LIMANARIN EFFECT IN THE CASSAVA-MEALYBUG RELATION

Cassava Manihot esculenta Crantz (Euphorbiaceae) is distinguished by t he presence of cyanid compounds in leaves, stems and tubers. In plant' s tissues, -CN group is linked with D-glucose to form cyanogenic gluco sides: mainly linamarin. In Congo, the cassava mealybug Phenacoccus ma nihoti Matile-Ferrero (Homoptera: Pseudococcidae) is the major pest of cassava. This insect is living mainly on genus Manihot. This oligopha gy of P. manihoti towards cassava suggests that the mealybug is adapte d to secondary compounds of its host plant, and more particularly to l inamarin. This specialization supposes the presence of an enzymatical fittings adjusted. In fact, our results shows that this insect has a l inamarase (participating in hydolysis of linamarin), an endogenous and an inductive enzyme in cassava mealybug. As other insects, P. manihot i has an enzymatical fittings hydolysing linamarin. In this insect, th e use of hydolysis products is discussed.