ^-1 ethylene diamine tetra acetate (EDTA) (pH 8.0), 1.4 mol l ^-1 sodium acetate and 200 μg/ml proteinase K. Further, 3% PVP (w/v) and β-mercaptoethanol (1% w/v) were added into the buffer. In case of stem samples, PVP was not applied and higher concentrations were used for other components. M. phaseolina could be detected from both leaf and stem samples generating amplicon of 350 bp. This is the first report of detecting M. phaseolina by a direct PCR method without DNA extraction.     

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。     

蜕皮激素对黑化黏虫体液免疫的影响

为揭示蜕皮激素(MH)对黑化黏虫免疫能力的影响, 本试验对被球孢白僵菌侵染后的黏虫体内MH含量的动态变化进行了分析比较, 并对被侵染的黑化黏虫注射20-羟基蜕皮酮(20E), 分析比较其注射20E后的死亡率以及酚氧化酶(PO)和溶菌酶活性的变化?结果表明:被白僵菌侵染后, 黑化黏虫6龄幼虫的MH含量在侵染后8 h( P <0.05)?72 h( P <0.05)和96 h( P <0.05)均显著高于对照(注射吐温-80)?注射球孢白僵菌后立即注射5 μg/μL的20E稀释液, 黑化黏虫的死亡率显著低于对照组(注射球孢白僵菌后注射无水乙醇)( P <0.05), 其原因是注射5 μg/μL 20E稀释液后, 被球孢白僵菌侵染后8 h和24 h的黑化黏虫体内PO和溶菌酶活性均显著高于对照组(注射球孢白僵菌后注射无水乙醇)( P <0.05)?试验结果表明MH在黏虫体液免疫反应中起到重要的调节作用?     

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.     

Potential of a strain of Beauveria bassiana (Hypocreales: Cordycipitaceae) for the control of the potato tuberworm,Phthorimaea operculella (Zeller)

The potato tuberworm, Phthorimaea operculella (Zeller), is one of the most important pests of potato, Solanum tuberosum L., worldwide. We evaluated six Beauveria bassiana strains with potential for control of larvae. Strain SD was the most virulent, causing up to 98% mortality 10 days after inoculation of first instars. The other tested strains (HL, XJ, SC, JL and GZ) were only marginally virulent compared to the controls. In cage trials, SD strain applied to potato plants significantly reduced the survival of tuberworm larvae. Our results suggest that strain SD may be recommended for effective biological control of P. operculella.     

Elimination of phytoplasma by stem culture from mulberry plants (Morus alba) with dwarf disease

Stem culture in vitro was attempted for the elimination of mulberry dwarf phytoplasma. Stem segments, from mulberry plants ( Morus alba ) seriously infected with the phytoplasma, were cultured on Murashige and Skoog (MS) solid nutrient medium without phytohormones for 2–3 months. The tissue cultures, and regenerated plants grown under greenhouse conditions for 3 years, were tested by polymerase chain reaction (PCR) and 4,6-diamidino-2-phenylindole (DAPI) staining for the presence of the phytoplasma, and also observed for mulberry dwarf symptoms. From 70% to 90% of regenerated plants were apparently freed from the phytoplasma since they remained PCR-negative, DAPI-negative and symptom-free for as long as tested (3 years).     

Assessment of short-term mortality of granary weevil,Sitophilus granarius (Coleoptera: Curculionidae) triggered by different microwave irradiation powers

Abstract

The insecticidal efficacy of microwave irradiation against the at 12, 24, 48 and 72?h following exposure to microwave irradiations (100, 300?W) and the progeny production was assessed 45?days later. Linearly increasing irradiation power range (100, 200 and 300?W) was set up for determining mortality tendency. An increase of insect mortality caused by higher irradiation period and times elapsed after treatment has become evident commencing from 12?h after the treatment, which has significantly decreased at later elapsed time after treatment. The irradiation periods inducing the highest mortality at the examined powers were at 10?min and at 100?W power (72?h: 64.93%) and at 4.5?min. and at 300?W power (12?h: 87.01). In addition, a complete suppression of progeny production was achieved by 4.5?min treatment at 300?W power. Lognormal-type mortality process was caused by the linearly increased irradiation range. The properly chosen microwave irradiation can be used for management of Sitophilus granarius larval and adult developmental stages. This treatment could provide an effective and friendly environmental treatment technique in Integrated Pest Management (IPM) program.     

用年龄-阶段两性种群生命表研究不同寄主上草地螟种群动态的差异

在温度(22±1)℃、相对湿度70%±5%和光周期L//D=16 h//8 h条件下通过年龄-阶段两性生命表探讨了寄主植物对草地螟Loxostege sticticalis种群动态的影响。结果表明,藜饲养的草地螟卵期和幼虫期最短,与大豆、向日葵和小麦处理组相比差异显著,雌雄蛹重显著高于小麦组,雌雄蛾寿命也显著长于向日葵及小麦组;表明藜是草地螟最适宜的寄主植物,其次为大豆、向日葵和小麦。以藜饲养的草地螟产卵前期较短,产卵历期较长,产卵量也显著高于向日葵及小麦组;与藜饲养相比,大豆饲养的草地螟产卵前期较长,但产卵历期和产卵量与藜组相比均无显著差异;以年龄-阶段两性种群生命表计算藜饲养的草地螟种群的幼虫存活率达90%,显著高于其他组;净增殖率、内禀增长率及周限增长率分别为84.01、0.111和1.117,显著高于其他组,平均世代周期为55.44 d,显著短于其他组;根据种群生命表参数预测90 d内种群动态结果表明藜最有利于草地螟种群的增长。     

A microscopic study of the different classes of symptoms coded by the Vf gene in apple for resistance to scab (Venturia inaequalis)

The different symptoms of resistance coded by the VF gene were studied on glasshouse-grown apple seedlings after inoculation with a conidial suspension of Venturia inaequalis. Scanning-electron microscopy and histological observations defined precisely three different classes of symptoms. Class 1 corresponds to a hypersensitive reaction. Class 2 is characterized by considerable tissue modifications but no sporulation whatsoever occurs; this reaction defines resistant hybrids. In class 3 the fungus remains active and can sometimes sporulate abundantly; this class was divided into two subgroups, one comprising all the hybrids of weak resistance, the other the hybrids of weak susceptibility.     

Role of perithecia as an inoculum source for stem rot type of pepper root rot caused by Fusarium solani f. sp. piperis (teleomorph: Nectria haematococca f. sp. piperis)

Pepper (Piper nigrum L.) root rot caused by Fusarium solani f. sp. piperis (FSP; teleomorph: Nectria haematococca f. sp. piperis) includes two symptom types called root rot (RR) type and stem rot (SR) type. In this study, the temporal and spatial associations between perithecial formation of FSP and development of SR were investigated in naturally infested fields to verify the hypothesis that ascospores from the perithecia are the major inoculum source of the SR type on vines in the field. In surveys of all vines in two neighboring pepper fields every month from December 2005 to November 2006, I mapped the locations of all vines with perithecia and all vines the SR type. The frequency of vines with perithecia increased during April and May, the late rainy season. In June, the early dry season, the number of vines with SR type greatly increased. The vertical range of perithecial formation on the vines extended to 200 cm in height, but was restricted to 30 cm in the dry season in both fields. The join-count statistics showed a significant spatial association between vines with perithecia and vines with SR type in one field (P = 0.042), while no significant spatial association was recognized in another field. The results suggested that ascospores from perithecia of FSP on pepper vines are likely to be one of the main inoculum sources of the SR type of the disease on adjacent vines, but they may not be the exclusive source.