The Effect of Landscape Composition on the Abundance of Laodelphax striatellus Fallén in Fragmented Agricultural Landscapes

Zhanyu Liu,Jiquan Chen,Ranjeet John,Zengrong Zhu,Jiaguo Qi,Jiaan Cheng

doi:10.3390/land5040036

Abstract

The spatial distribution of crop and non-crop habitats over segmented agricultural landscapes could be used as a means to reduce insect pest populations. Seven land cover categories such as wheat, rapeseed, vegetable, water, built-up, paved road, and unsurfaced road were extracted from GeoEye satellite images dating from late May to late June of 2010. Three diversity metrics and three evenness metrics were estimated from the abovementioned land cover categories for quantifying the effect of landscape composition on nymphal and adult Laodelphax striatellus Fallén. The degree of correlation between the proportion of crop cover and adjacent spatial scales (r: 0.651–0.983) was higher than the correlation between the proportion of crop cover and nonadjacent spatial scales (r: −0.255–0.896). While the degree of correlation between diversity indices and abundance of L. striatellus decreased gradually when the spatial scales varied from large (>100 m radius buffer) to small (<100 m). Our study suggests that when using natural biological pest control and ecological engineering practices in the rural-urban fringes, the crop field’s width should be less than 200 m and increasing vegetation diversity within such a scale will be helpful to regulate the insect pests under a certain density.

Highlights

Human activities have modified landscape characteristics through swift urbanization and farming practices across the world [1,2,3].Studies concerning these changes, have been conducted mostly in developed and industrialized countries, since post-industrial age governments pay more attention to ecological and environmental issues in the developed countries than those from the developing countries.human activities affect landscape characteristics at a faster rate in prosperous developing countries than in developed countries
The density of L. striatellus in nymphal or adult stage varied by study site
It cannot be concluded that the nymph population will be high if the adult populations is high in small segmented agricultural landscapes

Summary

Introduction

Human activities have modified landscape characteristics (e.g., land cover types and spatial configurations) through swift urbanization and farming practices across the world [1,2,3].Studies concerning these changes, have been conducted mostly in developed and industrialized countries, since post-industrial age governments pay more attention to ecological and environmental issues in the developed countries than those from the developing countries.human activities affect landscape characteristics at a faster rate in prosperous developing countries than in developed countries. Human activities have modified landscape characteristics (e.g., land cover types and spatial configurations) through swift urbanization and farming practices across the world [1,2,3]. Studies concerning these changes, have been conducted mostly in developed and industrialized countries, since post-industrial age governments pay more attention to ecological and environmental issues in the developed countries than those from the developing countries. A heterogeneous and fragmented agricultural landscape can affect forms of species richness and abundance in developing countries as well as developed ones. We investigate what effects that landscape composition— fragmented agricultural landscape in Asia—have on the insect species Laodelphax striatellus Fallén (small brown planthopper) during its two stages: nymph and adult

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