A survey of microbial antagonists of Otiorhynchus species from Germany


Abstract: Several species of the genus Otiorhynchus Germar (Coleoptera: Curculionidae) are serious polyphagous pests in horticulture. Not much is known about their natural microbial antagonists. During 2011 and 2013 a survey of naturally occurring Otiorhynchus species in Germany and their antagonists was conducted. Altogether, 3,821 beetles of 9 selected species were collected. 178 dead specimens were diagnosed by light microscopy for insect pathogens: 31 beetles contained unspecified bacterial infections, and 86 specimens displayed fungal growth with 33 infected by the entomopathogenic taxa Beauveria bassiana (15), Isaria sp. (1) and Lecanicillium sp. (17). On one beetle, a nematode infecting fungus, Arthrobotrys sp., was found, and another one carried an infection by an Entomophthoralean species. Microsporidia, a protist of the genus Mattesia, and nematodes were each observed in two dead individuals, 57 individuals showed no pathogen infections. The role of these entomopathogens as control factors in the field is still unknown.

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