Laboratory and field trials of bait formulations of the fungal pathogen, Metarhizium flavoviride, against a tropical grasshopper and locust

Extrusion technology was used to produce maize-starch 'contact bait' carriers, and vegetable-oil suspensions of Metarhizium flavoviride were incorporated into the baits after extrusion. Laboratory bioassays using the locust, Schistocerca gregaria, demonstrated mortality and reduction of feeding after exposure to the baits, and gave an LC(50) of 1.5 x 10(8) spores l(-1) (slope = 0.63) for fifth instar nymphs. 62 laboratory trials, maize-starch contact baits showed improved efficacy relative to wheat-bran edible bait formulations of M. flavoviride. Field cage experiments, undertaken in Mail, using fourth and fifth instar nymphs of the grasshopper, Hieroglyphus dagenensis, demonstrated significant mortality with both fresh and weathered maize-starch contact bait formulations of M. flavoviride, relative to untreated controls.