球孢白僵菌与5种农药的相容性及其对韭菜迟眼蕈蚊的联合毒力

本文室内评价了5种防治韭菜迟眼蕈蚊常用化学农药(辛硫磷、噻虫嗪、噻虫胺、高效氯氟氰菊酯和高效氯氰菊酯)与高毒力球孢白僵菌YB8的相容性,并测定了菌药联合使用对韭菜迟眼蕈蚊的毒力效果。结果表明不同浓度的5种农药对菌株YB8生长均有一定的影响。其中噻虫嗪和噻虫胺在供试浓度下对孢子萌发无显著影响,5 d时能促进菌株YB8菌落生长,且随着浓度降低促进作用加强(抑制率为-2.26%~-15.69%),10 d时对菌株YB8生长略有抑制作用(抑制率为0.29%~8.33%);高效氯氟氰菊酯(16.7 mg/L)和高效氯氰菊酯高浓度(30 mg/L)均对孢子萌发有抑制作用(孢子萌发率分别为86.87%、86.82%),而低浓度(1.67、3 mg/L)则促进孢子萌发(孢子萌发率分别为124.96%、104.10%);二者不同浓度对菌落生长均有一定的影响,其中高效氯氰菊酯在低浓度3 mg/L时,5和10 d的菌落生长抑制率分别为-32.64%和-13.11%;辛硫磷与菌株YB8相容性差,随着浓度增加,孢子萌发率明显降低,菌落生长明显受到抑制。5种农药与菌株YB8联合使用的生物测定结果表明,联合作用时农药的LC50值降低,菌株YB8对韭蛆的LT50缩短。因此,生产上推荐菌株YB8与噻虫嗪和噻虫胺联合使用,而避免与高浓度辛硫磷、高效氯氟氰菊酯和高效氯氰菊酯联合使用。

Compatibility of Beauveria bassiana with Five Pesticides and Their Cotoxicity to Bradysia odoriphaga

We evaluated the compatibility of five pesticides (phoxim,thiamethoxam,clothianidin,λ-cyhalothrin and β-cypermethrin) commonly used against Bradysia odoriphaga with a high virulence strain of Beauveria bassiana YB8,and determined their co-toxicity against B.odoriphaga in the laboratory.Results showed that the pesticides had different effects on the growth of B.bassiana at different concentrations.Thiamethoxam and clothianidin had no significant effect on the conidia germination at the tested concentrations.Both of them promoted the growth of B.bassiana 5 days after treatment,which increased with the concentration increase (inhibition rate were-2.26％ to-15.69％),while inhibited the growth ofB.bassiana 10 days after treatment,with the inhibition rate of 0.29％ to 8.33％.λ-cyhalothrin (at 16.7 rg/L) and β-cypermethrin (at 30 mg/L) reduced conidia germination rate (86.87％,86.82％),while at low concentrations (at 1.67 mg/L and 3 mg/L,respectively) promoted conidia germination rate (by 24.96％ and 4.10％,respectively).Both λ-cyhalothrin and β-cypermethrin at different concentrations had effect on the growth ofB.bassiana,the inhibition rates of λ-cyhalothrin to the colony growth 5 and 10 days after treatment were the lowest (-32.64％ and-13.11％,respectively) at low concentration (3 mg/L).Phoxim inhibited the growth of B.bassiana significantly in a dose dependent manner.The results of bioassay against B.odoriphaga showed that the LC5o values of combination B.bassiana with insecticides were lower than that of insecticide alone,and LT50 values of combination was shorter than that of B.bassiana alone.It is recommended that thiamethoxam and clothianidin can be combined with B.bassiana for control ofB.odoriphag,while phoxim,λ-cyhalothrin and β-cypermethrin can be used only at low concentration.