115.1 Saturday, Jan. 7 Nuptial thief: male spiders steal food from mating partners DANIELSON-FRANCOIS, A.*; DROBOT, Y.; University of Michigan - Dearborn; University of Michigan - Dearborn email@example.com
Adult male spiders do not build webs. Once males molt to maturity, they wander in search of females to mate. For orb-weaving spiders, not building a web means that no prey can be captured and hence males cannot feed themselves. In some sexually dimorphic orb-weaving species with extremely tiny males, such as Nephila, the males are kleptoparasitic and subsist on the leftover remains of prey not eaten by females. No spider species has been observed to have males that steal prey items caught by females. Here, we report for the first time that males of at least one orb-weaving species, Tetragnatha elongata, are able to feed as adults by actively stealing food from their female partners after mating. We collected adult T. elongata in southeastern Michigan and performed 165 staged matings in the laboratory. We found that male food-stealing behavior was significantly influenced by the relative body masses of males and females. When the difference in body mass was minimal, males were able to steal prey. This finding suggests that males may have a trade-off between acquiring food resources and achieving greater reproductive success with larger more fecund females.