Manipulation of soil temperatures to influence brood emergence in the alkali bee (Nomia melanderi)

Abstract

Soils in beds of commercially managed Nomia melanderi were manipulated with surface treatments to reduce or increase temperatures at nest depths of 20 cm. Modifying soil temperatures affected pupation rate and emergence date of N. melanderi. In 2010, white chalk dust delayed peak bee emergence by one week, and clear plastic mulch initiated peak emergence one week earlier, significantly increasing overall bee emergence compared to uncovered areas. In 2011, treatments included white chalk dust and plastic agricultural sheets including clear, red, black, white-on-black, blue, and brown. In 2011, clear plastic sheeting initiated early emergence while white chalk dust and white-on-black plastic plots delayed emergence. Expediting or postponing N. melanderi emergence could potentially allow alfalfa seed producers to extend the bees’ foraging season over a greater time period, subsequently increasing pollination, seed set, and economic returns.