A taste for exotic food: Neotropical land planarians feeding on an invasive flatworm

Abstract

Invasive species establish successfully in new habitats especially due to their ability to include new species in their diet and due to the freedom from natural enemies. However, native species may also adapt to the use of new elements in their ecosystem. The planarian Endeavouria septemlineata, first recorded in Hawaii, was later found in Brazil. Recently, we found it in human-disturbed areas in southern Brazil and here we investigate its interactions with other invertebrates both in the field and in the laboratory. We observed the species in the field during collecting activities and hence maintained some specimens alive in small terraria in the laboratory, where we offered different invertebrate species as potential prey and also put them in contact with native land planarians in order to examine their interaction. Both in the field and in the laboratory, E. septemlineata showed a gregarious behavior and was found feeding on woodlice, millipedes, earwigs and gastropods. In the laboratory, specimens often did not attack live prey, but immediately approached dead specimens, indicating a scavenging behavior. In an experiment using the slug Deroceras laeve and the woodlouse Atlantoscia floridana, there was a higher consumption of dead specimens of woodlice and slugs compared to live specimens, as well as a higher consumption of dead woodlice over dead slugs. Four native land planarians of the genus Obama and one of the genus Paraba attacked and consumed E. septemlineata, which, after the beginning of the attack, tried to escape by tumbling or using autotomy. As a scavenger, E. septemlineata would have no impact on the populations of species used as food, but could possibly exclude native scavengers by competition. On the other hand, its consumption by native land planarians may control its spread and thus reduce its impact on the ecosystem.

Hammerhead worms everywhere? Modelling the invasion of bipaliin flatworms in a changing climate

“…In this regard, invading South America might be more challenging for hammerhead flatworms than in other areas in the world. Indeed, competition has been described for several species in this area (Boll & Leal-Zanchet, 2016;Boll et al, 2015), and it is thus likely that competition with the numerous native terrestrial flatworms may also play a role in limiting the invasibility of South America.…”

The invasive alien freshwater flatworm Girardia tigrina (Girard, 1850) (Platyhelminthes, Tricladida) in Western Europe: new insights into its morphology, karyology and reproductive biology

“…Sluys, 2016). Therefore, detailed knowledge on the biology of an invasive species is of utmost importance for understanding the process of invasion, the cause of its success, and the subsequent ecological impact on native species (Ducey et al, 2005;Boll et al, 2015). To this end, we provide in this paper further insights into the biology of introduced populations of the freshwater flatworm Girardia tigrina (Girard, 1850).…”

Negative impacts of invasive predators used as biological control agents against the pest snail Lissachatina fulica: the snail Euglandina ‘rosea’ and the flatworm Platydemus manokwari

“…and ribbon worms (Geonemertes pelaensis) feed on snails (Gerlach 1998;Jones and Sterrer 2005;Can 2018) and have been implicated in the decline of Bermuda's endemic land snails (Outerbridge et al 2019). Endeavouria septemlineata will attack live snails (Mead 1979) despite its relatively small size but appears to prey mainly on dead animals (Boll et al 2015) and was not thought by Hadfield (1986) to be a serious threat to Hawaii's Achatinellinae. In experiments, Okochi et al (2004) showed that Platydemus manokwari consumed snails readily but that Bipalium kewense did not prey on snails at all, while other flatworms (different species of Bipalium and Platydemus and a species of Australopacifica) ate the snails in some instances.…”