A comparison of adhesive performance among six cursorial spider species

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  A comparison of adhesive performance among six cursorial spider species Abstract The ability to adhere to surfaces is particularly relevant for cursorial predatory arthropods like hunting spiders, which often traverse relatively complex environments characterized by large variation in substrate properties. Here, we evaluated the adhesive performance of six hunting spider species that are common in eastern temperate North America and lack specialized tarsi for climbing smooth or inclined surfaces [Lycosidae: Pardosa lapidicina Emerton, 1885 and Rabidosa rabida (Walckenaer, 1837); Oxyopidae: Oxyopes salticus Hentz, 1845; Pisauridae: Pisaurina mira (Walckenaer, 1837); Dolomedidae: Dolomedes triton (Walckenaer, 1837), and Dolomedes scriptus Hentz, 1845]. We tested adhesion performance as shear load resistance (g) on a glass plate, and as the angle of failure (°) when the plate was gradually inclined relative to horizontal. Average angle of failure and shear resistance differed among ...

The temperature preference, phenology and enzymatic activity of two winter-active spiders (Araneae)

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Anyphaena accentuata on a fence in Bouffémont, France.By Alexis Lours - Own work, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=114760824

The temperature preference, phenology and enzymatic activity of two winter-active spiders (Araneae)

Abstract

While the great majority of arthropod natural enemies present in commercial orchards are inactive during winter, a few spider species remain active and catch pests. This is the case of Anyphaena accentuata and Philodromus spp. spiders, which contribute significantly to a reduction in the population of psyllids during winter. These spiders were found to catch prey even at temperatures close to or below 0°C. Here, we investigated whether these spiders have a preference for low temperatures, when they reach maturity, and whether their enzymatic activity, specifically that of α-amylase, is adapted to low temperatures. The temperature preference, studied on a temperature gradient funnel, showed that Anyphaena preferred temperatures of around 20°C, while Philodromus preferred temperatures of around 30°C. On the basis of faunistic data, both Anyphaena and Philodromus are univoltine, with adults of Anyphaena occurring in late April, while those of Philodromus occur in early June. The amylolytic activity was measured in venom gland extracts and whole prosoma homogenates in the range from 0 to 60°C. Fitted triangular models revealed that α-amylase in the prosoma of Anyphaena has lower thermostability at higher temperatures than α-amylase in Philodromus. Fitted Arrhenius models revealed that, in Philodromus, the activation energy of the enzyme reaction in prosoma homogenates was lower than that in venom gland extracts. The obtained results show that Anyphaena is more adapted to lower temperatures than Philodromus.

Pekár, S., Michalko, R., & Šustr, V. The temperature preference, phenology and enzymatic activity of two winter-active spiders (Araneae). Physiological Entomology. https://doi.org/10.1111/phen.70010