Larsicidal Activity of Tephrosia vogelii Crude Extracts on Mosquito Larval Stages.

Abstract

The use of natural products and biological insect control methods is galillng Importance because of concerns about the environment, since they are more easily biodegradable. In some parts of Uganda, orgamc famners have adopted the use of Tephrosia vogelii, a shrubby, leguminous and woody plant for control of storage pests. However, the efficacy of Tephrosia vogelii crude extracts in the control of Dipteran Insect lawae under field conditions has not been well tested. Their use for the control of insect vectors such as mosquitoes has not also been fully evaluated. Tephrosia vogelii plant materials were collected from two selected sites, one on a higher altitude than the other usl_ng polythene study. The material was chopped, properly labeled and airdried in a shade for two weeks. Four solvents where used for extraction: Water: Petroleum ether: Chloroform, Methanol. The extract was dried in an oven at about 32-330 C for several days, after which it was weighed and stored in the fridge at CFC until the time of exposing the mosquito larvae. Shoot Evening Methanol (SEM) was the most effective among methanol extracts; killing an average of 4.57 mosquito lawae in 8 min while Shoot Evening Water (SEW) was the most effective of water extracts killing an average of 2.57 mosquito lawae in 8 min; hence the SEM was considered to be nearly two times more efficacious than SEW on mosquito lawae, at a concentration of 25%: 10.8% or 2.3: I SEM: SEW, respectively. Tephrosia yogelñ crude extracts could potentially therefore be used to control the larval stages of mosquitoes. Key words: Larvicithl activity, crude extracts, mosquito, larval stage, SEW, SEM