Impact of soil applications of Beauveria bassiana and Mariannaea sp. on nontarget forest arthropods

Parker, B.L.; Skinner, M.; Gouli, V.; Brownbridge, M.

Impact of soil applications of Beauveria bassiana and Mariannaea sp. on nontarget forest arthropods

1997

Parker, B.L. | Skinner, M. | Gouli, V. | Brownbridge, M.

Replicated plots were established in pear thrips-infested sugar maple stands. They were treated with Beauveria bassiana as an emulsifiable concentrate and a nutrient-based granular formulation and with Mariannaea sp. as a wettable powder. Postapplication invertebrates moving across plots were collected daily for 10 days in pitfall traps. Collected individuals were identified, held for 10 days, and then evaluated for the presence of fungal infection and other potential pathogenic microorganisms. A total of 3615 invertebrates were collected and identified. Of the invertebrate population in treated plots that fell into pitfall traps, 2.8% became infected with either B. bassiana or Mariannaea sp. The fungi applied also occur naturally in sugar maple forest soils; therefore, it was impossible to confirm whether the infection we observed in treated plots was a result of contact with the spores we applied. Because we obtained infection among invertebrates collected from control plots, it is likely that these fungi do attack invertebrates under natural forest conditions. Of the 2584 invertebrates examined further for obligate internal pathogens, 2.5% were infected with entomophthoralean fungi, protozoans, and/or nematodes. Results suggest that B. bassiana and Mariannaea sp. could be applied to forest soil without a significant negative impact on the forest-dwelling invertebrate population.

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