Female Black Widow Latrodectus hesperus introduced from California to Ružomberok, northern Slovakia. (source: SAV)
The first occurrence of a dangerous spider known as the Black Widow has been confirmed in Slovakia. The adult female arrived in Slovakia from California in a shipment of machine parts goods. She also laid eggs. The find was confirmed by Pavol Purgat from the Institute of Landscape Ecology of the Slovak Academy of Sciences (SAV) and Lucia Švecová from Comenius University.
"It was the first confirmed discovery of a Black Widow in Slovakia," said Pavol Purgat, adding for the Plus Jeden Deň daily that there are several dozen reports of Black Widows in Slovakia every year, but this is only a false alarm. "So far, it has always been the common southern Black Widow living in our country."
Purgat informed about the find in the scientific magazine Check List.
A single female Latrodectus hesperus, along with an egg sac, was discovered inside a building within a consignment of machine parts originating from San Bernardino, California, USA, in Ružomberok, northern Slovakia, in November 2023. She was captured and maintained alive under laboratory conditions, where it produced eight fertile egg sacs. Juveniles of both sexes were reared to maturity to facilitate the identification of the species.
Pavol Purgat, arachnologist from the Institute of Arachnology of the Slovak Academy of Sciences, who managed to record the first occurrence of the black widow in Slovakia. (source: SAV)
"With Black Widows, the arachnologist usually also needs an adult male when he wants to correctly determine the species," Purgat explained.
Latrodectus hesperus occurs naturally mainly in the western USA and Mexico. The detected species of the Black Widow has not yet been domesticated in Europe, except in Cyprus, but other subspecies of these spiders live in Spain and also in the Mediterranean area.
The female spider died naturally in the lab. She is preserved and stored in the arachnological collection of the SAV's Institute of Landscape Ecology, noted Purgat.
The female of the Black Widow spider is known to sometimes eat the male after mating, hence the nickname "black widow". The venom of these spiders contains the neurotoxin latrotoxin and can be dangerous to humans.
"Black Widow's venom poses a risk to humans, although it is rarely fatal," said Purgat. "Symptoms range from mild local - pain at the site of the bite, to severe systemic - painful muscle twitching, often requiring symptomatic treatment and in some cases even the administration of an antidote."
There may be more such Black Widow findings in the future.
"Black Widows are accidentally imported into Europe quite often," he said. For now, however, there are no reason for concerns. "There are no species of spiders in Slovakia that could pose a significant threat to human health."
