Abstract:
This study investigated the impact of a neonicotinoid seed-applied insecticide (Poncho Beta) and two plant densities
(86,487 and 61,776 plants per hectare) on the sugarbeet root aphid (Pemphigus betae Doane), beneficial epigeal
arthropods, and selected crop yield parameters in sugarbeet (Beta vulgaris L. var. vulgaris). Ground beetles
and centipedes were the most commonly collected taxa during 2012 and 2013, respectively. Centipede, spider,
and rove beetle activity densities were not affected by the seed-applied insecticide, whereas plant density had a
marginal effect on centipede activity density during 2012. Ground beetle species richness, diversity, and evenness
were also not impacted by the seed treatments. However, during 2013, ground beetle activity density was significantly
higher in plots planted with untreated sugarbeet seeds due to the abundance of Bembidion quadrimaculatum
oppositum Say. Sugarbeet root aphid populations were significantly higher in the untreated plots during
both years. In 2012, sugarbeet tonnage and sugar yield were higher under the low plant density treatment, while
higher sugar content was recorded from the seed-applied insecticide plots (2013). Seed-applied neonicotinoids
and plant density had little impact on beneficial epigeal arthropod activity density. Seed treatment did result in
decreased root aphid populations; however, these reductions were not sufficient to be considered as an adequate
control. This limited aphid control likely contributed to inconsistent effects on yield parameters.
