Web-building spiders (Araneae; Theridiidae, Linyphiidae, Araneidae) are catagorized as searchers ... more Web-building spiders (Araneae; Theridiidae, Linyphiidae, Araneidae) are catagorized as searchers because they devote a large amount of energy to the construction of the web which constitutes the search phase in the foraging sequence. In this study search energy is equated with the density of threads in a web and the effectiveness of a variety of webs in three broad catagories (tangle webs, sheet webs & orb webs) is tested in the light of current foraging theory. Within each web type there is a distinct thread density at which the number of approaching Drosophila (Diptera; Drosophilidae) that are captured is maximized (Figs. 1, 2, 3). That maximum results from a combination of factors that are a function of the density of threads in the web. The visibility of the web to an approaching Drosophila increases which acts to decrease the number of flies that enter the web (Tables 2, 3, 4). The ability of the web to detain a Drosophila that contacts it (capture efficiency) increases to an asymptote as a function of thread density (Fig. 4). These data support an assumption of many optimal foraging models that with increasing investment in search the predator receives a diminishing return.More Drosophila intercept orb webs than intercept sheet or tangle webs. In addition orb webs detain a greater proportion of the flies that contact them (Fig. 4). Sheet webs are intermediate between orb and tangle webs in their relative abilities to contact and detain Drosophila.
... 1997, Schmitz and Settle 2001, Schmitz and Sokol-Hessner 2002). In those examples, thegrassho... more ... 1997, Schmitz and Settle 2001, Schmitz and Sokol-Hessner 2002). In those examples, thegrasshoppers had access to visual and vibratory cues as well as the chemotactile cues that were important in this study. ... Beckerman, AP, M. Uriarte, and OJ Schmitz. ...
The wolf spider, Pardosa milvina, displays effective antipredator behavior (reduced activity) in ... more The wolf spider, Pardosa milvina, displays effective antipredator behavior (reduced activity) in the presence of silk and excreta cues from adults of another cooccurring wolf spider, Hogna helluo. However, Pardosa and Hogna engage in size-structured intraguild predation, where Pardosa may be either the prey or predator of Hogna. We tested the ability of adult female Pardosa to vary antipredator responses toward kairomones produced by Hogna that vary in size. Hogna were maintained on filter paper for 24 hr. We then presented the paper to adult female Pardosa simultaneously paired with a blank sheet of paper. One treatment had two sheets of blank paper to serve as a control. The Hogna stimulus treatments were as follows (N = 15/treatment): 1 Hogna half the mass of Pardosa; (2) 1 Hogna of equal mass of a Pardosa; (3) 1 adult Hogna, 30 times the mass of Pardosa; and (4) 8 Hogna each 0.25 the mass of Pardosa. Pardosa decreased activity in the presence of kairomones from Hogna of equal or larger size, but showed no change in activity in the presence of a blank control or from a single Hogna smaller than itself. Pardosa showed a reduction in activity in the presence of cues from eight small Hogna. Pardosa avoided substrates with adult Hogna cues, but showed no avoidance response to any other treatment. These results suggest that Pardosa is showing graded antipredator behavior relative to the quantity of predator kairomones present rather than directly discriminating among the different sizes of the predator. * * * <0.001. (A) Chemical cues from large adult female Hogna (LH) vs. a blank (LB). (B) Chemical cues from a medium-sized Hogna (MH) equal in body mass to the Pardosa being tested vs. a blank control (MB). (C) chemical cues from a small Hogna (SH) half the body mass of the test spider vs. a blank (SB). (D) a double blank control, B1 and B2. (E) chemical cues from eight small Hogna (EH) each ca. one fourth the mass of the Pardosa being tested vs. a blank control (EB). Locomotor activity and initial side choice was recorded for each spider.
Annual Review of Ecology, Evolution, and Systematics, 2009
Sexual cannibalism, the consumption of the male by the female before, during, or after mating, ca... more Sexual cannibalism, the consumption of the male by the female before, during, or after mating, can be a striking example of sexual conflict with potentially large fitness consequences for males and females. In this review, we examine how ecological and ...
We studied the distribution of 2 wolf spider species in 2 soybean, Glycine max (L.), agroecosyste... more We studied the distribution of 2 wolf spider species in 2 soybean, Glycine max (L.), agroecosystems in southwestern Ohio, USA. We used replicated 0.42-ha soybean fields maintained under 2 different tillage regimes (conservation tillage and conventional tillage) and 2 wolf spider species [ ...
Sexual cannibalism varies widely among spiders, but no general evolutionary hypothesis has emerge... more Sexual cannibalism varies widely among spiders, but no general evolutionary hypothesis has emerged to explain its distribution across taxa. Sexual size dimorphism (SSD) also varies widely among spiders and could affect the vulnerability of males to cannibalistic attacks by females. We tested for a relationship between SSD and sexual cannibalism within and among species of spiders, using a broad taxonomic data set. For most species, cannibalism was more likely when males were much smaller than females. In addition, using phylogenetically controlled and uncontrolled analyses, there was a strong positive relationship between average SSD of a species and the frequency of sexual cannibalism. This is the first evidence that the degree of size difference between males and females is related to the phylogenetic distribution of sexual cannibalism among a broad range of spiders.
... 3, 1992 Foraging Behavior of the Communal Spider, Philoponella republicana (Araneae: Uloborid... more ... 3, 1992 Foraging Behavior of the Communal Spider, Philoponella republicana (Araneae: Uloboridae) Greta J. Binford 1'2 and Ann L. Rypstra i ... An open fruit fly culture was maintained in each enclosure from which adult Drosophila emerged and the spiders could feed ad libitum. ...
2. Because web spiders have limited dispersal abilities and an energetically costly prey capture ... more 2. Because web spiders have limited dispersal abilities and an energetically costly prey capture device, they do not have the ability to sample potential foraging sites. Structural complexity of the vegetation to which the web must be attached is relatively easy to assess. The ...
... (Araneae, Lycosidae) Shawn M. Wilder1,2) &amp;amp; Ann L. Rypstra3) (1 Department of Zool... more ... (Araneae, Lycosidae) Shawn M. Wilder1,2) &amp;amp; Ann L. Rypstra3) (1 Department of Zoology, Miami University, Oxford, OH 45056; 3 Department of Zoology, Miami University, Hamilton, OH 45011) ... in parental care (Darwin, 1871; Bateman, 1948; Trivers, 1972; Andersson, 1994). ...
Female Pardosa milvina wolf spiders carry large eggsacs. We quantified the effects of carrying eg... more Female Pardosa milvina wolf spiders carry large eggsacs. We quantified the effects of carrying eggsacs on foraging success and susceptibility to predation. In addition to monitoring individuals carrying natural eggsacs, we induced females to carry artificial eggsacs of varying mass. We determined the propensity of females to attach eggsacs or plastic beads of various sizes. We then quantified prey capture success and the avoidance of the predatory wolf spider, Hogna helluo, for Pardosa with and without eggsacs or plastic beads attached. Females attached their own eggsacs significantly more than plastic beads of equal mass and attached artificial eggsacs 10 times larger than natural eggsacs significantly less often than smaller plastic beads (ones equal to or 2.7 times the size of natural eggsacs). Females carrying real or artificial eggsacs of any mass captured fewer prey, but prey capture success did not vary among females with different-sized eggsacs. Except females of the 10 × eggsac treatment, individuals carrying an eggsac suffered significantly greater predation compared to females without eggsacs. Eggsac transport carries significant predation and foraging costs, but we found little evidence that carrying heavier eggsacs incur incrementally greater increases in predation risk or decreased foraging efficiency than carrying lighter eggsacs.
Sexual cannibalism can occur before, during or after mating. Relatively few experimental studies ... more Sexual cannibalism can occur before, during or after mating. Relatively few experimental studies have examined why there is variation in the timing of sexual cannibalism. We examined the latency and number of attacks required for female spiders to capture male spiders pre-vs. postcopulation. We also examined the effects of female mating status and hunger level on the occurrence of pre-and postcopulatory cannibalism, which reflects the contribution of both relative capture success and female motivation to cannibalize males. Precopulatory cannibalism occurred after a shorter interval and required fewer chases and physical interactions for the female to successfully capture the male than was the case for postcopulatory cannibalism. Virgin females were more likely to engage in postcopulatory rather than precopulatory cannibalism and mated females vice versa. Those virgin females that did engage in precopulatory cannibalism had significantly lower body condition than virgin females engaging in postcopulatory cannibalism. While precopulatory cannibalism occurred more quickly and required fewer attacks by females, it comes at a potential cost of not mating with males. Hence, females are more likely to engage in precopulatory cannibalism if they have already mated or, if virgins, if they have low body condition. These results indicate that the decision of when to cannibalize males is dynamic and depends upon the relative value of a male as a mate versus a meal.
Mate availability can vary widely in nature depending upon population density and sex ratio and c... more Mate availability can vary widely in nature depending upon population density and sex ratio and can affect the ability of individuals to be selective in mate choice. We tested the effects of prior encounters with the opposite sex (i.e., exposure to the opposite sex either with or without mating) on subsequent mating behavior in two experiments that manipulated mate availability for both males and females in the wolf spider, Hogna helluo. The probability of mating in the experimental trial depended upon whether the prior encounter involved mating or not, and males and females responded in opposite directions. Exposure without mating resulted in a higher subsequent frequency of mating for females and a lower subsequent frequency of mating for males, while prior mating experience resulted in a lower frequency of female remating and a higher frequency of male remating. Prior exposure without mating did not affect female aggression. However, mated females engaged in precopulatory cannibalism more frequently than virgins. Mated males escaped postcopulatory cannibalism more frequently than virgins. Our results show that males respond to exposure without mating in the expected manner. However, prior mating (1 week earlier) had unexpected effects on males, which may be due to mated males being of higher quality. There were little or no effects of the size of the prior exposure individual or mate on subsequent mating behaviors. Further research is needed to determine why different species use different degrees of prior information in mate choice.
Annals of the Entomological Society of America, 2003
... 1997, Schmitz and Settle 2001, Schmitz and Sokol-Hessner 2002). In those examples, thegrassho... more ... 1997, Schmitz and Settle 2001, Schmitz and Sokol-Hessner 2002). In those examples, thegrasshoppers had access to visual and vibratory cues as well as the chemotactile cues that were important in this study. ... Beckerman, AP, M. Uriarte, and OJ Schmitz. ...
Most research on sexual cannibalism has focused on factors influencing female motivation to engag... more Most research on sexual cannibalism has focused on factors influencing female motivation to engage in cannibalism. However, a critical factor that may mediate the actual occurrence of sexual cannibalism is male vulnerability to female attacks. We tested whether sexual size dimorphism (SSD) affected whether hungry females were successful in sexual cannibalism in a moderately size dimorphic wolf spider, Hogna helluo. Experimentally food-limited females cannibalized males more frequently than did well-fed females. However, in a correlational study, female body condition was only a significant predictor of the occurrence of sexual cannibalism if SSD was included in the model. Our results suggest that SSD is an important factor mediating the occurrence of sexual cannibalism in H. helluo by affecting male vulnerability to female attacks. Consideration of factors affecting male vulnerability to cannibalistic attacks by females may be critical to understanding the occurrence and evolution of sexual cannibalism.
Background/Question/Methods Generalist arthropod predators have been shown to impact the grazing ... more Background/Question/Methods Generalist arthropod predators have been shown to impact the grazing component of terrestrial food webs, but less attention has been given to detrital systems. Ground-dwelling spiders and beetles are common in terrestrial ecosystems, and detritivores have been found to compose a large portion of their diet. These predators have been shown to indirectly alter soil processes through consumption of microarthropods. However, studies of detrital systems have focused on density-mediated interactions between predators and detritivores, leaving trait-mediated interactions largely unexplored. We used the wolf spiders Pardosa milvina, Tigrosa helluo, and Rabidosa rabida along with the carabid beetle Scarites quadriceps to investigate their impacts on the survival of the collembolan Sinella curviseta, soil respiration, and soil carbon content. Additionally, we isolated trait-mediated effects between Pardosa and Sinella, as these species were believed to interact mos...
Web-building spiders (Araneae; Theridiidae, Linyphiidae, Araneidae) are catagorized as searchers ... more Web-building spiders (Araneae; Theridiidae, Linyphiidae, Araneidae) are catagorized as searchers because they devote a large amount of energy to the construction of the web which constitutes the search phase in the foraging sequence. In this study search energy is equated with the density of threads in a web and the effectiveness of a variety of webs in three broad catagories (tangle webs, sheet webs &amp;amp;amp; orb webs) is tested in the light of current foraging theory. Within each web type there is a distinct thread density at which the number of approaching Drosophila (Diptera; Drosophilidae) that are captured is maximized (Figs. 1, 2, 3). That maximum results from a combination of factors that are a function of the density of threads in the web. The visibility of the web to an approaching Drosophila increases which acts to decrease the number of flies that enter the web (Tables 2, 3, 4). The ability of the web to detain a Drosophila that contacts it (capture efficiency) increases to an asymptote as a function of thread density (Fig. 4). These data support an assumption of many optimal foraging models that with increasing investment in search the predator receives a diminishing return.More Drosophila intercept orb webs than intercept sheet or tangle webs. In addition orb webs detain a greater proportion of the flies that contact them (Fig. 4). Sheet webs are intermediate between orb and tangle webs in their relative abilities to contact and detain Drosophila.
... 1997, Schmitz and Settle 2001, Schmitz and Sokol-Hessner 2002). In those examples, thegrassho... more ... 1997, Schmitz and Settle 2001, Schmitz and Sokol-Hessner 2002). In those examples, thegrasshoppers had access to visual and vibratory cues as well as the chemotactile cues that were important in this study. ... Beckerman, AP, M. Uriarte, and OJ Schmitz. ...
The wolf spider, Pardosa milvina, displays effective antipredator behavior (reduced activity) in ... more The wolf spider, Pardosa milvina, displays effective antipredator behavior (reduced activity) in the presence of silk and excreta cues from adults of another cooccurring wolf spider, Hogna helluo. However, Pardosa and Hogna engage in size-structured intraguild predation, where Pardosa may be either the prey or predator of Hogna. We tested the ability of adult female Pardosa to vary antipredator responses toward kairomones produced by Hogna that vary in size. Hogna were maintained on filter paper for 24 hr. We then presented the paper to adult female Pardosa simultaneously paired with a blank sheet of paper. One treatment had two sheets of blank paper to serve as a control. The Hogna stimulus treatments were as follows (N = 15/treatment): 1 Hogna half the mass of Pardosa; (2) 1 Hogna of equal mass of a Pardosa; (3) 1 adult Hogna, 30 times the mass of Pardosa; and (4) 8 Hogna each 0.25 the mass of Pardosa. Pardosa decreased activity in the presence of kairomones from Hogna of equal or larger size, but showed no change in activity in the presence of a blank control or from a single Hogna smaller than itself. Pardosa showed a reduction in activity in the presence of cues from eight small Hogna. Pardosa avoided substrates with adult Hogna cues, but showed no avoidance response to any other treatment. These results suggest that Pardosa is showing graded antipredator behavior relative to the quantity of predator kairomones present rather than directly discriminating among the different sizes of the predator. * * * <0.001. (A) Chemical cues from large adult female Hogna (LH) vs. a blank (LB). (B) Chemical cues from a medium-sized Hogna (MH) equal in body mass to the Pardosa being tested vs. a blank control (MB). (C) chemical cues from a small Hogna (SH) half the body mass of the test spider vs. a blank (SB). (D) a double blank control, B1 and B2. (E) chemical cues from eight small Hogna (EH) each ca. one fourth the mass of the Pardosa being tested vs. a blank control (EB). Locomotor activity and initial side choice was recorded for each spider.
Annual Review of Ecology, Evolution, and Systematics, 2009
Sexual cannibalism, the consumption of the male by the female before, during, or after mating, ca... more Sexual cannibalism, the consumption of the male by the female before, during, or after mating, can be a striking example of sexual conflict with potentially large fitness consequences for males and females. In this review, we examine how ecological and ...
We studied the distribution of 2 wolf spider species in 2 soybean, Glycine max (L.), agroecosyste... more We studied the distribution of 2 wolf spider species in 2 soybean, Glycine max (L.), agroecosystems in southwestern Ohio, USA. We used replicated 0.42-ha soybean fields maintained under 2 different tillage regimes (conservation tillage and conventional tillage) and 2 wolf spider species [ ...
Sexual cannibalism varies widely among spiders, but no general evolutionary hypothesis has emerge... more Sexual cannibalism varies widely among spiders, but no general evolutionary hypothesis has emerged to explain its distribution across taxa. Sexual size dimorphism (SSD) also varies widely among spiders and could affect the vulnerability of males to cannibalistic attacks by females. We tested for a relationship between SSD and sexual cannibalism within and among species of spiders, using a broad taxonomic data set. For most species, cannibalism was more likely when males were much smaller than females. In addition, using phylogenetically controlled and uncontrolled analyses, there was a strong positive relationship between average SSD of a species and the frequency of sexual cannibalism. This is the first evidence that the degree of size difference between males and females is related to the phylogenetic distribution of sexual cannibalism among a broad range of spiders.
... 3, 1992 Foraging Behavior of the Communal Spider, Philoponella republicana (Araneae: Uloborid... more ... 3, 1992 Foraging Behavior of the Communal Spider, Philoponella republicana (Araneae: Uloboridae) Greta J. Binford 1'2 and Ann L. Rypstra i ... An open fruit fly culture was maintained in each enclosure from which adult Drosophila emerged and the spiders could feed ad libitum. ...
2. Because web spiders have limited dispersal abilities and an energetically costly prey capture ... more 2. Because web spiders have limited dispersal abilities and an energetically costly prey capture device, they do not have the ability to sample potential foraging sites. Structural complexity of the vegetation to which the web must be attached is relatively easy to assess. The ...
... (Araneae, Lycosidae) Shawn M. Wilder1,2) &amp;amp; Ann L. Rypstra3) (1 Department of Zool... more ... (Araneae, Lycosidae) Shawn M. Wilder1,2) &amp;amp; Ann L. Rypstra3) (1 Department of Zoology, Miami University, Oxford, OH 45056; 3 Department of Zoology, Miami University, Hamilton, OH 45011) ... in parental care (Darwin, 1871; Bateman, 1948; Trivers, 1972; Andersson, 1994). ...
Female Pardosa milvina wolf spiders carry large eggsacs. We quantified the effects of carrying eg... more Female Pardosa milvina wolf spiders carry large eggsacs. We quantified the effects of carrying eggsacs on foraging success and susceptibility to predation. In addition to monitoring individuals carrying natural eggsacs, we induced females to carry artificial eggsacs of varying mass. We determined the propensity of females to attach eggsacs or plastic beads of various sizes. We then quantified prey capture success and the avoidance of the predatory wolf spider, Hogna helluo, for Pardosa with and without eggsacs or plastic beads attached. Females attached their own eggsacs significantly more than plastic beads of equal mass and attached artificial eggsacs 10 times larger than natural eggsacs significantly less often than smaller plastic beads (ones equal to or 2.7 times the size of natural eggsacs). Females carrying real or artificial eggsacs of any mass captured fewer prey, but prey capture success did not vary among females with different-sized eggsacs. Except females of the 10 × eggsac treatment, individuals carrying an eggsac suffered significantly greater predation compared to females without eggsacs. Eggsac transport carries significant predation and foraging costs, but we found little evidence that carrying heavier eggsacs incur incrementally greater increases in predation risk or decreased foraging efficiency than carrying lighter eggsacs.
Sexual cannibalism can occur before, during or after mating. Relatively few experimental studies ... more Sexual cannibalism can occur before, during or after mating. Relatively few experimental studies have examined why there is variation in the timing of sexual cannibalism. We examined the latency and number of attacks required for female spiders to capture male spiders pre-vs. postcopulation. We also examined the effects of female mating status and hunger level on the occurrence of pre-and postcopulatory cannibalism, which reflects the contribution of both relative capture success and female motivation to cannibalize males. Precopulatory cannibalism occurred after a shorter interval and required fewer chases and physical interactions for the female to successfully capture the male than was the case for postcopulatory cannibalism. Virgin females were more likely to engage in postcopulatory rather than precopulatory cannibalism and mated females vice versa. Those virgin females that did engage in precopulatory cannibalism had significantly lower body condition than virgin females engaging in postcopulatory cannibalism. While precopulatory cannibalism occurred more quickly and required fewer attacks by females, it comes at a potential cost of not mating with males. Hence, females are more likely to engage in precopulatory cannibalism if they have already mated or, if virgins, if they have low body condition. These results indicate that the decision of when to cannibalize males is dynamic and depends upon the relative value of a male as a mate versus a meal.
Mate availability can vary widely in nature depending upon population density and sex ratio and c... more Mate availability can vary widely in nature depending upon population density and sex ratio and can affect the ability of individuals to be selective in mate choice. We tested the effects of prior encounters with the opposite sex (i.e., exposure to the opposite sex either with or without mating) on subsequent mating behavior in two experiments that manipulated mate availability for both males and females in the wolf spider, Hogna helluo. The probability of mating in the experimental trial depended upon whether the prior encounter involved mating or not, and males and females responded in opposite directions. Exposure without mating resulted in a higher subsequent frequency of mating for females and a lower subsequent frequency of mating for males, while prior mating experience resulted in a lower frequency of female remating and a higher frequency of male remating. Prior exposure without mating did not affect female aggression. However, mated females engaged in precopulatory cannibalism more frequently than virgins. Mated males escaped postcopulatory cannibalism more frequently than virgins. Our results show that males respond to exposure without mating in the expected manner. However, prior mating (1 week earlier) had unexpected effects on males, which may be due to mated males being of higher quality. There were little or no effects of the size of the prior exposure individual or mate on subsequent mating behaviors. Further research is needed to determine why different species use different degrees of prior information in mate choice.
Annals of the Entomological Society of America, 2003
... 1997, Schmitz and Settle 2001, Schmitz and Sokol-Hessner 2002). In those examples, thegrassho... more ... 1997, Schmitz and Settle 2001, Schmitz and Sokol-Hessner 2002). In those examples, thegrasshoppers had access to visual and vibratory cues as well as the chemotactile cues that were important in this study. ... Beckerman, AP, M. Uriarte, and OJ Schmitz. ...
Most research on sexual cannibalism has focused on factors influencing female motivation to engag... more Most research on sexual cannibalism has focused on factors influencing female motivation to engage in cannibalism. However, a critical factor that may mediate the actual occurrence of sexual cannibalism is male vulnerability to female attacks. We tested whether sexual size dimorphism (SSD) affected whether hungry females were successful in sexual cannibalism in a moderately size dimorphic wolf spider, Hogna helluo. Experimentally food-limited females cannibalized males more frequently than did well-fed females. However, in a correlational study, female body condition was only a significant predictor of the occurrence of sexual cannibalism if SSD was included in the model. Our results suggest that SSD is an important factor mediating the occurrence of sexual cannibalism in H. helluo by affecting male vulnerability to female attacks. Consideration of factors affecting male vulnerability to cannibalistic attacks by females may be critical to understanding the occurrence and evolution of sexual cannibalism.
Background/Question/Methods Generalist arthropod predators have been shown to impact the grazing ... more Background/Question/Methods Generalist arthropod predators have been shown to impact the grazing component of terrestrial food webs, but less attention has been given to detrital systems. Ground-dwelling spiders and beetles are common in terrestrial ecosystems, and detritivores have been found to compose a large portion of their diet. These predators have been shown to indirectly alter soil processes through consumption of microarthropods. However, studies of detrital systems have focused on density-mediated interactions between predators and detritivores, leaving trait-mediated interactions largely unexplored. We used the wolf spiders Pardosa milvina, Tigrosa helluo, and Rabidosa rabida along with the carabid beetle Scarites quadriceps to investigate their impacts on the survival of the collembolan Sinella curviseta, soil respiration, and soil carbon content. Additionally, we isolated trait-mediated effects between Pardosa and Sinella, as these species were believed to interact mos...
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