Three isolates of Metarhizium anisopliae var. acridum, FI-985, from the spur-throated locust, Austracris guttulosa from Australia, and QF-01 and QF-02 both from Schistocerca piceifrons in Mexico were compared. FI-985 had much larger conidia than the other two isolates and also had a different colony appearance. The two Mexican isolates showed small differences in conidial size and colony morphology. Over a range of 6 primers, RAPDs patterns were very similar in that the two Mexican isolates being identical, and FI-985 having some unique bands only with 2 primers. The 3 isolates were also similar in growth profiles on agar plates, and at high temperatures (36degreesC), QF-01 did not grow while the other two isolates grew slowly. All three isolates were similar in virulence for wingless grasshoppers, Phaulacridium vittatum, at 20-30 degreesC but at 35 degreesC, FI-985 was the most virulent and QF-01 the least over a range of 3 doses. At 15 degreesC, FI-985 was also the most virulent with QF-02 being least virulent. At 30 degreesC, the LD50 at 17 days ranged from 248 conidia for QF-02 to 501 conidia for FI-985, however the differences were not significant (p > 0.05). It is suggested that consideration should be given to using an exotic isolate such as FI-985 as a commercial locust biopesticide in countries such as Mexico, since the isolate is cheap to mass produce, more effective at higher temperatures common in tropical to subtropical Mexico, and relatively resistant to UV.
