Spatio-temporal dynamics of corn rootworm, Diabrotica spp., adults and their spatial association with environment

Multiyear and multilocation studies were conducted to investigate the within- and the between-year spatial dynamics of corn rootworms Diabrotica spp. (Coleoptera: Chrysomelidae), adults and their spatial associations with environmental factors in cornfields. Grid-based spatial sampling was conducted by trapping adults emerging from the soil (i.e., 'emergence-trap counts') and by counting the number of adults in the ear zone of corn plant (i.e., 'ear-zone count'). Spatial analysis with distance indices (SADIE) was used to determine spatial distribution patterns and to investigate spatial associations. Ear-zone counts and emergence-trap counts were spatially dynamic within a year and more frequently aggregated in the middle of growing seasons and random early and late in the season. However, during the peak population periods, spatial distribution of ear-zone counts and emergence-trap counts were significantly consistent between years, indicating predictability of future spatial distributions. Spatial distribution of emergence-trap counts and ear-zone counts were positively associated with soil moisture and presence of corn plants with silks, respectively. This study demonstrated that within-year spatial distribution patterns were dynamic and that there was between-year spatial consistency of corn rootworm adult distributions. Such information can be used to improve preventative management of corn rootworms.