Abstract

We made a search in Kerala, India for teak (Tectona grandis) trees resistant to attack from the defoliator, Hyblaea puera, by surveying extensive areas of plantations, clonal seed orchards and natural forests, during periods of defoliator outbreak. Although we found many isolated trees which remained unattacked amidst totally defoliated trees, detailed investigations revealed that this was not due to genetic resistance, but to what may be called 'phenological resistance'. Phenological resistance is defined as resistance caused by phenological reasons, in this case, early or late flushing in comparison to surrounding trees. Although older larvae can feed on mature leaves, as moths lay eggs only on tender leaves, trees with mature leaves are left unattacked, giving the impression of resistance. Due to asynchrony between the flushing time of trees and insect population cycles, different trees escape defoliation at different times, and may appear as resistant. Early flushers