Observations on the occurrence and phenology of the invasive elm defoliator Aproceros leucopoda (Hymenoptera: Argidae) in the Czech Republic

- Aproceros leucopoda has been found in urban areas and in forests in the Czech Republic.
- Aproceros leucopoda distribution ranged from 150 to 700 m a.s.l.
- The occurrence of three generations per year was confirmed in the southeastern Czech Republic.
- Aproceros leucopoda endangers solitary elms in urban greening areas more than elms in forests.

Aproceros leucopoda has been found at nine locations in urban areas and in forests in the Czech Republic. Aproceros leucopoda was first reported at a location 700 m a.s.l. in the northern part of the country in 2011. The other locations range in elevation from 150 to 460 m a.s.l. In the current study, A. leucopoda was studied in four plots, where larvae and their zigzag feeding tracks were observed on 10 Ulmus trees located south of Lanžhot (southeastern Czech Republic) in 2014 and 2015. In 2014, feeding tracks and larvae were detected in late May, from 22 June to 13 July, and from 9 August to 6 September, suggesting the occurrence of three generations per year in the southeastern Czech Republic. The southern Czech Republic has been colonized much earlier than other parts of the country because of its proximity to localities with A. leucopoda in Slovakia and Austria. The presence of larvae or evidence of larval feeding was detected on only 2.84% of monitored leaves. We suggest that A. leucopoda endangers solitary elms in urban greening areas more than elms in forests.