First report of Melanaspis corticosa in Portugal
The NPPO of Portugal recently informed the EPPO Secretariat of the first finding of Melanaspis corticosa (Hemiptera: Diaspididae – South African obscure scale) on its territory. In the Algarve region, the presence of an unusual scale in olive (Olea europaea) orchards had been reported by various growers, as well as by the Tavira Agrarian Experimentation Centre. Samples were collected in autumn 2021 and throughout 2020 by the regional plant protection authorities, but the identity of the scale could not be determined. Further samples were collected at the end of 2021, and in 2022 the pest was finally identified as Melanaspis corticosa.
Information on this scale species is scarce. It is known to occur in Africa (Guinea, Mozambique, South Africa, Zimbabwe), and is considered to be polyphagous. The following trees are reported to be hosts: Celastrus, Diospyros pallens, Erythrina caffra, Juglans, Olea, Platanus, Populus, Prunus persica, Pyrus, Robinia, Robinia, Schinus mole, Sclerocarya birrea, Virgilia oroboides.
Further surveys conducted in Portugal have shown that M. corticosa occurs in several counties in Algarve, but only on olive trees. Infested trees show drying of branches where the scale species is present. Phytosanitary treatments with insecticides that are approved against scale insects in olive trees have been applied, but with limited effectiveness. The NPPO considers that the knowledge acquired so far is too limited to be able to decide on measures to be taken.
The pest status of Melanaspis corticosa in Portugal is officially declared as: Present, only in some parts of the Member State concerned.
Sources
NPPO of Portugal (2022-08).
García Morales M, Denno BD, Miller DR, Miller GL, Ben-Dov Y, Hardy NB (2016) ScaleNet: A literature-based model of scale insect biology and systematics. Database. https://scalenet.info/catalogue/Melanaspis%20corticosa/