Australian Journal of Entomology (2011) 50, 200-206

Guillermo Cabrera-Walsh, Shon Schooler and Mic Julien (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 (2), 200-206
Abstract: Cabomba caroliniana, otherwise known as cabomba, is a submerged, rooted macrophyte with heavily dissected leaves that produces flowers that extend above the water surface. It has been disseminated around the world by aquarium traders and enthusiasts, 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. Because of the lack of alternative control methods, a search for biological control agents was initiated in 2003. The most promising natural enemy found during surveys of C. caroliniana in Argentina was the aquatic weevil Hydrotimetes natans. 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 leaf axils where the petiole joins the stem, and adults feed on the leaves and the stems, primarily at the growing tips. Field surveys of C. caroliniana and other submerged plant species, as well as results from preliminary laboratory host range trials suggest that the weevil is specific to cabomba. Adults were found only 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 stem width or plant 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 of H. natans in its native range may guide researchers studying the laboratory fundamental host range and determining the potential effectiveness of the weevil for biological control of cabomba in its introduced range.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Guillermo Cabrera Walsh, Mic Julien

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
general biology - morphology - evolution
non-target effects/fate in environm.

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Cabomba caroliniana (weed)		Argentina
Hydrotimetes natans (weed bioagent)	Cabomba caroliniana (weed)		Argentina