Sublethal effects of Paecilomyces fumosaroseus on feeding and fecundity of the diamondback moth,Plutella xylostella

The diamondback moth,Plutella xylostella,is an important insect pest of cruciferous vegetables in South China and has developed higher resistance to insecticides commonly used in the field.In an effort to select effective biological control agents against the diamondback moth,sublethal effects of a Paecilomyces fumosaroseus strain(SCAU-PFCF01) on the feeding,development and fecundity of the diamondback moth were studied in the laboratory.Results showed that food consumption of the larvae could be reduced by P.fumosaroseus conidia at sublethal concentration.When the 2nd instar larvae were treated with 102 and 103 conidia/ml,the total food consumption of larval stage was reduced by 29.3%and 54.1%,respectively.Although the sublethal concentration could not kill all the 4th instar larvae,it could significantly decrease the pupation rate,emergence rate,longevity and fecundity of adults.When treated with concentration of 103 conidia/ml at the 4th instar larvae,the average weight of pupa(4.3 mg),longevity of adult (15.3 d for male,17.2 d for female) and fecundity(135.1 eggs/female) were significantly lower than that of control,respectively.