RELATIVE TOXICITY AND PERSISTENCE OF PYRETHROID DEPOSITS ON DIFFERENT SURFACES FOR THE CONTROL OF PROSTEPHANUS-TRUNCATUS (HORN) AND SITOPHILUS-ZEAMAIS (MOTSCH)

Permethrin (e.c.) and deltamethrin (e.c. and s.c.) were applied at doses ranging from 0.05 to 0.5 a.i.m-2 to glass, jute, or plywood panels, or blocks of mud, and the persistence and activity against Prostephanus truncatus (Horn) and Sitophilus zeamais (Motsch.) were compared. The effectiveness of the treatments were influenced by the type of surface, the insecticide, its concentration and the age of deposits. The treated surfaces were bioassayed up to 18 weeks after initial treatment. Deltamethrin s.c. was the most effective treatment on all surfaces against both insect species. S. zeamais was less susceptible to the pyrethroids than P. truncatus.