Dl. Johnson et Ms. Goettel, REDUCTION OF GRASSHOPPER POPULATIONS FOLLOWING FIELD APPLICATION OF THE FUNGUS BEAUVERIA-BASSIANA, Biocontrol science and technology, 3(2), 1993, pp. 165-175
Conidia of the Hyphomycete fungus Beauveria bassiana (Bals.) were appl
ied in an attempt to reduce field populations of grasshoppers, primari
ly the migratory grasshopper Melanoplus sanguinipes (Fabricius). Dry s
pores were applied with wheat bran carrier to three fallow fields at a
rate of 2.0 x 10(13) spores ha-1 in 10 kg bait ha-1. Examination of c
ulture plates that had been placed in the field to capture spores and
of bran carrier with scanning electron microscopy indicated that a sub
stantial portion of the B. bassiana colony-forming units (spores and c
lumps of spores) did not adhere to the bran and were applied in the fi
eld as free particles. Grasshoppers collected from the treated plots a
t intervals after application were assayed for infection by B. bassian
a. The observed rate of mycosis in the treated populations was 70% of
those collected after 2 days, declining to 41% by 13 days and 5% by 19
days after application. Analysis of reductions in population density
gave results in agreement with the infection data. Treated populations
declined 60% and 33% by 9 and 15 days after application respectively.
The reductions were significant on both post-treatment sampling dates
(p < 0.05) and the three replicated fields gave comparable results. T
his is the first field demonstration of effectiveness of this fungus a
s a microbial control agent of grasshoppers.