Efficacy of microencapsulated diazinon against German cockroach Blattella germanica L.

The laboratory tests of the microencapsulated formulation of diazinon (KNOX OUT[○!R] 2FM, diazinon microcapsule) were undertaken against the German cockroach to evaluate the residual efficacy. The diazinon EC and the fenitrothion EC which have been in a practical use as the cockroach insecticides were employed as the reference. The diazinon microcapsule has been proved to be a very promising insecticide against the cockroach when the residual treatment was applied. 1. In the petri dish test, the diazinon microcapsule on plywood panels at 250 and 1,000mg of the active ingredient per m^2 showed 100% mortality of the cockroach at even 12 weeks after the treatment in 24-hr continuous contact. On the other hand, fenitrothion sprayed with 2% solution on the plywood panel showed the efficacy for only 3 weeks. 2. In the 45×45cm enclose test, the diazinon microcapsule showed more quick knock-down effect than the diazinon EC or the fenitrothion EC. The diazinon microcapsule also killed 100% cockroaches which were released 6 times repeatedly during 28 days after thetreatment. On the other hand, diazinon EC showed only 80% mortality of the cockroaches releaesd 14 days after the treatment, and the fenitrothion EC showed even less efficacy than the diazinon EC.