''Cyrtobagous salviniae'' is a species of
weevil
Weevils are beetles belonging to the superfamily Curculionoidea, known for their elongated snouts. They are usually small, less than in length, and herbivorous. Approximately 97,000 species of weevils are known. They belong to several families, ...
known as the salvinia weevil. It is used as an agent of
biological pest control against the
noxious aquatic plant giant salvinia (''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
rhizomes 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.
...
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 thei ...
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'', 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