www.tjprc.org editor@tjprc.org EVALUATION OF ACUTE TOXICITY OF THIAMETHOXAM IN ALGERIAN HONEYBEE APIS MELLIFERA INTERMISSA AND APIS MELLIFERA SAHARIENSIS NORA CHAHBAR 1 , MOHAMED CHAHBAR 2 & SALAHEDDINE DOUMANDJI 3 1 Département de Biologie, Faculté des Sciences, Université M’Hamed Bougara, Boumerdes, Algérie 2,3 Département de Zoologie Agricole et Forestière, Ecole Nationale Supérieure Agronomique El-Harrach, Alger, Algérie ABSTRACT Thiamethoxam [3-(2-chlorine-1, 3-thiazole-5-ylmethyl)-5-methyl-1,3,5-oxadiazinan-4-ylidene(nitro) amine], a systemic insecticide of the group of neonicotinoids with a large spectrum of action at low concentrations. It is used in the control of sucking insects and some chewing species, because of its excellent absorption and translocation in plants. The acute toxicity of contact and oral applications on two Apis mellifera subspecies, Apis mellifera intermissa and Apis mellifera sahariensis was investigated. In all toxicological studies, each dose included three cages of 20 individuals and each study was replicated three times. The dose–mortality relation revealed directly proportional relationship between the administered dose of thiamethoxam and mortality observed. The mortality is reached maximum at 24 hours after treatment with doses above 50 ng / bee after oral application. Response kinetics showed classic kinetics. The higher the dose of thiamethoxam and faster is high mortality appears. After oral intoxication, the LD50 values of thiamethoxam at 24h were about 12,3 ng/bee for A. m. intermissa and 13.3 ng/bee for A. m. sahariensis. After contact application, the LD50 values at 24 h were approximately 26 ng/bee for A. m. intermissa and 43.3 ng/bee for A. m. sahariensis. KEYWORDS: Thiamethoxam, Apis mellifera intermissa, Apis mellifera sahariensis, Honeybees, Lethal Dose, Acute Toxicity INTRODUCTION The place of bees in the environment has many aspects; agronomic, economic, ecological and scientific. It plays an important economic role as a carrier of beekeeping (honey, royal jelly, pollen, propolis and wax) and agriculture by providing a quantitative and qualitative increase crop (Vaissiere 2002; Haubruge et al., 2006; Breeze et al, 2011). With its complex social behavior, the honeybee is one of the best scientific models to study the learning functions, memory and orientation, particularly in the activity of chiseling. In addition, an ecological point of view, this is a useful insect bio- indicator of high environmental sensitivity because it is in contact with pollutants from various sources (Kevan, 1999). Bees can get in contact with pesticides when foraging in treated crops. Of weakening phenomena apiaries with a decrease in activity without the observation of pathogens (Faucon & Colin, 1983). In Algeria, for ten years, beekeepers observed serious disturbances in their colonies and highlight the responsibility of some insecticides used in crop protection. Indeed, many beekeepers indicate a weakening or even a total depopulation of the hive. This may be due to alterations in the nervous system of bees, especially since 90% of the insecticides used in agricultural and forest areas have neurotoxic properties. Thiamethoxam is the first representative of the second generation neonicotinoid and belongs to the subclass of thianicotinyls (Maienfisch et al., 1999). It has exceptional systemic features International Journal of Zoology and Research (IJZR) ISSN(P): 2278-8816; ISSN(E): 2278-8824 Vol. 5, Issue 1, Feb 2015, 43-54 © TJPRC Pvt. Ltd.