title: The effects of photoperiod and light intensity on the sporulation of Brazilian and Norwegian isolates of Neozygites floridana.
abstract: The objective of this study was to determine the effects of light intensity and duration (photoperiod) on the sporulation (discharge of primary conidia) and conidia germination (from non-infective primary conidia to infective capilliconidia) of Neozygites floridana isolates from Tetranychus urticae originating from Norway and Brazil. Two light intensities (40 and 208 μmolm(-2)s(-1)), three photoperiods (24 h of continuous light (24 h D), 12 h of darkness followed by 12 h of light (12 h D: 12 h L) and 24 h of continuous darkness (24 h D)) and two temperatures (18°C and 23°C) were tested. The fungus produced similar amounts of primary conidia and capilliconidia at 12 h D:12 h and 24 h D, indicating that the fungus discharges almost all of its conidia during the first 12 h of darkness. Light had less of an effect on the production of primary conidia than on capilliconidia formation. At 24 h L, capilliconidia formation was significantly lower for all tested light intensities, temperatures and isolates compared to 12 h D:12 h L and 24 h D. At both light intensities, 24 h L resulted in a significantly lower capilliconidia formation for the Norwegian isolate compared to the Brazilian isolate. Our data suggest that, even though 24 h L reduced sporulation, some capilliconidia formation may occur at the low light intensities found on the underside of strawberry leaves during parts of the day as well as the top of a non-shaded strawberry leaf during the dim evening and morning hours in the tropics and during the dim, long summer days in temperate regions.
authors.affiliation: Department of Entomology and Acarology, ESALQ - University of São Paulo, Av. Padua Dias, 11, P.O. Box 9, 13418-900 Piracicaba, SP, Brazil.
authors.forename: Thiago Rodrigues
authors.initials: TR
authors.lastname: de Castro
authors.forename: Vitalis Wafula
authors.initials: VW
authors.lastname: Wekesa
authors.forename: Rafael de Andrade
authors.initials: Rde A
authors.lastname: Moral
authors.forename: Clarice Garcia Borges
authors.initials: CG
authors.lastname: Demétrio
authors.forename: Italo
authors.initials: I
authors.lastname: Delalibera
authors.forename: Ingeborg
authors.initials: I
authors.lastname: Klingen
mesh_terms: D000818:Animals; D001938:Brazil; D031985:Fragaria / Q000382:microbiology; D005658:Fungi / Q000302:isolation & purification / Q000502:physiology / Q000528:radiation effects*; D008027:Light; D009664:Norway; D017440:Photoperiod; D013172:Spores, Fungal / Q000528:radiation effects; D040102:Tetranychidae / Q000382:microbiology; D013997:Time Factors
keywords: Entomopathogenic fungi; Microbial control; Photoperiod; Spider-mites; Temperature; Tetranychus spp