Evolutionary impact of invasive Cardiospermum species on native Leptocoris bugs in South Africa
Cardiospermum halicacabum and C. grandiflorum (Sapindaceae) were introduced into South Africa approximately 100 years ago and are classified as minor and major invasive species, respectively. Within the EPPO region, C. grandiflorum is included in the EPPO A2 list of pests recommended for regulation and it is an invasive alien species of Union concern (EU). In South Africa, Leptocoris soapberry bugs (Hemiptera: Rhopalidae) are specialised predators of seed of the Sapindaceae family and feed on both native species and the two aforementioned species. They use their elongated proboscis to pierce the fruits and feed on the seeds within. To evaluate if there is a potential evolutionary impact of the two invasive plant species on native soapberry bugs, individuals of L. mutilatus were collected from C. halicacabum and C. grandiflorum populations in the Kruger National Park and phylogenetic and morphological analyses were conducted. In addition, fruits and soapberry bugs feeding on those fruits, were collected from C. halicacabum and C. grandiflorum populations and fruit size and proboscis length were measured. Soapberry bugs associated with C. halicacabum were genetically different and morphologically distinct from those associated with C. grandiflorum. This suggests that soapberry bugs in the Kruger National Park show host preference for the non-native Cardiospermum species and this may have some evolutionary consequences for the insects.
Foster JD, Ellis AG, Foxcroft LC, Carroll SP, Le Roux JJ (2019) The potential evolutionary impact of invasive balloon vines on native soapberry bugs in South Africa. NeoBiota 49, 19–35. https://doi.org/10.3897/neobiota.49.34245