Studies On The Arthropod Communities In Two Types Of Paddy Fields

This paper focused particularly on systematic studies of the arthropod communities in 2 types of paddy fields in Gutian County, Fujian Province, China.1. Based on the experiments and investigations conducted both in the field and in the laboratory from May 2001 to May 2002, the total collection produced 226 taxa, of which there were 55 taxa of insect pests, 78 taxa of predators (27 taxa carnivorous insects and 51 taxa spiders), 69 taxa of parasitoids, and 24 taxa of non-pests. Their proportion was 24%, 34%, 31%, 11%, respectively. 87,715 individuals of arthropods were collected, of which insect pests occupied 75.05%, predators possessed 12.44%, parasitoids hadl .32%, as well as non-pests took up 11.19%.2. In the arthropod community of rice fields, the number of pest taxa occupying 24% of total arthropods was less than that of natural enemies occupying 65% of total arthropods. Natural enemies were very rich in paddy fields.3. At the early and late stages of rice growth, the number of non-pests was large. Non-pests could be preys/hosts for predators/parasitoids. The ecological significance of non-pests might be a nutrient bridge for predators/parasitoids.4. Abundances of arthropod taxa and individuals in the rice field located in the heterogenous habitats (Field 2) were higher than ones in the other rice field located in the homogenous habitats (Field 1).5. In two fields located in the homogenous and heterogenous habitat, respectively, the number of arthropod taxa and individuals gradually increased after the rice seedlings were transplanted, and then decreased with the close to the maturation of the rice. The pattern of temporal dynamics was shaped like aparabola. The community diversity and evenness of arthropods varied with the growing stages of the rice and with different paddy fields located in different habitats. In both fields, the dominant concentration of arthropods was obvious in some certain growing stages of the rice, such as, for insect pests, at the stages of rice tillering and milk-ripe in Field 2 and at the rice stem elongation stage in Field 1; for non-pests, at the stage of rice tillering in Field 2 and at the rice heading stage in Field 1.