Phitaya Chuailua

Dispersal of Aglaia spectabilis , a large-seeded tree species in a moist evergreen forest in Thailand

We investigated the seed dispersal of Aglaia spectabilis , a large-seeded tree species in a moist evergreen forest of Khao Yai National Park in Thailand. Although one-to-one relationships between frugivores and plants are very unlikely, large-seeded plants having to rely on few large frugivores and therefore on limited disperser assemblages, might be vulnerable to extinction. We assessed both the frugivore assemblages foraging on arillate seeds of Aglaia spectabilis and dispersing them and the seed predator assemblages, thereby covering dispersal as well as the post-dispersal aspects such as seed predation. Our results showed that frugivores dispersing seeds were a rather limited set of four hornbill and one pigeon species, whereas two squirrel species were not dispersers, but dropped the seeds on the ground. Three mammal species were identified as seed predators on the forest floor. Heavy seed predation by mammals together with high seed removal rates, short visiting times and regurgitation of intact seeds by mainly hornbills lead us to the conclusion that hornbills show high effectiveness in dispersal of this tree species.

Dispersal of Canarium euphyllum (Burseraceae), a large-seeded tree species, in a moist evergreen forest in Thailand

We investigated the dispersal of a large-seeded tree species, Canarium euphyllum (Burseraceae), in the moist evergreen forests of the Khao Yai National Park in Thailand. By combining direct observations of fruit consumption in tree canopies (543 h) and the camera-trapping observations of fallen fruit consumption on the forest floor (175 camera-days), we identified the frugivore assemblage that foraged on the fruits of C. euphyllum and assessed their role in seed dispersal and seed predation. In the canopy, our results showed that seeds were dispersed by a limited set of frugivores, one pigeon and four hornbill species, and predated by two species of squirrel. On the forest floor, seven mammal species consumed fallen fruits. A combination of high rates of fruit removal and short visiting times of mountain imperial pigeons (Ducula badia) and hornbills (Buceros bicornis, Aceros undulatus, Anorrhinus austeni and Anthracoceros albirostris) led us to conclude that these large frugivorous birds provide effective seed dispersal for this tree species, in terms of quantity. These frugivorous species often have low tolerance to negative human impacts and loss of these dispersers would have severe deleterious consequences for the successful regeneration of C. euphyllum.

Pattern and impact of hornbill seed dispersal at nest trees in a moist evergreen forest in Thailand

Following the entire process of frugivore seed dispersal, from intake of seeds to seed deposition, is a difficult task. One alternative is to monitor areas of heavy seed rain deposited by animals. We quantified the number of seeds deposited by hornbills and followed the fates of these seedlings for 3 y to evaluate the effectiveness of hornbill seed dispersal at nest trees, on the basis of seedling survival. For 14 mo, fallen fruits and seeds were collected in traps established around four nest trees of each of two hornbill species ( Aceros undulatus and Anthracoceros albirostris ) and the seedlings were monitored in adjacent quadrats. Seedfall and seedlings of species represented in hornbill diets occurred at significantly higher densities in the traps/quadrats in front of nest cavities than in other traps/quadrats. Fewer seedling species and individuals germinated under nest trees than expected from the composition of the seedfall. Our results suggest that the quality of hornbill seed dispersal might be poor at nest trees due to the highly concentrated seedfall, which results in high seed and seedling mortality. Although seed deposition at nest trees is a useful guide to hornbill diet during the breeding season, it is clearly not of benefit to the plants involved. However, the pattern and consequences of hornbill seed dispersal at nest sites is likely very different from that during the non-breeding season.

Characteristics of hornbill-dispersed fruits in a tropical seasonal forest in Thailand

Asian hornbills are primarily frugivorous. We studied the characteristics of fruits consumed by four sympatric hornbill species in Thailand: Great Hornbill ( Buceros bicornis ), Wreathed Hornbill ( Aceros undulatus ), Austins Brown Hornbill ( Anorrhinus austeni ) and Oriental Pied Hornbill ( Anthracoceros albirostris ). We compared the frequency of distribution of 11 variables for all fruit species collected in the study area ( n = 259) and fruit species consumed by hornbills ( n = 73). Our analysis revealed that fruits consumed by hornbills are: (1) large, (2) easily accessible within the canopy, (3) red, purple or black and (4) dehiscent or indehiscent with a thin husk. The range of fruit sizes eaten by hornbills in our study is comparable to that reported from other sites in Southeast Asia and Africa. The large gape width of hornbills enables them to consume large fruits that small frugivores would find difficult to consume.

Cytotoxic Activities of Trichothecenes Isolated from an Endophytic Fungus Belonging to Order Hypocreales

Bioassay-guided fractionation of the extract of the endophytic fungus KLAR 5 belonging to order Hypocreales, which was isolated from the twig of Knema laurina (Blume) Warb., resulted in the isolation of brefeldin A (1), 8-deoxy-trichothecin (2), trichothecolone (3), 7α-hydroxytrichodermol (4), and 7α-hydroxyscirpene (5). Compound 5 was isolated from natural source for the first time. Compound 1 was very highly active against human epidermoid carcinoma of the mouth, human breast cancer (BC-1), and human small cell lung cancer (NCI-H187) cells whereas compounds 2 and 4 were selectively active against BC-1 and NCI-H187 cells. Compounds 3 and 5 were moderately active against these three cancer cell lines.