Physiological evaluation of newly invasive jorō spiders (Trichonephila clavata) in the southeastern USA compared to their naturalized cousin, Trichonephila clavipes

Abstract

A newly-invasive spider from east Asia, Trichonephila clavata, or “jorō spider”, is spreading in the southeastern United States. Little is known about the biology or physiology of this species in this new range. Interestingly, a closely-related species in the same genus, the “golden silk spider,” Trichonephila clavipes, is already successfully established in this same region over the last 160 years. The golden silk spider, which is native to the tropics, has not expanded its range beyond the southeast, likely because of thermal limitations. This investigation is to determine how the biology and physiology of T. clavata compare to T. clavipes. We reason that if their physiologies are similar, then T. clavata would be similarly confined to the southeast. We examine online records submitted to iNaturalist.org to compare seasonal distributions and timing, and we collect females to measure physiological traits that help predict environmental tolerance, including metabolic rates, cardiac functioning (heart rate) during cold-exposure, and survival during brief (2 min) below-freezing temperature. Results show the jorō spider has a shorter season than its cousin, indicating it can complete its lifecycle within a narrow period of suitable weather. It has an inherently higher metabolism (twice as high), and has a 77% higher heart rate when exposed to low temperature. Finally, jorō spiders survive better (74% compared to 50%) in a brief freeze. These findings suggest the jorō spider can exist in a colder climatic region than the southeastern USA, which can be useful information for management or planning purposes.