Further spread of the gypsy moth fungal pathogen, Entomophaga maimaiga , to the west and north in Central Europe

The gypsy moth, Lymantria dispar, is one of the most important pests of deciduous trees in Europe, occurring in all environmental zones of Europe except the Alpine North and part of the Boreal zone. The gypsy moth fungal pathogen Entomophaga maimaiga, originally from Asia, was imported from the USA and released in Bulgaria, in 1999–2000. Spread of E. maimaiga in Central Europe was documented from 2011 to 2013, but this pathogen was only detected as far north as Slovakia. Collections of dead L. dispar larvae in 2019 (but not 2018), in areas of both sporadic and cyclic L. dispar outbreaks, resulted in the first detections of E. maimaiga in the Czech Republic. Lymantria dispar larvae were exposed to soil from oak forests in 2014–2018, but only infection by the gypsy moth nucleopolyhedrovirus (LdNPV) and the microsporidium Vairimorpha (= Nosema) lymantriae was detected. At most localities in the cyclic outbreak area, in 2017 the first defoliations of a new outbreak cycle occurred and the numbers of gypsy moth egg masses began to increase, so the calculated duration of approximately 13 years from outbreak to outbreak in the Czech Republic was verified.