Laboratory bioassays to test the persistence of floating unformulated fungal spores. The average percentage corrected mortality (±S.E.) of An. stephensi larvae (n = 3) exposed to spores of Metarhizium anisopliae and Beauveria bassiana that had been floating on the water surface for 1, 2, 3, 5 or 7 days. Bars with letter in common show no significant difference (LSD post hoc test, α = 0.05).