Establishment, spread, and impact of an invasive planthopper on its invasive host plant: Prokelisia marginata (Homoptera: Delphacidae) exploiting Spartina anglica (Poales: Poaceae) in Britain

Abstract

1. Since its recent arrival in Britain, the planthopper Prokelisia marginata has spread widely around saltmarshes on the east and south coast of England and south Wales, feeding on Common Cordgrass, Spartina anglica, itself an invasive non-native species. 2. Results suggest that P. marginata populations in Britain benefit from a degree of natural enemy release. No evidence of parasitism was found in over 71 000 eggs, nymphs, and adults inspected. The only potential natural enemy control was suggested by a positive correlation between the densities of planthoppers and generalist spiders. 3. Experimental exposure under both glasshouse and field conditions to typical field densities of planthoppers resulted in significant negative effects on a number of host plant performance metrics. 4. Spartina anglica is important for stabilising estuarine sediments and has been deliberately planted for this purpose in the past. Its weakening as a result of heavy planthopper herbivory could have serious consequences for the long-term stability of Britain's vulnerable saltmarsh habitats.

Differential outcomes of novel plant-herbivore associations between an invading planthopper and native and invasive Spartina cordgrass species

“…It should be noted, however, that all planthoppers used in the experiments were cultured on S. anglica, raising the possibility of prior conditioning to this host species (Coaker and Cheah 1993). However, as S. anglica is now the most abundant, widespread and dominant Spartina species in Britain, this is increasingly likely to reflect the reality of field conditions (Harkin and Stewart 2020). Our second hypothesis predicted that P. marginata would achieve the greatest performance outcomes on S. alterniflora, the host to which it is expected to be best adapted by virtue of their shared evolutionary history, and on which it has previously been shown to achieve the greatest survival in no-choice host specificity tests (Denno et al 1986;Grevstad et al 2003).…”

“…It should be noted, however, that all planthoppers used in the experiments were cultured on S. anglica , raising the possibility of prior conditioning to this host species (Coaker and Cheah 1993 ). However, as S. anglica is now the most abundant, widespread and dominant Spartina species in Britain, this is increasingly likely to reflect the reality of field conditions (Harkin and Stewart 2020 ).…”

“…P. marginata is presumed to have arrived in Britain sometime since 2000, with preliminary studies suggesting it is in the early stages of successful invasion (Harkin and Stewart 2020 ). Across its introduced continental European range, P. marginata has been recorded primarily on S. anglica or S. x townsendii (de Blauwe 2011 ), with a single Slovenian population recorded on S. maritima (Seljak 2004 ).…”

“…Ten potted plants of each of the four Spartina species were transported to the Spartina -dominated marsh at Hythe, a site previously shown to have an established P. marginata population (Harkin and Stewart 2020 ). Hythe is considered to be the site of origin for both Spartina x townsendii and Spartina anglica (Raybould et al 1991 ), although it is no longer possible to locate the former at the site.…”

“…Across its introduced continental European range, P. marginata has been recorded primarily on S. anglica or S. x townsendii (de Blauwe 2011), with a single Slovenian population recorded on S. maritima (Seljak 2004). Prior to the work presented here, S. anglica was the only recorded host for P. marginata in its British range (Badmin 2013;Harkin and Stewart 2020).…”