Author
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CABRERA WALSH, GUILLERMO - South American Biological Control Lab(SABCL) |
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SCHOOLER, SHON - Commonwealth Scientific And Industrial Research Organisation (CSIRO) |
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JULIEN, MIC - Commonwealth Scientific And Industrial Research Organisation (CSIRO) |
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Submitted to: Australian Journal of Entomology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 10/6/2010 Publication Date: 5/1/2011 Citation: Cabrera Walsh, G., Schooler, S., Julien, M. 2011. Biology and preliminary host range of Hydrotimetes natans Kolbe (Coleoptera:Curculionidae)a natural enemy candidate for biological control of Cabomba caroliniana Gray (Cabombaceae) in Australia. Australian Journal of Entomology. 50,200-206. Interpretive Summary: Cabomba is a submerged fresh water plant that has been disseminated around the world through the aquarium trade and has become a noxious weed in numerous countries, where it often produces dense monospecific stands. It is considered native to southern parts of North and South America, and is a common plant in floodplain streams and lakes in north-east Argentina. Due to the lack of alternative control methods, a search for biological control agents was instigated in 2003. The most promising natural enemy found during surveys of C. caroliniana in Argentina was the aquatic weevil Hydrotimetes natans Kolbe. The entire life-cycle is completed on the plant, primarily underwater except when the adults climb onto emergent flowers to mate. Larvae mine the stems, pupal cases are constructed in the axil where the leaf petiole joins the stem, and adults feed on leaf and stem material, primarily at the growing tips. Field surveys on cabomba and other submerged plant species, as well as evidence from laboratory trials suggest that the weevil is specific to cabomba. The information provided in this study on the host specificity and biology in the native range may guide researchers studying the laboratory host range and determining the potential effectiveness of the weevil for biological control of cabomba in its introduced range. Technical Abstract: Cabomba caroliniana Gray (Cabombaceae), otherwise known as cabomba or water fanwort, is a submerged, rooted macrophyte with heavily dissected leaves that produces flowers that extend above the water’s surface. It has been disseminated around the world through the aquarium trade and has become a noxious weed in numerous countries, including Australia, where it often produces dense monospecific stands. It is considered native to southern parts of North and South America, and is a common plant in floodplain streams and lakes in north-east Argentina. Due to the lack of alternative control methods, a search for biological control agents was instigated in 2003. The most promising natural enemy found during surveys of C. caroliniana in Argentina was the aquatic weevil Hydrotimetes natans Kolbe. The entire life-cycle is completed on the plant, primarily underwater except when the adults climb onto emergent flowers to mate. Larvae mine the stems, pupal cases are constructed in the axil where the leaf petiole joins the stem, and adults feed on leaf and stem material, primarily at the growing tips. Field surveys of C. caroliniana and other submerged plant species, as well as evidence from laboratory trials suggest that the weevil is specific to cabomba. Adults were only found on other plant species when intertwined with C. caroliniana in the field and did not move onto other plant species in aquaria trials. The distribution of the larvae in the field was studied in relation to depth and plant size. No preferences for plant width or length were found, although a significant portion of the larval mines were located near the root crown of the plant. This information on the host specificity and biology in the native range may guide researchers studying the laboratory host range and determining the potential effectiveness of the weevil for biological control of cabomba in its introduced range. |
