The Invasion and Long Naturalization of Solanum elaeagnifolium affects the Soil Nematode Community: Evidence from a Comparative Study

Abstract

To date, the effects of invasive plants on soil communities and the concomitant interactions thereof have been the subject of ever-growing concern. Solanum elaeagnifolium (S) is a noxious invasive weed originating from south-central America, which has been recognized as a serious threat around the Mediterranean basin and worldwide. Herein, we compared soil nematode communities in the rhizospheres of (S), against those of its native antagonist Cichorium intybus (C), in sites where these two ruderal plants coexist (“species” effect—hereafter “sp”). These sites differed regarding the time after the initial invasion of (S) and were regarded as recently and historically invaded (10 years and 70 years after invasion; “year” effect—hereafter “yr”). Neither “sp” nor “yr” affected total nematode abundance and nematode functional indices. Diversity was lower in (S) and was reduced even more with time after invasion in both plant species. Plant parasites decreased significantly from S–10yr to S–70yr, i.e., over time after invasion, while predators were fewer in (C). Distinct nematode communities in terms of genera structure were formed under the two plant species and these were significantly affected by the time after (S) invasion. Differences between these communities related to loss of genera but also to changes in the abundance of common ones, such as Acrobeloides and Pratylenchus. Our results showed that the responses of the examined soil communities to the invasion of (S) are not straightforward and cannot be easily explained on the basis of existing theories. However, the first-time results furnished herein may be useful to integrated management strategies in the future.