View specimen record. Add Specimen. Add attribute Show information from supporting collections: On Off. View all images. Yes No. Alternative caption. Edit Delete. Add Image. Add new link. Since it was sterile and had the egg-beater shaped hairs on the upper leaf surfaces characteristic of species in the S. She found the native range of S. This permitted targeted surveys by Wendy Forno on species in the S.
This weevil imported as C. Host testing by Wendu Forno determined that it was specific to species in the S. Adults of the small 2 mm black longsnouted weevil C. When first collected by Wendy Forno from salvinia in south-eastern Brazil it was thought to be a biotype of C. It was only after releases in Australia that detailed comparative studies determined that it was a new undescribed species, later to be named C.
The first releases of the salvinia weevil as a biological control agent were at Lake Moondarra, Mt Isa, Qld in June The damage caused by the huge population of weevils that developed following release resulted in spectacular destruction of the mat within 15 months, reducing it to less than 1 t see Figure below. Similar successes were repeated on impoundments, billabongs, rivers, creeks and dams throughout tropical and subtropical Australia.
Biological control of salvinia in temperate areas of Australia took longer than in tropical areas, but was successful in coastal catchments in central NSW. The other candidate pest released as a potential control agent was the moth Samea multiplicalus.
It lays its eggs singly among leaf hairs and its larvae have five to seven, usually six, instars that feed on leaves under a canopy of silk and leaf hairs. When larvae are numerous they destroy most leaves and the salvinia looks very ragged. Its main hosts include S. The material imported, tested and released in Australia originated from Joinville, Santa Catarina province, Brazil. Dispersal was rapid and it caused considerable but patchy defoliation of salvinia.
Although defoliation could be severe, buds were not damaged and plants continued to grow. The success of the salvinia weevil C. It is a good example of the importance of knowing the native range of the weed.
In this case new associations biological control agents selected from other Salvinia species were not useful, whereas a useful agent was found once the native range had been defined. Adult weevils also affect plant growth by feeding on buds.
In the initial stages of weevil damage, some salvinia leaves will turn brown. As salvinia weevils continue their control efforts, the whole mat will turn brown, sink and decompose. Although effective in tropical areas, the salvinia weevil is not establishing as intensely in cooler southern areas of Queensland and may take several years to control infestations there.
Depending on infestation size and environmental conditions, time taken for weevils to control salvinia varies from 13 years. They may take more than five years to establish in cooler areas.
To ensure maximum build up, it is best to release salvinia weevils in spring. When releasing weevil-infested salvinia, it is essential to choose warm, sunny positions where a drop in water level will not leave the salvinia stranded. To establish an effective breeding population of weevils, infested plants should be placed in an area where salvinia is concentrated.
Legal requirements Salvinia molesta is a category 3 restricted invasive plant under the Biosecurity Act You must not give away, sell or release Salvinia molesta into the environment. Penalties may apply. You must take all reasonable and practical measures to minimise the biosecurity risks associated with dealing with Salvinia molesta under your control. This is called a general biosecurity obligation GBO. All other Salvinia species are prohibited invasive plants.
All sightings of other Salvinia species must be reported to Biosecurity Queensland within 24 hours of the sighting. At a local level, each local government must have a biosecurity plan that covers invasive plants in its area. This plan may include actions to be taken on Salvinia molesta. Some of these actions may be required under local laws. Contact your local government for more information. Last reviewed: 30 Sep Last updated: 6 Oct Print Page.
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