The Spatial Distribution Of Japanese Beetles, Popillia Japonica, In Soybean Fields

Abstract

The Japanese beetle, Popilliajaponica Newman, is a serious pest of many agricultural and horticultural plants. Little is known about the distributions of Japanese beetles in agricultural fields which makes pest managyment more difficult. We studied the spatial distribution of Japanese be~tles in soybean fields. In particular, we examined how distance from an edge, edge direction, and edge type affected the distribution and abundance of beetles. Twenty-five soybean fields were transected parallel with the field edges at varying distances from the field edges and sampled for beetles. An edge effect for density was discovered; beetle numbers decreased significantly with increasing distance to the field edge. The east and south sides averaged higher numbers of beetles than the north and west. Downwind edges, in particular downwind edges adjacent to hedgerows, also had significantly higher beetle densities. Sex ratio and individual size did nqt vary with distance from the edge or edge type, but the egg loads of females increased with increasing distance from the edge. Differences in aggregation seeking behavior, in combination with movement in relation to wind and obstructions such as hedgerows are possible explanations for these spatial patterns.

Date of Award	2010
Original language	American English
Awarding Institution	Eastern Illinois University
Supervisor	Paul V Switzer (Supervisor)