Aquatic Plant Control Research Program: Host Specificity and Biology of the Weevil Neohydronomus pulchellus Hustache, Biological Control Agent of Waterlettuce (Pistia stratiotes L.) in Florida

摘要

Waterlettuce continues to be a problem plant in Florida waterways where it interfers with recreation and irrigation, impedes water flow, and causes water loss through transpiration. The roots of waterlettuce host several species of mosquito larvae, some species of which are vectors of disease. There is concern that current declines in waterhyacinth populations will be followed by a resurgence in waterlettuce populations. Although some native natural enemies of waterlettuce have been found in Florida, these are not effective in controlling the weed. Waterlettuce has been successfully controlled in Australia with a weevil, Neohydronomus pulchellus Hustache, imported from South America. In the study reported herein, the weevil was imported from Australia and tested in quarantine against 34 plant species in 27 families in non-replicated no-choice tests. Plants on which the weevils fed or oviposited during this test were retested in a replicated choice test. The few plants fed or oviposited upon by the weevils during this project were non-economic plant species generally considered undesirable by aquatic plant managers. The tests indicated that the weevils are sufficiently host-specific to waterlettuce and are unable to complete development on any other plant. Keywords: Biological weed control; Aquatic weeds. (kt)