title: Dependence of the entomopathogenic fungus, Beauveria bassiana, on high humidity for infection of Rhodnius prolixus.
abstract: The impact of relative humidity (RH) on the infective potential of the isolate Bb INRA 297 of Beauveria bassiana (Bals.) Vuillemin (Deuteromycotina: Hyphomycetes) against first instar nymphs of Rhodnius prolixus Stål. (Hemiptera: Reduviidae) was determined. Fungus-treated insects were exposed to RHs ranged from 75 to 100% at 25 degrees C. Results clearly showed a threshold of humidity at ca. 96% for high and rapid mortality. After initial exposure to increasing periods of 97% (4, 8, 16, 24, 36 and 48 h) and subsequent transfer to constant lower RHs (43, 53, 75 and 86%) at a constant 25 degrees C, an incubation of at least 48 h at 97% RH was necessary to kill all insects. On changing RHs of 97/75% and different regimes of temperature (15/28 degrees C, 20/25 degrees C, 25/28 degrees C, and 25/35 degrees C), at least 72 h of initial exposure at 97% RH for the 15/28 degrees C regime, 48 h for the 20 degrees/25 degrees C and 25/28 degrees C regimes and 36 h for 25/35 degrees C were needed to kill all insects over a 6-day incubation time. Delayed exposure to favorable moisture condition (97% RH), significantly affected infection for up to a 3-day delay within the various temperature-humidity regimes tested.
authors.affiliation: Centre de Biologie et de Gestion des Populations, INRA-Montpellier, Campus International de Baillarguet, Montferrier-sur-Lez, France.
authors.forename: C
authors.initials: C
authors.lastname: Luz
authors.forename: J
authors.initials: J
authors.lastname: Fargues
mesh_terms: D000818:Animals; D006813:Humidity; D007300:Insect Control; D007303:Insect Vectors / Q000382:microbiology; D003904:Mitosporic Fungi / Q000472:pathogenicity*; D010572:Pest Control, Biological; D012239:Rhodnius / Q000382:microbiology*