FIELD TREATMENT OF DESERT LOCUST (SCHISTOCERCA-GREGARIA FORSKAL) HOPPERS IN MAURITANIA USING AN OIL FORMULATION OF THE ENTOMOPATHOGENIC FUNGUS METARHIZIUM FLAVOVIRIDE
J. Langewald et al., FIELD TREATMENT OF DESERT LOCUST (SCHISTOCERCA-GREGARIA FORSKAL) HOPPERS IN MAURITANIA USING AN OIL FORMULATION OF THE ENTOMOPATHOGENIC FUNGUS METARHIZIUM FLAVOVIRIDE, Biocontrol science and technology, 7(4), 1997, pp. 603-611
A field trial was conducted to test the efficacy of an oil formulation
of the entomopathogenic fungus, Metarhizium flavoviride Gams & Rozsyp
al (Deuteromycotina: Hyphomycetes), as a control agent for the desert
locust, Schistocerca gregaria Forskal (Orthoptera: Acrididae), in Maur
itania. The treatment was applied to hopper bands in the field. In cag
ed samples of the treated insects, 99% mortality was observed in 15 da
ys. On average during application only 51% of the hoppers received spr
ay droplets directly, the additional mortality being due to pick-up of
spores from the splay residue. This mortality was assessed by exposin
g insects to a treated plot at intervals, and monitoring disease level
s during subsequent incubation in cages. The spray residue remained hi
ghly infective for a period of 6 days after application. The number of
nymphs in the hopper bands was estimated using a computer-based photo
graphic image-processing technique. Unfortunately, most of the hopper
bands dispersed into small groups, but a population reduction could be
demonstrated for one hopper band. Maximal daily mortality in the fiel
d was observed 10-11 days after application, compared with 6-10 days i
n cages.