The genetic characterization of catfishes by means of phenotypic markers, karyotyping, protein and DNA polymorphisms contributes to or forms an integral part of the disciplines of systematics, population genetics, quantitative genetics, biochemistry, molecular biology and aquaculture. Judged from the literature, the general approach to research is pragmatic; the Siluroidei do not include model species for fundamental genetic research. The Clariidae and the Ictaluridae represent the best studied families. The systematic status of a number of species and families has been either elucidated or confirmed by genetic approaches. Duplication of ancestral genes occurred in catfishes just as in other vertebrates. The genetic structure of and gene flow among natural populations have heen documented in relatively few cases, while the evaluation of strains for aquaculture (especially Ictaluridae and Clariidae) is in progress. The mapping of genetic markers has started in Ictalurus.It appears that a more detailed knowledge of catfish populations is required from two perspectives. First, natural populations which are threatened by habitat loss and interfluvial or intercontinental transfers are poorly characterized at the genetic level. Secondly, the selection of suitable strains for aquaculture should be encouraged. Implementation should pose no problems given the present powerful means, such as DNA characterization combined with protein polymorphisms and phenotyping, to solve the above-mentioned issues.

The struggle to control populations of organisms that feed on agricultural crops, livestock, and directly on humans is as old as recorded history, and will continue into the perceivable future. Only 30 years ago, the availability of relatively cheap and highly effective synthetic organic pesticides was thought to be the ultimate solution to pest populations. However, our naïveté regarding the ability of pest populations to rapidly adapt to simplistic man-induced selection pressures has become increasingly apparent, as have the detrimental impacts of pesticides on the environment. The evolution of the integrated pest management paradigm can be traced to these concerns, and it is now accepted that sustainable solutions to the management of pest populations will only be borne out of an increased understanding of the functioning of ecosystems. Knowledge of the population dynamics, and underlying causes of density changes in pest populations, behavioural ecology, and population genetics of pests and natural enemies, are essential elements for designing appropriate biologically intensive strategies for pest management. Progress is being made, and several examples of innovative strategies and promising areas of research, are discussed. Future work must continue to be based on a solid foundation of ecological understanding, to avoid the pitfalls of simple opportunistic solutions.