The long-horned tick (Haemaphysalis longicornis) is native to the temperate areas of eastern and central Asia, including China, Korea and Japan, as well as certain Pacific islands such as Australia, New Zealand, Fiji and Hawaii. In August 2018, the New York City Department of Health announced the discovery of the first specimen of the species in the Staten Island district, although a year earlier some individuals had already been found in other areas of the east coast.
A new study, published in the journal Emerging Infectious Diseases, now reveals that the population of this arachnid, considered a potentially dangerous invasive pest, is larger than was thought on Staten Island. The reason is that, unlike other local species, this tick, normally found in the grass where deer graze, is capable of self-cloning in large numbers.
“The concern with this tick is that it could transmit human pathogens and make people sick,” says researcher Maria Diuk-Wasser, an associate professor in the department of Ecology, Evolution and Environmental Biology at Columbia University.
U.S. scientists conducted the most comprehensive local census to date of this species and found the tick in seven of the 13 parks analyzed in 2017. By 2018, the parasite was present in 16 of the 32 parks studied. In one of them, the density of ticks per thousand square metres increased by 1,698 % between 2017 and 2018, as the number of specimens collected increased from 85 to 1,529.
When the first individual of this species was sighted in New York, experts sounded the alarm to try to stop the spread of the tick, whose main characteristic is its ability to replicate quickly. Under certain environmental conditions, the female can clone herself through asexual reproduction. But it also has the ability to reproduce sexually, laying between 1,000 and 2,000 eggs at a time.