Establishment and spread of Typhlodromalus manihoti (Acari : Phytoseiidae), an introduced phytoseiid predator of Mononychellus tanajoa (Acari : Tetranychidae) in Africa

The phytoseiid predator Typhlodromalus manihoti Moraes was introduced into the cassava belt of Africa from South America against the exotic mite pest Mononychellus tanajoa (Bondar) beginning in 1988. The 1st population to bec ome established was released in 1989. Establishments are now found in Benin , Burundi, Ghana, and Nigeria where they cover an area estimated at +300 km (2). T. manihoti dispersed at a rate of 3.3 km/yr, spreading 5 times faster during the dry compared with the wet season and in proportion to the frequ ency of surrounding cassava fields. Populations of T. manihoti fluctuated w ith the seasonal abundance of M. tanajoa. Established populations of T. man ihoti comprised a quarter of the phytoseiids found on cassava with a higher proportion present during the dry season. T. manihoti was recovered from 1 2 species of plants including 5 Euphorbiaceae in addition to cassava. Evide nce of T. manihoti establishment in only part of the cassava belt suggests the search for other natural enemies of M. tanajoa in Africa should continu e.