Original Articles
Abdelkader Harizia
Abstract
A preliminary study of the toxicity of Nerium oleander leaf extract on Apis me llifera intermissa (Buttel-Reepen , 1906) workers bee has been studied under laboratory conditions . Nerium oleander (Apocynacaea) is an ornamental shrub very common in North Africa. Studies concerni ng contact toxicity towards bees show a 100 % morta lity rate with a 25 μ g/bee dose and 8.94- μ g/bee LD 50 48 hours after treatment has started. Mortality equ als 0 with a 5- μ g/bee dose. Controls mortality rate is 3.33%.Tested doses with 10, 15 and 25- μ g/bee has the same toxicity 4, 24 and 48 hours after topical application treatment has start ed. LD 50 values are 9.26 μ g/bee 4 hours (Fig.4) after treatment has started and 8.94 μ g/bee at 24and 48 hours. These preliminary LD 50 results assess that N.oleander extract toxicity is very weak compared to dimethoate (with a 0.16-μ g-SA/bee LD 50 ) , being the reference toxic insecticide towards bees.