Understanding drivers of population fluctuation,especially for agricultural pests,is central to the provision of agro-ecosystem services.Here,we examine the role of endogenous density dependence and exogenous factors of climate and human activity in regulating a population of an important agricultural insect pest,the cotton bollworm(Helicoverpa armigera),in North China over a 37-year period,from 1975 to 2011.Quantitative time-series analysis provided strong evidence explaining the long-term population dynamics of the cotton bollworm and its...
