Tritrophic interactions between host plants, the cassava mealybug Phenacoccus manihoti Matile-Ferrero (Hom., Pseudococcidae) and its parasitoid Apoanagyrus lopezi De Santis (Hym., Encyrtidae)

The influence of the host plant on the parsitism of third instar Phenacoccu s manihoti Matile-Ferrero by Apoanagyrus (Epidinocarsis) lopezi De Santis, was investigated under laboratory conditions. Four different host plants we re used: two cassava. varieties (Incoza and Zanaga, Manihot esculenta Crant z, Euphorbiaceae), the Faux caoutchouc (FC) (a hybrid of M. esculenta and M anihot glaziovii, Euphorbiaceae) and Talinum (Talinum triangularae Jack., P ortulacaceae). The percentage of parasitism of P. manihoti by A. lopezi var ied significantly between host plants and was 1.5 to 1.8 higher on Talinum than on the plants of the Manihot genus. The parasitism on Incoza did not d iffer from the one on Zanaga but was significantly higher than that on FC. The percentage of mummified hosts also differed among the four plants and w as lower on FC (80.5%) than on the others. A significantly lower percentage of emerged parasitoids (69.5%) was recorded with the Incoza variety, which was the most resistant cassava plant. The total mealybug mortality due to parasitoid activity was significantly higher on Talinum than on the others. The results for the Manihot plants suggest that the probability of achievi ng successful augmentative biological control will be greater on the plants of the M. esculenta species despite lower A. lopezi survival on Incoza due to its high level of antibiosis resistance. Talinum would be a better host plant for a mass rearing of the host and the parasitoid in the laboratory.