吡虫啉胁迫对褐飞虱共生解脂假丝酵母抗性及敏感菌株生长的影响

为明确吡虫啉对褐飞虱共生解脂假丝酵母Candida lipolytica抗性及敏感菌株生长的影响,通过菌株培养、菌落观察和菌丝镜检等方法,比较了褐飞虱共生解脂假丝酵母不同菌株在含不同质量浓度吡虫啉的固体培养基上的菌落数,以及在液体培养基中的生长量差异。结果发现:不同质量浓度吡虫啉对褐飞虱共生解脂假丝酵母敏感和抗性菌株菌落生长均有抑制作用,且吡虫啉浓度越高,抑制作用越强。经500、1 000和2 000 mg/L吡虫啉处理4 d后,敏感菌株的菌落数量分别为对照的46.61%、27.58%和6.25%,均与对照差异显著;500和1 000 mg/L处理组抗性菌株菌落数量与对照无显著差异,而2 000 mg/L处理组与对照差异显著。经吡虫啉处理后,敏感菌株假菌丝形态变得不规则,部分假菌丝不舒展、萎缩或弯曲、顶端出现膨大,酵母出现空泡等,且吡虫啉浓度越高,不规则程度越明显;抗性菌株的假菌丝形态也有类似变化,但与敏感菌株相比,其菌丝体不规则形态的比例明显下降。500 mg/L吡虫啉处理对敏感和抗性菌株的生长量及菌丝干重均无明显影响,1 000和2 000 mg/L吡虫啉对不同菌株前期生长的抑制作用明显,但对后期生长影响不明显。研究表明,吡虫啉对褐飞虱共生解脂假丝酵母抗性菌株生长的影响显著小于对敏感菌株的影响。

Effect of imidacloprid stress on growth of resistant and susceptible strain of yeast-like symbiote, Candida lipolytica, isolated from rice brown planthopper, Nilaparvata lugens Stål

In order to understand the effect of imidacloprid stress on the growth of resistant and susceptible strain of yeast-like symbiote, Candida lipolytica, the number of colonies cultured on solid medium and the growth amount of different strains of C.lipolytica cultured in liquid medium contained different concentrations of imidacloprid were compared by methods of strain culturing, colony observation and microscope examination of mycelium. The results showed that different concentrations of imidacloprid had inhibitory effects on the growth of resistant and susceptible strains of C.lipolytica; and the higher concentration of imidacloprid, the stronger the inhibitory effect. The number of colonies of susceptible strain treated with 500, 1 000 and 2 000 mg/L imidacloprid for four days were only 46.61%, 27.58% and 6.25% of the control, respectively, which were all significantly different with that of the control. The number of colonies of resistant strain treated with 2 000 mg/L imidacloprid were also significantly different with that of the control, however, that of 500 and 1 000 mg/L treatment were not. After being treated with imidacloprid, the morphology of susceptible strains of C.lipolytica became abnormal, for example, some mycelia were not stretched, became atrophy or bending, the top of mycelia appeared swollen, and yeast vacuoles generated; and the higher concentration of imidacloprid treated, the higher degree of abnormal was observed; the abnormal morphology of resistant strain was similar with that of susceptible strain, but the proportion of abnormal mycelia declined significantly. At treatment of 500 mg/L imidacloprid, the growth and dry weight of mycelia of resistant and susceptible strains were not affected significantly; while at treatment of 1 000 and 2 000 mg/L imidacloprid, the growth of different strains was inhibited significantly in the early stage, but was not affected obviously in the later stage. In conclusion, the effect of imidacloprid on the growth of resistant strain of C.lipolytica was significantly less than that of susceptible strain.