Development and Laboratory Evaluation of a Slow Release Formulation of Fipronil against Subterranean Termites (Odontotermes obesus Rambur)

Subterranean termites Odontotermes obesus (Isoptera: Termitidae) are economically important agricultural and structural pests. A wide range of insecticides with different modes of action are being used against these termite pests including organochlorines, organophosphates and pyrethroids. However, pesticidal control of termites is usually not persistent and long-lasting due to rapid decomposition and loss of insecticidal molecules active against target pests. This study was aimed to develop and evaluate a slow-release formulation (SRF) of a persistent insecticide (fipronil) against O. obesus. Technical grade insecticide fipronil was applied in the form of cellulose-made pellets made up of compressed powdered sugarcane (Saccharum officinarum L.) bagasse and maize (Zea mays L.) cobs. This pellet formulation was evaluated against worker individuals of O. obesus under laboratory conditions using soil macrocosms. Mortality of termites was determined at different time intervals after their exposure to formulated pellets treated macrocosm soils. Results revealed that fipronil formulated with Z. mays substrate remained more effective for longer period of time against subterranean termites as compared to that formulated with S. officinarum bagasse material. The maximum mortality of termites was observed at 15 days of treatment application in T3MPF (maize cob powder plus fipronil) treatment after 48 h of bioassay. It was concluded that fipronil can be used as a slow acting toxicantby formulating it with some cellulose-based material such as powdered maize cobs in order to attract and killthe subterranean termites.