Agonistic interactions between male Frontinella pyramitela (Araneae,Linyphiidae)

Summary Adult male bowl and doily spiders, Frontinella pyramitela (Walckenaer) (Linyphiidae), occupy females' webs during courtship, mating, and foraging. When males are abundant, they can be found on about 20% of all adult females' webs, and encounters between the territorial resident males and intruder males occur frequently. Stereotyped interactions take place in 78% of encounters when the resident male has recently copulated on the web, though the presence of the female during the encounters has no effect. When the resident male has had no recent copulatory experience on the web, only 33% of encounters evoke visible stereotyped interaction.Analyses of videotaped interactions reveal that transitions from one behavior to another, though non-random, are highly variable (Fig. 1). The overall ordering of the interactions is species-typical with respect to the relative frequency of behavioral units and the relative amount of time spent in each one.Outcomes of the stereotyped interactions are very predictable: the larger male wins in 75% of all interactions, though when male sizes are closely matched, some significant resident advantage is detectable. A weak but significant inverse correlation between mass difference and duration of the jawlock display (Fig. 2) suggests that the display provides each male with information about his opponent's relative size.