Niches and interspecific competitions of wolf spiders and mirid bug, Cyrtorhinus lividipennis under three pest management strategies in paddy fields

The duck-rice and fish-rice were two important strategies of pest management in the process of organic rice. The niches and interspecific competitions of wolf spiders and mirid bug, Cyrtorhinus lividipennis under three strategies of pest management in paddy fields were studied in order to understand the influences of different pest control methods on ecological relationships between the two main types of predators. The results of our study suggested that ducks might prey upon wolf spiders resting on the base of rice plants, thus the populations of wolf spiders decreased in duck-rice treatment. The impact of ducks on mirid bug was not significant because it preferred to congregate on the mid-part of rice plants. The temporal selectivity of wolf spiders was smaller than that of mirid bug, which meant occurrence frequency of wolf spiders was higher compared with mirid bug. In addition, competition between wolf spiders and mirid bug was significantly more intense in duck-rice or fish-rice treatment than in natural control treatment at different stages. Probably, ducks and fishes drove wolf spiders away from their original spatial niche, the base to the mid-part in rice plants, enhancing competition between wolf spiders and mirid bug in duck-rice or fish-rice treatment. Based on the results of this study, duck-rice or fish-rice, as a control pest method in the process of organic rice, should be prudentially treated.