Effects of human-induced environmental change in mangrove forests on armored scale (Coccoidea:Diaspididae) communities in Southern Thailand
2009
Numakura, Y. | Katagiri, T. | Saleekul, P. | Adati, T.
Mangroves provide for the livelihood of millions of people in the coastal area of the tropics and subtropics. They also minimize damage to property and losses of life from tsunamis and storms. Rehabilitation and conservation of mangroves have been implemented, however, influence of those human activities on mangrove ecosystem is difficult to assess and not clearly understood. Therefore, it would be useful if an ecological indicator that reflects the influence of human activities on mangroves is available. Several species of scale insects (Insecta:Coccoidea) are known to occur frequently in urban environment or artificially disturbed conditions. In earlier studies, they have been used as indicators for urbanization. Armored scales (Diaspididae), in particular, would be environmental indicators for mangroves due to their specific morphology and sedentary lifestyle. In the present study, the distribution and population constitution of three genera of armored scales Aulacaspis, Fiorinia, Lepidosaphes on mangroves were assessed in three experimental sites, which differ in human-induced environmental factors, in southern Thailand. A highly infested zone (HIZ) was defined as a series of some mangrove species with less than 10 m intervals, including any trees infested by any one of three armored scale genera with an average population more than 5 individuals in a 50 cm piece from a sampled branch. No HIZ of Aulacaspis were found in Site 1, which was a natural forest with few human's visits, while they were found in Site 2, which was a natural forest with frequent human's visit and in Site 3, which was an artificial forest. On the other hand, HIZs of Fiorinia and Lepidosaphes were found only in Site 1 and 2, but not in Site 3. Such difference in the distribution pattern between three armored scale genera seems to be useful as an indicator for human-induced environmental change in mangrove forests.
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