Testing the Enemy Release Hypothesis on tall-statured grasses in South Africa, using Arundo donax, Phragmites australis, and Phragmites mauritianus as models

Abstract

The Enemy Release Hypothesis (ERH) predicts that introduced plant species can escape herbivory and therefore have a competitive advantage over native plants, which are exposed to both generalist and specialist natural enemies. In this study, the ERH was explored using the invasive alien species, Arundo donax and two native tall-statured grasses, the cosmopolitan Phragmites australis and African endemic Phragmites mauritianus in South Africa. It was predicted that A. donax would have reduced species richness of herbivores compared with the native Phragmites spp., that it would be devoid of specialist herbivores and would thus be experiencing enemy escape in the adventive range. The herbivore assemblages were determined from both field surveys and a literature review. The assumptions of the ERH were for the most part not met; 13 herbivores were found on A. donax compared with 17 on P. australis and 20 on P. mauritianus. Arundo donax had two specialist herbivores from its native range, and shared native herbivores with Phragmites spp. Although A. donax had reduced species richness and diversity compared with that found in the native distribution, it has partially re-acquired a herbivore assemblage which is similar to that found on analogous native species. This suggests that enemy release may not fully explain the invasive success of A. donax in South Africa.

Generalized mycorrhizal interactions and fungal enemy release drive range expansion of orchids in southern Florida

“…This is particularly relevant in the context of rapid globalization, which has increased the movement of species well beyond their natural ranges. Successful establishment of a new introductions is rare and depends on the suitability of abiotic conditions as well as the number and types of biotic interactions a species encounters upon arrival (Pringle et al 2009, Canavan et al 2019, Frost et al 2019). For plants, the ability to acquire compatible mycorrhizal fungi in the recipient environment can facilitate the success of colonization and the lack of this ability can completely inhibit establishment as in obligate ectomycorrhizal trees (Nunez et al 2009, Harrison et al 2018).…”

Potential Solutions for the Water Shortage Using Towers of Fog Collectors in a High Andean Community in Central Ecuador

“…As the Ecuadorian mountain region is not able to grow bamboo for the "Urku Yaku" construction, the main material used was wild cane or giant reed, also known as "Arundo donax" [62]. This grass has been considered as an invasive plant in many subtropical, tropical and temperate regions all over the globe [65][66][67]. With the purpose of assuring the circular form of each module, we have used rings with different diameters, which were made with steel tubes of 75% of the cross section and 1.1 mm of thickness, plastic clamps, nylon rope, 50% of shadow polyester mesh and a plastic collector tank of 1.10 m 3 of capacity (Table 4).…”

Harnessing Ecosystem Services from Invasive Alien Grass and Rush Species to Suppress their Aggressive Expansion in South Africa

“…The least useful of all known invasive grass species, as measured by the number of citations in South Africa, is S. palmata (n = 1). This is because A. donax has a wide distribution range countrywide and worldwide [35,170,171]. Furthermore, although limited studies have cited the uses of some species including P. purpureum and P. villosum in South Africa, more studies (n = 7) have cited their uses elsewhere.…”

“…In South Africa, local people have been using various invasive alien grass species for various purposes since time immemorial [27,[34][35][36][37][38]; however, the use of invasive alien grass species for livelihoods has not been well comprehended and factored into the invasion management plans [23,39,40]. Recent scientific evidence shows that invasive alien plant species play a key role in human livelihoods [36][37][38][41][42][43][44][45][46][47][48].…”