Control of Culex quinquefasciatus in pit latrines, using shredded, waste polystyrene

As an alternative to the use of commercially available, expanded-polystyrene beads, a study was made of the effectiveness of shredded, waste polystyrene (SWAP) for the control of Culex quinquefasciatus. The relevant physical properties of the SWAP were first investigated in the laboratory. Then, under field conditions in wet pit latrines, mosquito emergence rates were measured before and after application of the material. In the laboratory, when compared with the commercial product, the irregular shape of the SWAP particles greatly reduced their capacity to spread over the water surface and the interstitial air spaces also permitted respiration and development of mosquito larvae. Nevertheless, under field conditions, with careful application of the SWAP over the water surfaces in wet pit latrines, almost complete control of mosquito breeding was observed within a few days. This was sustained for 60 days, at which time observations were discontinued. SWAP appears to offer an effective, cheap and readily available alternative to the commercial product for the control of C. quinquefasciatus. The practicality of using it in community-based, mosquito-control programmes warrants further study.