Armadillidium vulgare (crustacea: isopoda) new pest to soybeans in argentina?

E.V. TRUMPER; M. LINARES; F. FAVA & M. BATTÁN HORENSTEIN

Foz de Iguazú, Brasil

Congreso; XXI Congreso Internacional de Entomología; 2000

The influence of low or zero-tillage on soil related fauna has been documented, including changes of diversity, and density of particular species. In Argentina, cutworms grasshoppers, ants and slugs are among the organisms that show a clear increase of density as a result of more abundant refuges, higher levels of moisture and more stable microenvironments.  An unexpected new consequence was identified in zero-tillage soybeans, particularly in irrigated fields. At the beginning of the last two growing seasons, newly established crops begun to show patches of increasingly weak plants, or decreasing plant density. No factors such as mechanical failure during sowing, herbicidal phytotoxicity, and plant diseases or nutrients deficiencies could be associated with these symptoms, nor could the injuries observed in plants be attributed to any insect species present in those fields.  Due to the unusually high abundance of isopods in those soybeans crops, and in spite of their known detritivorous feeding habits, the working hypothesis that these crustaceans were the proximate cause of the damage observed was claimed. Essays and sampling were presence of different numbers of isopods per pot and a control with no isopods, and kept in a glasshouse for two weeks. The presence of isopods in the pots was associated with injuries on different parts of the seedlings, while no damages were observed in seedlings with no isopods present.