Abstract:
Odonata has long been studied as an insect order that plays an important role in the balance of
aquatic environment. The order represents one set of insects that is potential in indicating
environmental quality. In this study, the species diversity and distribution of Odonata in selected
river systems of North Cotabato, Mindanao, Philippines was assessed. Four rivers were sampled
in the study: Mirasol River in Alamada and Nicaan River in Libungan which are relatively
disturbed and Raradangan River in Alamada and Kimarayag River in Pigcawayan which are
relatively undisturbed. Opportunistic sampling was employed through sweep netting in visual
encounter surveys. The association of environmental factors to species distribution was evaluated
using Canonical Correspondence Analysis (CCA).Geographic Information System (GIS) was
used to create a distribution map of Odonata species in the sampling sites. Fifteen species
belonging to five families were recorded of which four (26.67%) species are Philippine endemic.
High species diversity (H’=2.13) was recorded in Raradangan River (Site 1). Kimarayag River
(Site 4) is considered high in diversity (H’=2.02) next to site 1. Moreover, Sites 2, Mirasol River
(H’=1.62) and site 3, Nicaan River exhibited moderate diversity (H’=1.53) inspite of the human
disturbances. The Oriental species, Pseudagrion p. pilidorsum (Brauer) is the most abundant
distributed in all sampling sites. The values for all the parameters (water temperature, pH,
dissolved oxygen and relative humidity) in all sampling sites are within the Philippine standard
of water quality. Eight species were identified to be affected by high dissolved oxygen, three
species were positively affected by relative humidity, and four species were found to have
tolerance to change in water temperature. GIS mapping clearly showed spatial aggregation of
species within the surrounding habitat. Results indicate that Odonata appears to be associated
with habitat variables.
