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journal1 ›› 2015, Vol. 31 ›› Issue (6): 853-859.DOI: 10.16409/j.cnki.2095-039x.2015.06.006

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Laboratory Assessment on Virulence of Entomogenous Fungi against Stephanitis nashi

HOU Mingming, LIU Yihao, WANG Bin   

  1. Anhui Provincial Key Laboratory of Microbial Control, Anhui Agricultural University, Hefei 230036, China
  • Received:2015-02-11 Online:2015-12-08 Published:2015-12-17

Abstract: Stephanitis nashi is one of the most destructive sap-sucking insect pests on various fruit and garden plants, especially in the regions of the Yangtze valley and Northern China. The pest reproduces many generations per year and easily develops resistance to chemical pesticides. Biological control might be helpful in reducing the selection pressure for resistance to chemical insecticides and in the sustainable control of the pest. The potential of entomopathogenic fungi as a biological control agent against the pest was evaluated in the laboratory assays. Fifteen strains of entomopathogenic fungi with good sporulation were tested for their pathogenicity both on S. nashi adults and the 2nd instar nymphs. The cumulative mortalities of six Beauveria strains and one Materhazium strain reached 100% both on S. nashi adults and the 2nd instar nymphs at an inoculation concentration of 1×106 conidia/mL. The LT50 of the strains of Bb2352, Bb2359 and Bb2372 against the adults were less than four days, while the LT50 of the strains of Bb2352, Bb2359 and Ma67 against the 2nd instar nymphs were less than five days. The LT50 difference between the adults and the nymphs showed the adults could be knocked down more quickly. In the time-dose-mortality model, the cumulative mortality of the pest increased sharply from the 3rd to the 7th day after the fungal innoculation, while showed only gentle changes before and after that period. The mortalities increased with the increase of inoculation dosage, presenting an obvious dose response. The strain Bb2359 showed the highest virulence against both S. nash adults and its nymphs, with a LC50 of 6.466×104 conidia/mL and of 4.747×104 conidia/mL, respectively. The LT50 for the adults and nymphs were 2.89 d and 3.54 d, respectively, at an inoculation concentration of 1×107 conidia/mL. This strain showed a great potential in the control of the hazardous S. nash as a fungal insecticide.

Key words: Stephanitis nashi, adult, nymph, entomopathogenic fungi, bioassay

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