A RAPID AND EASY BIOASSAY METHOD FOR STINGLESS BEES TETRAGONULA TRAVANCORICA SHANAS AND FASEEH

Abstract

An attempt was made to develop an effective bioassay method for toxicological studies for the stingless bee, Tetragonula travancorica Shanas and Faseeh. The developed bioassay employed stingless bees sampled from the forest area with no history of past insecticide exposure and vegetable ecosystem having frequeninsecticide exposure with insecticides viz., chlorantraniliprole and thiamethoxam. A residual film bioassay using pre-treated conical flasks and transferring the bees to the treated flasks in the field itself was easy and less time-consuming. Stingless bees survived for 12 hours in the control flasks with the bioassay method III. Whereas mortality was significantly low in bioassay method I and II within 3h and 6h, respectivelyChlorantraniliprole was less toxic (LC50 – 10.98 ppm to 17.30 ppm) to stingless bees than thiamethoxam (LC50 – 0.30 ppm to 0.78 ppm). Thiamethoxam was highly toxic (LC50 – 0.30 ppm to 0.37 ppm) to bees from the forest ecosystem, whereas bees in the vegetable ecosystem were more tolerant (LC50 – 0.67 ppm to 0.78 ppm). The findings may help carry out ecotoxicology and risk assessment studies in stingless beesa key pollinator of many crops, more rapidly and easily.