Effects of Crop Management Practices on Pollinators and Pollination in Alfalfa Seed
Lygus bugs are key pests in alfalfa seed production systems and control is often hampered by a need to protect alfalfa leafcutting bees, which are released in these fields as pollinators. Until recently, compounds available for lygus bug control in alfalfa seed consisted largely of broad spectrum, organophosphate, carbamate and pyrethroid insecticides. Since 2006, three new, low risk pesticides have received Special Local Needs (24c) registration for lygus bug control in alfalfa seed: novaluron (Rimon 0.83 EC), acetamiprid (Assail 70 WP) and flonicamid (Beleaf 50 SG). These compounds are expected to be safe to non-target insects, including bees. However, there is a need for research evaluating the effectiveness of these compounds when used in rotation during the bloom period. For example, do rotations that use the systemic compounds, (flonicamid or acetamiprid) early in the bloom period followed by a spray of novaluran late in the bloom period, effectively control lygus compared to rotations that use novaluron early and systemic compounds late? There presumably would be an advantage to using the systemic compounds early as plant uptake of these compounds, and therefore effectiveness, should be better early rather than late in plant development. Likewise, the use of the most selective compound, flonicamid, during early bloom may be less disruptive to bee nesting and pollination during this period. These compounds can also be applied as tank mixes. The project will determine the safety of these compounds and application methods to alfalfa leafcutting bees in the field, and as compared to more traditional insecticides.