[Monopolization of honeydew sources by Crematogaster macaoensis and its effects on lac production].

From October 2008 to May 2010, an investigation was made in a lac plantation in Yayi region of Mojiang County, Yunnan Province, China, aimed to understand the behavior of the monopolization of honeydew sources by ant Crematogaster macaoensis, and its effects on the sex ratio, mortality, fecundity, and lac production of Yunnan lac insect Kerria yunnanensis. The results showed that C. macaoensis fed and monopolized the honeydews around the clock during the whole life cycle of K. yunnanensis on the stick-lac, and the average number of visiting C. macaoensis ranged from 16.8 +/- 2.3 to 39.3 +/- 10.0 per 10 cm length of the stick-lac. C. macaoensis constructed shelters to prevent other animals from visiting the lac insect. C. macaoensis monopolization reduced the lac production of individual K. yunnanensi significantly, but had no significant effects on the lac production of whole lac insect colony. In addition, C. macaoensis monopolization reduced the mortality of K. yunnanensis significantly, and increased the percentage of K. yunnanensis females and the adult female fecundity. It was concluded that ant monopolization of the lac insect honeydew seemed to be beneficial to the lac production by the Yunnan lac insect.

[Coexistence mechanism of ant community in lac plantation under habitat heterogeneity].

In order to reveal the coexistence mechanism of ant community in lac plantation, an investigation was made on the ant community composition and the ability of ant species in discovering and holding food resources in a lac plantation in Yayi Town of Mojiang County, Yunnan Province, with the relationships between ant body size and its ability of finding food under habitat heterogeneity probed. There were six dominant ant species in the plantation, i. e., Tetraponera allaborans (Walker), Crematogaster macaoensis Wheeler, Crematogasterferrarii Emery, Dolichoderus thoracicus (Smith), Polyrhachis proxima Roger, and Camponotus parius Emery. The hind leg length (y) of the six ant species increased allometrically with their head width (x), and the regression equation was y = 0.56 + 1.02x + 5.97x2 - 10.85x3. Different ant species had significant differences in their actual and relative frequency in discovering food resources in different habitats, but habitat type had no significant effects on the actual frequency in holding food resources by the ant species. The ant species with bigger head width and bigger body size index could discover more food resources in simple habitat. In contrast, the ant species with smaller head width, shorter hind leg length, and smaller body size index could discover more food resources in complex habitat. The heterogeneity of habitat caused the coexistence of ants: the smaller ant species lived in complex habitat, while the larger ones lived in simple habitat. In addition, numerically dominant ant species were unable to possess all resources, and thereby, could provide the opportunity to other ant species for resources acquisition, making the species coexistence come true.