Control of Avicennia germinans recruitment and survival by Junonia evaretelarvae in a disturbed mangrove forest in Colombia

In the Cienaga Grande de Santa Marta, a brackish lagoon system on the Carib bean coast of Colombia, about 60% of the mangrove forests died from hypersa linization. The die-back was first encountered in 1964 and mass mortality s tarted in the late 1960s. Although efforts are being made to reestablish th e destroyed areas, regeneration is slow, which may be partly due to Junonia evarete caterpillars defoliating Avicennia germinans seedlings. The intera ction between insects and seedlings was studied. Both J. evarete butterflie s and caterpillars were abundant during the main rainy season, the time of highest fruit production in A. germinans. During the dry season the herbivo re disappeared. The caterpillars fed exclusively on A. germinans propagules , seedlings, and pneumatophores. They preferred young seedlings to older pl ants and did not feed on trees. At some sites, 100% of the A. germinans see dlings died due to the caterpillar attack. Seedlings at open, disturbed sit es were attacked more than seedlings protected by small roofs and trenches or those under a closed canopy. Only seedlings protected by insect nets or seedlings germinating at the beginning of the dry season had good chances o f survival. The results suggest that in the highly disturbed areas of the C ienaga Grande regeneration of A. germinans is strongly inhibited by the fee ding behaviour of J. evarete caterpillars.