Rice fields as a hot spot of water beetles : Coleoptera adephaga and polyphaga

The study is representative of wetlands subjected to strong anthropogenic impact as rice fields are. The aquatic Coleoptera have been collected monthly from channels, rice fields and a natural spring for one year, resulting in 31 species belonging to 8 families (Brachyceridae, Dytiscidae, Dryopidae, Elmidae, Gyrinidae, Haliplidae, Helophoridae, Hydrophilidae) which have been identified, 19 of which in rice paddies. The comparison of paddies subjected to different anthropogenic impacts shows that the flooding period is only one of the factors influencing the community of water beetles. Important information on the occurrence of the species during the year is also provided and adds to the few knowledge present in the literature. All the data, as well as the detection of vulnerable and rare species, evidence that rice agro-ecosystems are essential for the exploitation of water beetle biodiversity in areas densely colonized, industrialized and cultivated, where wetlands has strongly reduced over the last centuries.