The key to success : an investigation into oviposition of the salvinia weevil in cool climate regions

In cooler climates of Australia, where salvinia (Salvinia molesta D.S.Mitchell (Pteridophyta: Salviniales) is rapidly becoming a major problem, long-term establishment of the salvinia weevil (Cyrtobagous salviniae Calder and Sands (Coleoptera: Curculionidae)) has not yet been achieved. Biological control appears to offer the only cost-effective and long-term solution to salvinia but until the agent is successfully established, ongoing use of expensive chemical and mechanical control methods are required. The reasons that the salvinia weevil is failing to establish in cool climates are not fully understood. This paper describes preliminary studies on oviposition of the salvinia weevil at low temperatures as part of an investigation into the breeding ability of the weevil in temperate zones. The effect of air and water temperatures on the oviposition of the weevil in climate-controlled cabinets, and a glasshouse has been investigated and results are discussed. In understanding cool temperature effects on oviposition of the weevil, a significant contribution could be made towards the long-term management of salvinia in temperate climates.