First Report of Raoiella indica (Acari: Tenuipalpidae) in Amazonas State, Brazil

The occurrence of Raoiella indica Hirst, the red palm mite, found infesting coconut plants in Aug 2011, is reported for the first time in the urban area of Manaus, state of Amazonas, central region of the Amazon Basin. Additional hosts found infested were Dwarf Royal Palm, Veitchia merrillii (Becc.) H. E.Moore and Fishtail Palm Tree, Caryota mitis Lour. Despite quarantine efforts this mite has become established in the Southern Hemisphere in the Americas. The mite presents an imminent threat to coconut palm and banana plantations, as well as natural trees, located in the Northeast and Central regions of Brazil

Persistent luminescence excitation spectroscopy of BaAl2O4:Eu2+,Dy3+

BaAl2O4:Eu2+,Dy3+ is related, both by structure and luminescence, to one of the best persistent luminescent phosphors, SrAl2O4:Eu2+,Dy3+. At room temperature (RT), the green persistent emission of BaAl2O4:Eu2+,Dy3+ remains visible for hours after ceasing irradiation. Similar to SrAl2O4, BaAl2O4 with hexagonal P6(3) structure, has two M2+ sites, but, limited optical activity from the 2nd site is observed in the emission of BaAl2O4:Eu2+,Dy3+-even at 77 K. Using combined approach of photoluminescence, thermoluminescence (TL), and persistent (excitation) luminescence measurements, the origin and properties of persistent luminescence of BaAl2O4:Eu2+, Dy3+ were studied in detail. Ultraviolet (UV) excited and persistent emission are identical and no contribution from the Eu2+ in the high-symmetry Ba site was observed. TL excitation spectra clarified the unstructured conventional excitation spectrum; now it is evident that defects or the Dy3+ co-dopant do not contribute to persistent luminescence via direct energy absorption. Mechanisms for persistent luminescence should thus be revised