EFFECT OF SWEET-POTATO LATEX ON SWEET-POTATO WEEVIL (COLEOPTERA, CURCULIONIDAE) FEEDING AND OVIPOSITION

Latex in some laticiferous plants acts as a natural defense system aga inst certain herbivores. The potential of lates produced by the sweetp otato as a defense mechanism against the sweetpotato weevil, Cylas for micarius (F.) was investigated. Genetic and environmental differences were found in latex production in a broad cross section of sweetpotato germplasm (96 lines). Most Lines produced 2.6-10 mg fresh weight x vi ne(-1) of latex when the 2nd internode from the apex was severed. Some lines, however, produced more, the highest being 48.3 mg x vine(-1). Young vine material produced more latex and had less weevil feeding da mage than older more mature portions of the vine. Application of latex to the surface of root cores reduced feeding and oviposition. Additio n of latex to a semi-artificial media also significantly reduced the n umber of feeding punctures. Leaf feeding location (veins) and directio n (basipetal), however, were not indicative of a major deterrent role for latex against the sweetpotato weevil.