MYRMECOPHILONS FUNCTION OF CECROPIA OBTUS E TRECUL (CECROPIACEAE) IN FRENCH-GUIANA

Cecropia obtusa Trecul is a myrmecophytic plant associated in a strict relation with the ants Azteca (A. alfari Emery and A. traili Emery). The ants inhabit the internodes of the tree and leed on nutritive bodi es or mullerian bodies. These multicellular corpuscles are produced on the abaxial face of the base of the petiole. This region is covered w ith a velutinous mat of multicellular but uniseried trichomes called t richilium. The production activity of mullerian bodies and the activit y of the ants are synchronous: three hours before the sundown. A Phyci tinae caterpillar may occupy the Cecropia internodes and consumes mull erian bodies exclusively. A fungus, Fusanum moniliforme, grows on the trichilium in the absence of ants. The distribution of Cecropia obtsua is homogeneous in space and time but its growth is under control of t opographic, edaphic and climatic factors. The comparison between trees occupied by ants and inoccupied ones shows that these last ones grow less quickly and that the mullerian production is smaller. Cecropia tr ees cultivated in greenhouse show the same behaviour than inoccupied o nes in the field with, however, a greater production rate of mullerian bodies. When caterpillars inhabit the plant the production of mulleri an bodies is higher than in the case of inoccupied Cecropia. The part of ants and caterpillars in the plant growth and mullerian bodies prod uction is discussed. The partial chimical analyze of food bodies shows a clear dominance oi glycogen which add simple sugars, lipids, protei ns and C and E vitamins. The differences between the guiana food bodie s and mullerian bodies producted in greenhouse are discussed. The hist ological and cytological studies of mullerian body place in a prominen t position its development and the origin of the principal synthetized substances which have a trophic part for ants and caterpillars.