GLANDULAR TRICHOMES ON THE EXOTIC SOLANUM-SISYMBRIIFOLIUM LAMARCK (SOLANACEAE) - EFFECTIVE DETERRENTS AGAINST AN INDIGENOUS SOUTH-AFRICAN HERBIVORE

An examination of the leaves of several native and exotic Solanum spec ies revealed that they all possessed glandular and non-glandular trich omes. The density of glandular trichomes was, however, very much lower on the leaves of the indigenous species than on the leaves of a weed species, Solanum sisymbriifolium Lamarck, and two other South American Solanum species. This difference could have contributed to the depaup erate faunas supported by the exotic species. The morphology and behav iour of an indigenous Solanum-feeding tortoise beetle, Conchyloctenia tigrina Oliver (Coleoptera: Chrysomelidae), and a South American torto ise beetle, Gratiana spadicea (Klug) (Coleoptera: Chrysomelidae), were compared. The study revealed that while the exudate produced by the g landular trichomes afforded S. sisymbriifolium a level of resistance t o C. tigrina, it is probably only one of the factors limiting the recr uitment of indigenous herbivores onto S. sisymbriifolium.