Abdul N.H., Rawi Che S.Md., Ahmad A.H., Al-Shami S.A.: Effect of environmental disturbances on Odonata assemblages along a tropical polluted river. Ekológia (Bratislava), Vol. 36, No. 4, p. 388-402, 2017. Odonata larvae have been intensively used as bioindicators for freshwater pollution as their community structure closely follow changes in the environment and habitat settings. In this study, 28 taxa of Odonata larvae were collected from three stations (upper, middle and lower) of a polluted river in Malaysia. The upper river basin receives effluents from an oil palm plantation. However, the middle station is presumably contaminated with anthropogenic wastes. The lower station is found to receive polluted discharges from aquaculture outlet. Several environmental parameters of water and sediment were continuously measured during the study. The water parameters showed no significant differences amongst the three stations. The species richness of Odonata was 22, 24 and 20 in the upper, middle and lower stations, respectively. The abundance of Odonata was significantly different among the studied sites. The tolerant damselfly, Pseudagrion sp. (41.22%), and facultative dragonflies, Onychothemis sp. (17.12%), were the most dominant taxa along the river stations. Onychothemis sp. and Paragomphus capricornis were equally important at the upper station [Important Species Index (ISI) 25.3 and 24.2%, respectively]. Pseudagrion sp. only scored an ISI value of 9.7%. Pseudagrion sp., P. capricornis and Onychothemis sp. were dominant in the middle station (ISI: 41.2%, 25.9% and 10.9% respectively), and Pseudagrion sp., Onychothemis sp. and Prodasineura sp. dominated the areas with dense growth of submerged aquatic weeds Hydrilla sp. in the lower station (ISI: 47.9, 24.5 and 13.8%, respectively). On the basis of the variations in larval abundance and ISI values, microhabitats differences partly in response to different types of pollutions entering the water structured the Odonata communities in this river basin.

Highlights • Different patterns of FFG distribution reflect the habitat conditions of the river. • Predators, mainly Odonata, Hemiptera and Coleoptera, were the most common group in middle reach of Kerian River Basin.

The loss of aquatic biodiversity in tropical streams of SE Asia is evident due to increasing anthropogenic activities. Therefore, there is a necessity for immediate and feasible conservation plans. Effective conservation planning depends on successful application of surrogate groups. However, progress of this approach is hindered by the paucity of relevant reports based on cross-taxon congruence analysis. In this study, we investigated congruence patterns among aquatic groups (Plecoptera, Trichoptera, Ephemeroptera, Odonata and fish) in six rivers located in the Kerian River Basin (KRB), Malaysia. Species richness was significantly correlated among aquatic groups (except for Ephemeroptera and Trichoptera where r=0.040 and P=0.202). The strongest relationship in species richnesswas reported between Ephemeroptera and Plecoptera. The Mantel's r coefficient of similaritymatrices (based on the Bray-Curtis distance measure) showed a positive correlation between the matrices of Ephemeroptera-Trichoptera and Plecoptera-Trichoptera. However, a negative relationship was reported between Odonata-fish matrices. The relationships between average Trichoptera-Odonata distance to the centroid (i.e. beta diversity) among the aquatic groups were also investigated. The strongest relationship in the average to the centroids was reported between Ephemeroptera and Odonata (R2 = 0.424, P < 0.05). However, the weakest relationshipwas reported between Trichoptera and fish with R2 value of 0.024. It is concluded that richness of Plecoptera, Odonata and fish showed correlations patterns, and these can be used as surrogates for each other with some restrictions.

Pollinators are the key point for successful pollination in most flowering plants where around 90% of plants depend entirely on them. Majority of the pollinating species are wild, comprising bees, certain species of flies, wasps, moths, butterflies, thrips, beetles, bats, birds and other vertebrates, and among them insect pollinators are the most crucial. Fruit crops benefit in an impressive way from insect pollination, where there is a remarkable improvement both in the productivity and the quality of self-fertilized, self-incompatible and cross-cropping crops worldwide. The pollinators are responsible for assisting these flowering plants with their reproduction. However, the crisis of the pollinator's decline (wild and managed pollinators) which could seriously disrupt pollination activities in the ecosystems has attracted the attention of the world. Despite the growing concern about the decline in pollinators worldwide, some issues remain uncertain as data are often limited and undermined. Guava, Psidium guajava is a marketable fruit in numerous tropical and subtropical regions around the world. There has been a growing interest in pollination studies on guava because of its great economic importance. In guava, self-pollination is evident, however, it benefits greatly from insect pollination. This article aims to provide an overview of tropical pollination and pollination problems that have occurred around the world with a focus on pollination activities in guava.