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ARS Home » Pacific West Area » Corvallis, Oregon » Horticultural Crops Research » Research » Publications at this Location » Publication #229127

Title: Effects of a Novel Microsporidium on the Black Vine Weevil, Otiorhynchus sulcatus (F.) (Coleoptera: Curculionidae)

Author
item Bruck, Denny
item Solter, Leellen
item Lake, Amanda

Submitted to: Journal of Invertebrate Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/28/2007
Publication Date: 7/1/2008
Citation: Bruck, D.J., Solter, L.F., Lake, A.J. 2008. Effects of a novel microsporidium on the black vine weevil, Otiorhynchus sulcatus (F.) (Coleoptera: Curculionidae). Journal of Invertebrate Pathology. 98:351-355.

Interpretive Summary: A newly discovered microsporidium (a protozoan pathogen of insects) infecting the black vine weevil was studied to determine its impact on black vine weevil. Black vine weevil populations from several locations were sampled and evaluated for infection. A very low prevalence of the disease was observed in all locations surveyed (< 3.0%). The low prevalence observed in the field may be related to the high level of mortality of the disease in both larvae and adults. Laboratory studies were conducted by feeding larvae and adult black vine weevil varying concentrations of the pathogen. Larvae and adults were infected at all concentrations of the pathogen. Greenhouse trials were performed to determine if black vine weevil larvae feeding in soil acquired infections when the pathogen was topically applied as a drench. Established larvae feeding on plant roots in pots developed infections when exposed to drench treatments after 14-21 days. The microsporidium infecting the black vine weevil is an acute pathogen infective to both larvae and adults. Topical applications of the pathogen also resulted in infection in larvae feeding on roots in soilless potting media, suggesting the possibility for the use of this pathogen in a microbial control program.

Technical Abstract: A newly discovered microsporidium infecting the black vine weevil, Otiorhynchus sulcatus (F.) (Coleoptera: Curculionidae), provisionally placed in the genus Canningia, was studied to determine its impact on O. sulcatus. Otiorhyncus sulcatus populations from several locations were sampled and evaluated for microsporidiosis. A very low prevalence of the disease was observed in all locations surveyed (< 3.0%). The low prevalence observed in the field may be related to the high level of pathogenicity of the microsporidium in both larvae and adults. Laboratory studies were conducted by orally exposing both larvae and adults of O. sulcatus to varying concentrations of Canningia sp. spores. Larval bioassays at a variety of dosages (0, 10, etc.) were performed to evaluate disease transmission, longevity and growth. Adult bioassays (dosages: 0, 10, etc.) were performed to evaluate longevity, fecundity and mechanisms of disease transmission. Larvae and adults were infected in all spore treatments. Larval growth was significantly reduced at dosages above 10 spores/larva. Adults infected at all dosages experienced high levels of mortality and fecundity was reduced to zero. Greenhouse trials were performed to determine if larvae feeding in soil acquired infections when spores were topically applied as a drench application (0, 105, 106, 107 spores/pot). Established larvae feeding on plant roots in pots developed infections when exposed to drench treatments of 106 and 107 spores/pot after 14-21 days. Canningia sp. is an acute pathogen of O. sulcatus infective to both larvae and adults. Topically applied spores also infected larvae feeding on roots in soilless potting media, suggesting the possibility of using this pathogen in a microbial control program.