Figure 1 - available via license: Creative Commons Attribution 4.0 International
Content may be subject to copyright.
Structural formula of venom and illustrations of the four Monomorium species. Monomorium antarcticum (1) (5Z,8E)-3,5-di-(5-hexen-1-yl)-pyrrolizidine (2) and 2-butyl-5-(8-nonenyl)pyrrolidine; Monomorium smithii (3) (5Z,8E)-3-heptyl-5-methylpyrrolzidine, (4) (5Z,8E)-3-methyl-5-(8-nonenyl)pyrrolizidine, and (5) trans-2-butyl-5-heptylpyrrolidine in a 1:2:2 ratio; Monomorium antipodum (6) trans-2-ethyl-5-nonylpyrrolidine and (7) trans-2-ethyl-5-(10-undecenyl)pyrrolidine in a 1:1 ratio; and Monomorium sydneyense (8) trans-2-butyl-5-undecylpyrrolidine and (9) trans-2-butyl-5-(12-tridecenyl)pyrrolidine in a 1:2 ratio. Sketches of Monomorium species represent size differences of ant workers (sketches not to scale). Given LD50 values refer to the venom toxicity of the Monomorium venom to Argentine ant workers.
Source publication
Toxicity and the utilization of venom are essential features in the ecology of many animal species and have been hypothesized to be important factors contributing to the assembly of communities through competitive interactions. Ants of the genus Monomorium utilize a variety of venom compositions, which have been reported to give them a competitive...
Citations
... Since the alkaloids are lethal to competing ant species [25], fire ants in invaded areas may have pronounced effects on the functional properties of local communities, resulting in functional homogenization across the landscape [95]. Among the factors that contribute to the co-occurrence of sympatric ant species, such as size, moving speed, numerical abundance, and defensive strategies [96], venom's lethality, determined by its chemistry, appears to be one of the most important strategies utilized [97]. The venom alkaloids confer a competitive advantage to fire ants to exclude native ants from critical food resources [98]. ...
Venoms produced by arthropods act as chemical weapons to paralyze prey or deter competitors. The utilization of venom is an essential feature in the biology and ecology of venomous arthropods. Solenopsis fire ants (Hymenoptera: Formicidae) are medically important venomous ants. They have acquired different patterns of venom use to maximize their competitive advantages rendered by the venom when facing different challenges. The major components of fire ant venom are piperidine alkaloids, which have strong insecticidal and antibiotic activities. The alkaloids protect fire ants from pathogens over the course of their lives and can be used to defend them from predators and competitors. They are also utilized by some of the fire ants’ natural enemies, such as phorid flies to locate host ants. Collectively, these ants’ diverse alkaloid compositions and functions have ecological significance for their survival, successful invasion, and rapid range expansion. The venom alkaloids with powerful biological activities may have played an important role in shaping the assembly of communities in both native and introduced ranges.
... Coexistence of ant species is usually facilitated by complex trade-offs between dominance, food discovery, phenotypic plasticity and spatial segregation (Stanton et al. 2002;Sarty et al. 2006;Santini et al. 2007;Stuble et al. 2013;Balzani et al. 2021), although the role of dominance has been recently contested (Cerd a et al. 2013;Stuble et al. 2017). The resultant complex network of ecological interactions usually promotes diversity (Adler et al. 2007;Andersen 2008;van Oudenhove et al. 2018), but the presence of invasive ant species can disrupt this equilibrium as most of the other ant species may be excluded (Lach et al. 2009). ...
... Only physical aggression was recorded (biting) to focus solely on observable aggressive behaviors that can cause mortality (Roulston et al. 2003). The use of chemical weaponry was difficult to observe and was not considered, although it can be lethal (Westermann et al. 2015). We recorded the species that attacked first and the frequency of occurrence of aggressive events-that is, the number of aggressive events over the total number of interactionsfor each of the two opponents. ...
Ants are widespread in all terrestrial habitats, and competitive interactions between species are common. Although redistribution of food within a colony may buffer the negative effects of temporary resource shortages, colony functionality can be compromised when famine is prolonged. One of the possible effects of famine is impairment of the fighting ability of species, with cascade effects on community. Here, we investigated whether food shortage alters the fighting ability of workers of three dominant species in the Mediterranean area: the invasive alien species, Lasius neglectus and Linepithema humile, and one highly polydomous autochthonous species belonging to the Tapinoma nigerrimum complex. We performed laboratory tests of interspecific one-on-one aggression and pairwise group contests between species, with all possible combinations of artificially satiated and starved groups. Results showed that starvation had a scarce effect on the individual aggressiveness in all three species. Similarly, the outcomes of the group fights were only lightly affected, but with an important exception. The positions of species in the fighting hierarchies were in most cases clear and linear, with L. neglectus at the top. However, we found that L. humile and L. neglectus showed equal mortality when one of the two species was starved and the other satiated. Although we investigated only one aspect of competition, that is, fighting ability, our results provide a piece of the complex jigsaw of competitive interactions of ants, and suggest that food deprivation can be a determinant that alters the relationships between ants and promotes or hampers the coexistence of dominant species.
... Behavioural and ecological factors can influence the quality of venoms (as has been observed in bees Apis mellifera; Scaccabarozzi et al., 2021), having a direct or indirect effect on an individual's fitness. For example, aggressive individuals could experience higher metabolic costs associated with venom expenditure, but aggression could also be associated with higher venom concentration and quantity when they are exposed to predators and when the level of threat is higher (Westermann et al., 2015;Lira et al., 2017;Hernández Duran et al., 2021), increasing the likelihood that they can mount a stronger aggressive response. Studying these relationships will provide insights into understanding how venoms evolve, and could contribute to the identification of molecular changes in toxins, which are relevant in pharmacological applications and drug discovery (Herzig et al., 2020a;Schendel et al., 2019). ...
Atrax robustus is an iconic Australian spider because the venom can be lethal to humans. Moreover, some of the venom biomolecules have promise as therapeutic and bioinsecticidal leads. Nonetheless, aspects related to the life history and behaviour of this species, which might influence changes in venom components, have been overlooked. We assessed different behavioural traits (antipredator behaviour, defensiveness and activity) of juveniles and adult females across different contexts (predation, conspecific tolerance and exploration of a new territory) and stimuli (puff of air versus prod) over time. Adults responded to a puff of air faster than juveniles, but in response to a prod, both juveniles and adults become more defensive over time. No differences were observed between adults and juveniles for conspecific tolerance and exploration. Understanding behaviour of venomous species is important because behaviours may affect physiological traits, such as venom, and the ability of spiders to adapt to different conditions.
... Unfortunately, the quantity and composition of venom, as well as the physiological costs and the time taken to regenerate the venom (recovery period), have not been studied in relation to personality and behavioral syndromes in spiders. In social spiders, aggressive individuals interact more intensely with both predators and prey than do docile individuals (Riechert, 1993) (Macrander et al., 2015) and ants of the genus Monomorium (Westermann et al., 2015). Aggressive anemone polyps show a higher quantity of a particular type of gated potassium ion channel (toxins/Kunitz-type protease inhibitor and type II acrorhagins; Macrander et al., 2015), whereas ants using venom to withstand attack from the invasive Argentine ant Linepithema humile ...
... show higher concentrations of toxins compared to populations of ants that do not live in close proximity to these invasive ants (Westermann et al., 2015). In the funnel-web spider A. robustus, males are more aggressive and more prone to attack when they are provoked than females, which could be correlated with higher venom toxicity (Mullen & Vetter, 2019). ...
Spiders are useful models for testing different hypotheses and methodologies relating to animal personality and behavioral syndromes because they show a range of behavioral types and unique physiological traits (e.g., silk and venom) that are not observed in many other animals. These characteristics allow for a unique understanding of how physiology, behavioral plasticity, and personality interact across different contexts to affect spider's individual fitness and survival. However, the relative effect of extrinsic factors on physiological traits (silk, venom, and neurohormones) that play an important role in spider survival, and which may impact personality, has received less attention. The goal of this review is to explore how the environment, experience, ontogeny, and physiology interact to affect spider personality types across different contexts. We highlight physiological traits, such as neurohormones, and unique spider biochemical weapons, namely silks and venoms, to explore how the use of these traits might, or might not, be constrained or limited by particular behavioral types. We argue that, to develop a comprehensive understanding of the flexibility and persistence of specific behavioral types in spiders, it is necessary to incorporate these underlying mechanisms into a synthesized whole, alongside other extrinsic and intrinsic factors. Few studies have explored the mechanisms driving the expression of personality in spiders, and what effects extrinsic and intrinsic factors (and their interactions) have on the expression of personalities. Physiological traits, particularly venom and silk, may play an important role in the expression of personalities and/or behavioral flexibility in spiders
... Here we describe the new free-living species Megalomyrmex peetersi, which synthesizes trans-2-butyl-5-heptylpyrrolidine as its exclusive venom alkaloid. This alkaloid has previously been found in several Monomorium Mayr species [28,29], Solenopsis Westwood species [15,30], and other Megalomyrmex Forel species [24,25,31]. Given that M. peetersi sp. ...
... We confirmed with an authentic sample that the exclusive alkaloid of Megalomyrmex peetersi is trans-2-butyl-5-heptylpyrrolidine, which is also found in the venom of multiple species of Solenopsidini ants [15,25,28]. Research of Solenopsidini venom addresses several different topics, but we focused on possible antibiotic and insecticidal functions, given that M. peetersi is a soil-dwelling ant species likely to interact with microbial pathogens and other insect species through predation or competition. ...
... Comments (Figure 3). Boudinot et al.[28] described the male of this species as M. wallacei. According to the authors and with the specimen examined in this work, males of this species are morphologically recognized by (1) the presence of blackened piligerous punctures on the body surface(Figure 3a,b); (2) third antennal segment apically flattened and curved (Figure 3c); (3) in lateral view, petiole with raised and convex node and postpetiolar node globose dorsally (Figure 3b); (4) ventral region of postpetiole conspicuous, as inverted triangle (Figure 3b). ...
Alkaloids are important metabolites found across a variety of organisms with diverse ecological functions. Of particular interest are alkaloids found in ants, organisms well known for dominating the ecosystems they dwell in. Within ants, alkaloids are found in venom and function as potent weapons against heterospecific species. However, research is often limited to pest species or species with parasitic lifestyles and thus fails to address the broader ecological function of ant venom alkaloids. Here we describe a new species of free-living Megalomyrmex ant: Megalomyrmex peetersi sp. n. In addition, we identify its singular venom alkaloid (trans-2-butyl-5-heptylpyrrolidine) and elucidate the antibiotic and insecticidal functions of its venom. Our results show that Megalomyrmex peetersi sp. n. venom is an effective antibiotic and insecticide. These results are comparable to venom alkaloids found in other ant species, such as Solenopsis invicta. This research provides great insight into venom alkaloid function, and it is the first study to explore these ideas in the Megalomyrmex system.
... For instance, in predation, venom is expected to be positively selected when resources are limited because it confers a competitive advantage to predators [9]. On the other hand, in defense, venom is positively selected when predators are abundant because it confers a competitive advantage to preys [10,11]. These selective pressures have fostered changes in venom composition [4], resulting in adaptations to different environments, in turn leading to niche partitioning [12,13]. ...
Venomous animals use venom, a complex biofluid composed of unique mixtures of proteins and peptides, for either predation or defense. Bumblebees, which occur in various habitats due to their unique thermoregulatory properties, mainly use venom for defense. Herein, we conducted an exploratory analysis of the venom composition of a bumblebee species (Bombus pascuorum) along an elevation gradient in the western Swiss Alps using shot-gun proteomic approaches to assess whether their defense mechanism varies along the gradient. The gradient was characterized by high temperatures and low humidity at low elevations and low temperatures and high humidity at high elevations. Venom composition is changing along the elevation gradient, with proteomic variation in the abundances of pain-inducing and allergenic proteins. In particular, the abundance of phospholipase A2-like, the main component of bumblebee venom, gradually decreases toward higher elevation (lower temperature), suggesting venom alteration and thus a decrease in bumblebee defense towards harsher environments. Larger datasets may complement this study to validate the observed novel trends.
Ants have outstanding capacity to mediate inter- and intraspecific interactions by producing structurally diverse metabolites from numerous secretory glands. Since Murray Blum's pioneering studies dating from the 1950s, there has been a growing interest in arthropod toxins as natural products. Over a dozen different alkaloid classes have been reported from approximately 40 ant genera in five subfamilies, with peak diversity within the Myrmicinae tribe Solenopsidini. Most ant alkaloids function as venom, but some derive from other glands with alternative functions. They are used in defense (e.g., alarm, repellants) or offense (e.g., toxins) but also serve as antimicrobials and pheromones. We provide an overview of ant alkaloid diversity and function with an evolutionary perspective. We conclude that more directed integrative research is needed. We suggest that comparative phylogenetics will illuminate compound diversification, while molecular approaches will elucidate genetic origins. Biological context, informed by natural history, remains critical not only for research about focal species, but also to guide applied research.
Expected final online publication date for the Annual Review of Entomology, Volume 67 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
