A paper published in the journal PLOS ONE, written by former Bio-Protection Research Centre PhD student Francesco Martoni and BPRC senior research scientist Dr Karen Armstrong, describes two psyllids (also called jumping plant lice): Acizzia errabunda and Ctenarytaina insularis.
These extremely small insects, no more than 3 mm long, are not easy to detect. Both of these species live on common ornamental garden plants, but through this research, A. errabunda has been identified as a native of Australia, while C. insularis is thought to be native to New Caledonia
"We think both psyllids came here with their host plants, and have probably been here since the early years of European settlement," says Francesco, who will graduate with his PhD this year.
New Zealand scientists have closely studied psyllids since the recent arrival of the tomato-potato psyllid (TPP). As its name suggests, this insect damages tomatoes and potatoes and has caused significant economic damage to the horticulture industry. It has since also arrived in Western Australia, which is on high alert to prevent its spread to other Australian states.
Francesco spent two years sampling psyllids all around New Zealand and, as a result, discovered not only the two new exotic species but also suspects he has found 19 new native species. He studied the genetics of the insects using a method called DNA barcoding and also analysed the shape and structure (morphology) of psyllid samples held in museums and insect collections from New Zealand and around the world.
While not described, the exotic species had been collected before.
One had been collected from Auckland and Wellington, and the other was collected from Christchurch and Nelson. Both had also been reported to the website iNaturalistNZ, where people can upload photos of plants and animals they see and ask for identification.
Psyllids often carry diseases that can affect economically important crops. "Psyllid taxonomy and systematics is of primary importance, not only for a better understanding of worldwide biodiversity but also in order to recognise new or invasive species essential for international biosecurity and plant protection," the authors write in the paper.
However, while A. errabunda and C. insularis do not carry such diseases, describing two new species in New Zealand before they are identified in their native countries is unusual. "It also suggests we still have a long way to go to fully appreciate the biodiversity around us," says Francesco.
"While our focus as researchers is often on biosecurity – detecting and eradicating pests and diseases – in this case, it also helped to improve our knowledge of biodiversity in New Zealand," he says.
"By constantly monitoring New Zealand's biodiversity scientists also increase understanding of what new species are arriving, which can only strengthen biosecurity efforts."
The full paper is available at http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0214220.
Francesco Martoni now works as a research scientist for Agriculture Victoria, in Melbourne.