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About 130 species of parasitoids and predators are reported, most of them for the first time, to be associated directly or indirectly with the cassava pest Phenacoccus manihoti Matile-Ferrero and its parasitoid, Epidinocarsis lopezi (De Santis), newly introduced into Africa as a biological control agent. About 20 species are common. The species are grouped in 11 guilds, which include the indigenous hyperparasitoids, which originally attacked parasitoids of other mealybugs, the predators with which E. lopezi competes for the same food source and their antagonists.

The cassava mealybug, Phenacoccus manihoti Mat.-Ferr., spread in Zaire from foci at Kinshasa (1973), Mulandi (1978), and Goma (1982. It now occurs over an area of 560 000 km 2 , mainly in regions with a dry season of at least 90 days. Within these regions the pest occurs principally in areas having low green-leaf biomass towards the end of the dry season. Mealybug populations reached catastrophic levels mostly during prolonged periods of drought. The exotic parasitoid Epidinocarsis lopezi (De Santis) has spread over 130000 km 2 in western Zaire and southern Shaba, where no further mealybug outbreak has since been recorded.

Three severe outbreaks of cassava mealybug (CM), Phenacoccus manihoti, have occurred in Zaire. Two were associated with droughts. The third occurred in the driest part of the country and ended only when nearly all cassava plants had been killed. Native coccinellid predators sometimes greatly reduced CM populations, but only after the cassava crop had been heavily damaged. The exotic coccinellid Diomus sp. may be an effective biological control agent in Kinshasa, where CM on a hybrid form of cassava remained common during the rainy season. CM populations in Kinshasa declined greatly in the second year after the release of the exotic parasitoid Epidinocarsis lopezi. In one study the number of mummies with E. lopezi increased with host densities up to 20 CM per shoot tip. Since CM populations remained low after the releases of E. lopezi it is tentatively concluded that E. lopezi, despite considerable rates of hyperparasitism, prevents CM outbreaks over the whole area of its distribution (130,000 km 2 ) in western Zaire.Resume-Trois fortes pullulations de la cochenille du manioc, Phenacoccus manihoti, se sont produites au Zaire. Deux d'entre elles coinciderent avec des periodes seches. La troisieme a eu lieu dans la partie la plus aride du pays et ne prit fin qu'avec la destruction de la quasi-totalite des plantes de manioc. Les coccinellides predateurs indigenes peuvent entrainer des baisses substantielles de la population de cochenilles; toutefois, elles interviennent seulement lorsque les plantes de manioc ont deja subi de graves degats. Le coccinellide exotique Diomus sp. se presente comme un agent de lutte biologique potentiellement efficace a Kinshasa, oii les cochenilles subsistent durant toute la saison pluvieuse sur une forme hybride de manioc. On y observa un fort declin de la population de cochenilles lors de la deuxieme annee qui suivit le lacher du parasitoide Epidinocarsis lopezi. Une etude indique que le nombre de momies associees a E. lopezi augmentait jusqu'a des densites de l'ordre de 20 cochenilles par bourgeon apex. Dans la mesure ou la population de cochenilles s'est etablie a de faibles niveaux a la suite des lachers de E. lopezi, on a provisoirement tire la conclusion que malgre un taux d'hyperparasitisme eleve, E. lopezi pouvait prevenir les pullulations de cochenilles dans son aire de distribution (130,000 km 2 ) de l'ouest du Zaire.