INFESTATIONS OF INSECT AND RODENT PESTS IN MULTIOCCUPANCY DWELLINGS IN A LONDON BOROUGH - A STUDY TO INVESTIGATE FACTORS AFFECTING CONTROL

Abstract:
Records of visits to 22,615 dwellings in the London Borough of Southwark, for period October 1993 to December 1998, were examined. Data were analysed for ghost ants (Tapinoma melanocephalum Fab.), pharaoh ants (Monomorium pharaonis L.), house mice (Mus musculus L.) and brown rats (Rattus norvegicus Berk.). Factors identified as likely to influence infestation were block size, block height, heating type, standard of hygiene, turnover of tenancies and presence or absence of children in dwellings. Control methods using approved rodenticides and insecticides were applied during the study period. Correlations were established using chi square test. Results showed that high-density infestations of ghost ant, pharaoh ant and rat were associated with smaller blocks whilst house mice were associated with large blocks. High density of ghost ant, house mouse and rat infestations were associated with district heating but pharaoh ants favoured individual heating. The trend showed that ghost ant and pharaoh ant infestations were increasing over time whilst house mouse and rat infestations remained relatively stable. There was a correlation between density and persistence of infestation. Bad hygiene and infestation of ghost ants, house mice and rats were correlated, but pharaoh ants were not. Ghost ant and pharaoh ant infestations did not show a correlation with changes in tenancies. Mice infestation correlated with tenancy changes but rat infestation correlated with no tenancy changes. Presence of children in dwellings correlated with infestation of pharaoh ants, mice and rats, but not with that of ghost ants. Environmental factors increase the problems of pest control operators controlling infestations in multi-occupancy dwellings. Some infestations persisted in blocks despite five years of intensive and targeted control measures.