''Cyrtobagous salviniae'' is a species of

weevil Weevils are beetles belonging to the Taxonomic rank, superfamily Curculionoidea, known for their elongated snouts. They are usually small, less than in length, and Herbivore, herbivorous. Approximately 97,000 species of weevils are known. They b ...

known as the salvinia weevil. It is used as an agent of

biological pest control Biological control or biocontrol is a method of controlling pests, such as insects, mites, weeds, and plant diseases, using other organisms. It relies on predation, parasitism, herbivory, or other natural mechanisms, but typically also invo ...

against the noxious

aquatic plant Aquatic plants are plants that have adapted to living in aquatic environments (saltwater or freshwater). They are also referred to as hydrophytes or macrophytes to distinguish them from algae and other microphytes. A macrophyte is a plant that ...

giant salvinia ''Salvinia molesta'', commonly known as giant salvinia, or as kariba weed after it infested a large portion of Lake Kariba between Zimbabwe and Zambia, is an aquatic fern, native to south-eastern Brazil. It is a free-floating plant that does n ...

(''Salvinia molesta''). The adult weevil is about 2 millimeters long. It is brown in color during its first few days of adult life and soon turns shiny black. The female lays over 300 eggs one by one in the lower leaves and

rhizome In botany and dendrology, a rhizome (; , ) is a modified subterranean plant stem that sends out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow hori ...

s of the salvinia plant. The

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...

is white in color and about 4 millimeters long. It burrows through rhizomes and feeds voraciously on new buds, warping and stunting the plant until it eventually sinks. The larva

pupa A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their ...

tes underwater amongst the rhizomes of the plants in a cocoon it weaves from root hairs. Adults also feed on the buds and leaves of the plant, but do less damage than the larvae. This weevil is native to South America. It has been introduced to areas where giant salvinia is a problem. Early experimental successes occurred in parts of Africa and southeast Asia, and the weevil is now established in the southeastern United States and parts of Australia, along with the moth '' S. multiplicalis'', as biological control for invasive water weeds. In many cases the weevil has cleared salvina infestations by 90% or more in under one year. Entire waterways have been unclogged by the weevil's feeding. It also feeds upon ''

Salvinia minima ''Salvinia minima'' is a species of aquatic, floating fern A fern (Polypodiopsida or Polypodiophyta ) is a member of a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flower ...

'', a related aquatic weed. It is similar to the closely related ''Cyrtobagous singularis'', but the two weevil species have slightly different ecologies and ''C. singularis'' is generally an ineffective substitute for ''C. salviniae''.

References

* Coombs, E. M., et al., Eds. (2004). ''Biological Control of Invasive Plants in the United States''. Corvallis: Oregon State University Press, 175.

External links

USGS Profile

Brachycerinae Biological pest control beetles Insects used for control of invasive plants {{Curculionidae-stub