LIMITS OF INSECTICIDE COCKROACH CONTROL IN COUNCIL FLATS IN FRANCE

The aim of our study was to analyse the results of controlled series o f professional insecticide treatments on feral cockroach populations i n council flats in three similar multi-family buildings, and to try to understand why control success could be so low. Cockroach abundance a nd six general environmental characteristics were recorded after each treatment for each flat treated. Cockroach abundance was divided into five levels. The environmental characteristics recorded for each flat were: nationality of residents, duration of occupation, number of resi dents/m(2), application of domestic pesticides, reactions of residents to the presence of cockroaches, and degree of cleanliness. This serie s of treatments, proposed every two months, did not improve the situat ion as greatly as expected. The presence or the absence of cockroaches in flats can be explained at least partly by some environmental facto rs like human density in the flat, building effect and cleanliness, bu t no single factor explains the size of the cockroach population. The usual reasons evoked to explain pest control failures, such as cockroa ch insecticide resistance, inefficiency of treatments due to formulati on, proportion of constituent in compound, periodicity of application, etc., all influence the result of a treatment, of course, but our dat a show that the part played by the residents in a given dwelling has b een greatly underestimated so far. When the results of treatments were analysed, the results depended largely on the residents' attitude. (C ) 1995 Academic Press Limited