Original articleWireworms suppress spreading of the expansive weed Calamagrostis epigejos (L) Roth by feeding on its rhizomes

- Wireworms preferred rhizomes of the bush grass to belowground organs of other plants.
- Wireworm presence resulted in lower rhizome biomass of the bush grass.
- Accumulation of wireworms at the spoil heaps resulted in lower coverage of bush grass.

We tested whether wireworms (Elaterid beetle larvae) prefer the expansive grass Calamagrostis epigejos to other early-successional plant species from the spoil heaps in two microcosm experiments and in a field survey of wireworm abundance and C. epigejos coverage on the spoil heaps at different topographic positions at the spontaneously revegetated sites with an undulating surface. In the first experiment, wireworms reduced rhizome biomass of C. epigejos the most out of the belowground organs of the 5 plant species, but did not affect its root biomass. In the second greenhouse experiment, wireworms negatively affected the growth of rhizomes of a growing C. epigejos, whilst they did not affect the other plant species or the aboveground biomass. In the field survey, C. epigejos coverage was lowest at the bottoms of depressions, despite the higher moisture and nutrient levels at this position. Wireworm numbers were the highest in depressions. The results of this study support the hypothesis that wireworms can negatively impact the C. epigejos by feeding on its rhizomes and have the potential to slow down the expansion of this weed.