Brassica patch geometry and adjacent matrix: how small-scale changes in landscape can affect Plutella xylostella populations

Abstract

Herbivorous insects are predicted to have higher densities in larger patches, while their natural enemies will be more affected by the edge of these patches. In this paper, we investigate the effect of the relationship between brassica horticultural plot shape and the adjacent land use on the abundance of P. xylostella and its chances to be parasitised. Samples were collected from brassica plots during spring. Landscape metrics of the study area were estimated using Landsat images. We found a negative relationship between the pest abundance and the perimeter-to-area ratio of the brassica plot, and a positive relationship with land cover estimated from Landsat images. The proportion of parasitised immatures showed opposite relationship with the same variables. Implications of these findings are discussed.

Keywords:

• Diamondback moth
• perimeter-to-area ratio
• horticultural land use
• parasitism

Acknowledgements

MPG and REG conceived, designed and conducted the research. All authors have read, reviewed and approved the final version of the manuscript submitted for publication. A special thanks to Joss Heywood for checking and editing the English of this manuscript and to an anonymous reviewer for the suggestions that substantially improved the manuscript.

Disclosure statement

The authors declare that they have no conflict of interests. This article does not contain any studies with human participants or animals performed by any of the authors.

Additional information

Funding

This study was funded by a grant provided by the University of Córdoba – Secyt 162/2012, 124/13, 203/2014, 313/16, 411/18.