Laboratory evaluation of organophosphates as termiticides
K Tsunoda, K Nishimoto
In accordance with Japan Wood Preserving Association Standard 11(1) laboratory evaluations of five organophosphate insecticides and chlordane were conducted. Superficially treated sapwood of Pinus densiflora Sieb. et Zucc. (10 x 10 x 20 mm³) was compulsorily exposed to the attacks of 150 workers and 15 soldiers of Coptotermes formosanus Shiraki for 21 days at 28±2°C in the dark. Percentage weight loss of the wood blocks was determined at the end of the test. Termite mortality was additionally calculated at regular intervals. Of five organophosphate insecticides evaluated, chlorpyrifos and phoxim were the most effective and were followed by acephate and tetrachlorvinphos. Required treating concentrations were < 0.1% for chlorpyrifos, phoxim and tetrachlorovinphos, 0.1-0.2% for acephate and 0.2-0.4% for fenitrothion. For chlordane 0.5-1.0% was desired. Results based on the percentage weight loss indicated that organophosphates were generally more effective than chlordane in controlling termites. It is, therefore, worthy to take up potential chemicals for further investigation.
Keywords: TERMITICIDES; ORGANOPHOSPHATES; CHLORPYRIFOS; FENITROTHION; PHOXIM; ACEPHATE; TETRACHLORVINPHOS; CHEMICAL STRUCTURE; COPTOTERMES FORMOSANUS; MORTALITY; TESTING; WEIGHT LOSS