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Animal Behaviour 101 (2015) 169e177

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Animal Behaviour

journal homepage: www.elsevier .com/locate/anbehav

Delicate fangs, smart killing: the predation strategy of the reclusespider

Júlio M. G. Segovia a, b, c, Kleber Del-Claro a, Rodrigo Hirata Willemart b, c, d, *

a Instituto de Biologia, Campus Umuarama, Uberlandia, MG, Brazilb Laborat�orio de Ecologia Sensorial e Comportamento de Artr�opodes (LESCA), Escola de Artes Ciencias e Humanidades, Universidade de S~ao Paulo, SP, Brazilc Programa de P�os Graduaç~ao em Zoologia, Instituto de Biociencias, Universidade de S~ao Paulo, SP, Brazild Programa de P�os Graduaç~ao em Ecologia e Evoluç~ao, Universidade Federal de S~ao Paulo, SP, Brazil

a r t i c l e i n f o

Article history:Received 7 September 2014Initial acceptance 17 October 2014Final acceptance 3 December 2014Published onlineMS. number: A14-00721R

Keywords:ArachnidaforagingLoxoscelesOpilionesprey handlingsensory ecology

* Correspondence: R. H. Willemart, Laborat�orio dportamento de Artr�opodes (LESCA), Escola de Artes Cversidade de S~ao Paulo, SP, Brazil.

E-mail address: willemart@usp.br (R. H. Willema

http://dx.doi.org/10.1016/j.anbehav.2014.12.0250003-3472/© 2015 The Association for the Study of A

Prey consumption depends on the predator's ability to locate, capture and handle prey. We investigatedthese three steps in interactions between the delicate-bodied recluse spider Loxosceles gaucho (Araneae)and a heavy-bodied and armoured harvestman, Mischonyx cuspidatus (Opiliones). Although previousresearch suggested that the hard integument of such harvestmen protects them from being preyed uponby spiders larger than Loxosceles, indirect evidence suggested that Loxosceles spiders can subdue theseprey. In the present study, we tested the following three hypotheses with regard to L. gaucho: (1) spidersuse chemical cues left by prey to select foraging sites; (2) vibratory cues of prey are essential informationin the predatory process; and (3) the spider's web sheet allows adequate handling of prey so vulnerablebody regions of the prey can be bitten. To understand how a delicate predator can overcome the defencesof a heavy-bodied and well-defended prey, we also quantitatively described the spider's behaviour. Totest hypothesis 1, we compared the time spent in areas with harvestmen, crickets and no cues. Forhypothesis 2, we compared latency to bite and number of bites in the presence or absence of vibratoryinformation, and for hypothesis 3, we compared latency to detect prey, latency to capture prey andpredation success. All three hypotheses were rejected. Loxosceles gaucho seems to be exceptional amongspiders by not needing its web, indirect prey chemical cues, or prey's substrate borne vibrations to huntthe tested prey. What enables L. gaucho to prey upon M. cuspidatus is its unique hunting strategy,compared to previously studied spiders: it touches the prey with its tarsi possibly to locate weak parts ofthe prey's body, such as joints and distal parts of the legs, then it delivers several bites to these vulnerableareas. Our study is the first to document and describe how recluse spiders overcome the defences of anarmoured harvestman.© 2015 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

Predatoreprey interactions shape the behaviour andmorphology of the interactants so that both prey defences andpredatory strategies improve over evolutionary time in a processknown as an ‘arms race’ (Dawkins & Krebs, 1979). From the pred-ator's point of view, the predatory process encompasses the phasesof searching for, capturing and handling prey (Davies, Krebs, &West, 2012). The search phase begins with the choice of aforaging site. Distinct pieces of information are used to assess thequality of a site, such as the presence of conspecifics (see Danchin,Giraldeau, Valone, & Wagner, 2004; Valone, 2007), environmental

e Ecologia Sensorial e Com-iencias e Humanidades, Uni-

rt).

nimal Behaviour. Published by Els

characteristics that potentially attract prey, the presence of prey ortheir cues, or physical characteristics that facilitate prey capture(Chien & Morse, 1998; Clark, Jackson, & Cutler, 2000; Hanna &Eason, 2013; Hopcraft, Sinclair, & Packer, 2005; Johnson, Revis, &Johnson, 2011).

After selecting a foraging site, predators detect prey usingdistinct sensory modalities. These include vision in frogs(Gonz�alez-Bernal, Brown, Cabrera-Guzm�an, & Shine, 2011),perception of substrate-borne vibrations in scorpions (Mineo &Del-Claro, 2006), echolocation in bats (Schnitzler & Kalko, 2001),tactile sense in star-nosed moles and shrews (Anjum, Turni,Mulder, van der Burg, & Brecht, 2006; Catania & Remple, 2005),thermal sensitivity in snakes (Buning,1983) and chemoreception insalamanders (Placyk & Graves, 2002), for example. In some cases,multiple sensory modalities are important for prey detection (Piep,Radespiel, Zimmermann, Schmidt, & Siemers, 2008). Features of

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J. M. G. Segovia et al. / Animal Behaviour 101 (2015) 169e177170

the microhabitat and prey behaviour directly influence the foragingbehaviour and sensory modalities used by predators (e.g.Cunningham, Castro, & Potter, 2009; O'Rourke, Hall, Pitlik, &Fern�andez-Juricic, 2010; Van Buskirk & Nevitt, 2008).

After detecting prey, predators must capture and handle them,both of which involve use of distinct morphological structures andbehaviours. For example, snakes use venom or constriction (Greene& Burghardt, 1978; Kardong, 1986), chameleons rapidly extendtheir sticky tongues (de Groot & Leuween, 2004; Herrel, Meyers,Aerts, & Nishikawa, 2000), insects may move over the prey andbite them quickly (De la Mora, P�erez-Lachaud, & Lachaud, 2008) oruse raptorial legs to grasp prey (Betz & Mumm, 2001; Corrette,1990).

The three phases of the predatory process, namely searching,capturing and handling, have seldom been studied collectively inspiders. Most spiders are polyphagous (Foelix, 2011; Nelson &Jackson, 2011) and their diet often includes arthropods in general.During the search phase, spiders use multiple cues to locate preyand, depending on the species, chemical cues can be particularlyimportant (Jackson, Clark, & Harland, 2002; Persons & Rypstra,2000; Persons & Uetz, 1996). During the capture phase, when theprey is close, substrate-borne vibrations play a fundamental role inprey capture by web spiders, wandering spiders and even by spi-ders that capture prey in aquatic environments (Barth, 2002;Bleckmann & Barth, 1984; Masters, 1984). Spiders use specificbody structures (e.g. chelicerae, pedipalps or adhesive setae on thelegs) and/or venom to capture and/or handle prey (Foelix, 2011;Rovner, 1980). A web is also often used (Coyle, 1986; Zschokke,H�enaut, Benjamin, & García-Ballinas, 2006).

Harvestmen are among the several species eaten by spidersand they show many kinds of defences such as cripsis, thanatosis,anachoresis, aposematism, mimicry, deimatic behaviour andfleeing (see Gnaspini & Hara, 2007). Chemical defence has beenthe most studied, with harvestmen releasing defensive secretionsthrough glandular openings positioned laterodorsally on thebody (Eisner, Rossini, Gonz�alez, & Eisner, 2004; Hara, Cavalheiro,Gnaspini, & Santos, 2005; Hara & Gnaspini, 2003; Machado &Pomini, 2008; Pomini, Machado, Pinto-da-Rocha, Macías-Ord�o~nez, & Marsaioli, 2010). Such chemicals are effective againstsome spiders (e.g. Machado, Carrera, Pomini, & Marsaioli, 2005),but they are not always used (Segovia, Del-Claro, & Willemart, inpress). Instead, the thick cuticle of adult harvestman appears tobe protective against some predatory spiders (Dias & Willemart,2013; Souza & Willemart, 2011). A spider that cannot pierce thethick cuticle is left with only a few vulnerable spots to bite, suchas the distal parts of legs, mouth and articulations (Souza &Willemart, 2011). When tested with heavy-bodied laniatoridharvestmen as prey, wandering spiders showed low capture ratesdespite their large size or their ability to spit venom (Carvalho,Souza, & Willemart, 2012; Dias & Willemart, 2013; Eisner et al.,2004; Souza & Willemart, 2011). Moreover, the large Enoplocte-nus cyclothorax did not feed on Mischonyx cuspidatus harvestmaneven after sharing a small terrarium with it for about 70 days andwith no alternative food source (Willemart & Pellegatti-Franco,2006). In contrast, we often find dead harvestmen on the hori-zontal web sheets of recluse spiders (Loxosceles) (J. M. G. Segovia& R. H. Willemart, personal observations; Fischer, Vasconcellos-Neto, & dos Santos Neto, 2006). Despite being well known forcausing severe skin wounds and being of medical importance(Cardoso, França, Wen, Malaque, & Haddad, 2009), there are nodetailed studies on how Loxosceles spiders hunt their prey.Because the body and chelicerae of these spiders are delicate,Carvalho et al. (2012) hypothesized that they use sheet webs tocapture and immobilize harvestmen prey, allowing them to bitethe vulnerable parts of the harvestman's body.

We examined distinct phases of prey capture during in-teractions between a recluse spider (Loxosceles gaucho) and aheavy-bodied harvestman (Mischonyx cuspidatus). We first hy-pothesized that Loxosceles gaucho uses chemical cues left by prey toselect a foraging site. Then, we hypothesized that they rely onvibratory cues to detect prey, since recluse spiders have poor vision(Sandidge & Hopwood, 2005) and because vibratory cues provideimportant information for spiders (e.g. Barth, 2002). We also testedthe hypothesis that the web sheet allows recluse spiders to handletheir prey more easily so that vulnerable areas of the prey can bebitten (Carvalho et al., 2012). To understand howa delicate predatorcan overcome the defences of a heavy-bodied and well-defendedprey that is rejected by much larger predators (Dias & Willemart,2013; Souza & Willemart, 2011), we also quantitatively describedthe spider's behaviour.

METHODS

Study Species

The harvestmen Mischonyx cuspidatus (Roewer 1913) and spi-ders of the genus Loxosceles are activemainly at night (Fischer et al.,2006; Pereira, Elpino-Campos, Del-Claro, & Machado, 2004) andcan be found under tree trunks, dead palm fronds and man-madestructures, often under bricks (Fischer & Vasconcellos-Neto,2005; Mestre & Pinto-da-Rocha, 2004). Loxosceles spiders feed ona wide variety of arthropods (Fischer et al., 2006), and the webs ofthese spiders are uneven and can often be found inside or nearhouses (Sandidge & Hopwood, 2005). However, Loxosceles spiderscan also capture prey when wandering outside their webs (seeFischer et al., 2006; Vetter, 2008), but to our knowledge there is nodetailed study on the time spent off the web or the frequency withwhich they leave their webs.

We collected L. gaucho in Mairipor~a, S~ao Paulo, Brazil (23�190S,46�350W), from building material, between November 2012 andFebruary 2013. We found individuals of M. cuspidatus on the samebricks where the spiders were collected, but not in enough quantityfor the experiments. The harvestmen M. cuspidatus used in theexperiments were therefore collected from under tree trunks atParque Ecol�ogico do Tiete, S~ao Paulo, S~ao Paulo (23�250S, 46�280W),between December 2012 and May 2013.

Laboratory Conditions

We maintained the animals in the laboratory under ambienttemperature on a natural light:dark cycle, but with a weak red light(15 W) turned on 24 h per day, which allowed us to work at nightwithout disturbing the animals. We maintained spiders and har-vestmen individually in plastic containers (12 � 8 and 4 cm high,except in experiment 3; see below) with soil on the bottom. Weprovided water with a wet cotton ball only for harvestmen sincehigh humidity appeared to be deleterious to the Loxosceles spiders.We fed the spiders either harvestman or crickets, according to theexperiments, as described below, and we gave harvestmen moist-ened dog food once per week. The crickets (Gryllus sp.) were pur-chased from a commercial supplier. Theywere fed dry dog food andmaintained under the same laboratory conditions as the spidersand harvestmen. Themean ± SD body sizes of animals usedwere asfollows: spiders: 1.057 ± 0.15 cm (N ¼ 108); harvestmen:0.797 ± 0.07 cm (N ¼ 64); crickets: 1.284 ± 0.17 cm (N ¼ 30). Weused crickets that were longer than the harvestmen because theharvestmen were wider than the crickets. The integument of theharvestmen (thickness of tibia cuticle: ~58 mm) is also thicker thanthat of the crickets used in this experiment (thickness of tibiacuticle: ~19 mm; Dias & Willemart, 2013).

J. M. G. Segovia et al. / Animal Behaviour 101 (2015) 169e177 171

Experiment 1: Chemical Cues of Prey

In this experiment, we tested whether L. gaucho uses chemicalsleft on substrate by its prey when foraging, and compared cricketand harvestmen cues. Cricket chemical cues can be detected byspiders (Persons & Rypstra, 2000), and harvestmen may leavechemical cues not only when simply walking across substrates butalso because they often drag body parts on the substrate(Donaldson & Grether, 2007; Willemart, Chelini, De Andrade, &Gnaspini, 2007; Willemart & Hebets, 2012; Willemart, Osses,Chelini, Macías-Ord�o~nez, & Machado, 2009). We predicted thatthe spiders would spend more time on substrates with chemicalcues of harvestmen (M. cuspidatus) and crickets (Gryllus sp.) thanon clean controls.

The spiders used were previously fed crickets and harvestmento minimize biases, because previous feeding experience can in-fluence future decisions about what to eat (Persons & Rypstra,2000). However, to maximize their motivation to attack prey, spi-ders were deprived of food for 37e38 days before the trials. Insimilar previous studies, using other species, spiders were deprivedof food for 25e30 days (Carvalho et al., 2012; Dias & Willemart,2013; Souza & Willemart, 2011). Other species of Loxosceles live6e12 months without food, depending on their diet (Lowrie, 1987),so the spiders used in our study were not in a state of severestarvation.

The testing arenas (18 cm diameter, 6 cm high) had two piecesof filter paper and a neutral central area (5.5 cm diameter) on thebottom. We tested three pairs of choices in this experiment, eachwith two treatments: harvestmen chemicals/blank filter paper(N ¼ 17; 14 females, 3 males); cricket chemicals/blank filter paper(N ¼ 17; 14 females, 3 males); and harvestmen chemicals/cricketchemicals (N ¼ 19; 14 females, 5 males).

To impregnate the filter paper with chemicals of prey (har-vestmen or crickets), 15 individuals were left for 24 h in a containersimilar to the arenas, with two pieces of filter paper on the sub-strate that were the same size as those used in the testing arenas.The impregnated pieces of filter paper were removed just beforeeach test and used immediately. We used 15 individuals toimpregnate the filter paper to maximize the chances that thechemicals would be spread across the filter paper, since we couldnot control movement of prey.

The spider was introduced in the central neutral place in a vial(5 cm diameter, 6 cm high) and allowed to acclimate for 3 min.After releasing the spider we covered the arena with a sheet ofglass. We recorded the spider's behaviour for 30 min in each test.After each trial, we rotated the arena horizontally 90� clockwise tominimize side biases related to the position of the arena in relationto the laboratory. We used a Sony Handycam HDXR550V in night-shot mode to register the time spent on each side of the arena. Thearena was cleaned with 70% ethanol between trials and each pieceof filter paper was used only once. Datawere collected in May 2013,between 2000 hours and 0500 hours. We used paired t tests tocompare the time spent on each side of arena, and medians arepresented for differences in time spent on each side of the arena.

Experiment 2: Vibratory Cues of Prey and Predatory Behaviour

We tested whether substrate-borne vibrations of prey areimportant in the predatory process for L. gaucho, with harvestmenand cricket prey, tested separately.We predicted that spiders wouldhave lower latency to attack and higher capture success whentested on a substrate that transmits vibration (filter paper) than ona substrate that greatly reduces transmission of substrate-bornevibrations (granite) (Elias, Mason, & Hoy, 2004; Hebets, 2005).Because harvestmen have fewer vulnerable body regions than

crickets, and thus fewer regions sensitive to venom from a spider'sbite (Souza & Willemart, 2011), we also predicted that harvestmanwould require longer handling times and more bites to subdue.

Some weeks prior to the experiments, we fed the spiders beetlelarvae (Zophobas sp.) in their home terrariums (12 � 8 and 4 cmhigh). Uneaten prey were removed after 48 h. Only spiders that atethe larvae were used in the trials. Spiders were deprived of food for25e31 days before the trials. The substrate used was either a pieceof light granite (40 � 40 cm, 2 cm thick) or a square piece of paperfilter (21 � 21 cm).

We tested spiders' responses to prey using a plastic bottomlessarena (18 cm diameter, 6 cm high), placed on filter paper or granitesubstrate, in one of five treatments: (1) harvestman on filter papersubstrate (N ¼ 14 females); (2) harvestman on granite substrate(N ¼ 14 females); (4) cricket on filter paper substrate (N ¼ 14 fe-males); and (5) cricket on granite substrate (N ¼ 14; 13 females, 1male).

Each spider was tested only once. Both spider and prey wereintroduced into the arena and allowed to acclimate for 3 min inseparate containers (5 cm diameter, 6 cm high) on opposite sides ofthe arena. The animals were released together and the arena wascovered with a sheet of glass. The arena was cleaned with 70%alcohol after each trial.

We recorded the experiments with a camera Sony HandycamHDXR550V, in nightshot mode. Each trial lasted 40 min, startingwhen the prey and the predator touched each other. If the prey andthe predator did not touch each other after 40 min, we consideredthere had been no predation. The trials were conducted in April2013, during 2200e0500 hours. We compared predation successbetween substrates with a chi-square test, latencies to attack with aManneWhitney U test, time between first bite and long bite(described in Table 1) and number of bites with a t test.

Experiment 3: The Role of Silk in Predation

In this experiment, we tested the hypothesis that the web sheetfacilitates handling of prey, by allowing the spider to bite vulner-able areas of the prey more easily. We predicted that the spiderstested with a sheet of silk (control group) would have greatersuccess capturing prey and that the latency to detect, capture andsubdue preywould be shorter than in the absence of silk (treatmentgroup). Spiders in both the no-silk group (N ¼ 19; 17 females, 2males) and the silk group (N ¼ 19; 13 females, 6 males) receivedone harvestman each in their home containers (18 cm diameter,6 cm high). In total, 20 female and 18 male harvestmen wereoffered as food, with the sexes equally divided between spidertreatments.

We offered the spiders one cricket nymph (Gryllus sp., ~1.5 cm)and one beetle larva (Zophobas sp.) 25e29 days before the trials.Uneaten prey were removed after 48 h. To standardize the starva-tion period, we only tested spiders that ate at least one of the preyoffered before the tests. We assigned spiders to the silk or no-silkgroup based on the amount of silk present in their home terrar-iums just prior to testing. Although most spiders produced a websheet, spiders assigned to the silk group had more silk in their websheets. To ensure that spiders assigned to the no-silk group had nosilk in their home terrariums at the time of testing, we removed thespiders and all the soil from the terrarium, cleaned the terrariumwith a dry paper towel and put new soil in it. Changing the soil wasnecessary to completely remove the silk from the terrarium. Wethen reintroduced the spider. Spiders in the silk group were simplyremoved and put back in their terrarium. In both groups, weallowed the spider to walk freely in the terrarium for 15 min beforewe introduced a harvestman as far as possible from the spider.

8

7

6

5

4

3

2Harvestmen

Type of prey

Tim

e be

twee

n t

he

firs

t bi

tes

and

th

e fi

rst

lon

g bi

tes

(log

tra

nsf

orm

ed)

Crickets

Figure 1. Time between the first bite and the first long bite in harvestmen (N ¼ 15)and crickets (N ¼ 15). Dots are means and whiskers are standard errors. Data were logtransformed for normality.

Table 1Behavioural repertoire of the spider Loxosceles gaucho when interacting with theharvestman Mischonyx cuspidatus

Behaviouralcategory

Definition

Active contact Spider touches the prey with the distal portion of its first andsecond pair of legs

Approach Spider moves towards the prey, either in a straight line or azigzag manner

Detection ata distance

Spider slowly raises any of its legs dorsoventrally; often ofsmall amplitude and without touching the substrate(average±SD duration 0.755±0.371 s; N¼11); one variationof this category is to move the legs quickly

Drag Spider uses its fourth pair of legs to hold the prey, then dragsthe prey (<5 s) using its first pair of legs or its chelicerae

Handling silk Spider repeatedly extends its first, second or third pair oflegs and flexes them sideways, in shallow movements; mayinclude rubbing of the first, second or third pair of legsdorsoventrally and quick anteroposterior movements withpedipalps

Leg-threading Spider passes the second pair of legs between its cheliceraeLong bite Spider pinches the prey with the fangs of its chelicerae for

�10 s (the spider can hold the prey for minutes); sometimesthe spider weaves silk threads and/or apparently handlesthreads of silks often with its third pair of legs (Fig. 5)

Move away Spider walks away from the preyMove pedipalps

quicklyFast dorsoventral movements of pedipalps (N¼1)

Motionless Not moving the body or the locomotory appendagesOrient to prey Spider rotates its body without displacement, ending with

the anterior portion of its body facing the preyPassive contact While walking, a prey touches a spider, mainly on the

spider's legsShort bite Spider pinches the prey with the fangs of its chelicerae for

<10 s; may occur while the spider is touching the prey(mainly with its legs) and/or while the spider taps the preyand/or weaves threads of silk

Take down Spider primarily uses its first pair of legs to pull the preywhile grabbing the prey near the patella or femuretrochanter joint using its fourth pair of legs and throwingthe prey's dorsum to the substrate

Touch with legs Spider uses the distal part of its legs to touch the body and/orlegs of the prey; the spider may also tap the preywith its legsand/or pedipalps

Tremble Spider performs shallow dorsoventral flexing of the legswithout lifting them off the ground

Weave silk Spider weaves silk threads and/or handles threads of silk,often with the third pair of legs; spider may grasp (mainlywith the legs) or touch the prey's body, or move away fromthe prey and weave silk threads around it

J. M. G. Segovia et al. / Animal Behaviour 101 (2015) 169e177172

During the tests, each terrariumwas coveredwith a sheet of glass toprevent the spiders from escaping.

We recorded the trials using a Sony HandycamHDXR550V in thenightshot mode. We started recording after introducing theharvestman and recorded for 40 min after the predatory processstarted (defined as first bite). Each spider was tested only once. Weended the trial if predation had not occurred after 1 h. We collecteddata between February and March 2013, during 2100e0500 hours.We compared capture success with a chi-square test, latenciesbetween behavioural categories with a ManneWhitney U test, andnumber of bites with a t test.

RESULTS

Experiment 1: Chemical Cues of Prey

The time spent on side of the arena containing chemical cuesfrom harvestmen or crickets did not differ (median difference intime spent on each side of the arena ¼ 124 s, minimum ¼ 1800 s,maximum ¼ 1219 s; paired t test: t18 ¼ 0.190, P ¼ 0.852). For theharvestmen/blank combination, there was also no difference

(median difference in time spent on each side of the arena ¼ 255 s,minimum ¼ 1071 s, maximum ¼ 1518 s; paired t test: t16 ¼ 0.977,P ¼ 0.343). But spiders spent more time on blank filter paper thanon cricket cues (median difference in time spent on each side of thearena ¼ 217 s, minimum ¼ 897 s, maximum ¼ 1122 s; paired t test:t16 ¼ 2.387, P ¼ 0.03).

Experiment 2: Vibratory Cues of Prey and Predatory Behaviour

An equal number of harvestmen were preyed upon in the filterpaper and granite substrate treatments (10 out of 14 harvestmenwere preyed upon in each treatment; c2

1 ¼ 0, P ¼ 1). There was nosignificant difference in the number of crickets preyed upon: ninewere preyed upon in the filter paper treatment and seven werepreyed upon in the granite treatment (c2

1 ¼ 0.583, N ¼ 14 for eachtreatment, P ¼ 0.699). Latency to bite harvestmen also did not differbetween substrates (filter paper: median ¼ 268.5 s, mini-mum ¼ 111 s, maximum ¼ 745 s; granite: median ¼ 156 s, mini-mum ¼ 21 s, maximum ¼ 643 s; ManneWhitney U test: U ¼ 45,N1 ¼10, N2 ¼ 11, P ¼ 0.481). Latency to bite crickets also did notdiffer between substrates (filter paper: median ¼ 157 s, mini-mum ¼ 52 s, maximum ¼ 1358 s; granite: median ¼ 411 s, mini-mum ¼ 48 s, maximum ¼ 950 s; ManneWhitney U test: U ¼ 43,N1 ¼ 9, N2 ¼ 9, P ¼ 0.825).

Because substrate was unimportant, we pooled the substratedata and compared predation rates between crickets and harvest-men. We found no differences (c2

1 ¼1.244, P ¼ 0.265). Further-more, the percentage of time that prey spent walking on thesubstrate before the spider attacked did not differ between crickets(median ¼ 36%; maximum ¼ 86%; minimum ¼ 0%) and harvest-men (median ¼ 10%; maximum ¼ 87%; minimum ¼ 0%; Man-neWhitney U test: U ¼ 59, Ncrickets ¼ 9, Nharvestmen ¼ 10, P ¼ 0.248):92.9% of the crickets (N ¼ 28) and 75% of the harvestmen (N ¼ 28)walked around the arena before the spider attacked. However, thetime between the first bite and the first long bite was longer forharvestmen (t test: t28 ¼ 2.116, P ¼ 0.043; Fig. 1), and the number ofbites on harvestmen was higher (ManneWhitney U test:U ¼ 27.500, N1 ¼ 21, N2 ¼ 18, P < 0.001; Fig. 2).

70

60

50

40

30

20

10

0

Nu

mbe

r of

bit

es

*

Cricket Harvestman

Type of prey

Figure 2. Number of bites per event performed by Loxosceles gaucho when preyingupon crickets (N ¼ 16) and harvestmen (N ¼ 20). Horizontal bars correspond to themedian, whiskers indicate 1.5 times the interquartile range of the data (below or abovethe first and third quartiles), and asterisks are outliers.

J. M. G. Segovia et al. / Animal Behaviour 101 (2015) 169e177 173

Since therewere no differences in predation rates of harvestmenamong treatments, we used the videos of both substrate groups toanalyse where the spiders bit the harvestmen's body. We only usedvideos for which we had no doubt where the spider was biting(N ¼ 176 bites, 20 distinct pairs). In these videos, the harvestmenwere bitten either on the distal parts or articulations of the legs(Figs. 3 and 4).

Experiment 3: the Role of Silk on Predation

Contrary to our expectations, the presence of silk did not in-fluence L. gaucho's capture success of harvestmen (silk group: 17 of19 spiders captured harvestmen; no-silk group: 14 of 19 spiderscaptured harvestmen; c2

1 ¼1.576, P ¼ 0.209). The number of bitesalso did not differ between the silk group (mean ± SD ¼ 19.1 ± 12.9,minimum ¼ 8, maximum ¼ 52) and the no-silk group (20.5 ± 9.1,minimum ¼ 1, maximum ¼ 34) (t test: t30 ¼ 1.136, P ¼ 0.265).There was also no difference between groups in the latency to bite,time between first touch and first long bite or time between firstbite and first long bite (Table 2).

We describe 17 behavioural categories of L. gaucho spiders wheninteracting with harvestman (see Table 1). A typical capturesequence (Fig. 5) starts with prey detection either at a distance orafter ‘passive contact’, with either the prey or both the predator andthe prey walking. The spider then ‘approaches’ and/or ‘touches’ theprey and subsequently delivers several bites until the prey stopsattempting to flee, after which the spider begins to ‘weave silkthreads’. The spider then delivers ‘short bites’ (see Table 1 fordefinition) and a ‘long bite’, which can last several minutes. Addi-tional behaviours not shown in the flowchart, for the sake of clarity,were as follows: ‘take down’, which was preceded by ‘short bite’and ‘touch with legs’; ‘motionless’, which was preceded by ‘weavessilk’, ‘approach’, ‘detection at a distance’, ‘handling silk’ and ‘drag’;and ‘leg-threading’, which was preceded by ‘active contact’. Spidersthat did not prey upon the harvestmen (N ¼ 7) either fled aftertouching or being touched by the harvestmen (N ¼ 3), weretouched by the harvestmen but did not flee (N ¼ 1), or did not touchthe harvestmen (N ¼ 3).

DISCUSSION

Our results show that L. gaucho does not use chemical cues ofharvestmen or crickets to select foraging sites, nor does it rely onvibratory cues to detect these prey species. They also do not dependon silk sheets to capture heavy-bodied laniatorid harvestmen, asthey behaved similarly in the presence or absence of silk, at leastagainst this specific prey. Nevertheless, L. gaucho showed highpredation rates of harvestmen in the present study.

No preference for substrates with prey chemicals were detec-ted in our study. This was similar to results found for salticidspiders (Hoefler, Taylor, & Jakob, 2002) but contrasts with theresults obtained for lycosid and oxyopid spiders (Persons &Rypstra, 2000; Persons & Uetz, 1996; Punzo & Kukoyi, 1997). Theuse of chemicals as a source of information to find prey may berestricted to some spider species. On the other hand, spiders in thepresent study spent more time on the side of the arena with nochemicals than they did on the side with cricket chemicals. Thus,these spiders apparently can detect chemicals on the substrate,but for some reason they do not use this information to selectforaging sites.

Because spiders did not differ in their latency to attack prey on asubstrate that transmitted vibration and one that did not, we mustreject our hypothesis that substrate-borne vibrations are funda-mental information in the capture process of L. gaucho. This findingis quite interesting not only because the detection of vibrations is amain sensory modality among spiders (Barth, 2002; Foelix, 2011)but also because Loxosceles spiders use vibrations on the web sheetfor intraspecific communication (Fischer et al., 2009; Rinaldi &Stropa, 1998). Loxosceles intermedia Melo-Leit~ao 1934 (Fischeret al., 2009) and L. gaucho (Rinaldi & Stropa, 1998) are both foundon several kinds of substrates that probably vary in vibratorytransmission potential. Because the substrate relates to the efficacyof vibration transmission (e.g. Elias, Mason, & Hebets, 2010), notrelying only on substrate-borne vibration may be advantageous. Soit is possible that more than one sensory modality could release thepredatory behaviour in this species. Air displacement, contactmechanoreception and chemoreception are candidates for themodalities used by L. gaucho to recognize their prey. These threesensory modalities are known to be explored by spiders (e.g. Barth,2002; Persons & Rypstra, 2000).

Predation rates and handling times before subduing prey did notdiffer between spiders in the silk group and the no-silk group.These results clearly show that the presence of the sheet of silk isnot decisive. Moreover, L. gaucho predation rates on harvestmenwere high, contrasting with much more robust spiders such asEnoploctenus cyclothorax (Bertkau 1880) and Ctenus ornatus (Key-serling 1877) (Dias & Willemart, 2013; Souza & Willemart, 2011;Willemart & Pellegatti-Franco, 2006) or the spitting-spider Scyt-odes globula (Nicolet 1849), which usually does not eat these har-vestmen (Carvalho et al., 2012).

In the flowchart, there was a strong association between ‘touchwith legs’ and ‘short bite’ in the silk group and in the no-silk group.Touching with the legs probably allows the spider to find weakspots on the harvestman's body, such as joints and distal portions ofthe tarsi (Souza & Willemart, 2011). In contrast, C. ornatus and E.cyclothorax bite prey indiscriminately and do not display ‘touchwith legs’ (Dias & Willemart, 2013; Souza & Willemart, 2011).Loxosceles gaucho seems therefore to have a behavioural strategythat allows it to prey uponwell-armoured prey, as opposed to somespiders of the genus Dysdera (Dysderidae), which, in addition todistinct behaviours, also have modified chelicerae that allow themto prey upon armoured woodlouse (Isopoda: Oniscoidea) (�Rez�a�c,Pek�ar, & Lubin, 2008). The flowchart also shows that similarbehavioural sequences were effective in subduing harvestmen in

Figure 3. Spots where Loxosceles gaucho bit the harvestmen's body (sum of data from both sides of the body). Percentages are based on 176 bites in 20 events of predation ofharvestmen and spiders, each tested once.

J. M. G. Segovia et al. / Animal Behaviour 101 (2015) 169e177174

the presence or absence of silk. This may be because harvestmenlikeM. cuspidatus are not fast runners or jumpers, so silkmay not berequired to restrict their movements in order for the spider toinflict venomous bites in vulnerable regions.

Figure 4. Loxosceles gaucho inflicting a ‘long bite’ on the tib

Our results show that the time between the first bite and thefirst long bite was greater for harvestmen than for crickets, which isprobably related to the barrier imposed by the harvestmen's thickcuticle (Dias & Willemart, 2013; Souza & Willemart, 2011). The

iaepatella joint of the third right leg of a harvestman.

Table 2Time (in seconds) between behavioural acts during predation of Mischonyx cuspi-datus by Loxosceles gaucho

With silk Without silk U P

Median Min. Max. N Median Min. Max. N

Latency tobite

205 5 2252 17 581.5 1 2173 16 158 0.428

First touchefirst longbite

132.5 3 1435 16 279 58 1960 13 131 0.236

First biteefirst longbite

84 0 1378 16 125 48 1866 13 132 0.219

J. M. G. Segovia et al. / Animal Behaviour 101 (2015) 169e177 175

spiders also delivered more bites towards harvestman, which maybe because they use more venom against prey that are more diffi-cult to subdue (Wigger, Kuhn-Nentwig, & Nentwig, 2002).

Given the greater handling time and number of bites needed tosubdue harvestmen, L. gaucho probably spends more energyattacking harvestmen than crickets, potentially leading to preypreference. The nutrient content of prey can also influence preychoice in spiders (Wilder, 2011): there is evidence that orthop-terans have greater lipid content than Opiliones per unit of drybody mass (Lease & Wolf, 2011), which could also lead to prefer-ence. But our experimental set-up tested prey separately, and inthis case, both prey species were eaten equally. The same set-upwith a less intense starvation period could also increase prefer-ence for crickets. Preference for crickets is suggested by the lowproportion of harvestmen found on the webs of L. intermedia,

5%7%

100%

79%40%

17%

30%

43%

Passivecontact 29% Detection at

distance

Move away

44%

76% 100%

Orient to prey

Ignore Active contact

Long bite Touch withlegs

83%

83%

85%84%

33%

75%

36%

Take down

Figure 5. Flowchart showing behavioural transitions of Loxosceles gaucho that preyed upongroup (grey arrows and percentages; N ¼ 14). Arrows represent the percentage of times thatfrequencies higher than 25% are included (except the final categories ‘long bite’ and ‘ignoomitted because they were observed only once in one of the groups (silk/no-silk) or once

despite the great number of harvestmen using the same micro-habitat (Fischer et al., 2006).

Our results show that Loxosceles (1) does not use indirect preycues to choose a foraging site, (2) does not rely on substrate-bornevibrations to find prey, (3) builds a so-called ‘trap’ (web) that isuseful for intraspecific communication but is not essential forcapturing some types of prey and (4) demonstrates how a delicatepredator can subdue a well-defended and heavy-bodied prey byhandling it carefully, finding the weak spots and biting many times.Our results also clearly suggest the importance of tactile cues tofind such weak spots. Taken together, our study shows the impor-tance of avoiding generalizations when studying preyepredatorinteractions, since several of our results contrast with what wouldbe expected based on previous studies of spider behaviour.

Acknowledgments

We thank members of LESCA (Laboratory of Sensory Ecologyand Behavior of Arthropods), Gabriel Murayama, Guilherme Gain-ett, Guilherme Pagoti, Jessica Dias, Nathalia Fernandes, NortonSantos and Thaiany Costa for reviewing an early draft of themanuscript. Luiz Ernesto Costa-Schmidt, Marcelo Gonzaga andMichael Hrncir provided great suggestions that improved themanuscript. Two anonymous referees and the editors MichellePellissier Scott and Kris Maria Bruner also provided extremelyvaluable suggestions. We thank Marcelo Gonzaga, who also verykindly identified the spiders. Nathalia Fernandes, Norton Santos,Thaiany Costa and Andressa helped collect the animals, and GabrielMurayama helped collect preliminary data. Ana Cristina Machado

40%

42%

40%

100%

33%

74%

33%

51%

57%

50%

59% 50%

Motionless

Approach

Handling silk

Short bite Weaves silk

Leg–threading

harvestmen in the silk group (black arrows and percentages; N ¼ 17) and in the no-silkbehaviour A was followed by behaviour B. For clarity, only behavioural sequences withre’). The behaviours ‘move pedipalps quickly’, ‘drag’ and ‘tremble’ (see Table 1) wereper group.

J. M. G. Segovia et al. / Animal Behaviour 101 (2015) 169e177176

gave outstanding support maintaining the harvestmen in the lab-oratory. This study was funded by Fundaç~ao de Amparo �a Pesquisado Estado de Minas Gerais (FAPEMIG) to J.G.M.S., Fundaç~aodeAmparo �a Pesquisa do Estado de S~ao Paulo (FAPESP 2010/00915-0) to R.H.W., and Conselho Nacional de Desenvolvimento Científicoe Tecnol�ogico (CNPq) to K.D.C. (grant number 301605/2013-0).

Supplementary Material

Supplementary material associated with this article can befound, in the online version, at http://dx.doi.org/10.1016/j.anbehav.2014.12.025.

References

Anjum, F., Turni, H., Mulder, P. G., van der Burg, J., & Brecht, M. (2006). Tactileguidance of prey capture in Etruscan shrews. Proceedings of the NationalAcademy of Sciences of the United States of America, 103, 16544e16549.

Barth, F. G. (2002). A spider's world: Senses and behavior. Berlin, Germany: Springer.Betz, O., & Mumm, R. (2001). The predatory legs of Philonthus marginatus (Cole-

optera, Staphylinidae): functional morphology and tarsal ultrastructure.Arthropod Structure & Development, 30, 77e97.

Bleckmann, H., & Barth, F. G. (1984). Sensory ecology of a semi-aquatic spider(Dolomedes triton). Behavioral Ecology and Sociobiology, 14, 303e312.

Buning, T. D. C. (1983). Thermal sensitivity as a specialization for prey capture andfeeding in snakes. American Zoologist, 23, 363e375.

Cardoso, J. L. C., França, F. D. S., Wen, F. H., Malaque, C. M. S., & Haddad, V., Jr. (2009).Animais peçonhentos no Brasil: Biologia, clínica e terapeutica dos acidentes. S~aoPaulo, SP, Brazil: Sarvier.

Carvalho, L. A., Souza, E. S., & Willemart, R. H. (2012). Behavioral analysis of theinteraction between the spitting spider Scytodes globula (Araneae: Scytodidae)and the harvestman Discocyrtus invalidus (Opiliones: Gonyleptidae). Journal ofArachnology, 40, 332e337.

Catania, K. C., & Remple, F. E. (2005). Asymptotic prey profitability drives star-nosedmoles to the foraging speed limit. Nature, 433, 519e522.

Chien, S. A., & Morse, D. H. (1998). The roles of prey quality in the choice of huntingsites by adult male crab spiders Minusena vatia (Araneae, Thomisidae). Journalof Arachnology, 26, 238e243.

Clark, R. J., Jackson, R. R., & Cutler, B. (2000). Chemical cues from ants influencepredatory behavior in Habrocestum pulex, an ant-eating jumping spider (Ara-neae, Salticidae). Journal of Arachnology, 28, 309e318.

Corrette, B. J. (1990). Prey capture in the praying mantis Tenodera aridifolia sinensis:coordination of the capture sequence and strike movements. Journal of Exper-imental Biology, 148, 147e180.

Coyle, F. A. (1986). The role of silk in prey capture by nonaraneomorph spiders. InW. A. Shear (Ed.), Spider: Webs, behavior and evolution (pp. 269e305). Stanford,CA: Stanford University Press.

Cunningham, S. J., Castro, I., & Potter, M. A. (2009). The relative importance ofolfaction and remote touch in prey detection by North Island brown kiwis.Animal Behaviour, 78, 899e905.

Danchin, E., Giraldeau, L.-A., Valone, T. J., & Wagner, R. H. (2004). Public informa-tion: from nosy neighbors to cultural evolution. Science, 305, 487e491.

Davies, N. B., Krebs, J. R., & West, S. A. (2012). An introduction to behavioural ecology(4th ed.). Chichester, U.K.: Wiley-Blackwell.

Dawkins, R., & Krebs, J. R. (1979). Arms races between and within species. Pro-ceedings of the Royal Society B: Biological Sciences, 205, 489e511.

De la Mora, A., P�erez-Lachaud, G., & Lachaud, J. P. (2008). Mandible strike: the lethalweapon of Odontomachus opaciventris against small prey. Behavioural Processes,78, 64e75.

Dias, B. C., & Willemart, R. H. (2013). The effectiveness of post-contact defenses in aprey with no pre-contact detection. Zoology, 116, 168e174.

Donaldson, Z. R., & Grether, G. F. (2007). Tradition without social learning: scent-mark-based communal roost formation in a Neotropical harvestman (Prionos-temma sp.). Behavioral Ecology and Sociobiology, 61, 801e809.

Eisner, T., Rossini, C., Gonz�alez, A., & Eisner, M. (2004). Chemical defense of anopilionid (Acanthopachylus aculeatus). Journal of Experimental Biology, 207,1313e1321.

Elias, D. O., Mason, A. C., & Hebets, E. A. (2010). A signalesubstrate match in thesubstrate-borne component of a multimodal courtship display. Current Zoology,56, 370e378.

Elias, D. O., Mason, A. C., & Hoy, R. R. (2004). The effect of substrate on the efficacy ofseismic courtship signal transmission in the jumping spider Habronattus dos-senus (Araneae: Salticidae). Journal of Experimental Biology, 207, 4105e4110.

Fischer, M. L., �Cokl, A., Ramires, E. N., Marques-da-Silva, E., Delay, C., Fontana, J. D.,et al. (2009). Sound is involved in multimodal communication of Loxoscelesintermedia Mello-Leit~ao, 1934 (Araneae; Sicariidae). Behavioural Processes, 82,236e243.

Fischer, M. L., & Vasconcellos-Neto, J. (2005). Microhabitats occupied by Loxoscelesintermedia and Loxosceles laeta (Araneae: Sicariidae) in Curitiba, Paran�a, Brazil.Journal of Medical Entomology, 42, 756e765.

Fischer, M. L., Vasconcellos-Neto, J., & dos Santos Neto, L. G. (2006). The prey andpredators of Loxosceles intermedia Mello-Leitao 1934 (Araneae, Sicariidae).Journal of Arachnology, 34, 485e488.

Foelix, R. (2011). Biology of spiders. Oxford, U.K.: Oxford University Press.Gnaspini, P., & Hara, M. R. (2007). Defense mechanisms. In R. Pinto-da-Rocha,

G. Machado, & G. Giribet (Eds.), Harvestmen: The biology of Opiliones (pp.374e399). Cambridge, MA: Harvard University Press.

Gonz�alez-Bernal, E., Brown, G. P., Cabrera-Guzm�an, E., & Shine, R. (2011). Foragingtactics of an ambush predator: the effects of substrate attributes on preyavailability and predator feeding success. Behavioral Ecology and Sociobiology,65, 1367e1375.

Greene, H. W., & Burghardt, G. M. (1978). Behavior and phylogeny: constriction inancient and modern snakes. Science, 200, 74e77.

de Groot, J. H., & van Leeuwen, J. L. (2004). Evidence for an elastic projectionmechanism in the chameleon tongue. Proceedings of the Royal Society B: Bio-logical Sciences, 271, 761.

Hanna, C. J., & Eason, P. K. (2013). Juvenile crab spiders (Mecaphesa asperata) useindirect cues to choose foraging sites. Ethology. Ecology & Evolution, 25,161e173.

Hara, M. R., Cavalheiro, A. J., Gnaspini, P., & Santos, D. Y. (2005). A comparativeanalysis of the chemical nature of defensive secretions of Gonyleptidae(Arachnida: Opiliones: Laniatores). Biochemical Systematics and Ecology, 33,1210e1225.

Hara, M. R., & Gnaspini, P. (2003). Comparative study of the defensive behavior andmorphology of the gland opening area among harvestmen (Arachnida, Opi-liones, Gonyleptidae) under a phylogenetic perspective. Arthropod Structure &Development, 32, 257e275.

Hebets, E. A. (2005). Attention-altering signal interactions in the multimodalcourtship display of the wolf spider Schizocosa uetzi. Behavioral Ecology, 16,75e82.

Herrel, A., Meyers, J. J., Aerts, P., & Nishikawa, K. C. (2000). The mechanics of preyprehension in chameleons. Journal of Experimental Biology, 203, 3255e3263.

Hoefler, C. D., Taylor, M., & Jakob, E. M. (2002). Chemosensory response to prey inPhidippus audax (Araneae, Salticidae) and Pardosa milvina (Araneae, Lycosidae).Journal of Arachnology, 30, 155e158.

Hopcraft, J. G. C., Sinclair, A. R. E., & Packer, C. (2005). Planning for success: Serengetilions seek prey accessibility rather than abundance. Journal of Animal Ecology,74, 559e566.

Jackson, R. R., Clark, R. J., & Harland, D. P. (2002). Behavioural and cognitive influencesof kairomones on an araneophagic jumping spider. Behaviour, 139, 749e776.

Johnson, A., Revis, O., & Johnson, J. C. (2011). Chemical prey cues influence the urbanmicrohabitat preferences of western black widow spiders, Latrodectus hesperus.Journal of Arachnology, 39, 449e453.

Kardong, K. V. (1986). Predatory strike behavior of the rattlesnake, Crotalus viridisoreganus. Journal of Comparative Psychology, 100, 304e314.

Lease, H. M., & Wolf, B. O. (2011). Lipid content of terrestrial arthropods in relationto body size, phylogeny, ontogeny and sex. Physiological Entomology, 36, 29e38.

Lowrie, D. C. (1987). Effects of diet on the development of Loxosceles laeta (Nicolet)(Araneae, Loxoscelidae). Journal of Arachnology, 15, 303e308.

Machado, G., Carrera, P. C., Pomini, A. M., & Marsaioli, A. J. (2005). Chemical defensein harvestmen (Arachnida, Opiliones): do benzoquinone secretions deterinvertebrate and vertebrate predators? Journal of Chemical Ecology, 31,2519e2539.

Machado, G., & Pomini, A. M. (2008). Chemical and behavioral defenses of theNeotropical harvestman Camarana flavipalpi (Arachnida: Opiliones). Biochem-ical Systematics and Ecology, 36, 369e376.

Masters, W. M. (1984). Vibrations in the orbwebs of Nuctenea sclopetaria (Aranei-dae). Behavioral Ecology and Sociobiology, 15, 207e215.

Mestre, L. A. M., & Pinto-da-Rocha, R. (2004). Population dynamics of an isolatedpopulation of the harvestman Ilhaia cuspidata (Opiliones Gonyleptidae), inAraucaria Forest (Curitiba, Paran�a, Brazil). Journal of Arachnology, 32, 208e220.

Mineo, M. F., & Del-Claro, K. (2006). Mechanoreceptive function of pectines in theBrazilian yellow scorpion Tityus serrulatus: perception of substrate-borne vi-brations and prey detection. Acta Ethologica, 9, 79e85.

Nelson, X. J., & Jackson, R. R. (2011). Flexibility in the foraging strategies of spiders.In M. E. Herberstein (Ed.), Spider behavior: Flexibility and versatility (pp. 31e56).Cambridge, MA: Cambridge University Press.

O'Rourke, C. T., Hall, M. I., Pitlik, T., & Fern�andez-Juricic, E. (2010). Hawk eyes. I:Diurnal raptors differ in visual fields and degree of eye movement. PLoS One, 5,e12802. http://dx.doi.org/10.1371/journal.pone.0012802.

Pereira, W., Elpino-Campos, A., Del-Claro, K., & Machado, G. (2004). Behavioralrepertory of the Neotropical harvestman Ilhaia cuspidata (Opiliones, Gony-leptidae). Journal of Arachnology, 32, 22e30.

Persons, M. H., & Rypstra, A. L. (2000). Preference for chemical cues associated withrecent prey in the wolf spider Hogna helluo (Araneae: Lycosidae). Ethology, 106,27e35.

Persons, M. H., & Uetz, G. W. (1996). The influence of sensory information on patchresidence time in wolf spiders (Araneae: Lycosidae). Animal Behaviour, 51,1285e1293.

Piep, M., Radespiel, U., Zimmermann, E., Schmidt, S., & Siemers, B. M. (2008). Thesensory basis of prey detection in captive-born grey mouse lemurs, Microcebusmurinus. Animal Behaviour, 75, 871e878.

Placyk, J. S., Jr., & Graves, B. M. (2002). Prey detection by vomeronasal chemore-ception in a plethodontid salamander. Journal of Chemical Ecology, 28,1017e1036.

J. M. G. Segovia et al. / Animal Behaviour 101 (2015) 169e177 177

Pomini, A. M., Machado, G., Pinto-da-Rocha, R., Macías-Ord�o~nez, R., & Marsaioli, A. J.(2010). Lines of defense in the harvestman Hoplobunus mexicanus (Arachnida:Opiliones): aposematism, stridulation, thanatosis, and irritant chemicals.Biochemical Systematics and Ecology, 38, 300e308.

Punzo, F., & Kukoyi, O. (1997). The effects of prey chemical cues on patch residencetime in the wolf spider Trochosa parthenus (Chamberlin) (Lycosidae) and thelynx spider Oxyopes salticus Hentz (Oxyopidae). Bulletin of the British Arach-nological, Society, 10, 323e326.

�Rez�a�c, M., Pek�ar, S., & Lubin, Y. (2008). How oniscophagous spiders overcomewoodlouse armour. Journal of Zoology, 275, 64e71.

Rinaldi, I. M. P., & Stropa, A. A. (1998). Sexual behaviour in Loxosceles gaucho Gertsch(Araneae, Sicariidae). Bulletin of the British Arachnological Society, 11, 57e61.

Rovner, J. S. (1980). Morphological and ethological adaptations for prey capture inwolf spiders (Araneae, Lycosidae). Journal of Arachnology, 8, 201e215.

Sandidge, J. S., & Hopwood, J. L. (2005). Brown recluse spiders: a review of biology,life history and pest management. Transactions of the Kansas Academy of Science,108, 99e108.

Schnitzler, H. U., & Kalko, E. K. (2001). Echolocation by insect-eating bats. Bioscience,51, 557e569.

Segovia, J. M. G., Del-Claro, K., & Willemart, R. H. (in press). Defences of aNeotropical harvestman against different levels of threat by the recluse spider.Behaviour.

Souza, E. D. S., & Willemart, R. H. (2011). Harvest-ironman: heavy armature, and notits defensive secretions, protects a harvestman against a spider. AnimalBehaviour, 81, 127e133.

Valone, T. J. (2007). From eavesdropping on performance to copying the behavior ofothers: a review of public information use. Behavioral Ecology and Sociobiology,62, 1e14.

Van Buskirk, R. W., & Nevitt, G. A. (2008). The influence of developmental envi-ronment on the evolution of olfactory foraging behaviour in procellariiformseabirds. Journal of Evolutionary Biology, 21, 67e76.

Vetter, R. S. (2008). Spiders of the genus Loxosceles (Araneae, Sicariidae): a review ofbiological, medical and psychological aspects regarding envenomations. Journalof Arachnology, 36, 150e163.

Wigger, E., Kuhn-Nentwig, L., & Nentwig, W. (2002). The venom optimization hy-pothesis: a spider injects large venom quantities only into difficult prey types.Toxicon, 40, 749e752.

Wilder, S. M. (2011). Spider nutrition: an integrative perspective. Advances in InsectPhysiology, 40, 87e136.

Willemart, R. H., Chelini, M. C., De Andrade, R., & Gnaspini, P. (2007). An ethologicalapproach to a SEM survey on sensory structures and tegumental gland open-ings of two Neotropical harvestmen (Arachnida, Opiliones, Gonyleptidae).Italian Journal of Zoology, 74, 39e54.

Willemart, R. H., & Hebets, E. A. (2012). Sexual differences in the behavior of theharvestman Leiobunum vittatum (Opiliones, Sclerosomatidae) towards conspe-cific cues. Journal of Insect Behavior, 25, 12e23.

Willemart, R. H., Osses, F., Chelini, M. C., Macías-Ord�o~nez, R., & Machado, G. (2009).Sexually dimorphic legs in a Neotropical harvestman (Arachnida, Opiliones):ornament or weapon? Behavioural Processes, 80, 51e59.

Willemart, R. H., & Pellegatti-Franco, F. (2006). The spider Enoploctenus cyclothorax(Araneae, Ctenidae) avoids preying on the harvestman Mischonyx cuspidatus(Opiliones, Gonyleptidae). Journal of Arachnology, 34, 649e652.

Zschokke, S., H�enaut, Y., Benjamin, S. P., & García-Ballinas, J. A. (2006). Prey-capturestrategies in sympatric web-building spiders. Canadian Journal of Zoology, 84,964e973.