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journal1 ›› 2016, Vol. 32 ›› Issue (1): 70-75.DOI: 10.16409/j.cnki.2095-039x.2016.01.011

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Screening of Synergistic Combinations of Bacillus thuringiensis Proteins with High Activity against Lymantria dispar

YANG Fan1,2, YANG Sujuan2, CAO Lijun1, GENG Yongxin1, ZHANG Jie2, CHEN Min1   

  1. 1. Beijing Key Laboratory for Forest Pest Control/College of Forestry, Beijing Forestry University, Beijing 100083, China;
    2. State Key Laboratory for Biology of Plant Diseases and Insect Pests/Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
  • Received:2015-03-22 Online:2016-02-08 Published:2016-02-22

Abstract: Lymantria dispar (Linnaeus) is an important agricultural and forestry pest in the world. With the aim of identifying Bt proteins and their synergistic combinations that would be useful in the management of L. dispar, 11 Bt proteins were extracted to test their toxicity against 3 d old larvae of L. dispar. Cry1Ac, Cry2Ab, Cry1Ca and Vip3Aj had high insecticidal activity in the primary screen. Further bioassay showed that Cry1Ac was the most toxic among the four proteins at 7 d treatment, with LC50 of 2.47 μg/g. Cry2Ab and Cry1Ca also had a higher insecticidal activity, with LC50 of 29.19 and 42.45 μg/g, respectively. The novel protein Vip3Aj was found for the first time to have pesticidal activity, with LC50 of 101.26 μg/g. The larvicidal activities of four combinations (1:1 ratios) of the toxins (Cry1Ac+Cry2Ab, Cry1Ac+Cry1Ca, Cry1Ac+Vip3Aj, Cry2Ab+Cry1Ca) were evaluated. LC50 of Cry1Ac+Cry2Ab combination was 0.64 μg/g, and the synergistic coefficient (7.098) was the highest, suggesting that there is strong synergism between these two toxins. With LC50 of 0.76 and 1.06 μg/g, respectively, the Cry1Ac+Cry1Ca and Cry1Ac+Vip3Aj combinations, showed synergistic coefficients of 6.162 and 4.539,respectively, also indicating obvious synergistic effect.

Key words: Lymantria dispar, Bacillus thuringiensis, insecticidal proteins, bioassay, synergism

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