First report of Nematus lipovskyi in the Czech Republic
Larvae of an unidentified sawfly were first detected in Prague in 2010, causing defoliation to azaleas (Rhododendron spp.) grown in a botanical garden. Since 2011 there have been repeated records of this unknown species in other localities. In spring 2013, the species was identified as Nematus lipovskyi (Hymenoptera: Tenthredinidae). The identification was based on adult morphology and was carried out by Mr Jan Macek from the Entomological department of the National Museum in Prague. Larvae of N. lipovskyi feed on Rhododendron species, mainly Rhododendron (Azalea) molle and its hybrids. Young larvae are green, older larvae may become darker and are about 1 cm long. They feed on foliage and flowers. Leaves can be eaten completely with the exception of the mid-rib; a typical symptom being the presence of star-shaped rosettes from remaining portions of leaves. N. lipovskyi has only one generation per year. Larvae feed on plants in spring and complete their development in 10–14 days; then they fall down on the soil where they remain as pre-pupae until the next spring during which pupation and adult emergence take place. Until its discovery in the Czech Republic, N. lipovskyi was known to occur only in the USA, where it was first described in 1974 (Smith, 1974) causing defoliation on R. molle hybrids grown in parks and gardens. It is not known how the pest was introduced into the Czech Republic. From May to June 2013 an official survey was carried out throughout the territory of the Czech Republic to delimit the extent of the infestation, based on the detection of larvae and/or typical damage symptoms. According to the official survey results as well as the other data available, infestation by N. lipovskyi occurs in most of the Bohemian regions (Western part of the Czech Republic), being most prevalent in the Central Bohemian Region, whilst no findings have been reported from Moravia (Eastern part of the country). Infested host plants were observed in gardens, parks as well as garden centres. Heavy defoliation has been regularly observed, as well as feeding damage on flowers. Preliminary results of an Express PRA (being finalized) show that the pest is already established in the territory of the Czech Republic and its impact can be effectively reduced by means of available control methods (e.g. insecticide treatments). Therefore no official control measures are recommended against N. lipovskyi in the Czech Republic.
The pest status of Nematus lipovskyi in the Czech Republic is officially declared as: Present, found in some areas.
Pictures of N. lipovskyi and its damage have been kindly provided by the NPPO of the Czech Republic and can be viewed on the EPPO Gallery: http://photos.eppo.org/index.php/album/657-nematus-lipovskyi-nemali-
NPPO of the Czech Republic (2013-05, 2013-08).
Smith DR (1974) Azalea sawflies and a new species of Nematus Panzer (Hymenoptera: Symphyta). Proceedings of the Entomological Society of Washington 76, 204-207. Available online: http://biostor.org/reference/83957