The Cassava green mite,
Mononychellus tanajoa
(Bonder) (Acari: Tetranychidae), became a conspicuous pest of cassava soon after its accidental introduction into Africa in the early 1970s. It has since spread across the entire cassava belt of the continent causing and estimated 30 to 80 percent reduction in yield and threatening the food security of resource- poor farmers. Biological control, host plant resistance and cultural practices are all promising pest management interventions. The classical biological control initiative coordinated by the International Institute of Tropical Agriculture (IITA) is currently the largest single cassava green mite pest management activity in Africa. Recent successes with several exotic phytoseiid mite predators and the introduction of a virulent strain of an exotic fungal pathogen enhances the prospects for classical biological control in targeted ecologies. Evidence of moderate genetic resistance prompted an increasing number of cassava breeding programmes to screen for mite damage symptoms during germplasm selection. New varieties are now being developed and their impact on the pest evaluated on-farm. However, adoption and distribution of new cultivars continue to slow. Muti-trophic cassava agroecosystem research identified cultural practices that hinder the development of cassava green mite population. Cultivars, soil fertility, time of planting, cropping system and time of harvest all influence the build-up of damaging pest populations. Packaging and disseminating this information to extension agents and farmers remains to be done. Much of the recent plant protection effort has focused on developing technologies without appropriate diagnosis, and relatively little effort has been made to implement, evaluate and integrate these interventions in the field. New intervention technologies will be difficult to introduce where cassava is of secondary economic importance. However, as the cassava market expands, more demand will be made for appropriate cassava green mite management solutions. Integrating these interventions into a comprehensive plant protection strategy remains a challenge.
