Study on prey regime of Rana ridibunda in rice farms in northern provinces of Iran

Among Anuras, Pelophylax (=Rana) ridibunda has great interest in living in farms and fields. This species can always be seen in the vast areas of rice fields, particularly in North of Iran. Therefore, they have always been important because of their close relationship with crops there is a debate as whether these animals can be used as biological pest control in the fields. So that, the type and method of their nutrition is specifically important from the perspective of agriculture and conservation of natural resources. This study is an attempt to investigate the diet of P. ridibundas around Caspian Sea and its effect on pest control in rice fields. For achieving this aim, 90 samples were collected from 14 stations in the North of Iran between 2009- 2012. After being hunted, they were anesthetized and got an injection of formalin in their stomachs. Then all the samples were transferred to laboratory, and after being coded, they were fixed. Their stomach contents were dissected and identified. The results indicated that the frequency of these animals is the only factor determining their nutrition kind. It is also indicated that females eat more plants and have a stronger tendency toward cannibalism. These characteristics of P. ridibunda leave no doubt that they are one of the natural pest controls that can regulate the frequency of pests in the fields.