Potential of entomopathogenic fungus Isaria javanica for controlling the potato tuberworm Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae)

Abstract

The potato tuberworm Phthorimaea operculella is an important cosmopolitan quarantine pest of the Solanaceae crops. Comparing the relative virulence of five entomopathogenic fungi against P. operculella, the results showed that Isaria javanica was more effective against eggs, larvae and pupae compared to the other tested isolates. Mean infection rates of ca 80% were obtained for individuals at different life stages treated with 1×10⁸ conidia/mL. Based on the linear regression analyses of the mortality data, a median lethal concentration <1×10⁶ conidia/mL was calculated for eggs, larvae and pupae, suggesting that this isolate of I. javanica may be a useful biocontrol agent for P. operculella. Variation was observed in the growth rates and sporulation of I. javanica on different culture media and at different temperatures. When cultured on peptone maltose agar, the fungus grew quickly, but sporulation rates were higher on corn meal agar and potato dextrose agar, producing 8.16×10³ and 7.39×10³ conidia/cm², respectively. When cultured at different temperatures, the fungus grew faster at 27°C, and produced more conidia when grown at temperatures under 30°C. Our results indicate that I. javanica is a promising biocontrol agent for the potato tuberworm.

摘要

马铃薯块茎蛾 Phthorimaea operculella 是茄科作物上重要的世界性检疫害虫。本文通过比较五种不同昆虫病原真菌对马铃薯块茎蛾的相对毒力，发现与其它测试菌株相比，爪哇棒束孢 (Isaria javanica) 对马铃薯块茎蛾的卵、幼虫和蛹的作用效果更为明显，用浓度为1×10⁸ 孢子/mL的孢子悬浮液处理各虫态，平均死亡率约80%。通过线性回归分析所得爪哇棒束孢对卵、幼虫和蛹的平均致死中浓度（LC₅₀）均小于1×10⁶ 孢子/mL，表明爪哇棒束孢对马铃薯块茎蛾有较好的生防效果。该生防真菌在不同培养基上和不同温度条件下的生长速率和产孢能力具有一定的差异。在蛋白胨麦芽糖琼脂（SMA）培养基上，其生长速率最快，但在玉米粉琼脂（CMA）培养基和马铃薯葡萄糖琼脂（PDA）培养基上，其产孢量最大，分别为 8.16×10³孢子/cm² 和7.39×10³ 孢子/cm²。在27 ^oC培养条件下，其生长速率最快，但在30 ^oC 培养条件下，其产孢量最大。以上研究结果表明，爪哇棒束孢是具有广阔应用前景的生防因子，可用于马铃薯块茎蛾的生物防治。

关键词：生物防治，昆虫病原真菌，爪哇棒束孢，Isaria javanica，马铃薯块茎蛾，Phthorimaea operculella.

Cite as: Cheng, X.-y., Gao, Y.-y., Yang, Ch.-l., Zhang, X., Qin, F.-f., Lu, J., Gao, Y.-l. & Xu, R.-m. (2018). Potential of entomopathogenic fungus Isaria javanica for controlling the potato tuberworm Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae). Israel Journal of Entomology 48 (2): 197–208. <published 10 October 2018>

DOI: 10.5281/zenodo.1453866

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