Ant-like Research Articles

Vision-based innate aversion to ants and ant mimics

Innate vision-based aversions to model and mimic were investigated using a mimicry system in which the models were ants (Formicidae), and both the mimics and the predators were jumping spiders (Salticidae). Jumping spiders are a large group of predatory invertebrates that usually prey opportunistically on prey of similar size. We used 12 representative species from this group, the ‘‘ordinary salticids’’ as predators. The mimics considered belonged to another group, salticids that resemble ants. A choice arena containing an empty chamber and a stimulus chamber was used for testing predator responses to a variety of dead arthropods (ants, ant mimics, and an array of non–ant-like species) mounted in a lifelike posture. When presented with visual cues from arthropods other than ants or ant-like salticids, naive predators chose the empty chamber no more often than the stimulus chamber. However, when visual cues were from ants or from ant-like salticids, ordinary salticids chose the empty chamber significantly more often than the stimulus chamber. These findings suggest learning by the predator is not necessary in order for ant-like salticids to gain Batesian mimicry advantages. Key words: ants, innate aversion, mimicry, myrmecomorphy, spiders, vision. [Behav Ecol]

Innate aversion to ants (Hymenoptera: Formicidae) and ant mimics: experimental findings from mantises (Mantodea)

Field data suggest that ants may be important predators of mantises which, in turn, may be important predators of jumping spiders (Salticidae). Using a tropical fauna from the Philippines as a case study, the reactions of mantises to ants, myrmecomorphic salticids (i.e. jumping spiders that resemble ants) and ordinary salticids (i.e. jumping spiders that do not resemble ants) were investigated in the laboratory. Three mantis species (Loxomantis sp., Orthodera sp., and Statilia sp.) were tested with ten ant species, five species of Myrmarachne (i.e. myrmecomorphic salticids), and 23 ordinary salticid species. Two categories of the myrmecomorphic salticids were recognized: (1) ‘typical Myrmarachne’ (four species with a strong resemblance to ants) and (2) Myrmarachne bakeri (a species with less strong resemblance to ants). Ants readily killed mantises in the laboratory, confirming that, for the mantises studied, ants are dangerous. In alternate-day testing, the mantises routinely preyed on the ordinary salticids, but avoided ants. The mantises reacted to myrmecomorphic salticids similarly to how they reacted to ants (i.e. myrmecomorphic salticids appear to be, for mantises, Batesian mimics of ants). Although myrmecomorphic salticids were rarely eaten, M. bakeri was eaten more often than typical Myrmarachne. Because the mantises had no prior experience with ants, ant mimics or ordinary salticids, our findings suggest that mantises have an innate aversion to attacking ants and that this aversion is generalized to myrmecomorphic salticids even in the absence of prior experience with ants. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 88, 23–32.

Conditional use of honest signaling by a Batesian mimic

Jumping spiders (Salticidae) usually avoid ants, but some species within this family single out ants as preferred prey, while others (especially the species in the genus Myrmarachne) are Batesian mimics of ants. Field records show that ant-eating salticids sometimes prey on Myrmarachne, suggesting that the unwanted attention of predators that specialize on the model may be an important, but poorly understood, cost of Batesian mimicry. By staging encounters in the laboratory between living ant-eating salticids and Myrmarachne, we determined that ant-eating salticids attack Myrmarachne. However, when Myrmarachne detects a stalking ant-eating salticid early enough, it adopts a distinctive display posture (legs almost fully extended, elevated 45� , and held out to the side 45� ), and this usually deters the predator. When Myrmarachne detects an ant-eating salticid before stalking begins, Myrmarachne makes preemptive displays that appear to inhibit the initiation of stalking. Using immobile lures made from dead Myrmarachne that were either in a display posture or a nondisplay posture, we ascertained that specifically the display posture of Myrmarachne deters the initiation of stalking (ant-eating salticids stalked nondisplaying more often than displaying lures). In another experiment, we ascertained that it is specifically the interjection of display posture that deters stalking. When ant-eating salticids that had already begun stalking experienced lures that switched from a nondisplay to a display posture, they stopped stalking. Although the unwanted attentions of its models’ predators may be, for Myrmarachne, a hidden cost of Batesian mimicry, Myrmarachne appears to have an effective defense against these predators. Key words: antipredator behavior, ants, Batesian mimicry, Salticidae, signals. [Behav Ecol]

Out of the Frying Pan and into the Fire: a Novel Trade‐Off for Batesian Mimics

AbstractA mimicry system was investigated in which the models were ants (Formicidae) and both the mimics and the predators were jumping spiders (Salticidae). By using motionless lures in simultaneous‐presentation prey‐choice tests, how the predators respond specifically to the static appearance of ants and ant mimics was determined. These findings suggest a rarely considered adaptive trade‐off for Batesian mimics of ants. Mimicry may be advantageous when it deceives ant‐averse potential predators, but disadvantageous in encounters with ant‐eating specialists. Nine myrmecophagic (ant‐eating) species (from Africa, Asia, Australia and North America) and one araneophagic (spider‐eating) species (Portia fimbriata from Queensland) were tested with ants (five species), with myrmecomorphic (ant‐like) salticids (six species of Myrmarachne) and with non‐ant‐like prey (dipterans and ordinary salticids). The araneophagic salticid chose an ordinary salticid and chose flies significantly more often than ants. Portia fimbriata also chose the ordinary salticid and chose flies significantly more often than myrmecomorphic salticids. However, there was no significant difference in how P. fimbriata responded to ants and to myrmecomorphic salticids. The myrmecophagic salticids chose ants and chose myrmecomorphic salticids significantly more often than ordinary salticids and significantly more often than flies, but myrmecophagic salticids did not respond significantly differently to myrmecomorphic salticids and ants.

Compound mimicry and trading predators by the males of sexually dimorphic Batesian mimics

Sexual dimorphism is pronounced in Myrmarachne, a large genus of ant-like jumping spiders (Salticidae) and one of the major animal groups in which Batesian mimicry of ants has evolved. Although adult females and juveniles of both sexes are distinctly ant-like in appearance, Myrmarachne males have elongated chelicerae that might appear to detract from their resemblance to ants. Experimental findings suggest that the Myrmarachne male's solution is to adopt compound mimicry (i.e. the male's model seems to be not simply an ant worker but a combination of an ant and something carried in the ant's mandibles: an "encumbered ant"). By becoming a mimic of a particular subset of worker ants, Myrmarachne males may have retained their Batesian-mimicry defence against ant-averse predators, but at the price of receiving the unwanted attention of predators for which encumbered ants are preferred prey. Two salticid species were used as predators in the experiments. Portia fimbriata is known to choose other salticids as preferred prey and to avoid unencumbered ants and their mimics (Myrmarachne females). In experiments reported here, P. fimbriata avoided encumbered ants and Myrmarachne males. Ants are the preferred prey of Chalcotropis gulosus. In our experiments, C. gulosus chose safer encumbered ants in preference to more dangerous unencumbered ants, chose Myrmarachne males more often than Myrmarachne females and showed no evidence of distinguishing between Myrmarachne males and encumbered ants. The cost of reconciling sexual dimorphism with Batesian mimicry appears to be that Myrmarachne males attract the unwanted attention of specialist predators of their compound model.

Butterfly mimics of ants

Large blue butterflies are notable for their rarity and ability to dupe ants, and they are endangered. A genetic reconstruction of how social parasitism evolved among them will overturn conservation priorities.

Taxonomic revision and phylogenetic hypothesis for the jumping spider subfamily Ballinae (Araneae, Salticidae)

The subfamily Ballinae is revised. To test its monophyly, 41 morphological characters, including the first phylogenetic use of scale morphology in Salticidae, were scored for 16 taxa (1 outgroup and 15 ingroup). Parsimony analysis of these data supports monophyly based on five unambiguous synapomorphies. The paper provides new diagnoses, descriptions of new genera, species, and a key to the genera. At present, Ballinae comprises 13 nominal genera, three of them new: Afromarengo, Ballus, Colaxes, Cynapes, Indomarengo, Leikung, Marengo, Philates and Sadies. Copocrossa, Mantisatta, Pachyballus and Padilla are tentatively included in the subfamily. Nine new species are described and illustrated: Colaxes horton, C. wanlessi, Philates szutsi, P. thaleri, P. zschokkei, Indomarengo chandra, L sarawakensis, Leikung kinabaluensis and Marengo deelemanae. Colaxes nitidiventris and Ballus segmentatus are redescribed. The Seychelles species Baviola spatulata is considered a junior synonym of B. braueri. The phylogenetic analysis suggests two independent origins of tentative Batesian mimicry of ants within Ballinae. (C) 2004 The Linnean Society of London.

Diffractive optics in spiders

The mechanisms behind the metallic colours of two species of spider are examined here with particular reference to the surface structures involved. Cosmophasis thalassina possesses a combination of a first-order diffraction grating and an underlying broadband multilayer reflector. The diffraction grating causes one spectral component to be selectively directed away from the direction of incident illumination. The laminar structure beneath produces a broadband ('white') reflectance, and with a significant proportion of the blue light being removed from the incident white light by the grating, the reflectance observed at most angles is yellow (white minus blue). Castaneira sp. possesses a zero-order diffraction grating, resulting in the antireflection of ultraviolet light. Beneath this lies a quarter-wave stack, reflecting saturated colours that change with angle of observation. The reflections of both species appear conspicuous against their natural environments, probably facilitating conspecific recognition (and/or mimicry of ants in Castaneira sp.), and constitute the first cases of structural colours analysed in spiders.

Mimicry of host cuticular hydrocarbons by salticid spider Cosmophasis bitaeniata that preys on larvae of tree ants Oecophylla smaragdina.

The salticid spider Cosmophasis bitaeniata preys on the larvae of the green tree ant Oecophylla smaragdina. Gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) reveal that the cuticle of C. bitaeniata mimics the mono- and dimethylalkanes of the cuticle of its prey. Recognition bioassays with extracts of the cuticular hydrocarbons of ants and spiders revealed that foraging major workers did not respond aggressively to the extracts of the spiders or conspecific nestmates, but reacted aggressively to conspecific nonnestmates. Typically, the ants either failed to react (as with control treatments with no extracts) or they reacted nonaggressively as with conspecific nestmates. These data indicate that the qualitative chemical mimicry of ants by C. bitaeniata allows the spiders to avoid detection by major workers of O. smaragdina.

Prey classification by Portia fimbriata, a salticid spider that specializes at preying on other salticids: species that elicit cryptic stalking

Abstract Portia fimbriata from Queensland, Australia, is an araneophagic jumping spider (Salticidae) that includes in its predatory strategy a tactic (cryptic stalking) enabling it to prey effectively on common sympatric salticids from other genera. Using standardized tests in which only optical cues were available (prey enclosed in small glass vial within large cage), the reactions of P. fimbriata to 114 salticid species were investigated. Except for Myrmarachne spp. (ant mimics), all salticids tested triggered cryptic stalking by P. fimbriata. This included not only sympatric, but also allopatric, salticids. The salticid on which P. fimbriata most commonly preys in nature is Jacksonoides queenslandicus, but cryptic stalking was triggered by salticid species with considerably different appearances, including beetle mimics, species with unusual body shapes and species with a wide variety of camouflaging markings. Portia fimbriata was also tested with lycosid, clubionid, theridiid and desid spiders and with flies and ants, but none of these arthropods triggered cryptic stalking. Optical cues used by P. fimbriata for discrimination between salticid and non‐salticid prey are discussed.

ATTRACTANT PHEROMONE AND ALLOMONE FROM THE METATHORACIC SCENT GLAND OF A BROAD-HEADED BUG (HEMIPTERA: ALYDIDAE)

AbstractFemales of Alydus eurinus (Say) release an attractant pheromone from their metathoracic scent gland. Conspecific males and, to a lesser extent, females and nymphs were attracted to blends containing the female-specific essential pheromone components 2-methylbutyl butyrate and (E)-2-methyl-2-butenyl butyrate, whereas individuals of Alydus pilosulus Herrick-Schaeffer were not attracted. When attacked, however, alydid adults emit chemicals for defense—butyric and hexanoic acids in A. eurinus—from the metathoracic scent glands. Mimicry is actually the first line of defense for most broad-headed bugs, including the common North American species studied here, whose nymphs are remarkable ant mimics and whose adults strongly resemble spider wasps (Hymenoptera: Pompilidae). The possibility that disparate heteropterans (Hemiptera) produce sexual pheromones in their metathoracic scent glands must be considered in future pheromone research on heteropterans, especially for species with the specialized lines of defense indicated by aposematism or mimicry.

Why are there good and poor mimics?

Among the many Batesian mimetic hoverflies (Diptera: Syrphidae) some have a very precise resemblance to the presumed model («good» or «specific» mimics) while others have a much less precise resemblance («poor» or «general» mimics). Intuitively one might expect that the specific mimics would be commoner and more successful than the general mimics. However, many specific mimics (e.g. Sericomyia silentis, Volucella bombylans) are quite rare, while general mimics are common (e.g. Syrphus ribesii, Episyrphus balteatus andEristalis intricarius ). Similarly, some ant-mimicking spiders from several different families are very good morphological and behavioural mimics of just one species of ant while others have a less detailed resemblance to ants in general. Six hypotheses are presented to explain the occurrence of so many poor mimics, and a theoretical model is outlined (the multi-model hypothesis) which shows how a poor general mimic can have a larger population than a good, specific mimic. This hypothesis may apply to some species of hoverfly and to some ant-mimicking spiders.

Why are there good and poor mimics?

Abstract Among the many Batesian mimetic hoverflies (Diptera: Syrphidae) some have a very precise resemblance to the presumed model («good» or «specific» mimics) while others have a much less precise resemblance («poor» or «general» mimics). Intuitively one might expect that the specific mimics would be commoner and more successful than the general mimics. However, many specific mimics (e.g. Sericomyia silentis , Volucella bombylans ) are quite rare, while general mimics are common (e.g. Syrphus ribesii , Episyrphus balteatus and Eristalis intricarius ). Similarly, some ant-mimicking spiders from several different families are very good morphological and behavioural mimics of just one species of ant while others have a less detailed resemblance to ants in general. Six hypotheses are presented to explain the occurrence of so many poor mimics, and a theoretical model is outlined (the multi-model hypothesis) which shows how a poor general mimic can have a larger population than a good, specific mimic. This hypothesis may apply to some species of hoverfly and to some ant-mimicking spiders.

Red legs and golden gasters: Batesian mimicry in Australian ants.

There are numerous reports of invertebrates that are visual mimics of ants, but no formal reports of mimicry of an ant, by an ant. Two endemic Australian ants, Myrmecia fulvipes and Camponotus bendigensis are remarkably similar in colour and size; both are generally black but have red legs and golden gasters. The density and hue of the pubescence of each ant's gaster are relatively uncommon in ants, but are very rare when combined with the black forebody and red legs. The ants are similarly sized but are smaller than other species closely related to M. fulvipes. The range of C. bendigensis lies entirely within that of M. fulvipes, and both species excavate ground nests in open woodland. Finally, workers of both species are crepuscular and forage solitarily. These data suggest that the relatively benign formicine C. bendigensis is a Batesian mimic of the formidable myrmeciine M. fulvipes.

OVIPOSITION BEHAVIOUR OF APHIDIINE WASPS (HYMENOPTERA: BRACONIDAE, APHIDIINAE): MORPHOLOGICAL ADAPTATIONS AND EVOLUTIONARY TRENDS

AbstractWe examined oviposition behaviour in 49 species representing 19 genera of Aphidiinae. All species are solitary parasitoids of aphids (Hemiptera: Aphidoidea). Six general types are described that differ in oviposition time, behaviour, and morphology. The Ephedrini have the least specialized oviposition behaviour within the subfamily, with Praini and Aphidiini displaying various adaptations for host capture and oviposition. Use of the forelegs to grasp and orient aphids for oviposition has arisen twice, in Praini and, independently, in the genus Monoctonus Haliday (Aphidiini: Monoctonina). Morphological modifications of the terminal abdominal segments for host capture are found in Trioxina and in several species of Pauesia Quilis (Aphidiina). A “quick” sting is characteristic of species in the genus Aphidius Nees and related genera. The greatest degree of behavioural diversification occurred among Pauesia species, including cryptic behaviour, ant mimicry, and “sneak” oviposition. Acquired chemical camouflage and mimicry of the host’s cuticular hydrocarbon pattern to avoid detection by guarding ants is found in Aclitus obscuripennis Foerster, the genus Paralipsis Foerster, and the two closely related genera Adialytus Foerster and Lysiphlebus Foerster. It is suggested that the main driving forces in the evolution of parasitoid oviposition behaviour were aphid defensive behaviour and avoidance of aggression by trophobiotic ants. The results are compared with phylogenetic relationships inferred from morphological and molecular data.

Ultraviolet cues affect the foraging behaviour of blue tits

The function of avian ultraviolet (UV) vision is only just beginning to be understood. One plausible hypothesis is that UV vision enhances the foraging ability of birds. To test this, we carried out behavioural experiments using wild–caught blue tits foraging for cabbage moth and winter moth caterpillars on natural and artificial backgrounds. The light environment in our experiments was manipulated using either UV–blocking or UV–transmitting filters. We found that the blue tits tended to find the first prey item (out of four) more quickly when UV cues were present. This suggests that UV vision offers benefits to birds when searching for cryptic prey, despite the prey and backgrounds reflecting relatively little UV. Although there was no direct effect of UV on the time taken to find all four prey items in a trial, search performance in the absence of UV wavelengths tended to increase over the course of an experiment. This may reflect changes in the search tactics of the birds. To our knowledge, these are the first data to suggest that birds use UV cues to detect cryptic insect prey, and have implications for our understanding of protective coloration.

Myrmecomorphy: Morphological and Behavioral Mimicry of Ants

The influence of ants on ecological communities is well documented by their quantitative effect on populations of other organisms (66, 176) and through the variety of relationships in which they are involved (166). Ants have influenced the evolution of other organisms in numerous ways: by being partners in symbiotic relationships, by providing exploitable resources, and by serving as models for the evolution of a remarkable variety of mimetic species (72). Myrmecomorphy, or the morphological and behavioral resem­ blance to ants, has evolved at least 70 times-IS times in the spiders (145), at least 10 times in the plant bugs (154), and 7 times in the staphylinid beetles (158). More than 2000 species of myrmecomorphic arthropods have been described thus far, belonging to over 200 genera in 54 families. Myrmecomorphy, or myrmecoidy (sensu 41, 42, 118), forms a subset of ant mimicry, which includes all species that resemble ants through convergence in morphological, behavioral, chemical, or textural characters. The other major group of ant-mimetic species are the myrmecophiles, or those arthropods that associate closely with ants, but do not necessarily resemble them (83). Unlike most myrmecomorphic species, myrmecophiles are typi­ cally convergent in chemical and/or textural characters that facilitate a close relationship with their ant models (71). Some myrmecophiles are also

Myrmecomorphy: Morphological and Behavioral Mimicry of Ants

With a growing world population and increasingly demanding consumers, the production of sufficient protein from livestock, poultry, and fish represents a serious challenge for the future. Approximately 1,900 insect species are eaten worldwide, mainly in ...Read More

Ant-mimicry in some Brazilian salticid and clubionid spiders (Araneae: Salticidae, Glubionidae)*

This paper describes the morphological and behavioural adaptations responsible for ant-like appearance in eight species (genera Zuniga, Synemosyna, Sphecotypus, and Myrmecium) of salticid and clubionid spiders studied in Amazonian and SE Brazil. All ant-mimicking spiders have body and legs thin, and the shiny integument typical of their models. Light horizontal hair bands and constrictions of the cephalothorax and abdomen simulate, respectively, the head-thorax joint and segmented gaster of ants. The petiole and postpetiole of the ants are usually mimicked by a lengthened pedicel, together with a narrowing of the posterior cephalothorax and/or anterior abdomen. The prominent pedipalps of the spiders often simulate ant mandibles, but they may also be strikingly similar to an ant's head. All ant-mimicking spiders walked in a zig-zag ant-like pattern, and frequently raised and moved about the first pair of legs as ‘antennae’. The mimics were found in the same microhabitats (foliage or ground) as their models, and displayed strong avoidance reactions toward the latter both in the field and in captivity. The inoffensive characteristics of the mimics and the noxious traits of their models (strong mandibles, potent sting, hard integument, venomous secretions) strongly suggest that the spiders are Batesian ant-mimics. The detailed structural and behavioural adaptations enhancing ant-mimicry provide strong circumstantial evidence that the selective agents involved must have good visual acuity, and are probably small insectivorous vertebrates (e.g. birds, lizards and toads) or arthropods (e.g. wasps and spiders) which avoid ants.

The biology of ant-like jumping spiders (Araneae, Salticidae): prey and predatory behaviour of Myrmarachne with particular attention to M. lupata from Queensland

Myrtnarachne is a genus of ant-like salticids. Eight species were observed feeding, in nature, in Australia, Kenya, Malaysia and Sri Lanka, on varied types of insects but not ants. The behaviour of M. lupata, from Australia, was studied in the laboratory. Predatory sequences were found to differ considerably from those of typical salticids. Attacking by lunging instead of leaping and the pronounced use of pre-attack tapping are especially noteworthy. The unusual behaviour of M. lupata when preying on insects is consistent with maintenance of ant mimicry. Myrmarachne lupata also preys on the eggs of other spiders which it extracts from their nests. The males of many species have very large chelicerae, and the large chelicerae of M. lupata males influence the course of predatory sequences, with insects and with eggs.