THE EFFECTS OF TEMPERATURE ON THE WEB-BUILDING BEHAVIOR OF THE COMMONHOUSE SPIDER, ACHAEARANEA-TEPIDARIORUM

1. Because spiders are ectothermic animals, the temperature regime of the microhabitat in which an individual finds itself may affect import ant performance traits of that individual, The present study examined the effects of temperature on attributes of webs spun by Achaearanea t epidariorum (C. Koch), as well as testing temperature preference in th is species. The effects of temperature on the amount of silk per web p roduced by Achaearanea tepidariorum and the prey-capture efficiency of webs produced at different temperatures were determined by using webs constructed at 5, 10, 15, 20, 25 and 30 degrees C. The temperature pr eferences of A. tepidariorum within a thermal gradient were also deter mined, 2. Web mass was related to temperature, exhibiting a quadratic relation with a maximum web mass occurring at approximately 20 degrees C. 3. Number of strands per cm(3) of webs varied directly with web ma ss; webs with greater strand densities were more efficient at capturin g flies. 4. The number of spiders observed in each temperature range i n the thermal gradient indicated a non-uniform distribution, with the spiders avoiding temperatures in the highest range (27.3 +/- 2.0 degre es C). 5. These data suggest an optimal temperature for web constructi on at which webs produced are more efficient at capturing prey. The da ta also suggest that this species may avoid sites that do not provide an adequate thermal environment.