Populations of Hyptis suaveolens (L.) Poit. (Labiatae) were accompanied during their development in three sites: Horto Florestal de Sumaré, Campus of UNICAMP (Campinas), and Fazenda Santa Genebra (Distrito de Barão Geraldo, Campinas), all in the State of São Paulo, Brazil, from 1981 through 1983. At each site, a population exposed to full sunlight and another in the shade were studied. The objective was to evaluate, during plant development, the period when they were more susceptible to attack by herbivores; to consider the abundance of herbivores, and the role of variation in the chemistry of monoterpenes in the development of herbivores. Populations were more susceptible to attack by herbivores in the period preceding flowering. Heavy herbivore damage was not detected during this period, in spite of higher herbivore densities. The results suggest that the variation in chemical composition probably has an effect on the development of generalist herbivores. On the other hand, Pyrausta insignatalis Guenée (Lep.-Pyralidae-Pyraustinae) is probably well adapted to the plant and appears to be resistent to the terpenes. Differences in chemistry and differences in protection against herbivores were not observed between populations in sunny and shady sites. The results support an important role for genetic variability in populations in protection against herbivory and inhibition of specialization.
Hyptis suaveolens; herbivory; genetic variability