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Biological control of Cabomba caroliniana: biology and host range of the cabomba weevil Hydrotimetes

Kumaran, N., Vance, T., Comben, D. F., Dell, Q., Oleiro, M., Mengoni Goñalons, C., Cabrera Walsh, G. and Raghu, S. (2022) Biological control of Cabomba caroliniana: biology and host range of the cabomba weevil Hydrotimetes. In: 22nd Australasian Weeds Conference, 25 – 29 September 2022, Adelaide, South Australia.



Cabomba caroliniana Gray is a submerged aquatic weed, invasive in the waterways of Australia and several other countries. In Australia, C. caroliniana is a Weed of National Significance, and its detrimental effects include choking of waterways, reducing the water holding capacity of dams supplying drinking water and affecting native flora. During preliminary surveys and host specificity tests in the native range (Argentina and Paraguay), the aquatic weevil, Hydrotimetes natans Kolbe has been identified as a potential biological control agent to control C. caroliniana. We imported H. natans from the native range to Australia and studied its biology and host specificity. From biology studies, we found that eggs were laid on submerged leaves of C. caroliniana semi-embedded in a small divot and hatched in 7.65 ± 0.86 days. Larvae developed tunnelling through the leaves (early instar) or stems (late instar) and pupated outside the stem near the base of petioles after 25 to 27 days of development. Pupae developed into adult in 14.3 ± 2.7 days. The full lifecycle, from oviposition through to adult eclosion, took 46.5 ± 4.4 days. Host specificity trials were setup with Brasenia, Nymphaea and Trithuria species selected based on the centrifugal phylogenetic method, and data on oviposition, larval development, pupation and lifecycle completion were recorded. We found no evidence of oviposition and development of H. natans on any of the Nymphaea or Trithuria plant species tested. While Brasenia schreberi supported partial development (which was significantly lower than that on C. caroliniana), it did not support multiple generations of H. natans. In this talk, we discuss these results in light of risks of H. natans to native and other nontarget species in Australia, and its potential to be part of the integrated weed management of C. caroliniana.

Item Type:Conference or Workshop Item (Paper)
Business groups:Biosecurity Queensland
Keywords:Biocontrol, cabomba, brasenia, WoNS, invasion, weeds, weed management, host specificity, erirhininae
Subjects:Science > Entomology
Science > Invasive Species > Plants > Eradication and containment
Science > Invasive Species > Plants > Weed ecology
Plant pests and diseases > Weeds, parasitic plants etc
Plant pests and diseases > Plant pathology
Plant pests and diseases > Pest control and treatment of diseases. Plant protection > Organic plant protection. Biological control
Agriculture > By region or country > Australia
Live Archive:18 Jan 2023 04:24
Last Modified:06 Feb 2024 05:24

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