EXPERIMENTS ON THE BIOLOGICAL-CONTROL OF THE CASSAVA MEALYBUG IN GABON .1. ESTABLISHMENT, DISPERSAL OF THE EXOTIC PARASITE EPIDINOCARSIS-LOPEZI [HYM, ENCYRTIDAE] AND COMPETITIVE DISPLACEMENT OF LOCAL PARASITES

The exotic parasite, Epidinocarsis lopezi De Santis (Hymenoptera, Encyrtidae) was introduced in Gabon for the biological control of the Cassava mealybug (CM), Phenacoccus manihoti Matile-Ferrero in 1986. The establishment of the parasite after introduction, shows a speed of dispersal of 70 to 120 km/year. The parasite spread more slowly in the rain forest than in the savannah zone. Changes in the parasitization rates according to CM density shows that the parasite is capable of maintaining a percentage of parasitism of 20 to 56 % over a range of host densities of 2 to 16 parasitizable mealybugs. The establishment of the introduced parasite results in a competitive displacement of the local primary parasites and in a decline of the relative abundance of the hyperparasites in the fauna associated with the CM.