Prescribed fire effects on biological control of leafy spurge

The flea beetle, Aphthona nigriscutis Foudras, is a potentially useful agen t for biological control of leafy spurge (Euphorbia esula L.) in grasslands devoted to wildlife conservation. However, effects of other grassland mana gement practices on the persistence and dynamics of flea beetle populations are not well understood. We conducted small plot tests to evaluate 1) the effect of prerelease burning on establishment of A. nigriscutis colonies, a nd 2) the ability of established A. nigriscutis colonies to survive prescri bed fire. More colonies established on plots that were burned prior to beet le release (83% establishment) than on unburned plots (37% establishment), possibly due to litter reduction and baring of the soil surface. However, m ost colonies established with the aid of fire did not survive past the firs t generation unless the habitat was otherwise suitable for the species, and we conclude that the primary benefit of prerelease burning is increased re cruitment of A. nigriscutis during the first few generations. Established c olonies were not harmed by burns in October and May, Both spring and fall b urns resulted in an increase in leafy spurge stem density during the first growing season, but stem density declined to the preburn level by the secon d growing season.