Abstract

A search was made in Kerala for teak (Tectona grandis) clones resistant to attack by the defoliator Hyblaea puera, by examining extensive areas of plantations, natural forests and 3 seed orchards representing 31 plus trees during periods of pest outbreak. Many isolated trees were found unattacked amid totally defoliated trees. However, detailed investigations showed that this was not due to genetic resistance but to 'phenological' resistance caused by asynchrony between the flushing time of the trees and insect population cycles, so that tender foliage was not available to the pest; the variation in flushing patterns was not consistent over several years, and is, therefore, of little practical utility. During the study, evidence was obtained indicating genetic resistance of a related species, Tectona hamiltoniana, to H. puera, standard methods were developed for screening trees for defoliator resistance, and an artificial diet was developed for laboratory rearing of H. puera