Increasing numbers of studies show correlations between agricultural landscape diversity, natural enemy populations, and suppressed pest densities. However, most studies focus on the role of diverse landscapes in suppressing pest populations by conserving natural enemies without considering the role such landscapes may play in directly suppressing herbivorous pests. In this paper, we constructed spatially explicit models to explore the direct effects of agricultural landscape diversity on the population dynamics of herbivorous insects. Characteristics of the landscape, such as the amount of suitable host habitat, its degree of clustering and the crop rotation rate, as well as characteristics of the herbivore such as dispersal behavior and host plant specificity were varied.
Results/Conclusions
Landscape structure plays a strong role in determining whether herbivore populations become established in a landscape. Landscape diversification is especially effective in reducing metapopulation densities of specialist insects that are not directed dispersers. However, landscape diversification has little effect on herbivores with wide diet breadths. Insect dispersal ability, habitat clustering, and habitat diversity interact to affect metapopulation dynamics. Our modeling approach underscores the role that landscapes play in directly suppressing or promoting insect herbivore populations at landscape scales that are difficult to study empirically.
