Neuenschwander, P. 1996 Evaluating the efficacy of biological control of three exotic homopteran pests in tropical Africa.. Entomophaga 41: 405-424.

Notes: Proceedings of the global IOBC/OILB conference on Technology transfer in biological control. From research to practice. Montpellier, France, September 1996. Techniques for evaluating biological control of Phenacoccus manihoti, Rastrococcus invadens and Aleurodicus dispersus in tropical Africa are described. In each case, two exotic hymenopterous parasitoids were introduced, which controlled the pest species, with indigenous and exotic coccinellids playing a minor role. Control was achieved in large areas where the exotic parasitoid(s) had been present for more than 2-4 years. The impact was documented by: exclusion experiments; long-term population dynamics studies; laboratory and field experiments contributing to simulation models; and quantitative results from large-scale surveys. In many countries, the main introduced parasitoid proved to be the most important factor contributing to the decline of pest populations, and recovery of plant growth and yields. Nontarget species were only affected through reduction in their food sources. The impact was scale-neutral, benefiting subsistence and commercial farmers alike. The population reduction remained stable (in the order of 10 fold over outbreak levels). In economic terms, both the P. manihoti and R. invadens projects returned benefits to African farmers that amounted to a multiple of the research and implementation costs.