Sexual Cannibalism Research Articles

Female Phalangium opilio use fellatio to compensate sexual avoidance

Sexual conflict arises from differences in reproductive interests between the sexes. We allowed the female harvestman Phalangium opilio to sequentially mate with two different males to examine female sexual receptivity in this species. Virgin females were more sexually receptive than non-virgins. Males exhibited a high interest in repeated copulations with the same female, often engaging in aggressive behaviours such as biting and reversed sexual cannibalism. Fellatio, a behaviour in which females lick the male’s penis, was observed in 44% of trials and was associated with female unwillingness to mate and shorter copulation duration. Fellatio was repeatable, suggesting that it is influenced by individual characteristics or underlying physiological factors. Female lifespan was negatively correlated with the total number of eggs produced, suggesting a trade-off between reproduction and longevity. These findings provide evidence of the appearance of fellatio, a female mating strategy that evolved as compensation of avoiding unwanted sexual intercourse.

Condition‐Dependent Female Aggression and Its Effects on Mating Success and Sexual Cannibalism in Jumping Spiders

ABSTRACTPre‐copulatory sexual cannibalism is an extreme form of aggression toward potential mates. In this study, we examined condition‐dependent female aggression and its effects on mating success and frequency of pre‐copulatory sexual cannibalism in the jumping spider Phidippus audax Hentz 1845. We examined two of the leading hypotheses of why sexual cannibalism may occur, (1) female mate choice and (2) adaptive female foraging. We separated 137 adult virgin female P. audax into three feeding treatments: (1) well‐fed spiders, (2) 14‐day food deprived, and (3) 28‐day food deprived. We recorded weight loss (14‐ and 28‐day treatments) and survival rates. We conducted mating trials to measure the proportion of non‐aggressive and aggressive male and female behaviors, male mating success, and pre‐copulatory sexual cannibalism. Females deprived of food had higher weight loss and lower survival rates than well‐fed females. In addition, food deprived female spiders exhibited higher proportions of aggressive behaviors and pre‐copulatory sexual cannibalism, and lower mating success compared to well‐fed spiders. We found that as male size increased females were less likely to cannibalize males, but we found no effect of male body condition on whether a male mated with or was cannibalized by a female. Our results are consistent with the adaptive foraging hypothesis and corroborates prior research on pre‐copulatory sexual cannibalism.

Males discriminate between substrate-borne cues of conspecific females based on age and mating status in the jumping spider, Habronattus brunneus.

Sexual selection is often studied with a focus on female mate choice, wherein females evaluate male signals to select an optimal mate. However, in some systems, males should also make careful decisions about the females they choose to court, particularly when faced with the risk of precopulatory sexual cannibalism. Here, we explore the idea that male jumping spiders (Habronattus brunneus) may mitigate this risk by responding to female cues probably associated with female aggression and/or receptivity. We tested mature male spiders' ability to discriminate between substrate-borne cues (i.e. silk and excreta) produced by conspecific females of different ages and mating statuses. We found that males spent more time exploring cues produced by mature, non-mated females compared with either immature females or mated females. Heightened interest in cues produced by females that are sexually mature but not yet mated may allow males to reduce cannibalism risk, reduce wasted courtship effort and increase their reproductive success. The use of chemical and/or tactile cues in jumping spider courtship behaviour has been vastly understudied compared with the ways they use vision; this study provides the groundwork for understanding how these sensory modalities interact.

Sex-specific manipulation of sexually cannibalistic mantid mating behavior by hairworms

Abstract Changes in the morphology, physiology, and behavior of parasitized organisms provide an ideal opportunity to examine the extended phenotype of parasites. Because the quality of the host directly affects the fitness of the parasite, parasites may increase their fitness by manipulating phenotypes of low-quality hosts. Males are usually preyed on by females in sexual cannibalism. Thus, the males of sexually cannibalistic species are unsafe and low-quality hosts for parasites, whereas females may be beneficial hosts because of the chance of nutrient intake from cannibalized males. Under passive modes of transmission, parasites cannot choose the host sex. Such parasites exploiting sexually cannibalistic organisms are subjected to contrasting fitness effects and may evolve to manipulate host mating behavior in a sex-specific manner: decreasing male mating to avoid cannibalism and promoting female mating to engage in cannibalism. We examined this hypothesis by a behavioral experiment using a mantid–hairworm system. Parasitized male mantids (Tenodera angustipennis) changed their behavior as expected, exhibiting increased escapes and decreased courtships and mountings, potentially avoiding encounters with the female. Interestingly, male attack behavior was promoted, possibly decreasing contact with the encountered female. However, contrary to our prediction, parasitized females also exhibited decreased propensities of mating, suggesting costs or little benefits of host mating for parasites in the female host. This study provides novel insights into the evolution of parasite strategies in response to sexual differences in host quality.

Does female control and male mating system predict courtship investment and mating outcomes? A comparative study in five widow spider species (genus Latrodectus) tested under similar laboratory conditions

BackgroundMale courtship investment may evolve in response to the male’s expectation of future mating opportunities or the degree of female control during mating interactions. We used a comparative approach to test this hypotheses by assessing the courtship and mating behaviors of five widow spider species (genus Latrodectus) under common laboratory conditions. We predicted male investment in courtship would be higher in species where males mate only once because of high cannibalism rates (monogyny, L. geometricus, L. hasselti, L. mirabilis), compared to species with rare cannibalism (L. mactans, L. hesperus) in which males should reserve energy for future mating opportunities. Increased male investment, measured as courtship duration, might also evolve with increased female control over mating outcomes if females prefer longer courtships. We tested this by assessing the frequency of copulations, timing of sexual cannibalism, and the degree of female-biased size dimorphism, which is expected to be negatively correlated with the energetic cost of rebuffing male mating attempts.ResultsCopulation frequency was consistently lower in species with extreme female-skewed size dimorphism, and where sexual cannibalism was more prevalent, suggesting the importance of female control for mating outcomes. We confirmed significant interspecific variation in average courtship duration, but contrary to predictions, it was not predicted by male mating system, and there was no consistent link between courtship duration and sexual size dimorphism.ConclusionWe show that the degree of sexual dimorphism is not only correlated with sexual cannibalism, but also with mating success since restriction of male copulation frequency by female Latrodectus affects paternity. However, predictions about male mating system or female control affecting courtship duration were not supported. We propose that the form of female control over mating and cannibalism, and male responses, might be more informative for understanding the evolution of courtship duration. For example, male tactics to avoid female aggression may drive lower courtship duration in species like L. mirabilis. Nonetheless, our results differ from inferences based on published studies of each species in isolation, illuminating the need for standardized data collection for behavioural comparative studies.

Meal or mate: Exploring the evidence of sexual cannibalism among amphibians.

Active forms of cannibalism that involve predation of live conspecifics occur widely among amphibians, most notably by tadpoles that feed on each other and adults that feed on juveniles. In contrast, cannibalism among amphibian adults (adult-adult cannibalism) is less often reported and there have been no investigations on the occurrence of sexual cannibalism in this group to date. In this study, we present an observation of potential sexual cannibalism involving an adult female green and golden bell frog, Litoria aurea, preying on a conspecific adult male during the species' breeding season. By comparing our observation to the available literature, we show that adult-adult cannibalism among amphibians is rare but tends to be committed by females against their male counterparts. We thus suggest that the occurrence of sexual cannibalism should be extended to include this group, where sexual size dimorphism occurs widely among adults that congregate spatially during breeding periods, both predictors of intra-specific predation. We hypothesise that amphibian females may be able to exploit male advertisement calls to differentiate suitable partners from potential prey and that male individuals are vulnerable to sexual cannibalism as they must risk attracting and physically exposing themselves to females in order to reproduce. Our findings reveal the complex dynamics that exist within adult amphibian populations, suggesting that females may have a choice when deciding how to interact with and utilise their male counterparts. As our findings are preliminary, based on a small sample size of records, including several from captive individuals, we encourage authors to publish their observations of cannibalism in the field, including unsuccessful attempts, to confirm the presence of sexual cannibalism in this group.

Herbicide changes the role of body condition in mating interactions of a wolf spider but courtship is primarily affected by female immunity

AbstractAnimals that live in human‐impacted landscapes experience an onslaught of novel stimuli that may interfere with natural communication pathways. During mating, this interference may alter the criteria deployed to assess potential mates as males and females find they must shift their focus and emphasize alternative sensory modalities. The wolf spider, Tigrosa helluo (Araneae, Lycosidae) is common in agricultural fields where commercial formulations of herbicides with glyphosate as the active ingredient are regularly applied. With the development of genetically resistant crops, glyphosate‐based herbicides have become among the most widely used and heavily applied agricultural chemicals in the world. In a laboratory experiment, we explored the effects of this herbicide on male—female interactions during courtship, mating, and sexual cannibalism. We expected that it might impact assessment such that there was a shift in the features that were important to the outcome of mating interactions. When herbicide was present, female body condition, an indication of recent feeding success, became important to mating success. This result was, in part, due to higher rates of sexual cannibalism in parings of males and females with low body condition values. The leg raises and pedipalp waves that males perform in courtship were not affected by herbicide nor were they related to mating success but, across all treatments, they were negatively correlated with lytic activity of females as measured just prior to pairing. This result indicates that males detected this aspect of the female's physiology and that a strong immune response made the female less attractive, possibly because it indicated a current or recent infection. Taken together, these results verify that a common herbicide shifts mating criteria used by an agribiont spider and, separate from the herbicide, the immune status of females affects the reactions of courting males.

Interspecific variability of the external female genital mutilation rate and its relationship with female aggression and sexual cannibalism in Cyclosa spiders

Interspecific variability of the external female genital mutilation rate and its relationship with female aggression and sexual cannibalism in Cyclosa spiders

Impact of pre-copulatory sexual cannibalism on genetic diversity and efficacy of selection.

Factors that increase reproductive variance among individuals act to reduce effective population size (Ne), which accelerates the loss of genetic diversity and decreases the efficacy of purifying selection. These factors include sexual cannibalism, offspring investment and mating system. Pre-copulatory sexual cannibalism, where the female consumes the male prior to mating, exacerbates this effect. We performed comparative transcriptomics in two spider species, the cannibalistic Trechaleoides biocellata and the non-cannibalistic T. keyserlingi, to generate genomic evidence to support these predictions. First, we estimated heterozygosity and found that genetic diversity is relatively lower in the cannibalistic species. Second, we calculated dN/dS ratios as a measure of purifying selection; a higher dN/dS ratio indicated relaxed purifying selection in the cannibalistic species. These results are consistent with the hypothesis that sexual cannibalism impacts operational sex ratio and demographic processes, which interact with evolutionary forces to shape the genetic structure of populations. However, other factors such as the mating system and life-history traits contribute to shaping Ne. Comparative analyses across multiple contrasting species pairs would be required to disentangle these effects. Our study highlights that extreme behaviours such as pre-copulatory cannibalism may have profound eco-evolutionary effects.

An Advanced Bio-Inspired Mantis Search Algorithm for Characterization of PV Panel and Global Optimization of Its Model Parameters.

Correct modelling and estimation of solar cell characteristics are crucial for effective performance simulations of PV panels, necessitating the development of creative approaches to improve solar energy conversion. When handling this complex problem, traditional optimisation algorithms have significant disadvantages, including a predisposition to get trapped in certain local optima. This paper develops the Mantis Search Algorithm (MSA), which draws inspiration from the unique foraging behaviours and sexual cannibalism of praying mantises. The suggested MSA includes three stages of optimisation: prey pursuit, prey assault, and sexual cannibalism. It is created for the R.TC France PV cell and the Ultra 85-P PV panel related to Shell PowerMax for calculating PV parameters and examining six case studies utilising the one-diode model (1DM), two-diode model (1DM), and three-diode model (3DM). Its performance is assessed in contrast to recently developed optimisers of the neural network optimisation algorithm (NNA), dwarf mongoose optimisation (DMO), and zebra optimisation algorithm (ZOA). In light of the adopted MSA approach, simulation findings improve the electrical characteristics of solar power systems. The developed MSA methodology improves the 1DM, 2DM, and 3DM by 12.4%, 44.05%, and 48.88%, 28.96%, 43.19%, and 55.81%, 37.71%, 32.71%, and 60.13% relative to the DMO, NNA, and ZOA approaches, respectively. For the Ultra 85-P PV panel, the designed MSA technique achieves improvements for the 1DM, 2DM, and 3DM of 62.05%, 67.14%, and 84.25%, 49.05%, 53.57%, and 74.95%, 37.03%, 37.4%, and 59.57% compared to the DMO, NNA, and ZOA techniques, respectively.

Female state and condition-dependent chemical signaling revealed by male choice of silk trails

Abstract Male mate choice is predicted in systems with high costs of mating, as for those with male nuptial gifts and/or sexual cannibalism. We ask whether males of the nuptial gift-giving spider Pisaura mirabilis exert preferences for mates varying in their reproductive potential based on chemical information during mate search. Males were presented with binary trails consisting of silk lines and substrate-borne chemicals deposited while females were walking, from females varying in 1) body condition (high vs. low), 2) developmental state (subadult vs. adult), and 3) mating state (unmated vs. mated). If female chemical signaling co-varies with individual state, we expect males to choose trails of females that are 1) in higher body condition, indicating higher fecundity, 2) adults, which can successfully reproduce, and 3) unmated, to avoid sperm competition. We show that female signaling is condition-dependent, with males being more likely to follow trails of higher body condition females, but not dependent on female mating state. Males also tended to prefer trails of adults over subadults. Choice did not depend on male individual body condition. Our findings suggest costs to chemical signaling in nutritionally deprived females, often considered negligible, and their potential as reliable indicators of individual quality. Selection may favor male preferences for more fecund partners given the energetic investment nuptial gifts entail. Nutritional and reproductive benefits of multiple mating to females and high share of paternity for males, may instead select against signaling of female mating state, and/or male discrimination and choice.

Mantis Search Algorithm: A novel bio-inspired algorithm for global optimization and engineering design problems

This study presents a new nature-inspired optimization algorithm, namely the Mantis Search Algorithm (MSA), inspired by the unique hunting behavior and sexual cannibalism of praying mantises. In brief, MSA consists of three optimization stages, including the search for prey (exploration), attack prey (exploitation), and sexual cannibalism. Those operators are simulated using various mathematical models to effectively tackle optimization challenges across diverse search spaces. The performance of MSA is rigorously tested on fifty-two optimization problems and three real-world applications (five engineering design problems, and the parameter estimation problem of photovoltaic modules and fuel cells) to show its versatility and adaptability to different scenarios. To disclose the MSA’s superiority, it is compared to two categories from the rival optimizers: the first category involves well-established and highly-cited optimizers, like Differential evolution; and the second category contains recently-published algorithms, like African Vultures Optimization Algorithm. This comparison is conducted using several performance metrics, the Wilcoxon rank-sum test and the Friedman mean rank to disclose the MSA’s effectiveness and efficiency. The results of this comparison highlight the effectiveness of this new approach and its potential for future optimization applications. The source codes of the MSA algorithm are publicly available at https://www.mathworks.com/matlabcentral/fileexchange/131833-mantis-search-algorithm-msa.

Diverse strategies that animals use to deter intraspecific predation.

Intraspecific predation is a special case of prey-predator system that is taxonomically widespread. While a heterospecific predator's main goal is to achieve nutrition, intraspecific predation provides conspecifics with other benefits including elimination of competitors for resources and mates. Traditionally intraspecific predation is termed based on the context they occur within, for example egg cannibalism, infanticide and sexual cannibalism. These diverse forms of intraspecific predation and the strategies by which animals are known to deter them are summarized categorically in this review. The diversity of defence strategies animals deploy against conspecific predators is appreciable and raises interesting questions on their evolution for future research.

Females adopt sexual catalepsy to facilitate mating.

Theory predicts that males and females of dioecious species typically engage in an evolutionary sexual conflict over the frequency and choice of mating partner. Female sexual cannibalism, a particularly dramatic illustration of this conflict, is widespread in certain animal taxa including spiders. Nevertheless, females of some funnel weaving spiders that are generally aggressive to conspecifics enter a cataleptic state after male courtship, ensuring the males can mate without risk of attack. In this study, we demonstrated that the physical posture and duration, metabolites, and central neurotransmitters of females of Aterigena aculeata in sexual catalepsy closely resemble females in thanatosis but are distinct from those in anesthesia, indicating that the courted females feign death to eliminate the risk of potentially aggressive responses and thereby allow preferred males to mate. Unlike the taxonomically widespread thanatosis, which generally represents a deceptive visual signal that acts against the interest of the receivers, sexual catalepsy of females in the funnel weaving spiders may deliver a sexual-receptive signal to the courting males and thereby benefit both the signal senders and receivers. Therefore, sexual catalepsy in A. aculeata may not reflect a conflict but rather a confluence of interest between the sexes.

You Look Good Enough to Eat: A Brief Exploration of Human Cannibalism and Mental Illness

IntroductionAlthough evidence of cannibalism in humans dates back millennia, for most civilized societies, it is an unthinkable act of violence and strictly taboo. It is commonly relegated to the domain of horror films and literature, often associated with the likes of Jeffrey Dahmer or Hannibal Lecter. However, for some, this theme encompasses a pathological or sexual realm. Vorarephilia or sexual cannibalism is, at its simplest level, a psychosexual disorder characterized by the erotic desire to be consumed by, or to personally consume, another human being´s flesh.ObjectivesThe authors aim to review human sexual cannibalism as a concept and its eventual relationship to mental illness with recourse to the description of cases of human cannibalism documented in the literature.MethodsA brief non-systematized literature review utilizing various databases including Pubmed and Google Scholar, as well as complimentary literature and case reports when pertinent to the theme was performed.ResultsAlthough cannibalism is a common phenomenon in the animal kingdom, its expression in humans is assumed to be a minority occurrence and relegated to stories of a more primal past. Pathological cannibalism is an extremely rare occurrence and has been described in association with severe psychotic mental illness and extreme forms of significant paraphilia. Sexual cannibalism appears as a rarity in humans and although the majority with this paraphilia do not partake in actual human consumption, remaining a fantasy-based desire, cases of cannibalism have been reported and tried.ConclusionsEating the flesh of one’s own species is probably one of the few remaining taboos in modern human societies. In humans, cannibalism is a rare occurrence and has been associated with mental illness. Due to the rarity of this phenomenon, with few cases documented in the literature, the underlying etiology, as well as potential environmental and individual risk factors are still to be defined, indicating a potential for further study.Disclosure of InterestNone Declared

Ultimate sacrifice or opportunistic foraging?: The selective forces behind sexual cannibalism: The selective forces behind sexual cannibalism.

The discovery of rare cases of males cannibalising females sheds new light on the selective forces behind sexual cannibalism in the animal kingdom.

Chemotactile social recognition in the blue-ringed octopus, Hapalochlaena maculosa

Social recognition is the ability of individuals in a species to differentiate among conspecifics based on their identity or biologically meaningful demographic. Despite evidence that they have sophisticated brains, complex behavioural repertoires, and acute sensory processing, surprisingly little is known about mechanisms aiding social recognition in cephalopods. This class’s unique chemotactile sense by the ventral arm surfaces gathers considerable information used in predator–prey interactions. Does it also help mediate social interactions? This study utilised 366 h of focal animal observations to assess the likelihood of Hapalochlaena maculosa, a nocturnal species, to retreat after physically contacting conspecifics based on their sex, familiarity and mating history. Females retreated from both sexes equally, while males were more likely to retreat after contacting female conspecifics. Most conspicuously, males were significantly more likely to retreat after contacting females with which they had already mated. These findings provide the first evidence for chemotactile sex discrimination and mate recognition within cephalopods, and supplement previous observations that male H. maculosa do not appear to detect the sex of conspecifics from a distance. The decision to retreat from or stay with an individual based on their sex or mating history, only after physical contact, emphasises the importance of chemotactile behaviour in octopus sensory ecology and behaviour. Furthermore, male octopuses have limited spermatophore production, and the use of chemotactile social recognition observed here may highlight the importance of reproduction, specifically sperm allocation and avoidance of sexual cannibalism, on the evolution of sensory ecology and cognition within this lineage.

Male mating strategies to counter sexual conflict in spiders

When sexual conflict selects for reproductive strategies that only benefit one of the sexes, evolutionary arms races may ensue. Female sexual cannibalism is an extreme manifestation of sexual conflict. Here we test two male mating strategies aiming at countering sexual cannibalism in spiders. The “better charged palp” hypothesis predicts male selected use of the paired sexual organ (palp) containing more sperm for their first copulation. The “fast sperm transfer” hypothesis predicts accelerated insemination when cannibalism is high. Our comparative tests on five orbweb spider species with varying levels of female sexual cannibalism and sexual size dimorphism (SSD) reveal that males choose the palp with more sperm for the first copulation with cannibalistic females and that males transfer significantly more sperm if females are cannibalistic or when SSD is biased. By supporting the two hypotheses, these results provide credibility for male mating syndrome. They, however, open new questions, namely, how does a male differentiate sperm quantities between his palps? How does he perform palp choice after assessing his cannibalistic partner? By conducting follow-up experiments on Nephilengys malabarensis, we reveal that it is sperm volume detection, rather than left-right palp dominance, that plays prominently in male palp choice.

Male spiders avoid sexual cannibalism with a catapult mechanism

In the animal world, numerous mechanisms have been described that allow for extremely fast actions or reactions via the slow storage of energy, typically in elastic structures, which is then nearly instantly released1-4, similar to the operation of a catapult. Many of these mechanisms are employed for prey capture1,2 or for predator avoidance3,4; however, such superfast actions have not yet been reported as a means to dodge sexual cannibalism. Here, we unveil a novel mechanism in a communal orb-weaving spider Philoponella prominens (Uloboridae) (Figure S1), whereby males undertake a split-second catapult action immediately after mating, thereby fleeing their partner (Video S1). We demonstrate that males achieve their superfast action (up to 88.2 cm/s) by extending the tibia-metatarsus joint of their first leg pair via hydraulic pressure in a joint that is known to lack extensor muscles in spiders. This rapid expansion greatly reduces the likelihood of the male being sexually cannibalized.

Male spiders avoid sexual cannibalism with a catapult mechanism

Male spiders avoid sexual cannibalism with a catapult mechanism