The black vine weevil, Otiorhynchus sulcatus (Fabricius) (Coleoptera: Curculionidae) is the major pest of container-grown nursery crops in the Pacific Northwest. This study was conducted to determine the persistence and population dynamics of Metarhizium anisopliae in container-grown nursery stock. The persistence and population dynamics of M. anisopliae in peat and bark based soil less potting mixes were quantitatively determined for 1 yr. The effect of fungal incorporation technique (granules incorporated, granules ground and incorporated, 7 day incubation of concentrated fungal granule preparation in appropriate potting mix) and amendment with multiple rates of crab meal (0, 1.5, and 3.0 lb/cu yard) on fungal persistence and population dynamics were determined. Over the course of the study, the fungal population remained fairly stable averaging 106 (cfu)/g potting mix regardless of potting mix or crab meal amendment. Black vine weevil larvae were also exposed in bioassays to samples of each potting mix over the course of the experiment and mortality assessed. The level of inoculum persisting in the potting mix caused an average of 65-75% larval mortality. In addition, the isolate of M. anisopliae used in the study was found to be rhizosphere competent with the host plant (Picea abies Nidiformis). The population of M. anisopliae in the rhizosphere was approximately 10× that supported in the bulk soil in all treatments. Metarhizium anisopliae appears to be capable of persisting in both peat and bark based potting mix at relatively high levels for at least 1 yr in the Pacific Northwest.
Species 1: Coleoptera Curculionidae Otiorhynchus sulcatus (Black vine weevil)
Keywords: fungal biology, rhizosphere competence
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