Cellular composition of the Corpus luteum of Indian fruit bat, Rousettus leschenaulti (Desmarest) during early embryonic development

The fine structure of luteal cell of the corpus luteum of Indian fruit bat, Rousettus leschenaulti was studied at three stages unilaminar blastocyst stage, Implanted bilaminar blastocyst stage and limb bud stage of early pregnancy. At unilaminar blastocyst stage luteal cells had small nuclei euchromatin. Mitochondria were small, round shaped with tubular cristae. Numerous less osmiophilic lipid droplets were observed in cytoplasmic field of the luteal cells. After implantation at implanted bilaminar blastocyst stage nuclear heterochromatin were reduced and nucleoli were larger and complex. Mitochondria were enlarged and often bizarre shaped with tubular cristae. Golgi complex and agranular endoplasmic reticulum were more conspicuous. Lipid droplets were less osmiophilic. At the stage of limb bud formation the luteal cells suggests different morphological picture, the nuclear size is reduced with clumps of heterochromatin. The agranular endoplasmic reticulum assumes the form of bundles of parallel tubules dispersed in several planes. Mitochondrial size was reduced then the previous stage and they posses vesicular cristae. These observations suggest that the steroidogenic activity of the luteal cells is highest during implantation and comparatively regresses during limb bud formation. It is suggested that the luteal cells is an important ovarian source of pregnancy hormones.

Seed dispersal of Syzygium oblatum (Myrtaceae) by two species of fruit bat (Cynopterus sphinx and Rousettus leschenaulti) in South-West China

In this study we investigated the importance of two species of fruit bat (Rousettus leschenaulti and Cynopterus sphinx) as seed dispersers for a species of fruit tree (Syzygium oblatum) found in the Xishuangbanna Tropical Botanical Garden in South-West China. We found that although R. leschenaulti and C. sphinx were the two primary seed dispersers of S. oblatum over half of the fruit produced by the tree (65%) fell to the ground. Out of the fruit collected, R. leschenaulti and C. sphinx were able to disperse seeds up to 73 m from the parent tree with the highest density of feeding roosts occurring at 21.3 m (SE = 5.2 m). We found no signs that either species of bat used the parent tree as a feeding roost, instead choosing specific trees that were at lower densities compared with other trees in the forest that were not used. When comparing the viability of seeds in three different habitats (under parent tree, in forest gap, under feeding roost) survival analysis revealed that seedling survival was significantly higher in the forest gap (91.7% ± 4.41%) than under the parent tree (78.3% ± 1.67%), but was not significantly different to seedling survival underneath feeding roosts (86.7 ± 1.67%). Further work also showed that the seeds did not have to be removed from the fruit or ingested by the bat in order to germinate. We conclude that although S. oblatum is not dependent on R. leschenaulti and C. sphinx for successful germination of its seeds, these two species of bat are important seed dispersers and can move seeds to areas where there is a greater chance of germination success and survival.

Foraging areas of Rousettus leschenaulti on the Hainan Island of China

We investigated the foraging area of three individuals (1 female and 2 males) of Rousettus leschenaulti (Chiroptera, Pteropodidae) in suburban Haikou City, Hainan Province, South China from November 2005 to January 2006 using radio telemetry. These animals left the daytime roosting sites about 90 min after sunset with no significant difference in departure time between the male and female bats. The average active times were 391.8 min for males and 533.7 min for the female, respectively. By reconstructing 93 radio-telemetry recording positions, we found that the long axis of foraging area of the bats ranged from 7.45 to 11.70 km. The foraging area of the female (3867 ha) was larger than that of the males (1138 ha), and there was overlap between the foraging areas of different individuals. These bats usually kept the same flight routes across a few successive days from the daytime roosting site to the foraging areas. Our findings suggested that female R. leschenaulti may explore a larger foraging area than males. No obvious territorial behaviors were observed in our studied area.