title: Tolerance to solar ultraviolet-B radiation in the citrus red mite, an upper surface user of host plant leaves.
abstract: Plant-dwelling mites are potentially exposed to solar ultraviolet-B (UVB) radiation that causes deleterious and often lethal effects, leading most mites to inhabit the lower (underside) leaf surfaces. However, in species of spider mite belonging to the Genus Panonychus, a substantial portion of individuals occur on upper leaf surfaces. We investigated whether the upper leaf surfaces of citrus trees are favorable for P. citri, and to what extent they are tolerant to UVB radiation. If eggs are not adequately protected from UVB damage, females may avoid ovipositing on the upper surfaces of sunny leaves. To test this, we conducted laboratory experiments using a UVB lamp, and semioutdoor manipulative experiments. As a result, P. citri eggs are tolerant to UVB. Field studies revealed that the ratio of eggs and adult females on upper leaf surfaces were larger for shaded than for sunny leaves. However, 64-89% of eggs hatched successfully even on sunny upper leaf surfaces. Nutritional evaluation revealed that whether on sunny or shaded leaves, in fecundity and juvenile development P. citri reaped the fitness benefits of upper leaf surfaces. Consequently, P. citri is tolerant to UVB damage, and inhabiting the upper surfaces of shaded leaves is advantageous to this mite.
authors.affiliation: Laboratory of Ecological Information, Graduate School of Agriculture, Kyoto University, Kyoto, Japan.
authors.forename: Midori
authors.initials: M
authors.lastname: Fukaya
authors.forename: Ryuji
authors.initials: R
authors.lastname: Uesugi
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Ohashi
authors.forename: Yuta
authors.initials: Y
authors.lastname: Sakai
authors.forename: Masaaki
authors.initials: M
authors.lastname: Sudo
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kasai
authors.forename: Hidenari
authors.initials: H
authors.lastname: Kishimoto
authors.forename: Masahiro
authors.initials: M
authors.lastname: Osakabe
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D002957:Citrus / Q000469:parasitology; D005260:Female; D010058:Oviposition / Q000528:radiation effects*; D018515:Plant Leaves / Q000469:parasitology; D011829:Radiation Dosage; D011836:Radiation Tolerance / Q000502:physiology*; D013472:Sunlight; D040102:Tetranychidae / Q000502:physiology / Q000528:radiation effects*; D014466:Ultraviolet Rays; D015053:Zygote / Q000528:radiation effects*