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The article discusses a study on the prey selection behavior of assassin bugs, Scipinnia repax and Nagusta species on jumping spiders. These bugs prey on the social jumping spiders that build nest complexes in vegetation near the shoreline of Lake Victoria. Nagusta species preys on PortiaAfricana and S. repax preys on salticid eggs and also on Nagusta. They avoid ants which suggest that sensory modalities play important role in prey detection.

Evarcha culicivora Wesolowska & Jackson, a salticid from the Lake Victoria region of east Africa, is known to associate with Lantana camara L. (family Verbenaceae) and Ricinus communis L. (family euphorbiaceae), two plant species that are common in the same habitat. E. culicivora is an unusual salticid because, by choosing blood-carrying mosquitoes as preferred prey, it feeds indirectly on vertebrate blood, and E. culicivora apparently also feeds on nectar taken from L. camara and R. communis. The experimental findings reported here show that the odour of these two plants is salient to E. culicivora. A Y-shaped olfactometer was used in the experiments, with plant odour on one side and the other side a control (no odour). Juveniles, adult males and adult females chose the odour of L. camara and R. communis more often than the control. [ABSTRACT FROM AUTHOR]

Abstract: Evarcha culicivora is an unusual salticid spider because each sex actively courts the other and both sexes make distinctive mate-choice decisions. Here we use olfactometer experiments for investigating the ability of each sex to identify potential mates on the basis of odour alone. Test spiders spent more time in the vicinity of opposite-sex conspecific source spiders, regardless of whether or not these source spiders had previously mated, when the alternatives were conspecific individuals of the same sex, juveniles or a control (no odour source). This trend held regardless of the test spider''s and source spider''s age after reaching maturity and, for male test spiders, it held regardless of the test spider''s mating status. However, after females had mated they no longer expressed a preference for male odour. [Copyright &y& Elsevier]

Abstract: An important prediction from game theory is that the value of a resource influences the level to which conflict escalates. Here we use jumping spiders (Salticidae) to consider this prediction in the context of species adopting different mating systems (‘female mate-choice’ and ‘mutual mate-choice’). Our experiments are designed for determining whether the odour of conspecific females, more than the odour of heterospecific females, primes males to escalate conflict with a potential same-sex rival and also whether the odour of conspecific males, more than the odour of heterospecific males, primes females to escalate conflict with a potential same-sex rival. Four species were studied: Evarcha culicivora, a species in which mutual mate-choice is pronounced, and Portia fimbriata, Portia africana, and Jacksonoides queenslandicus, more conventional salticids in which female mate-choice and male–male competition appear to be dominant. Our hypothesis is that, for all four species, there is strong competition between males for access to females and that, for E. culicivora, but not for the other three species, there is also strong competition between females for access to males. Our findings are consistent with this hypothesis, as we show that, although the odour of conspecific females primes escalation of vision-based male–male conflict for all four species, E. culicivora is the only species for which there is evidence of odour from conspecific males priming the escalation of female–female conflict. [Copyright &y& Elsevier]

Myrmarachne melanotarsa, an ant-like jumping spider (Salticidae) from East Africa, is an accurate mimic of Crematogaster sp. and associates unusually closely with its models. M. melanotarsa is remarkable in that it forms dense aggregations and builds large nest complexes (numerous individuallyoccupied nests connected to each other by silk). other salticids (Pseudicius spp., Menemerus spp.) live with M. melanotarsa in the same nest complex. These aggregations, which can exceed 50 conspecific individuals per colony, are considerably larger than those few previously described, and seem to have primarily a protective function. We provide baseline information on the natural history of M. melanotarsa, paying particular attention to predatory behaviour and association with Crematogaster sp., and fit this within current theory on the function of sociality in spiders. other unusual behaviour of M. melanotarsa includes "mouthing", in which the spider opens and closes its chelicerae while pressing its mouthparts against nest silk. We investigated the role of prior presence of Crematogaster sp. on nest silk in eliciting this previously unreported behaviour. [ABSTRACT FROM AUTHOR]

Instances are documented of finding individuals of Portia africana in the field living aggregated in the webs of other spiders, in the nest complexes of other salticids, around solitary nests of other salticids, and around the nests of oecobiid spiders. Aggregation members included all active juvenile stages of P. africana, as well as adult males and females. More than one individual of P. africana sometimes fed on the same prey. Small juveniles of P. africana were more often than other stages found aggregated and more often observed feeding together. Small juveniles of P. africana surrounded the nests occupied by other salticid genera and nests occupied by oecobiid spiders. When the resident salticid or oecobiid attempted to leave or enter the nest, one of the P. africana juveniles lunged and captured it, after which other P. africana individuals sometimes joined to feed. [ABSTRACT FROM AUTHOR]

Evarcha culicivora, an East African jumping spider (Salticidae), is an unusual predator because it feeds indirectly on vertebrate blood by choosing blood-carrying mosquitoes as preferred prey. It also associates with particular plant species, Lantana camara and Ricinus communis. Here we document this species' exceptionally complex display repertoire. In common with many other salticids, E. culicivora exhibits pronounced courtship versatility, with males using different tactics depending on the female's location and state of maturity. However, in contrast to most other salticids that have been studied, the males and the females of E. culicivora are both active at initiating and sustaining courtship, and both sexes are cannibalistic. Contrary to the emphasis in the literature on female spiders eating males, females of E. culicivora run a higher risk of being killed by males than vice versa during courtship. E. culicivora males also differ from other salticids that have been studied by adopting pronounced copulatory courtship. male-female interactions of E. culicivora are especially complex when encounters are in the foliage of L. camara and R. communis. [ABSTRACT FROM AUTHOR]

Abstract: The distinctions between a predator''s diet, its prey-choice behaviour and its preference are illustrated in a study of Aelurillus m-nigrum Kulczyn''ski, a salticid spider from Azerbaijan. The natural diet of A. m-nigrum was determined from records of individuals feeding in the field (N =58). Ten arthropod orders were represented. Nine were from the class Insecta (Coleoptera, Collembola, Diptera, Heteroptera, Homoptera, Hymenoptera, Lepidoptera, Orthoptera, Psocoptera) and one from the class Arachnida (Araneae). Of 50 insects among the prey, 21 (42%) were Hymenoptera, with ants (family Formicidae) alone accounting for 31% of all prey records. Although the majority (69%) of the natural prey were not ants, results from prey-choice testing in the laboratory implied that A. m-nigrum preferred ants as prey. However, this preference was evident only when the testing environment included sand and a small stone. Our findings illustrate the importance of not conflating the concept of a predator''s preference with the concept of a predator''s natural diet and illustrate that physical features of a predator''s habitat may be an important factor in influencing how strongly preference is expressed. [Copyright &y& Elsevier]

Abstract: An important prediction from game theory is that the value of a resource influences the level to which male–male conflict escalates. Earlier experimental studies have shown that the seven salticid species we study here (Bavia aericeps, Euryattus sp., Hypoblemum albovittatum, Jacksonoides queenslandicus, Marpissa marina, Portia africana and Simaetha paetula) determine by sight whether a female is a conspecific or a heterospecific and then escalate the intensity with which they interact (i.e., they adopt behaviour that is likely to put them at greater risk of injury after detecting the presence of a conspecific female). Here the earlier studies are extended by using the odour of conspecific females (experimental tests) and heterospecific females (control tests), and by presenting each male with his mirror image as well as having two males interact with each other. Findings from this study suggest that, for J. queenslandicus and P. africana, the odour of conspecific females, more than the odour of heterospecific females, primes the male to escalate conflict with a potential rival. However, this was not found for the other five species tested. [Copyright &y& Elsevier]

An important prediction from game theory is that resource value influences the level to which competitors will escalate conflict. An earlier study considered whether this prediction applies to the male–male interactions of Hypoblemum albovittatum, a jumping spider (Salticidae) from New Zealand. The males of this species escalated conflicts in the presence of a moving mount made from a conspecific female. However, because the control was only a similar-sized motionless cork, an alternative hypothesis (that the cue for escalation is seeing movement of any female-size object, rather than seeing specifically a female) was not ruled out. Here we show that a moving cork, without a mount present, is indeed sufficient to cause males to escalate, but a moving mount (made from a conspecific female) causes males to escalate further. The level of escalation in the presence of a moving mount made from prey (housefly) or from a rival (conspecific male) did not differ significantly from the level of escalation when only a moving cork was present. These findings suggest that, although seeing a moving object similar in size to a conspecific female is sufficient for priming males to escalate, males can also discern by sight that specifically a female is present and, when they have this precise information, they make strategic decisions to escalate conflict further. [ABSTRACT FROM AUTHOR]

Abstract: An important prediction from game theory is that the value of a resource influences the level to which male–male conflict escalates. An earlier experimental study showed that males of Hypoblemum albovittatum, a common salticid in New Zealand, can discern by sight alone whether a female is in the vicinity and that, having detected a female''s presence, males escalate (i.e., adopt behaviour that is likely to put them at greater risk of injury). Seeing a bare moving cork, a conspecific male or a prey item also elicits escalation, but not to the level elicited by seeing a conspecific female. Here the earlier study is extended by using non-conspecific females in control tests and by undertaking experiments with an additional six salticid species. Findings from these experiments suggest that the ability of interacting males to detect by sight alone that a conspecific, instead of a non-conspecific, female is present is widespread in the family Salticidae and that it may be routine for salticid males to use information about the presence of conspecific females when making strategic decisions related to escalation during encounters with other males. [Copyright &y& Elsevier]

Portia is a genus of web-invading araneophagic (spider eating) jumping spiders known from earlier studies to derive aggressive-mimicry signals by using a generate-and-test (trial and error) algorithm. We studied individuals of Portia labiata from two populations (Los Baños and Sagada) in the Philippines that have previously been shown to differ in the level to which they rely on trial-and-error derivation of signals for prey capture (Los Baños relied on trial and error more strongly than Sagada P. labiata). Here we investigated P. labiata's use of trial and error in a novel situation (a confinement problem: how to escape from an island surrounded by water) that is unlikely to correspond closely to anything the spider would encounter in nature. During Experiment 1, spiders chose between two potential escape tactics (leap or swim), one of which was set at random to fail (brought spider no closer to edge of tray) and the other of which was set for partially succeeding (brought spider closer to edge of tray). By using trial and error, the Los Baños P. labiata solved the confinement problem significantly more often than the Sagada P. labiata in Experiment I, both when the correct choices were positively reinforced (i.e., when the spider was moved closer to edge of tray) and when incorrect choices were punished (i.e., when the spider got no closer to edge of tray). In Experiment 2, the test individual's first choice was always set to fail, and P. labiata was given repeated opportunities to respond to feedback, yet the Sagada P. labiata continued to place little reliance on trial and error for solving the confinement problem. That the Los Baños P. labiata relied more strongly on trial-and-error problem solving than the Sagada P. labiata has now been demonstrated across two different tasks. [ABSTRACT FROM AUTHOR]

Spiders do not feed directly on vertebrate blood, but a small East African jumping spider (Salticidae), Evarcha culicivora, feeds indirectly on vertebrate blood by choosing as preferred prey female mosquitoes that have had recent blood meals. Experiments show that this spider can identify its preferred prey by sight alone and by odor alone. When presented with two types of size-matched motionless lures, E. culkivora consistently chose blood-fed female mosquitoes in preference to nonmosquito prey, male mosquitoes, and sugar-fed female mosquitoes (i.e., females that had not been feeding on blood). When the choice was between mosquitoes of different sizes (both blood- or both sugar-fed), small juveniles chose the smaller prey, whereas adults and larger juveniles chose the larger prey. However, preference for blood took precedence over preference for size (i.e., to get a blood meal, small individuals took prey that were larger than the preferred size, and larger individuals took prey that were smaller than the preferred size). When presented with odor from two prey types, E. culkivora approached the odor from blood-fed female mosquitoes significantly more often the odor of the prey that were not carrying blood. [ABSTRACT FROM AUTHOR]

An experimental study of search-image use by araneophagic jumping spiders (i.e., salticid spiders that prey routinely on other spiders) supports five conclusions. First, araneophagic salticids have an innate predisposition to form search images for specific prey from their preferred prey category (spiders) rather than for prey from a non-preferred category (insects). Second, single encounters are sufficient for forming search images. Third, search images are based on selective attention specifically to optical cues. Fourth, there are trade-offs in attention during search-image use (i.e., forming a search image for one type of spider diminishes the araneophagic salticid’s attention to other spiders). Fifth, the araneophagic salticid’s adoption of search images is costly to the prey (i.e., when the araneophagic salticid adopts a search, the prey’s prospects for surviving encounters with the araneophagic salticid are diminished). Cognitive and ecological implications of search-image use are discussed. [ABSTRACT FROM AUTHOR]

Using a subsocial spitting spider (Scytodes pallida) as the prey and a spider-eating jumping spider (Portia labiata) as the predator, the cost of parental care is investigated. Our findings suggest that being singled out as preferred prey by P. labiata is, for egg-carrying females of S. pallida, an important cost of parental care. In survival tests, during which P. labiata was given access to egg-carrying and eggless S. pallida females, egg-carrying females were preyed on more often than eggless females. In preference tests, motionless lures instead of living S. pallida were used. The lures were made by mounting dead egg-carrying and dead eggless S. pallida females in lifelike posture in webs. In these tests, P. labiata detected and identified, by vision alone, both kinds of prey (egg-carrying and eggless), and singled out egg-carrying females as preferred prey. [ABSTRACT FROM AUTHOR]

Phaeacius, a sit-and-wait jumping spider, is shown to base predatory decisions on simultaneous use of information about whether the background is matching or contrasting, whether or not the prey has good eyesight and whether the prey is oriented face on or facing away. In prey-choice testing in which mounts (dead prey in lifelike posture on a cork) were used, background and prey orientation influenced Phaeacius' behaviour specifically when a salticid came into view, salticids being prey with exceptionally good eyesight. When the prey was a non-salticid spider or an insect, Phaeacius' behaviour did not vary significantly with background or with prey orientation. In prey-reaction experiments, background and orientation influenced prey behaviour when the prey was a salticid, but not when it was a non-salticid spider or an insect. Phaeacius evidently takes special precautions to minimize the risk of being seen by a prey that has exceptional eyesight. [ABSTRACT FROM AUTHOR]

Investigates the influence of optical cues on predatory behavior used by the jumping spider, Portia fimbriata in Australia. Cryptic stalking against standard virtual lure; Influence of the size of anterior median (AM) eyes on cryptic stalking; Freezing response when faced with lure with large AM eyes.

In laboratory experiments, Portia fimbriata, an araneophagic salticid from Queensland, was influenced by olfactory and contact-chemical cues from Jacksonoides queenslandicus, an abundant salticid on which P.fimbriata preys. Four distinct effects were revealed: P.fimbriata (1) moved into and remained in the vicinity of J. queenslandicus, (2) performed undirected leaping, behaviour known to function as speculative hunting by inducing a turning response from not-yet-seen J. queenslandicus, (3) adopted a posture (retracted palps) known to be routine when stalking salticids and (4) showed enhanced attention to optical cues from J. queenslandicus. Laboratory experiments provided no statistical evidence that chemical cues from other prey species affected P.fimbriata, that J. queenslandicus was affected by chemical cues from P. fimbriata or that allopatric Portia were sensitive to chemical cues from J. queenslandicus. [ABSTRACT FROM AUTHOR]

Portia is a genus of web-invading araneophagic jumping spiders known from earlier studies to derive aggressive-mimicry signals by using a generate-and-test algorithm (trial-and-error tactic). Here P. fimbriata's use of trial-and-error to solve a confinement problem (how to escape from an island surrounded by water) is investigated. Spiders choose between two potential escape tactics (leap or swim), one of which will fail (bring spider no closer to edge of tray) and the other of which will partially succeed (bring spider closer to edge of tray). The particular choice that will partially succeed is unknown to the spider. Using trial-anderror, P.fimbriata solves the confinement problem both when correct choices are rewarded (i.e. when the spider is moved closer to edge of tray) and when incorrect choices are punished (i.e. when the spider gets no closer to edge of tray). [ABSTRACT FROM AUTHOR]