FIELD TRIALS OF METARHIZIUM-ANISOPLIAE (DEUTEROMYCOTINA, HYPHOMYCETES) AGAINST INOPUS-RUBRICEPS (DIPTERA, STRATIOMYIDAE) IN SUGARCANE

Two isolates of Metarhizium anisopliae (Metschnikoff) Sorokin were tes ted against the sugarcane pest Inopus rubriceps (Macquart) in separate field trials. Conidia were mixed with attapulgite and applied to soil at two rates by four different procedures. When conidia were applied in the planting drill at 8.5-13 x 10(14) per ha, concentrations of con idia exceeded 1 x 10(6) g-1 in soil soon after application and were ma intained above the background level for at least 34 mo. Residual conce ntrations were not significantly greater than background level when th e same amount of conidia was broadcast over the whole plot. Bioassays indicated that the isolate Fl 161 was more effective than FI 203. In t he trial using FI 161, soil samples after drill application at 8.5 x 1 0(14) conidia per ha showed infectivity against larvae of I. rubriceps for up to 4 mo in bioassays. Rates of infection and mortality were si gnificantly related to concentrations of conidia in the corresponding samples. However, numbers of larvae in the field 1 and 2 yr after plan ting were not affected by treatment in either trial. Larval densities were not high, and M. anisopliae may be more effective under other cir cumstances.