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Insect Communities in the Three Different Forest Habitats of Sungai Lalang Forest Reserve with Emphasis on Selected Orders of Insects
Abstract:
A study to investigate the abundance and diversity of insects in forest habitat of different age after logging was conducted in the Sungai Lalang Forest Reserve, Selangor, Malaysia. The main objective of the study was to determine the (1) dominant insect in different forest habitats, (2) biodiversity of insects, and (3) assemblage of insects that can be used as bioindicator. Three different forest habitats were selected; namely, primary forest, five-year-old logged forest, and 10-year-old logged forest.
Various trapping methods were used to collect insects; namely, pitfall trap, yellow-pan trap, malaise trap, window trap, and sticky trap. A total of 269,547 individuals comprising of 17 orders and 361 morphospecies were collected. Four major orders represented by Diptera, Hymenoptera, Collembola, and Coleoptera were recorded. The number of Diptera and Coleoptera was higher in five-year-old logged forest than in 10-year-old logged forest, while Collembola was abundant in primary forest. These results suggested that Diptera, Hymenoptera, and Coleoptera could adapt to the logged forests and they were able to utilize available resources from those forests. The richness and diversity of Hymenoptera and Coleoptera were higher in primary forest compared with the logged forests. Moreover, Collembola and Diptera had high richness and diversity index in logged forests; however, abundance, richness, and diversity of insects differ among forest habitats.
At the family level, Formicidae was the most dominant insect in the three forest habitats. Ichneumonidae, Braconidae, Phoridae, and Chrysopidae were also found in high number. The abundance of Formicidae and Ichneumonidae was higher in primary forest than in both logged forests, while Phoridae, Braconidae, and Chrysopidae was higher in 10-year-old logged forest than in primary and five-year-old logged forest.
Formicidae and Phoridae diversity and richness was higher in primary forest than both logged forests, while Braconidae and Ichneumonidae were higher in five-year old logged forest than in primary and 10-year old logged forests.
Composition of Formicidae was dominated by Pheidole sp. and Odontomachus sp. in logged forest, while primary forest was dominated by Camponotus sp. Microgastrinae subfamily (Braconidae) and Cryptinae sub-family (Ichneumonidae) were abundant in logged forest, while Orthocentrinae sub-family (Ichneumonidae) was numerous in primary forest.The phorid in the logged forest was abundantly represented by Megaselia, Woodiphora, and Puliciphora.
Of the measured habitat variables, relative humidity and litter layer were important factors affecting the abundance of Diptera, Hymenoptera, Collembola, and Coleoptera in five-year-old logged forest. In primary forest, litter layer was the most important factor affecting Collembola, Diptera, and Hymenoptera, while canopy cover was important for Coleoptera and Collembola. Environmental factors, litter layer, relative humidity, canopy cover, and understory plant could be used as potential predictor for Diptera, Hymenoptera, Collembola, and Coleoptera. Those variables, as well as temperature, light intensity, and rainfall, were significant factors for Formicidae, Phoridae, Braconidae, Ichneumonidae, and Chrysopidae.
The composition of insects was found to be different in the three study areas. The relatively high number of insect biodiversity in the logged forest was due to differences in habitat condition between logged and primary forest. The number of trees and understory plants were significantly different among habitats. Apparently, after forest logging, some undisturbed forest fragment patches contributed to the higher number of species in the logged forest. This difference was also evident in species richness, abundance, composition, and diversity that corresponded to the intensity level of logging, age of the logged forest, proximity of the other forest habitats, and the insects’ adaptability in the logged habitats.
The results presented in this study show that surveys of insects should be conducted using a wide variety of methods as possible because every method undoubtedly has at least one advantage over the other. Pitfall and yellow-pan traps collected ground insects such as Collembola and Coleoptera while malaise trap and window trap collected flying insect, particularly Hymenoptera, Diptera, and Coleoptera.
Moreover, the high abundance of Phoridae, Formicidae, Ichneumonidae, Braconidae, and Chrysopidae in all habitats, suggested that further studies should be concentrated on this group for possible useful indicator of forest condition.