Abstract:

 Mucor hiemalis BO-1 is a newly reported entomopathogenic fungus that infects Bradysia odoriphaga, a destructive root maggot. However, the pathogenicity and field control efficiency of M. hiemalis BO-1 against B. odoriphaga are unknown. In this study, we analyzed the pathogenicity of M. hiemalis BO-1 to B. odoriphaga larvae and its relation to temperature and evaluated its application value by pot and field experiments. The results indicated that M. hiemalis BO-1 was of acute pathogenicity against B. odoriphaga larvae and was as toxic as some chemical pesticides. At 3 d after treatment, the median lethal concentrations (LC₅₀) to the 2^nd and 4^th instar larvae were 3.714×10⁵ spores/mL and 4.680×10⁶ spores/mL, respectively. Moreover, M. hiemalis BO-1 also showed pathogenic activities against B. difformis and Delia antiqua larvae. The optimal temperatures for high pathogenic activity of M. hiemalis BO-1 were 16―28 ℃, especially at 20―24 ℃. The results of pot and field experiments confirmed excellent control efficiency of M. hiemalis BO-1 against B. odoriphaga larvae, which exceeded 80% at 7 d after treatment with spore concentration of 1×10⁷ spores/mL, the equivalence to the chemical insecticide clothianidin. In addition, M. hiemalis BO-1 exhibited high persistence in control of B. odoriphaga. Therefore, M. hiemalis BO-1 is of high perspective as a biocontrol agent against B. odoriphaga.

Key words:

Bradysia odoriphaga, Mucor hiemalis, entomopathogenic fungi, pathogenicity bioassay; control efficiency