Impact of different densities of Neohydronomus affinis (Coleoptera:Curculionidae) on Pistia stratiotes (Araceae) under laboratory conditions

Abstract

In Senegal, a laboratory study was conducted in 2005 to ascertain the effect that different numbers of the host-specific weevil Neohydronomus affinis Hustache (Coleoptera: Curculionidae) per plant had on selected plant growth parameters of its target weed, water lettuce Pistia stratiotes Linnaeus (Araceae). Compared to the control, the weevil caused a significant reduction in all parameters measured, except for daughter plant production. There were no significant differences in impact on the plant between the three different densities of weevil (one, two and three pairs per plant). Under laboratory conditions one pair per plant is deemed sufficient to effect complete control of water lettuce over a six-week period.