Neochetina bruchi 1, a Biological Control Agent of Waterhyacinth: Host Specificity in Argentina2

Abstract

Neochetina bruchi Hustache strongly preferred waterhyacinth, Eichhornia crassipes (Mart.) Solms., in a variety of laboratory tests. Host specificity was greatest in larval feeding and pupation, slightly less in ovipositional preference, and least in adult feeding preference and survival. Adults fed and oviposited a small amount on other members of the family Pontederiaceae, preferring Reussia rotundifolia (L.f.) Castellanos, Eichhornia azurea (Swartz) Kunth, and Pontederia lanceolata Nutt. in that order, and lesser amounts on the closely related family Commelinaceae and a few other plants that grow in the same habitat with waterhyacinth. However, larval feeding and pupation restricted N. bruchi to completing its entire life cycle on E. crassipes and probably rarely on Reussia and E. azurea, which are either noxious weeds themselves or do not occur in the United States. The small amount of feeding by adults poses no threat of damage to other plants. Neochetina bruchi is sufficiently host specific to introduce into the United States to control waterhyacinth without damage to economic plants or native vegetation.