title: Enhanced ovicidal activity of an oil formulation of the fungus Metarhizium anisopliae on the mosquito Aedes aegypti.
abstract: The effect of humidity on the activity of Metarhizium anisopliae IP 46 (Metsch.) Sorokin (Hypocreales: Clavicipitaceae) formulated in sunflower oil against Aedes aegypti (L.) (Diptera: Culicidae) eggs was examined. After exposure of eggs at 75% relative humidity (RH) for <or= 25 days, ovicidal activity was not increased by oil-in-water formulated conidia, hyphal bodies or pure-oil formulated conidia, compared with conidia or hyphal bodies prepared in water only. At optimal > 98% RH, eclosion was <or= 13.7% after treatment with oil-in-water formulated propagules in <or= 10% oil, and it was completely inhibited when conidia were applied in pure oil. At 86-100% RH, new conidia were found on eggs treated with oil-formulated conidia and incubated down to 91% RH. Ovicidal activity was still detected at 93% RH and was augmented with increasing humidity and time of exposure of eggs. Eclosion of larvae was distinctly reduced by IP 46 pure-oil formulated conidia after a minimal initial exposure of 3 days at > 98% RH, followed by: (a) a 12-day exposure at 75% RH before submersion in water; (b) a minimal 5-day exposure at > 98% RH and direct subsequent transfer of treated eggs to water, or (c) a minimal daily 20-h exposure at > 98% RH alternating with 4 h at 75% RH for 10 days. We demonstrate that oil-based formulations of conidia of M. anisopliae enhance ovicidal activity at high humidities and conclude that these formulations have potential in the integrated control of Ae. aegypti.
authors.affiliation: Departmento de Microbiologia, Immunologia, Parasitologia e Patologia, Instituto de Patologia Tropical e Saúde Pública, Universidade Federal de Goiás, Goiânia, Goiás, Brazil.
authors.forename: D A S
authors.initials: DA
authors.lastname: Albernaz
authors.forename: M H H
authors.initials: MH
authors.lastname: Tai
authors.forename: C
authors.initials: C
authors.lastname: Luz
mesh_terms: D000330:Aedes / Q000382:microbiology*; D000818:Animals; D052981:Metarhizium / Q000502:physiology*; D009032:Mosquito Control / Q000379:methods*; D010063:Ovum / Q000382:microbiology*; D010572:Pest Control, Biological