New study provides key to identifying spiders in international cargo

(Press-News.org) Spiders found in international cargo brought into North America are sometimes submitted to arachnologists for identification. Often, these spiders are presumed to be of medical importance because of their size or similarity to spiders that are known to be venomous.

In 2006, after witnessing multiple episodes where harmless spiders were mistaken for toxic ones, Dr. Richard Vetter, an arachnologist at the University of California, asked other arachnologists to provide data on specimens they found in international cargo that had been submitted to them for identification. He also asked that they identify spiders in their museum collections that had previously been found in cargo.

Together with colleagues from Canada and Washington State, Dr. Vetter identified 135 spiders taken from international cargo between 1926 to June 2014, which they describe in an ad hoc study in the Journal of Medical Entomology. The authors hope that their paper will fill a knowledge gap and facilitate the proper identification of cargo-borne spiders because misidentifications can lead to costly and unwarranted eradication measures, unnecessary employee health education, heightened employee anxiety, and spoilage when perishable goods are left unloaded due to safety concerns.

In order to help avoid misidentifications in the future, the new paper contains a simple key that covers the most common non-mygalomorph spiders found in their study.

"This key should provide some utility for those confronted with a spider found in international shipments," they wrote.

The authors found that the most frequently submitted spiders were the pantropical huntsman spider (Heteropoda venatoria) and the redfaced banana spider (Cupiennius chiapanensis), and that the most common cargo from which spiders were submitted was bananas, with most specimens coming from Central America, Ecuador, or Colombia.

Spiders of medical importance were rare.

"Spiders found in international cargo, especially those in banana cartons, are typically harmless species," they wrote. "It would be beneficial if this article curtails the hyperbole and media attention whenever a large spider is discovered in a banana shipment, and thereby, reduce unwarranted paranoia and anxiety when media stories about toxic banana spiders are unleashed onto an unsuspecting and easily frightened North American general public."

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