Abstract:
Trebon' (Generic name: Etofenprox) is a recently developed potential pyrethroid
insecticide, and reported to bring about adverse effects to non-targeted organisms in
agricultural fields and associated habitats. In the present investigation, toxic effects
of Trebon' on the fingerlings of tilapia (Oreochromis mossambicuSi were studied
under laboratory conditions following standard experimentation and analytical
techniques. Results revealed that the 24-hr and 96-hr LCso of Trebon' were in low
concentration Le. 0.0657 ml L-' and 0.0087 ml L-' respectively, which is well below
its recommended field concentration of 1.5 ml L". As such Trebon' causes tilapia
fingerlings mortality at 23 times and 172 times milder concentrations than the
recommended field concentrations at 24-hr and 96-hr exposure periods. Gill
hyperplasia, deformation and telangiectasis of secondary gill lamella, mucosal cell
proliferation, lamella disorganization and fusion were observed in the test fishes.
The liver tissues were also damaged with intracellular vacuolation, aggregation of
melanomacrophages, blood congestion, and focal necrosis. The severity of these
damages increased with the level of dosage and exposure period. The fingerlings
suffered respiratory distress while the body colouration gradually changed into a
pale hue upon exposure to Trebon*.
