Residual efficacy of deltamethrin applied on porous and non-porous surfaces against Sitophilus granarius (L.), Plodia interpunctella (Hübner) and Blattella germanica (L.)

Residual efficacy of the insecticide deltamethrin, EC formulation with 25 g/L AI + 225 g/L PBO (synergist piperonyl butoxide), against lab populations of S. granarius and P. interpunctella by applying product water solutions (12.5 mg AI/m2) to porous surface, and against B. germanica by applying them to non-porous surface, was investigated in laboratory (at 25±1°C and 55-60% r.h.). The mortality of cockroach adults on deposits aged 0, 14, 30 and 45 days was estimated after 30 minutes of their contact with the treated surfaces, and additional 24 h and 48 h of recovery, while the mortality of stored-product insects (adults or larvae) on 0, 7, 14 and 30 days old deposits was estimated after 2, 7 and 14 days of exposure to treated surfaces and additional 7 days of recovery. Mortality of cockroaches in all variants was 100%, except on 45 days old deposit and after 24 h of recovery, when it was 97%. Deltamethrin caused 0% weevil mortality after 2 days of exposure to deposits of all ages (0-30 days), while P. interpunctella larval mortality was 87-93%. However, mortality was 100% after 7 and 14 days of weevil/moth exposure in all variants of deposit ages and/or additional 7 days of recovery. The results show that deltamethrin applied to porous and non-porous surfaces is a highly effective insecticide for weevil/moth and cockroach control, and it showed a good residual activity for up to 30 and 45 days, respectively.