Effect of pH and type of formulation on the persistence of imidacloprid in water.

Imidacloprid [ 1-[(6-Chloro-3-Pyridinyl) methyl ]N-nitro -2Imidazolidinimine] is a newly introduced broad spectrum systemic insecticide in the Indian subcontinent by M/s. Bayer India Ltd.. This new chloronicotinyl compound is fairly soluble in water as compared to other non-polar insecticides (Kagabu 1997). It is effective against sucking insects, soil insects, termites and some species of chewing insects and is used as seed dressing, soil treatments and foliar treatment in different crop (Tomlin 1994). Some information regarding the fate of imidacloprid in soil are available (Cox et al. 1997; Rouchaud et al. 1994; 1996 ). Photolysis of the insecticide in aqueous solution was reported by Moza et al. (1998). But little is known about its persistence behaviour in water. The objective of the present investigation is to evaluate the effect of pH of water as well as the type of formulations on the persistence behaviour of imidacloprid in aqueous solution.