The distribution of Melanoplus femurrubrum:: fear and freezing in Connecticut

A central challenge for those Studying organism distributions is to identify the relevant scale at which a distribution is established and the relevant mechanism driving the maintenance of the pattern. Melanoplus femurrubrum grasshoppers in NE Connecticut are missing from grass dominated fields. I examined two hypotheses about why the grasshopper is missing from these types of fields in this region. The first hypothesis was that behavioural responses to predation and competition prevent establishment by limiting above ground stages of the grasshopper. The second hypothesis was that soil temperature and grass habitat characteristics influence oviposition, behaviour and limit egg development. Testing among these different hypotheses (trophic vs abiotic), data from experiments and field observations indicated that while the within field distribution of M. femurrubrum can be sensitive to the effects of trophic interactions during the above ground phase of the life-cycle, the among field distribution is limited by female oviposition choice, limited heating degree-days for egg development, and poor resource conditions for. the first instar grasshoppers. These results highlight the need to examine behaviour and community interactions across habitats and life stages in studies of distribution patterns.