Effects of farmland landscape patterns on the population dynamics of two lady beetles

Author of the article:WANG XiuXiu1,2**OUYANG Fang2LIU YuFang1***

Author's Workplace：(1.College of Agriculture and Biotechnology, China Agricultural University, Beijing100193, China; 2. State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, inese Academy of Sciences, Beijing100101, China

Key Words：agricultural landscape pattern， Propylaea japonica， Harmonia axyridis, population dynamic， biocontrol service

Abstract：Population dynamics of two predatory beetles, Propylaea japonica (Thunberg) and Harmonia axyridis (Pallas) were surveyed in agricultural landscapes composed of cotton and maize in North China. Crop composition (cotton and maize) was found to significantly affect population densities of the beetles in this agricultural landscape system. Population densities of both beetles in maize patches were higher than in cotton patches, and adults of both species prefer to inhabit maize plants. The population densities of the two species varied through time in the cotton patches, with more adults of P. japonica in the earlier and middle stages and fewer in the later stage, and fewer adults of H. axyridis in the earlier and middle stages and more in the later stage. These results suggest that maize can serve as a habitat or refuge for predatory beetles and its presence may enhance biological control of insect pests in cotton. The proportion of maize patches in the agricultural landscape significantly affected adult densities of these two predatory beetles. This suggests that habitat management with a suitable ratio and spatial arrangement of cotton and maize may enhance the biological control of pest insects.