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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2008.12.026 Byline: Ann L. Rypstra (a)(b), Ann M. Schlosser (c)(d), Patrick L. Sutton (c)(d), Matthew H. Persons (e) Abstract: Many animal signals, especially those important to finding and attracting mates, are multimodal, which means they involve two or more sensory modalities. Among other sensory modalities, the wolf spider, Pardosa milvina (Araneae, Lycosidae), uses a variety of chemical and visual information in reproductive activities. Here we report the results of four laboratory experiments in which we explored the effects of visual and chemical information on the behaviour of males. First we established that chemical cues enabled males to find females and that visual cues kept the males' attention focused in the area of the females. Subsequently, we examined the separate and combined effects of visual and chemical cues on the interactions between males competing for virgin or mated females. The behaviour of interacting males revealed that either chemical or visual information was sufficient for them to discriminate between mated and virgin females. Chemical cues elicited more courtship activity and more intense aggressive interactions between males than visual cues. When males were able to see live mated females but were in contact with chemical cues from virgins, aggression was lower and, conversely, when males were able to see live virgin females but were in contact with chemical cues from mated females, aggression increased. We conclude that chemical cues provided males with the most critical discriminatory information. Although the two types of signals are largely redundant, there are some circumstances where they enhance the response of the males and there is an intersignal interaction that allows males to adjust their behaviour when presented with a receptive female. Author Affiliation: (a) Center for Animal Behavior, Miami University, Hamilton, OH, U.S.A. (b) Department of Zoology, Miami University, Hamilton, OH, U.S.A. (c) Center for Animal Behavior, Miami University, Oxford, OH, U.S.A. (d) Department of Zoology, Miami University, Oxford, OH, U.S.A. (e) Department of Biology, Susquehanna University, Selinsgrove, PA, U.S.A. Article History: Received 21 July 2008; Revised 22 September 2008; Accepted 18 December 2008 Article Note: (miscellaneous) MS. number: A08-00477

Females of many spider species invest in chemical advertisements to attract males, yet variation in investment relative to the presence or quality of males remains poorly understood. Males of the wolf spider Pardosa milvina court females longer and more intensively when in contact with female silk and also court more intensively when encountering silk from virgin rather than mated females; therefore, females may use silk as a medium to advertise their receptivity to mate. We estimated female investment in advertisements by measuring variation in the quantity and type of silk deposited by females in the presence or absence of males and among males that varied in their courtship intensity. We measured dragline silk, cord silk, and attachment disk deposition from females on gridded sheets of paper in response to four stimuli over a 30-min period (n = 39/treatment): (1) an intensively (high) courting male with access to female silk, (2) a weakly courting or non-courting male (low) without access to female silk, (3) no male present, but female silk present (silk control), and (4) no stimulus present (control). Females produced significantly more dragline silk and significantly less cord silk in the presence of low-courting males compared to any other treatment, but we found no difference in attachment disk deposition across treatments. Our results suggest that females invest more heavily in dragline deposition when encountering low-courting males. Additional studies are necessary to determine the relative role of different silk types in male-female sexual communication. [ABSTRACT FROM AUTHOR]

Fighting behavior has been studied extensively with strong emphases on factors that independently determine winners and losers as well as how much effort an individual should invest in a given contest for a resource. Much less attention has been paid to how interacting qualities of disputed resources modulate aggression. In a laboratory study, we examined the interactive effects of female condition and mating status on dyadic male aggression in the wolf spider Pardosa milvina. We discovered that males exhibited significantly more aggressive behaviors when in the presence of virgin females in good condition and displayed lower and statistically similar levels of aggression when placed with virgin, poor condition females; mated, good condition females; mated, poor condition females; and no females. Because previous studies have suggested that virgin females alone should be highly prized because of putative first-mate sperm priority patterns, this study contributes to this body of literature by suggesting that diet history and body condition mitigate the reproductive advantages of mating with virgin females as indicated by levels of male-male aggression, but further investigation is needed. [ABSTRACT FROM AUTHOR]

Understanding how animals weigh habitat features, exposure to predators and access to resources is important to determining their life history and distribution across the landscape. For example, when predators accumulate in structurally complex habitats, they face an environment with different competitive interactions, foraging opportunities and predatory risks. The wolf spider Pardosa milvina inhabits the soil surface of highly disturbed habitats such as agricultural fields throughout eastern North America. Pardosa displays effective antipredator behavior in the presence of chemical cues produced by a larger coexisting wolf spider, Hogna helluo. We used those cues to simulate predation risk in laboratory and field experiments designed to test the effects of habitat substrate and predation risk on site selection and prey consumption of Pardosa. In general, Pardosa preferred more complex substrates over bare dirt but those preferences were eliminated or reversed when cues from Hogna were present. Feeding trials revealed that substrate alone had few effects on Pardosa prey consumption, which we measured by documenting the change in the abdomen width. Although the presence of Hogna cues reduced prey consumption overall in field feeding trials, the negative effect of predation risk on prey consumption was only observed in grass and bare dirt substrates in the laboratory. We also found that prey capture was negatively affected by habitat complexity for both spider species but that same complexity offered Pardosa protection from predation by Hogna. This study provides insight into how two predator species interact to balance site selection and feeding in order to avoid predation. Shifts in foraging and distributional patterns of predators can have profound implications for their role in the food web. [ABSTRACT FROM AUTHOR]

The wolf spider Pardosa milvina exhibits effective antipredator behavior (reduced movement) in the presence of silk and excreta from a larger co-occurring predatory wolf spider Hogna helluo. As the quantity and quality of the silk and excreta may vary with the hunger state of the predator, we tested if chemical cues from a hungry vs. satiated H. helluo affected the activity level and survival of P. milvina. Pardosa milvina response was measured on substrates containing chemical cues from (1) a satiated H. helluo, (2) a H. helluo that had been withheld food for 2 wk, (3) cues from adult domestic crickets ( Acheta domesticus), or (4) a blank test substrate (20 replicates/treatment). Pardosa milvina activity level was recorded on each substrate over a 30-min period using video-tracking equipment (Videomex-I®; Columbus Instruments, Columbus, OH, USA). We then measured P. milvina survival in the presence of hungry or satiated H. helluo on cues from a hungry H. helluo, satiated H. helluo, or a blank control (2 × 3 design). Pardosa milvina significantly reduced activity in the presence of H. helluo cues and showed significantly less activity in the presence of cues from a hungry H. helluo compared with a satiated one. Cue type and predator hunger state significantly affected P. milvina survival in the presence of live predators. However, cues from hungry vs. satiated H. helluo resulted in no difference in P. milvina survival. Pardosa milvina can discriminate between hungry vs. satiated predators based on silk and excreta cues alone, but differences in behavior as a result of this discrimination did not translate into increased survival in the presence of a live predator. [ABSTRACT FROM AUTHOR]

The wolf spider, Pardosa milvina, reduces activity in the presence of chemical cues (silk and excreta) from a larger predatory wolf spider, Hogna helluo. Hogna is sexually dimorphic in body size and males and females differ in their propensity to attack prey. Consequently, each sex may present different levels of risk to Pardosa. We measured predation risk of Pardosa in the presence of male or female Hogna. We also assessed Pardosa antipredator responses and survival in the presence or absence of previously deposited chemical cues from male or female Hogna. In the absence of predator chemical cues, Pardosa survived significantly longer in the presence of male Hogna compared with female Hogna. We then assessed Pardosa survival in the presence of chemical cues from each Hogna sex by placing Pardosa in containers previously occupied by a female Hogna, a male Hogna, or no Hogna (control). We then introduced a female Hogna into each container and measured predation latency. Pardosa survived significantly longer in the presence of female and male cues compared with the control treatment. Median survival time of Pardosa was over four times longer on substrates with female Hogna cues compared with male cues, but this difference was not statistically significant. We tested Pardosa activity levels in the presence of chemical cues from male or female Hogna. Both Hogna sexes were maintained in separate containers after which we placed an adult female Pardosa in one of the containers or a blank control container. Pardosa significantly decreased activity in the presence of chemical cues from either sex relative to the control. Activity was lowest on substrates with female Hogna cues, but not significantly lower than on substrates with male Hogna cues. Results suggest that chemical information from male or female Hogna significantly reduces Pardosa activity which results in increased survival. [ABSTRACT FROM AUTHOR]

In the wolf spider, Hogna helluo, we tested the response to insect and spider prey chemical cues and whether they show a preference for cues associated with prey consumed most recently. Thirty adult female H. helluo were maintained on a diet of either females of a smaller co-occurring wolf spider (Pardosa milvina) or domestic crickets (Acheta domesticus). A single P. milvina or cricket nymph was maintained on filter paper for 24 h, after which the papers from both prey sources were simultaneously presented to individual H. helluo from each diet treatment group. H. helluo locomotor behavior on each treatment and initial substrate preference was recorded (n = 15/treatment). H. helluo fed crickets showed significantly longer residence time and decreased mobility on filter paper previously occupied by a cricket; spiders fed P. milvina showed longer residence times and decreased mobility on filter paper previously occupied by P. milvina. H. helluo fed P. milvina exhibited an initial preference for substrates previously occupied by P. milvina but H. helluo fed crickets did not show a corresponding initial preference for crickets. Results suggest that H. helluo can detect distant cues associated with P. milvina but not crickets before contacting the substrate and that H. helluo respond to chemical cues from prey and show a preference for those cues associated with their most recent prey. [ABSTRACT FROM AUTHOR]

Examines the influence of sensory cues without food reward on residence time wolf spiders and the interaction of visual and vibratory information in foraging decisions. Sensory modes of wolf spiders; Emphasis on foraging models; Forms of pre-sampling information.

Predation has widespread influences on animal behaviour, and reproductive activities can be particularly dangerous. Males and females differ in their reactions to sensory stimuli from predators and potential mates, which affects the risk experienced by each sex. Thus, the information available can cause differential survival and have profound implications for mating opportunities and population structure. The wolf spider, Pardosa milvina , detects and responds in a risk-sensitive manner to chemotactile information from a larger predator, the wolf spider Tigrosa helluo . Male P. milvina use similar chemotactile cues to find females whereas female P. milvina focus on the visual, and perhaps vibratory, aspects of the male display. Our aim was to document the risk posed by T. helluo predators on P. milvina during reproduction and to determine whether augmenting chemotactile information would affect that outcome. In the laboratory, we explored the effects of adding predator and/or female cues on the predatory success of T. helluo on P. milvina males or observing females. Additional cues from prospective mates or from predators enhanced male survival. The addition of female cues increased predation on females whereas predator cues augmented female survival. In field enclosures, we documented the impact of T. helluo , with and without additional predator cues, on the sex ratio of survivors and the reproductive success of females. Additional predator cues shifted the sex ratio towards males, however, 90% of the remaining females in that treatment produced eggsacs whereas less than 60% reproduced in female-biased populations. Thus, augmenting the available predator information shifted the risk from males to females, presumably due to differences in their sensory priorities. By altering the availability of potential mates, this shift appears to have influenced the intensity of sexual selection for this spider. [ABSTRACT FROM AUTHOR]

Indirect benefits derived by females that mate with males that express preferred traits are important to our understanding of ‘good genes’ models of sexual selection. However, few studies have explored male courtship behaviours with potential indirect benefits conferred to females in order to ascertain whether these behaviours serve as honest indicators of male quality. Using a common species of wolf spider, Pardosa milvina, we addressed the honesty of male courtship behaviours in two laboratory experiments. In our first experiment, we quantified the repeatability of courtship rate in adult males that were manipulated to be in high or low condition and were sequentially presented with adult virgin females that similarly differed in body condition. In our second experiment, we explored the effect of male courtship rate on several measures of fitness: number of offspring produced, days until offspring emerged and offspring viability measured as offspring survival. Our experiments show that male courtship rate is statistically significantly repeatable except when males in high condition have repeated encounters with females in low condition. Our results also reveal that females have the potential to gain indirect genetic benefits by mating with males that naturally court at high rates: females produced more offspring that emerged from eggsacs sooner and survived starvation better compared to females that mated with males that naturally courted at low rates. Our study provides additional support that male courtship rate is an honest indicator of quality, and it makes the novel finding that the repeatability of courtship rate is context sensitive. [Copyright &y& Elsevier]