Microbial Control of Schistocerca americana (Orthoptera: Acrididae) by Metarhizium flavoviride (Deuteromycotina): Instar Dependent Mortality and Efficacy of Ultra Low Volume Application Under Greenhouse Conditions
The entomopathogenic fungus Metarhizium flavoviride Gams & Rozsypal has been widely tested for the suppression of African grasshoppers, but there has been no research on Nearctic species. We examined the potential of M. flavoviride for the control of the American grasshopper,
Schistocerca americana (Drury). When tested under conidial dosages of 1.2× 103, 1.2 × 104, and 1.2 ×105,4th-instar S. americana were significantly more susceptible to M. Flavoviride than 6th-instar and adult S. Americana.
At the conidial dosage of 1.2 ×105, M. Flavoviride produced 89.7, 12.8, and 17.6% mean mortality 7 d after treatment in 4th-instar, 6th-instar, and adult S. americana, respectively. By the 14th d after treatment, the M. flavoviride conidial dosage of 1.2
×105 produced 99.4, 86.1, and 80.8% mean mortality in 4th-instar, 6th-instar, and adult S. americana, respectively. The LD50 estimates for M. flavoviride of 1.7 × 104 conidia for the 4th-instar, 1.3 ×104 conidia for
the 6th-instar, and 3.1 ×104 conidia for the adult S. americana are generally greater than those used for other acridids. Furthermore, mortality in M. flavoviride-treated S. americana was positively dosage dependent, as described by mean percentage of
cumulative mortality and LT50 estimates. Greenhouse trials evaluating ultra low volume application to grasshoppers, foliage, or grasshoppers and foliage produced from 78.1 to 92.0% mean mortality 14 d after treatment. In this simulated field trial, grasshoppers and M. flavoviride
were exposed to temperatures ranging from 10 to 40ºC, which demonstrated the potential of M. flavoviride to be effective under large temperature fluctuations, as may occur in the field.
Document Type: Research Article
Publication date: February 1, 1998
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Journal of Economic Entomology is published bimonthly in February, April, June, August, October, and December. The journal publishes articles on the economic significance of insects and is divided into the following sections: apiculture & social insects; arthropods in relation to plant disease; forum; insecticide resistance and resistance management; ecotoxicology; biological and microbial control; ecology and behavior; sampling and biostatistics; household and structural insects; medical entomology; molecular entomology; veterinary entomology; forest entomology; horticultural entomology; field and forage crops, and small grains; stored-product; commodity treatment and quarantine entomology; and plant resistance. In addition to research papers, Journal of Economic Entomology publishes Letters to the Editor, interpretive articles in a Forum section, Short Communications, Rapid Communications, and Book Reviews.
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