Pseudomantis Albofimbriata Research Articles

Studies in Australian Mantodea: New synonyms, notes on distributions, and an updated checklist

Despite recent advances in Mantodean systematics that have resolved many historical problems within the order, the Australian fauna still contains many erroneously recorded or incorrectly placed species. An investigation of these problematic species and related taxa necessitated a number of taxonomic changes: Exparoxypilus Beier is a new synonym of Paraoxypilus Saussure, Paraoxypilus verrauxii Wood-Mason and Exparoxypilus africanus Beier are new synonyms of Paraoxypilus verreauxii Saussure, Pthersigena Hinton is a new synonym of Phthersigena Stål, Austromantis alboterminata Sjöstedt is a new synonym of Austromantis albomarginata Sjöstedt, Deiphobe australiana Giglio-Tos is a new synonym of Coenomantis kraussiana Saussure, Notomantis Tindale is a new synonym of Pseudomantis Saussure, Hierodula dimorpha Werner is a new synonym of Pseudomantis albofimbriata (Stål), Notomantis chlorophana Tindale is a new synonym of Pseudomantis hartmeyeri Werner, Pseudomantis papua (Werner) comb. nov. is transferred from Hierodula, Orthodera marginata (Saussure) is reinstated as a valid species, and Ciulfina liturgusa Giglio-Tos and Orthodera gunnii Le Guillou are considered nomina dubia. In addition, notes are provided on the nomenclature, systematics, distribution, and ecology of several other Australian taxa, and a synonymic checklist of Australian Mantodea is provided. Finally, the origins and diversification of the Australian fauna are discussed in light of these and other recent changes.

Citizen scientists track a charismatic carnivore: Mapping the spread and impact of the South African Mantis (Miomantidae, Miomantis caffra) in Australia

The recent integration of citizen science with modern technology has greatly increased its applications and has allowed more people than ever to contribute to research across all areas of science. In particular, citizen science has been instrumental in the detection and monitoring of novel introduced species across the globe. This study provides the first records of Miomantis caffra Saussure, 1871, the South African Mantis, from the Australian mainland and uses records from four different citizen science and social media platforms in conjunction with museum records to track the spread of the species through the country. A total of 153 wild mantises and oothecae were observed across four states and territories (New South Wales, Norfolk Island, Victoria, and Western Australia) between 2009 and 2021. The large number of observations of the species in Victoria and the more recent isolated observations in other states and territories suggest that the species initially arrived in Geelong via oothecae attached to plants or equipment, likely from the invasive population in New Zealand. From there it established and spread outwards to Melbourne and eventually to other states and territories, both naturally and with the aid of human transport. We also provide a comparison of M. caffra to similar native mantises, specifically Pseudomantis albofimbriata (Stål, 1860), and comment on the potential impact and further spread of the species within Australia. Finally, we reiterate the many benefits of engaging directly with citizen scientists in biodiversity research and comment on the decision to include them in all levels of this research investigation.

Mantid sex pheromones: female calling behaviour and male responses in the Australian false garden mantid, Pseudomantis albofimbriata (Dictyoptera: Mantidae)

ABSTRACTPheromones are important components of insect reproductive biology. They play a broader role in praying mantid behaviour by aggregating individuals and facilitating sexual recognition. Female calling behaviour in praying mantids is a specific posture associated with the emission of pheromones. We describe the calling behaviour of female Australian false garden mantids, Pseudomantis albofimbriata (Stal), and identify the age at which they first start calling based on observations conducted both in the laboratory and in large field enclosures. We found that unmated females displayed a characteristic calling posture that exposed coloured abdominal intersegment membranes, whilst exhibiting a rhythmic pumping movement of the abdomen. Unlike other mantid species, P. albofimbriata females did not lift their wings during this display. Both observations showed that the female calling posture is typically adopted throughout the night; however, it predominantly occurs at 2300 hrs. The average female age at first calling is 14 days after adult emergence. We also found that males did not respond to mated females but responded only to the signals emitted by calling unmated females under natural and semi-natural conditions. Males responded towards calling females within a short period (10–15 minutes) and were attracted from long distances. Importantly, female calling behaviour and male response behaviour occurred in a synchronous manner during the entire nocturnal period. This study provides evidence that female calling behaviour and pheromone emission are intimately linked in praying mantids.

Post-attack defensive displays in three praying mantis species

Investigating the stimuli that elicit dynamic defensive displays can indicate when throughout the predation sequence prey are likely to perform them. This is crucial to understanding whether these displays function as classic deimatic ‘startle’ displays, facultative aposematism or aid in facilitation of predator learning. We investigated the triggers of defensive display in three different praying mantis species found in eastern Australia; Archimantis latistyla, Hierodula majuscula and Pseudomantis albofimbriata. Dynamic displays in praying mantises have been described as ‘deimatic’ and given the risks inherent in sustaining an attack, especially as mantises are not chemically defended, we predicted that mantises would perform their displays to stimuli that simulate early cues of predation. In a randomised order, we exposed each mantis to five different stimuli simulating a non-specific predator, including tactile and non-tactile stimuli. All species performed their display in response to tactile stimuli however A. latistyla and H. majuscula were more likely to respond than P. albofimbriata. The smallest species, P. albofimbriata, did not readily respond to simulated attacks and was the least likely to perform a display. Our results do not meet the prediction that mantises should respond to stimuli that correspond with early stages of the predation sequence. This raises questions surrounding the utilisation of defensive displays in non-chemically defended prey and contributes to our understanding of predator-prey dynamics during the predation sequence. Startle displays, or deimatic displays, present some of the most charismatic and well-known examples of animal behaviour and colouration. Particularly in animals such as praying mantises, defensive displays are classically cited examples of anti-predator adaptations. It is generally stated that defensive displays in animals function by startling the predator before they have attacked; however, evidence is accumulating that dynamic displays may function in a number of ways including facilitating predator learning, or facultative aposematism. We found that three species of praying mantises only performed dynamic displays in response to simulated predator attacks. This contrasts with predictions that displays should happen before predator attacks, thus fundamentally challenging our understanding of why these strategies have evolved and how they are utilised in nature. This adds to growing evidence that apparent ‘deimatic displays’ may actually function in other ways such as facilitating predator learning, even in non-chemically defended animals such as praying mantises.

Chemical signalling and context dependent polyandry in the false garden mantid Pseudomantis albofimbriata (Mantodea: Mantidae)

AbstractMultiple mating by females is a common phenomenon in nature. Polyandrous females may benefit from genetically diverse progeny that may survive better in a changing environment. Males in polyandrous systems, however, may not achieve their maximum paternity. Therefore, males are predicted to carry traits that prevent or reduce female polyandry. Praying mantids are predatory insects in which females can mate multiple times, predicting the evolution of male counter‐strategies. However, the rate of polyandry and male strategies against polyandry are rarely studied in these insects. In the current study, we used false garden mantids Pseudomantis albofimbriata to quantify the rate of multiple mating when several males are present within close visual range of an unmated female. We further determined how long mated females stay unattractive after mating. We found that in a scramble scenario, the subsequent males stay with a copulating pair and attempt mating once the first male has completed copulation. These second copulation attempts are often successful. If only one male is attracted as a result of the initial pheromone plume, then polyandry is unlikely because the female will remain chemically unattractive for 8 days on average (thus preventing subsequent male attractions), which is longer than the usual latency to lay the first egg sac. From previous studies, we know that single male attraction is the most common scenario in this system in both natural and semi‐natural contexts. Therefore, polyandry depends on the number of males attracted to the initial pheromone plume of the female and is likely to be a relatively uncommon phenomenon in this system.

Male antenna morphology and its effect on scramble competition in false garden mantids.

Well-developed antennae are crucial for many insects, but especially for scramble competitors, who race to find their mates using female sex cues. In these systems, the ability of males to locate females quickly is thought to be under strong selection. A rarely tested assumption is that males with more sensory structures are able to locate females faster. In the present study, we used the false garden mantid Pseudomantis albofimbriata to investigate male antennal morphology and its effect on male efficiency in finding a mate. We used scanning electron microscopy to describe the major sensilla types and their arrangement along the length of male antennae. We also conducted field enclosure trials relating male antennal morphology to scramble competition in this system. We identified six different types of antennal sensilla (cheatic, trichoid, basiconic, grooved peg, ceolocapitular and campaniform) on male P. albofimbriata antennae. As expected, males who had more trichoid sensilla located females quicker than did males with fewer sensilla. Results of the current study suggest that antenna morphology plays a significant role in mate location and hence scramble competition in the P. albofimbriata mating system.

The risk of sexual cannibalism and its effect on male approach and mating behaviour in a praying mantid

Precopulatory sexual cannibalism is an extreme form of sexual conflict because it has the potential to eliminate current and future reproductive success for males. Several female factors such as body condition, mating status and orientation are predicted to impact the likelihood of cannibalism, and males are expected to respond to these factors by altering their approach behaviours in ways that minimize the chance of being attacked (i.e. slower approach and greater distance at mounting). We used the sexually cannibalistic praying mantid Pseudomantis albofimbriata to test whether and how certain female risk factors affect male approach and mating behaviour. We created three different risk treatments by manipulating female body condition, mating status and orientation, and recorded the frequency of cannibalism, male mating success, male approach behaviours and copulation duration. As predicted, female body condition and mating status had an effect on the frequency of sexual cannibalism, and cannibalized males had significantly lower mating success than noncannibalized males. Female orientation was the least important factor in determining the rate of sexual cannibalism in this system, with no significant difference between front- and rear-facing females. Contrary to what we predicted, male P. albofimbriata did not alter/shape their approach or mating behaviours relative to any of the proposed female risk factors of sexual cannibalism. There was also no difference in copulation duration between cannibalized and noncannibalized males. Future studies that investigate the effect of sexual cannibalism on postcopulatory male mating strategies will provide better clarification of the costs and benefits of sexual cannibalism in this system and will also be useful in understanding why males do not respond to the risk of sexual cannibalism in a precopulatory scenario.

The effect of female quality on male ejaculatory expenditure and reproductive success in a praying mantid.

Strategic ejaculation is a behavioural strategy shown by many animals as a response to sperm competition and/or as a potential mechanism of cryptic male choice. Males invest more mating resources when the risk of sperm competition increases or they invest more in high quality females to maximize their reproductive output. We tested this hypothesis in the false garden mantid Pseudomantis albofimbriata, where females are capable of multiply mating and body condition is an indicator of potential reproductive fitness. We predicted male mantids would ejaculate strategically by allocating more sperm to high quality females. To determine if and how males alter their ejaculate in response to mate quality, we manipulated female food quantity so that females were either in good condition with many eggs (i.e. high quality) or poor condition with few eggs (i.e. low quality). Half of the females from each treatment were used in mating trials in which transferred sperm was counted before fertilisation occurred and the other half of females were used in mating trials where fertilisation occurred and ootheca mass and total eggs in the ootheca were recorded. Opposed to our predictions, the total number of sperm and the proportion of viable sperm transferred did not vary significantly between female treatments. Male reproductive success was entirely dependent on female quality/fecundity, rather than on the number of sperm transferred. These results suggest that female quality is not a major factor influencing postcopulatory male mating strategies in P. albofimbriata, and that sperm number has little effect on male reproductive success in a single mating scenario.

Sexual signals for the colour‐blind: cryptic female mantids signal quality through brightness

Summary Cryptic coloration may evolve in response to selective pressure imposed by predators, yet effective intraspecific communication may require some level of detectability. This creates a tension between the benefits of sexually selected visual traits and the predatory costs imposed by greater conspicuousness, and little is known about how this tension may be ameliorated in highly cryptic species. We explore these competing demands in the false garden mantid Pseudomantis albofimbriata, a colour‐blind and seemingly cryptic insect. We use reflectance spectrometry and receptor‐noise modelling to characterize the conspicuousness of mantid body regions in the visual systems of mates (mantids), as well as potential predators (birds) and prey (bees). We then use condition manipulation and conspecific choice tests to further explore the colour traits of interest. Based on visual modelling, we find that male mantids are inconspicuous to conspecifics, prey and predators – that is, they are chromatically and achromatically cryptic. In contrast, female mantids are chromatically cryptic to all potential receivers, but their abdomens are achromatically conspicuous. Our food manipulation experiment shows that females in good condition (and therefore with more eggs) have brighter abdomens than females in poor condition. Choice assays show male mantids are consistently attracted to females bearing brighter abdomens. Our results reveal brightness‐mediated sexual signalling in a colour‐blind and classically cryptic insect. By communicating in the only visual channel available to them, female mantids are conspicuously signalling their quality to mates, while potentially minimizing their conspicuousness to predators and prey. Furthermore, by signalling with only a single body region, female mantids are apparently using coincident disruptive coloration to further decrease detectability to potential eavesdroppers. Our data reveal a novel example of the way in which the trade‐off between sexual selection for conspicuousness and natural selection for crypsis may be mediated in a visual signalling system. Such signals may be common in apparently cryptic species, and this study once again demonstrates the importance of analysing visual signals beyond the capacity of human vision.

You Are What You Eat: Food Limitation Affects Reproductive Fitness in a Sexually Cannibalistic Praying Mantid

Resource limitation during the juvenile stages frequently results in developmental delays and reduced size at maturity, and dietary restriction during adulthood can affect longevity and reproductive output. Variation in food intake can also result in alteration to the normal pattern of resource allocation among body parts or life-history stages. My primary aim in this study was to determine how varying juvenile and/or adult feeding regimes affect particular female and male traits in the sexually cannibalistic praying mantid Pseudomantis albofimbriata. Praying mantids are sit-and-wait predators whose resource intake can vary dramatically depending on environmental conditions within and across seasons, making them useful for studying the effects of feeding regime on various facets of reproductive fitness. In this study, there was a significant trend/difference in development and morphology for males and females as a result of juvenile feeding treatment, however, its effect on the fitness components measured for males was much greater than on those measured for females. Food-limited males were less likely to find a female during field enclosure experiments and smaller males were slower at finding a female in field-based experiments, providing some of the first empirical evidence of a large male size advantage for scrambling males. Only adult food limitation affected female fecundity, and the ability of a female to chemically attract males was also most notably affected by adult feeding regime (although juvenile food limitation did play a role). Furthermore, the significant difference/trend in all male traits and the lack of difference in male trait ratios between treatments suggests a proportional distribution of resources and, therefore, no trait conservation by food-limited males. This study provides evidence that males and females are under different selective pressures with respect to resource acquisition and is also one of very few to show an effect of juvenile food quantity on adult reproductive fitness in a hemimetabolous insect.

Different paths to sexual size dimorphism in two praying mantids,Pseudomantis albofimbriataandHierodula majuscula

Sexual size dimorphism (SSD) is widespread among diverse animal taxa and has attracted the attention of evolutionary biologists for over a century. SSD is likely to be adaptive and the result of divergent selection on different size optima for males and females, given their different roles in reproduction. The developmental trajectory leading to SSD may help us to understand how selection acts on male and female size. Here, we describe the growth and development of two Australian praying mantids, Pseudomantis albofimbriata and Hierodula majuscula including the number of moults, time to adulthood, size at each moult, and the degree of SSD. While both species exhibit the common pattern of female-biased SSD, the number of moults required for individuals to reach adulthood differed between males and females and between species. Despite their larger adult size, P. albofimbriata females require fewer moults and less time than males to reach adulthood, but are significantly larger than males from the second instar onwards. In contrast, H. majuscula males reached adulthood in fewer moults, and less time than females, however males and females did not differ in size until females went through their final moult into adulthood. H. majuscula also required more time and more moults to reach adulthood than P. albofimbriata. We discuss these different developmental pathways in light of the existing knowledge of reproductive biology for each species. We also suggest that these differences may relate to the different phenologies that occur in strongly seasonal temperate environments compared with those in the tropics. This study provides evidence that SSD can result from two different patterns of growth and development in closely related species.

Macronutrient intake affects reproduction of a predatory insect

Prey quality has previously been shown to affect the growth and reproduction of predatory arthropods, however relatively little is known about the specific nutrients responsible for these effects. We tested if the macronutrient content (i.e. lipid and protein) of live prey affected mate attraction, reproductive behavior, egg production and nutrient reserves of adult female praying mantids, Pseudomantis albofimbriata. Females on a high‐protein diet produced more than twice as many eggs as females on a high‐lipid diet despite being fed the same overall biomass of prey. Furthermore, the lipid and protein composition of eggs and the female body was directly related to the diet that females were fed (i.e. high lipid content on the high‐lipid diet). Even more striking was the effect of diet treatment on the number of males attracted to females – only one male was attracted to females on the high‐lipid treatment and 56 males were attracted to females on the high‐protein treatment. Although it is not unexpected that females with more eggs would attract more males, the extreme nature of this difference is certainly surprising because previous studies have shown that females with only a couple of eggs can attract multiple males. Hence, our results suggest that female pheromone production may be affected by the quality/nutritional composition of eggs rather than simply the number of eggs. We found no significant difference in any of the other behaviours measured during mating trials, including the frequency of sexual cannibalism. The positive effects of prey protein content on mate attraction and egg production suggest that praying mantids might be expected to choose more protein‐biased prey in nature or, if prey choice is limited, to have higher reproductive output or population growth in communities dominated by protein‐rich prey.

Perceived risk of sperm competition affects juvenile development and ejaculate expenditure in male praying mantids

Sperm competition occurs when a female mates with more than one male, and the sperm of those males compete directly over fertilizing her eggs. In polyandrous animals, males can respond to the perceived risk of sperm competition by flexibly adjusting aspects of their development and reproductive investment. In high-risk scenarios we might expect males to accelerate development so as to mature quickly and locate receptive females first and/or transfer more sperm so as to outcompete rival sperm. We examined these predictions using the false garden mantid, Pseudomantis albofimbriata, a medium-sized praying mantid found on the east coast of Australia. Males are less than half the mass of females. Sexual cannibalism occurs in up to 40% of interactions, highlighting the importance of investing optimally in reproductive opportunities for males. We housed juvenile males in two operational sex ratio treatments: three males, one female (high risk of sperm competition) and one male, three females (low risk). We found no evidence of accelerated development in the high-risk group; instead, high-risk males took longer to mature. Possibly, males exposed to a higher risk of sperm competition delay maturity in order to invest in testes development and sperm production. We also found that males reared in the high-risk treatment transferred significantly more sperm than males reared in the low-risk treatment, providing evidence of strategic ejaculation in male P. albofimbriata. This is the first study demonstrating a male response to the perceived risk of sperm competition via delayed development and increased ejaculate investment in praying mantids.

Influence of female nutritional status on mating dynamics in a sexually cannibalistic praying mantid

The classical paradigm of sexual selection is that of advertising males and choosy females; however, male mate choice may be more common than previously thought. Unlike visual and acoustic cues, females rather than males usually emit long-distance chemical signals for mate attraction, thus providing an excellent opportunity to examine male mate choice further. Here, I used the sexually cannibalistic praying mantid Pseudomantis albofimbriata to determine the effect of female body condition on male mate choice via chemical cues in a natural scenario. Female body condition is positively correlated with fecundity and negatively correlated with the propensity to cannibalize in this system, so I predicted strong male mate choice for good-condition females to maximize male reproductive fitness. Results of field-based choice tests showed differential male attraction to good-condition females: all males were found on the cages of good-condition females and none on those of poor-condition females. In a second series of choice tests conducted in large field enclosures, I found that some poor-condition females attracted males in the absence of good-condition females, and that these females had significantly more eggs in their ovaries than the unattractive poor-condition females. Furthermore, when egg number was controlled but female body condition varied, males no longer had a significant preference for good-condition females. I therefore propose that the male preference for fecund females is a result of egg-bearing females producing a greater quantity/quality of pheromone than egg-free females, and that chemical cues are likely to be an honest indicator of female fecundity in this system.

Male mate choice: why sequential choice can make its evolution difficult

Male reproductive success is typically mate limited, which implies that males should rarely be choosy. On the other hand, females often vary greatly in their fecundity or other determinants of male reproductive success. There are two coexisting threads in the current literature on male mate choice: a number of studies emphasize that male mate choice has been underappreciated in the past, while another set reminds us that it nevertheless evolves less easily than female choice. Here we show that when mate choice is sequential rather than simultaneous (which is often the case for the mate-limited sex), male mate choice may fail to evolve even if there is large variation among fitness prospects offered by various females, and when mating is very costly. Our model is inspired by the mating system of the sexually cannibalistic praying mantid Pseudomantis albofimbriata. Males of this species do not stop approaching females that have turned to face them even though this female behaviour greatly increases the risk of being cannibalized. We show that low mate availability can override the effect of all other factors that select for male mate choice: rejecting a current mating opportunity in the hope of better future opportunities is then not easily selected for. We conclude that studies of mate choice should examine why individuals refuse to take advantage of every opportunity, instead of merely focusing on the fact that some opportunities are better than others. Our results also call for more rigorous empirical tests of mate choice.

A paternity advantage for speedy males? Sperm precedence patterns and female re-mating frequencies in a sexually cannibalistic praying mantid

Scramble competition polygyny is expected when females and/or resources are widely dispersed and not easily monopolized by males, or when there is an abundance of mates during an extremely restricted reproductive period. Additional factors such as first male sperm precedence or low female re-mating rate might further explain the propensity of males to engage in scramble competition. The sexually cannibalistic praying mantid Pseudomantis albofimbriata exhibits a polygynous mating system, where females exist in low-density populations and male competition manifests as the race to find females rather than as direct physical fighting. Here, we aim to determine whether there is a paternity advantage for the first-male to mate and/or a low frequency of female re-mating. First, we determined sperm precedence patterns in P. albofimbriata using the sterile male technique. Second, we tested the likelihood of female re-mating in P. albofimbriata by comparing the close-range approach behaviour and frequency of successful mating attempts for males when paired with virgin as opposed to recently mated females, and by comparing the frequency of long-distance male attraction between virgin and mated females. We found no paternity advantage for the first male to mate, rather a second male advantage. Although mated females were not rejected by males when approached from close-range, they were chemically unattractive to males searching from a distance. Since initial mate attraction in many praying mantids, including P. albofimbriata, is mediated via long-distance chemical communication, we believe the latter result is more ecologically relevant and therefore more important. These results suggest that the relatively low frequency of female re-mating observed in P. albofimbriata may be an additional factor driving scramble competition in this system.

Male mating behaviour reduces the risk of sexual cannibalism in an Australian praying mantid

In cases where sexual cannibalism represents a sexual conflict, we should expect to find male traits that reduce the risk of cannibalism. In fact, a wide variety of such traits have been proposed, including elaborate courtship displays, cautious approach behaviours, and opportunistic mating whilst a female is feeding. However, there is very little direct evidence that these behaviours actually reduce the risk of sexual cannibalism for males, and the evidence that does exist comes mainly from spider studies. In this study of Pseudomantis albofimbriata praying mantids we found evidence of various male behaviours that reduced the risk of sexual cannibalism. Most males attempted to avoid detection entirely and others moved in a slow and stealthy manner. We also observed five cases of opportunistic mating, but saw no evidence of any male courtship routine. It seems that mounting from the rear of a female or slowly approaching her from the front, allows many males to go unnoticed and, therefore, substantially reduces the risk of sexual cannibalism in this mating system. Interestingly, we could not identify any female traits that males use to assess the risk of sexual cannibalism. It may be that P. albofimbriata males use alternative means to assess these risks. The presence of these behavioural strategies by males suggests a net cost of being consumed, and that sexual cannibalism is likely to be a female strategy in this system.

Female praying mantids use sexual cannibalism as a foraging strategy to increase fecundity

Several hypotheses have been proposed to explain the evolution of sexual cannibalism. The foraging strategy hypothesis states that sexual cannibalism may arise as an adaptive foraging strategy, providing females with the nutrients to increase future fecundity. Yet, very few studies have found that nourishment through cannibalism translates into increased fecundity. One explanation for this may be that most of these investigations have concentrated on sexually dimorphic spider species with tiny males that do not significantly increase female body mass on consumption. The current study focuses on the praying mantid, Pseudomantis albofimbriata, a moderately size dimorphic species with relatively large males. Cannibalistic females of such species may be more likely to gain nutritional benefits from male consumption, which translate into increased fecundity. Here, cannibalistic females substantially improved their body condition and subsequently produced heavier egg cases than their noncannibalistic counterparts. An additional prediction of the foraging strategy hypothesis is that sexual cannibalism will increase with decreasing female condition. We found that the prevalence of sexual cannibalism in this system was indeed affected by female body condition; females in poor condition were more likely to consume their potential mates than females in good condition. Additional analysis of the data refuted the relevance of each of the remaining hypotheses for this species, providing clear evidence for the foraging strategy hypothesis as an explanation for the maintenance of sexual cannibalism in this species.

Mate location, antennal morphology, and ecology in two praying mantids (Insecta: Mantodea)

The sensory systems employed by animals to locate potential mates are diverse. Among insects, chemical and acoustic signals are commonly used over long distances, with visual signals playing a role in close-range orientation and courtship. Within groups that exhibit a scramble competition mating system, selection on mate searching ability will be particularly strong. Clearly, aspects of the species ecology, such as habitat complexity and population density, will be crucial in the evolution of mate searching systems and sexual signals. Praying mantids exhibit both chemical and visual sexual signalling behaviour, and also vary in their ecology. This study employs scanning electron microscopy of antennal sensory morphology and behavioural assays to investigate the relative importance of chemical and visual signalling in two Australian praying mantid species: Pseudomantis albofimbriata and Ciulfina biseriata. As predicted, the high level of habitat complexity, low population density and strong male dispersal capability of P. albofimbriata corresponded to the use of airborne sex pheromones. Conversely, the open habitat, high population density, and poor dispersal of C. biseriata corresponded to a greater reliance on short-range visual cues for mate location.

The influence of predator cues on orb-web spider foraging behaviour

Animals are expected to alter their foraging behaviour depending on the risk of predation. We tested this idea using the orb-web spider Argiope keyserlingi. We measured the foraging investment of spiders in terms of web size and size of silk decorations in the presence of a predatory praying mantid, Pseudomantis albofimbriata. However, no limited evidence that A. keyserlingi alters its decorating behaviour and no evidence that this spider alters its web architecture in response to the presence of a mantid predator. We suggest that these spiders may use multiple cues to assess predation pressure and that they respond differently to predators based on past experience.