USE OF METARHIZIUM-FLAVOVIRIDE FOR CONTROL OF ZONOCERUS-VARIEGATUS - A MODEL, LINKING DISPERSAL AND SECONDARY INFECTION FROM THE SPRAY RESIDUE WITH MORTALITY IN CAGED FIELD SAMPLES
J. Langewald et al., USE OF METARHIZIUM-FLAVOVIRIDE FOR CONTROL OF ZONOCERUS-VARIEGATUS - A MODEL, LINKING DISPERSAL AND SECONDARY INFECTION FROM THE SPRAY RESIDUE WITH MORTALITY IN CAGED FIELD SAMPLES, Entomologia experimentalis et applicata, 82(1), 1997, pp. 1-8
A field trial was conducted using an oil formulation of the entomopath
ogenic fungus. Metarhizium flavoviride Gams & Rozsypal (Deuteromycotin
a: Hyphomycetes), to control the variegated grasshopper: Zonocerus var
iegatus L. (Orthoptera: Pyrgomorphidae). The influence of dispersal an
d secondary pick-up from the spray residue on mortality was assessed b
y sampling insects from the treated plots at intervals and monitoring
disease levels during subsequent incubation in the laboratory. The cum
ulative mortality curves showed the pathogen to be highly effective, e
ven in samples taken 8 days after spraying. A model was developed to l
ink the influence of mortality, incubation, secondary pick-up of spore
s and insect dispersal, on the shape of these cumulative mortality cur
ves. The model proved useful for data received from an experiment usin
g small plot sizes, where insect dispersal is a big problem. The spray
residue had an important influence on overall insect mortality. The m
odel also indicated a difference in speed of kill between field and la
boratory samples, suggesting an incubation delay in the field.