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Animals may exhibit a variety of defensive behaviors in the presence of indirect predator cues. Such behavior offers immediate fitness benefits but may also incur substantial foraging and reproductive costs. We measured shifts in space use (vertical climbing) by the wolf spider Pardosa milvina induced by chemotactile cues (silk and excreta) from a co-occurring predatory wolf spider Hogna helluo. We then measured foraging and reproductive costs, as well as survival benefits, of this behavior. For 2 weeks, we maintained mated adult female Pardosa in plastic containers with one of three treated peat moss substrates: a container previously occupied by a conspecific for 3 days, a container previously occupied by an adult Hogna for 3 days, and a container devoid of either cue (control). We measured prey capture efficiency, body condition, egg sac production, egg sac weight, and egg number for individuals in each treatment. We also counted the number of Pardosa that survived and exhibited climbing behavior in the presence of a live Hogna with and without silk and excreta cues. Pardosa climbed container walls significantly more often in the presence of Hogna silk and excreta relative to other treatments. Pardosa exposed to Hogna cues coupled with live Hogna survived significantly longer than spiders that had no predator cues available. Pardosa placed in containers with Hogna cues, but no Hogna, lost weight more quickly, ate fewer prey, were in poorer body condition, produced lighter egg sacs, and produced fewer eggs than spiders in control or conspecific treatments.

Spatial subdivision of the landscape can reduce the intensity of interspecific interactions, whether they be predation or competition. Recent models examining the ways in which spatial pattern in the landscape will influence the outcome of species interactions assume a trade-off between colonization ability and competitive ability in the interacting species. We tested for differential colonization and competitive ability in two interacting species of wolf spider (Hogna helluo and Pardosa milvina) which co-occur in agricultural and early successional habitats in the eastern USA. We conducted our research in replicated experimental soybean plots in which we created islands of enhanced habitat by supplementing natural litter and enhancing weed growth. Our experimental manipulations were repeated once for each of the two spider species: (1) spiders added, (2) prey attractants (composted vegetable waste) added, (3) spiders and prey attractants added, and (4) one control, for a total of eight subplots. We replicated the experiment six times, three times each in conventionally tilled fields and conservation tilled fields. We censused these plots at the end of the summer and found that conspecific addition significantly elevated numbers of one species (H. helluo) but not the other (P. milvina). These findings were consistent with our predictions that H. helluo is limited in colonization ability when compared to P. milvina. The addition of prey attractants significantly elevated numbers of both species, but the effect was far stronger for the superior colonist (P. milvina). This indicates that P. milvina is able to track resource abundance (both habitat structure and prey), a trait correlated with colonization ability. We found no strong evidence for a negative effect of H. helluo addition on numbers of P. milvina, as would be predicted if H. helluo strongly competed with or significantly preyed upon P. milvina. Body condition of P. milvina was lowest in subplots with higher numbers of H. helluo, indicating that H. helluo may have influenced the foraging success of P. milvina. We also found a strong and unexpected effect of the context of the plots (background tillage regime) on numbers of P. milvina, with there being approximately twice the P. milvina in the subplots in conventionally tilled fields.

When males engage in conspicuous courtship displays, it seems obvious that females would use characteristics of that display in mating decisions. However, males must also have a way to identify and evaluate females prior to engaging in what might be a costly mating ritual. Although it was known that female wolf spiders of the species Pardosa milvina (Araneae; Lycosidae) attract males using volatile chemical cues, the nature of the cues used by males and females in mate selection had not been investigated. Specifically we determined whether males could detect the mating status of the female and if chemotactile cues from the female played a role in that process. In addition, we quantified conspicuous aspects of the male courtship (leg raises and body shakes) to determine if courtship intensity was related to female choice. Although repeated mating occurred in our studies, males were more likely to court and mate with virgin females. Males used substrate‐borne cues deposited by females to discriminate between mated and virgin females. Females used the conspicuous behaviors of males during courtship, body shakes and leg raises, in mate selection. Thus males and females use different kinds of information and different sensory modalities to assess the suitability of a potential mate.

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