SURVEY OF HESPERIDS FOUND IN THREE AGE GROUPS OF <em>CALAMUS</em> <em>MANAN</em> PLANTED UNDER RUBBER TREES

Abstract

In the face of dwindling natural resources, rattan is slowly becoming a plantation crop. This is especially true for Calamus manan, which has been successfully planted in between rubber trees. However, systematic surveys of the associated insect fauna are few. In a study of phytophagous insects in plots of three different age-groups of C. manan planted under rubber trees, hesperid larvae were found to be the most important herbivores. Four different species, Gangara thyrsis, Erionota hiraca, Quedara monteithi and Salanoemia sala, were observed regularly, with increasing abundance in the stated order. An additional species, Zela sp. was found on a few occasions only. Abundance of G. thyrsis and E. hiraca were quite similar, while those of Q monteithi and S. sala were significantly different from the first two and from each other. Differences in abundance between the different aged plots were only significant for the two least abundant species. It was concluded that the hesperid fauna did not show any age-related differences between the plots of rattan. The dynamics of G. thyrsis, E. hiraca and Q. monteithi did not show any distinct pattern during the observation period, with only minor variation in their abundance. Salanoemia sala, while showing the same pattern in the first part of the survey, displayed a 10- to 20-fold abundance increase in one month during the second part of the survey. Possible relations with climatic data are discussed, as well as possible economic considerations. No adverse effects are expected at the current levels, but a close eye on the future development is recommended.