Does temperature affect the feeding behavior of Mecicobothrium thorelli (Araneae, Mecicobothriidae)?

Abstract

Mecicobothrium thorelli is a small mygalomorph spider (5-6 mm), endemic to the Ventania and Tandilia mountain systems in Argentina and Sierra de las Ánimas in Uruguay. It lives in funnel and sheet webs that it builds under rocks. In addition, it has a winter life cycle, reproducing and remaining active during the coldest months of the year, an unusual characteristic among spiders. In this work, it was proposed to evaluate feeding behavior traits of this species, such as prey acceptance and attack speed, in three different thermal ranges: cold (5-10°C), medium (15-20°C) and warm (25-30°C). For this, a larva of Tenebrio molitor was offered to 20 spiders previously acclimatized to the temperatures corresponding to each thermal range evaluated. The feeding event of each individual was recorded by video for the analysis of the parameters of prey acceptance and attack speed. It was observed that there were no significant differences in prey acceptance between the three thermal ranges evaluated. However, prey attack speeds were significantly higher in the warm thermal range than in the cold thermal range. The attack speeds of the medium thermal range did not present significant differences with the remaining temperatures. These results suggest that, although M. thorelli is a winter spider, its feeding efficiency could be optimal at higher temperatures than those to which it is exposed during its period of activity.