Influence, or the lack thereof, of host phenology, architecture and climate on the occurrence of Udranomia spitzi (Hesperiidae: Lepidoptera)

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AbstractThe occurrence of herbivores in nature is limited by biotic and abiotic factors which affect their development and survival. Udranomia spitzi is an endemic butterfly in the Brazilian savanna (cerrado) that feeds on young leaves of two sympatric plants, Ouratea hexasperma and O. spectabilis. It is not known which factors affect the occurrence of larvae on their hosts. Therefore, in this study we: (i) evaluated the oviposition preference of U. spitzi; (ii) evaluated the larval performance in both Ouratea species; (iii) investigated plant phenology; (iv) investigated climate (temperature and rainfall); and (v) investigated plant architecture (measured as plant height) on the abundance of skippers. Results showed that U. spitzi immatures (eggs and larvae) were far more abundant (n = 41, 96.7%) on O. spectabilis, whereas on O. hexasperma, the number of larvae was negligible (n = 1). In the laboratory, U. spitzi performed better on O. spectabilis than on O. hexasperma. The occurrence of larvae was not related to host phenology or environmental variations, but rather to plant height, since 92.7% (n = 38) of larvae were found on small O. spectabilis trees. A previous study showed that U. spitzi was not influenced by biotic factors (aggressive ants) and this study showed that plant structure plays a major role in skipper choice. The preference of U. spitzi for O. spectabilis is discussed.