Meeting Abstract
Burrowing through soil is among the most energetically costly forms of terrestrial locomotion. Many temperate insects burrow to protected sites beneath the soil surface prior to winter dormancy. Because soil buffers the effects of air temperature, insects that overwinter deeper underground may exploit mild, thermally-stable microclimates. However, the benefits of deeper sites could trade-off with the energetic costs of entry and exit from soil, constraining insects to shallow sites if moving through the soil is costly. To test this hypothesis, we used the western bean cutworm, Striacosta albicosta (Lepidotera: Noctuidae) which burrows deep into soil to overwinter. Using two artificial soils that varied in clay content, we described the burrowing behavior of the cutworms, and examined the effect of soil properties on the net cost of burrowing. The distribution of overwintering sites was measured in each artificial soil, and in two natural soils in the field. Initial results suggest that cutworms penetrate further into soils with lower clay content. Our work will provide insight into the costs of burrowing into soil to overwinter: a strategy used by many temperate insects.
