Diversity and microhabitat preferences of odonates larvae

Abstract

The order Odonata, is one of the most well-known and well documented insects for its adult stage, but the larval stage remain poorly known. This study was conducted three states namely Terengganu, Johor and Pahang, aimed to investigate the diversity of odonate (Order: Odonata) larvae and their microhabitat preferences. A rich collection of 301 individuals belonging to 55 genus from 15 families of Odonata were successfully recorded from twenty microhabitats selected, from August 2007 until January 2008. Anisopterans (239 individuals) were found to be more abundant than zygopterans (62 individuals), with Libellulidae (suborder Anisoptera) made up the most dominant family collected with 49.2% of total individuals recorded. Zygonyx sp. and Neurothemis sp. were found to be the most abundant species recorded in this study. More individuals were collected from freshwater inland and peat swamp than stream. Root of vegetation I (MH4) and riparian vegetation II (MH12) had showed the highest diversity and species richness of odonates larvae compared to other microhabitats. Kruskal-Wallis analysis showed that all microhabitats had significant differences based on sites and the total number of individuals (K=0.041, P<0.05) as well as between sites and the total number of families (K=0.025, P<0.05). By using Spearman Correlation analysis, dissolved oxygen (DO) and pH are positively correlated (r2=0.713, r2=0.653, P>0.05) with the number of individual collected while water temperature was negatively correlated (r2=-0.575, P<0.05). The microhabitats were also clustered according to their value of Sorensen's Coefficient of similarity using Unweighted Pair Group Method with Arithmetic averages (UPGMA) method. Rantau Abang estuarine (MH18) show no similarity to all microhabitats, while MH4 and MH8 show the highest similarity between them. This study findings show the freshwater and peat swamps support richer diversity of odonates larvae and more preferred microhabitat than riverine ecosystem.