Monomorium Pharaonis Research Articles

Geographic Records of Subfamilies, Genera and Species of Ants (Hymenoptera: Formicidae) in the Four Climatic Zones of Sri Lanka: A Review

Ants are a major biotic component in the terrestrial environment of Sri Lanka. For the first time, geographic records of worker ants from the surveys conducted in the four climatic zones of Sri Lanka from 1999 to 2016 have been summarized. Geographic records of subfamilies, genera and 95 species of ants from variety of localities in each climatic zone were pooled and tabulated for each taxon. Among the 11 subfamilies, Amblyoponinae, Dolichoderinae, Formicinae, Myrmicinae, Ponerinae and Pseudomyrmecinae were common to the lands in the four zones while each of the other subfamilies were recorded from a single zone or two or three zones only. The Sri Lankan Relict Ant in Aneuretinae has many records in the wet zone and two records in the intermediate zone. Twenty two among 64 ant genera were recorded from the four climatic zones; 42 genera were found in a single zone or two or three zones. Recorded occurrence of each of the 95 species showed that 24 including 8 invasive species, Anoplolepis gracilipes, Monomorium pharaonis, Paratrechina longicornis, Solenopsis geminata, Tapinoma melanocephalum, Technomyrmex albipes, Tetramorium bicarinatum and Trichomyrmex destructor were common to the four zones. Further surveys on ants of Sri Lanka are highly recommended for improving the current knowledge on their occurrence and to provide information on the distribution of endemic and invasive ant species in Sri Lanka.

Repellency of Two Essential Oils toMonomorium pharaonis(Hymenoptera: Formicidae)

Abstract The pharaoh ant (Monomorium pharaonis [L.]; Hymenoptera: Formicidae) is one of the most important pests in populated areas around the world where food and water are abundant. In this study, the repellency of the essential oils from Curcuma longa L. (Zingiberaceae) (turmeric) and Litsea cubeba (Lour.) Pers. (Lauraceae) (litsea) to the pharaoh ant was evaluated. For the tests, the area choice method was used, and 0.1 mL of essential oil at 1 of 3 concentrations (10,000 ppm, 1,000 ppm, and 100 ppm) was applied on a half disc of filter paper to obtain a final concentration of 31.4 µg/cm2, 3.1 µg/cm2, and 0.3 µg/cm2. The same volume of mixture but without essential oil (distilled water + dimethyl sulfoxide + Tween-20®) was used as a control. The repellency of the oils was tested with and without availability of food to the ants, with the food consisting of small maize kernels. Both oils repelled ants with and without the availability of food at a concentration of 10,000 ppm. Turmeric oil showed a high...

Chemical profiling, antimicrobial and insecticidal evaluations of Polygonum hydropiper L

BackgroundThe emergence of multidrug resistant (MDR) pathogens is of great concern to the global health community. Our ability to effectively treat diseases is based on the discovery of potent drugs for the treatment of these challenging diseases. Traditional medicines are one of the major sources for the discovery of safe, effective and economical drug candidates. In order to validate its antibacterial, antifungal and insecticidal potentials with respect to traditional uses, we have screened for the first time Polygonum hydropiper against pathogenic bacterial, fungal strains and a variety of insects.Methods Polygonum hydropiper samples including crude extract (Ph.Cr), subsequent fractions; n-hexane (Ph.Hex), chloroform (Ph.Chf), ethyl acetate (Ph.EtAc), n-Butanol (Ph.Bt), aqueous (Ph.Aq) and crude saponins (Ph.Sp) were tested against pathogenic bacterial and fungal strains. Insecticidal activities were performed against Tribolium castaneum and Rhyzopertha dominica and Monomorium pharaonis. Ph.Cr was analyzed by gas chromatography–mass spectrometry (GC-MS) for preliminary identification of chemical constituents.ResultsIn disc diffusion assay, Ph.Chf, Ph.Hex, Ph.EtAc and Ph.Sp exhibited highest activity against Enterococcus faecalis. MICs of Ph.Chf against Enterococcus faecalis, Klebsiella pneumoniae, Escherichia coli, P. mirabilis, Staphylococcus aureus, Salmonella typhi and Pseudomonas aeruginosa were 32.00, 13.33, 10.66, 5.33, 64.00, 8.66 and 10.66 μg/ml respectively. MFC’s of Ph.Chf against Aspergillus fumigatus, Aspergillus flavus, Aspergillus niger and Fusarium oxysporum were 16.66, 23.33, 125.00 and 46.66 μg/ml respectively. Ph.EtAc, Ph.Sp, Ph.Chf and Ph.Bt were most active fractions against T. castaneum and R. dominica. Ph.Sp being most active against A. punctatum exhibited LC50 of < 0.01 mg/ml. In GC-MS analysis of Ph.Cr, 124 compounds were identified among which several bioactive antibacterial, antifungal and insecticidal compounds were found.Conclusions P. hydropiper samples exhibited broad spectrum of activity against bacterial and fungal strains. Our results support previously reported insecticidal properties of saponins and may provide scientific justification for the ethno-medicinal uses of the plant.Electronic supplementary materialThe online version of this article (doi:10.1186/s12906-016-1491-4) contains supplementary material, which is available to authorized users.

Artificial selection on ant female caste ratio uncovers a link between female-biased sex ratios and infection by Wolbachia endosymbionts.

Social insect sex and caste ratios are well-studied targets of evolutionary conflicts, but the heritable factors affecting these traits remain unknown. To elucidate these factors, we carried out a short-term artificial selection study on female caste ratio in the ant Monomorium pharaonis. Across three generations of bidirectional selection, we observed no response for caste ratio, but sex ratios rapidly became more female-biased in the two replicate high selection lines and less female-biased in the two replicate low selection lines. We hypothesized that this rapid divergence for sex ratio was caused by changes in the frequency of infection by the heritable bacterial endosymbiont Wolbachia, because the initial breeding stock varied for Wolbachia infection, and Wolbachia is known to cause female-biased sex ratios in other insects. Consistent with this hypothesis, the proportions of Wolbachia-infected colonies in the selection lines changed rapidly, mirroring the sex ratio changes. Moreover, the estimated effect of Wolbachia on sex ratio (~13% female bias) was similar in colonies before and during artificial selection, indicating that this Wolbachia effect is likely independent of the effects of artificial selection on other heritable factors. Our study provides evidence for the first case of endosymbiont sex ratio manipulation in a social insect.

Caste regulation in the ant Monomorium pharaonis (L.) with emphasis on the role of queens

The role of queens in caste regulation of pharaoh ant colonies has been puzzling biologists for decades. Worker-fertility-inhibiting pheromones are lacking, as workers of this polygynous species are completely sterile. Yet, fertile queens possess inhibiting powers over the production of new gynes and males. Here we test whether queen-produced cuticular compounds or factors related to eggs affect sexual brood survival. Additionally, the influence of dead queens and virgin queens is investigated. Hereto, subcolonies consisting of workers, mixed worker brood and sexual larvae are treated with eggs, living queens, dead queens, virgin queens or queen extracts. The extracts are prepared with (phosphate-buffered saline), hexane or acetone and applied on either glass dummies (chemical cue only) or queen dummies (visual and chemical cue). Subsequently, the number of surviving larvae and their sex ratio are recorded. Only treatments containing living queens show a significant drop in eclosing sexual larvae. In all other treatments the survival of sexual larvae is unaffected. Several hypotheses are discussed involving competition for ‘royal’ food between queens and sexual larvae, food deprival of sexual larvae by workers or cannibalism of sexual brood by queens and/or workers. Although brood cannibalism seems the most valid explanation, as it allows recycling the energy used for brood production throughout the colony, our data could not sufficiently support this hypothesis. Therefore, additional research on different aspects of caste regulation is required to fully understand its mechanism in pharaoh ants.

Late-instar ant worker larvae play a prominent role in colony-level caste regulation

The success of social insect societies is often attributed to an efficient reproductive division of labor between queen and worker castes. At the group level, social insect colonies must decide both the timing and amount of resources to allocate to each caste. Queen production is typically restricted by factors such as season or the presence of fertile queens in colonies. In the absence of such inhibition, the relative production of new queens versus workers varies between and is regulated by colonies. Here, we investigate social regulation of caste in the ant Monomorium pharaonis through a series of experiments manipulating the environment in which developing larvae are reared. The number of new queens produced depended strongly on diet as well as the number of late-instar worker larvae in the colony at the time of caste regulation. Given that these late-instar larvae are known to process solid protein for the rest of the colony, their stimulatory effect on queen production is likely a result of their contribution to a colony’s nutrient assimilation. Our results emphasize the need to consider late-instar larvae as critical social players and effectors of colony regulatory dynamics.

Symmetry breaking in mass-recruiting ants: extent of foraging biases depends on resource quality.

The communication involved in the foraging behaviour of social insects is integral to their success. Many ant species use trail pheromones to make decisions about where to forage. The strong positive feedback caused by the trail pheromone is thought to create a decision between two or more options. When the two options are of identical quality, this is known as symmetry breaking, and is important because it helps colonies to monopolise food sources in a competitive environment. Symmetry breaking is thought to increase with the quantity of pheromone deposited by ants, but empirical studies exploring the factors affecting symmetry breaking are limited. Here, we tested if (i) greater disparity between two food sources increased the degree to which a higher quality food source is favoured and (ii) if the quality of identical food sources would affect the degree of symmetry breaking that occurs. Using the mass-recruiting Pharaoh ant, Monomorium pharaonis, we carried out binary choice tests to investigate how food quality affects the choice and distribution of colony foraging decisions. We found that colonies could coordinate foraging to exploit food sources of greater quality, and a greater contrast in quality between the food sources created a stronger collective decision. Contrary to prediction, we found that symmetry breaking decreased as the quality of two identical food sources increased. We discuss how stochastic effects might lead to relatively strong differences in the amount of pheromone on alternative routes when food source quality is low.Significance statementPheromones used by social insects should guide a colony via positive feedback to distribute colony members at resources in the most adaptive way given the current environment. This study shows that when food resources are of equal quality, Pharaoh ant foragers distribute themselves more evenly if the two food sources are both of high quality compared to if both are of low quality. The results highlight the way in which individual ants can modulate their response to pheromone trails which may lead colonies to exploiting resources more evenly when in a resource rich environment.Electronic supplementary materialThe online version of this article (doi:10.1007/s00265-016-2187-y) contains supplementary material, which is available to authorized users.

Functional morphology of the maxillary and propharyngeal glands of Monomorium pharaonis (L.)

The maxillary and propharyngeal gland of all 3 castes of Monomorium pharaonis were examined with light and electron microscopy. Although both glands possess a pouch in which secretion can be stored temporarily, a proper reservoir is lacking. The paired maxillary gland opens at the base of the maxilla and consists of 4 secretory cells, which are smaller in workers as compared to queens and males. A digestive role is unlikely as the gland is not directly linked to the digestive system and the amount of rER is negligible. The propharyngeal gland consists of 2 clusters of 16 secretory cells, which open in the pharyngeal atrium through a duct. Secretory cells are smallest in males. Two types of endoplasmic vesicles are observed around the end apparatus, suggesting a release of at least 2 substances. High levels of rER indicate the production of digestive enzymes as one of its functions. No differences between mated versus virgin queens were observed for both glands. Further experiments on chemical and behavioural essays can improve our understanding of the role of both glands in the ant colony. Literature on this topic is very inconsistent. We provide a survey to unravel this chaotic nomenclature issue.

Effects of pyriproxyfen and chlorfluazuron on the external bacteria isolated from Monomorium pharaonis (L.) collected from different cities in Cairo governorate

Effects of pyriproxyfen and chlorfluazuron on the external bacteria isolated from Monomorium pharaonis (L.) collected from different cities in Cairo governorate

Effects of pyriproxyfen and chlorfluazuron on the external bacteria isolated from Monomorium pharaonis (L.) collected from different cities in Cairo governorate

The present study was examined the effect of two IGRs (pyriproxyfen & chlorfluazuron) on the external bacterial flora isolated from the Pharaoh ant workersMonomorium pharaonis (L.). The Pharaoh ant workers were collected from three different cities in Cairo governorate. Different concentrations of 0.1%, 0.5% & 1% pyriproxyfen and 0.001%, 0.01% & 0.1% chlorfluazuron were used. Bacteria associated with Pharaoh ant workers (indoors & outdoors collected samples) were isolated before and after treatment with IGRs. It was found that, the external bacteria isolated from outdoors samples were less counted than those collected from indoors.The presence of some pathogenic bacteria was recorded. The used IGRs cause significant reduction in the count of bacteria in external isolates. Kinds of isolated bacteria were also affected by IGRs treatment and some kinds of them were disappeared in treated samples.

Induced Disturbances Cause Monomorium pharaonis (Hymenoptera: Formicidae) Nest Relocation.

Budding and relocation of nests are important characteristics of the Pharaoh ant, Monomorium pharaonis (L.), an important pest of artificial structures. Pharaoh ant colony movements induced by several types of disturbances were evaluated in the laboratory. The percentages of workers and brood in the source and new nest sites were determined at Days 0, 1, 3, and 5 following physical disturbance (temporal removal of nestmates), chemical disturbance (application of pyrethroid insecticide), invasion by heterospecific ants, food depletion, and moisture depletion in the laboratory. All disturbances were performed in the source nest, which was connected to an empty new nest site. Almost all workers moved and carried the entire brood to the new nest site when subjected to physical disturbance, chemical disturbance, and ant invasion on Day 1, whereas only <5% of workers were present in the new nest site in the undisturbed control. After these disturbances, the brood was never relocated back to the original nest site in this 5-d study. When subjected to food depletion, ∼60% of the brood were found in the new nest site and ∼40% of the brood remained in the original nest on Day 5, resulting in a polydomous population. In contrast, moisture depletion did not show any significant effect on colony movement. These results provide useful information about the causes of Pharaoh ant colony budding and guidance about how to develop effective control and prevention strategies.

Genes associated with ant social behavior show distinct transcriptional and evolutionary patterns.

Studies of the genetic basis and evolution of complex social behavior emphasize either conserved or novel genes. To begin to reconcile these perspectives, we studied how the evolutionary conservation of genes associated with social behavior depends on regulatory context, and whether genes associated with social behavior exist in distinct regulatory and evolutionary contexts. We identified modules of co-expressed genes associated with age-based division of labor between nurses and foragers in the ant Monomorium pharaonis, and we studied the relationship between molecular evolution, connectivity, and expression. Highly connected and expressed genes were more evolutionarily conserved, as expected. However, compared to the rest of the genome, forager-upregulated genes were much more highly connected and conserved, while nurse-upregulated genes were less connected and more evolutionarily labile. Our results indicate that the genetic architecture of social behavior includes both highly connected and conserved components as well as loosely connected and evolutionarily labile components.

A statistical approach to identify candidate cues for nestmate recognition

The ability of social insects to discriminate nestmates from non-nestmates is mainly achieved through chemical communication. To ultimately understand this recognition and its decision rules, identification of the recognition cues is essential. Although recognition cues are most likely cuticular hydrocarbons, identifying the exact cues for specific species has remained a daunting task, partly due to the sheer number of odor compounds. Perhaps unsurprisingly, one of the few species where the recognition cues have been identified, Formica exsecta, has only around ten major hydrocarbons on its cuticle. In this study we use previous results of this species to search for nestmate recognition cues in two other species of ants, Camponotus aethiops and Monomorium pharaonis. Employing chemical distances and observed aggression between colonies, we first ask which type of data normalization, centroid, and distance calculation is most diagnostic to discriminate between nestmate recognition cues and other compounds. We find that using a “global centroid” instead of a “colony centroid” significantly improves the analysis. One reason may be that this new approach, unlike previous ones, provides a biologically meaningful way to quantify the chemical distances between nestmates, allowing for within-colony variation in recognition cues. Next, we ask which subset of hydrocarbons most likely represents the cues that the ants use for nestmate recognition, which shows less clear results for C. aethiops and M. pharaonis than for F. exsecta, possibly due to less than ideal datasets. Nonetheless, some compound sets performed better than others, showing that this approach can be used to identify candidate compounds to be tested in bio-assays, and eventually crack the sophisticated code that governs nestmate recognition.

Ant colonies prefer infected over uninfected nest sites.

During colony relocation, the selection of a new nest involves exploration and assessment of potential sites followed by colony movement on the basis of a collective decision making process. Hygiene and pathogen load of the potential nest sites are factors worker scouts might evaluate, given the high risk of epidemics in group-living animals. Choosing nest sites free of pathogens is hypothesized to be highly efficient in invasive ants as each of their introduced populations is often an open network of nests exchanging individuals (unicolonial) with frequent relocation into new nest sites and low genetic diversity, likely making these species particularly vulnerable to parasites and diseases. We investigated the nest site preference of the invasive pharaoh ant, Monomorium pharaonis, through binary choice tests between three nest types: nests containing dead nestmates overgrown with sporulating mycelium of the entomopathogenic fungus Metarhizium brunneum (infected nests), nests containing nestmates killed by freezing (uninfected nests), and empty nests. In contrast to the expectation pharaoh ant colonies preferentially (84%) moved into the infected nest when presented with the choice of an infected and an uninfected nest. The ants had an intermediate preference for empty nests. Pharaoh ants display an overall preference for infected nests during colony relocation. While we cannot rule out that the ants are actually manipulated by the pathogen, we propose that this preference might be an adaptive strategy by the host to “immunize” the colony against future exposure to the same pathogenic fungus.

Thermal Tolerances of Three Tramp Ant Species (Hymenoptera: Formicidae)

Tramp ant species present a set of adaptations to their urban habitats, and there is a paucity of knowledge about how they interact with abiotic factors, like temperature. Temperature is well known to interfere with insect activity. The present study evaluated the temperature tolerance of three important tramp ant species: Monomorium floricola ( Jerdon), Monomorium pharaonis (Linnaeus) and Tetramorium bicarinatum (Nylander). Tested temperatures were 0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 25, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48 and 50.C. Ten repetitions with 20 workers each were done with each temperature and analyzed species. The number of dead workers was recorded every hour over a total of 8 hours. All procedures were done using thermal incubators at relative humidity within 50-95%. Workers of M. pharaonis proved more tolerant to high temperatures (30-50.C) than workers of M. floricola and T. bicarinatum. The higher the temperatures tested, greater was the recorded ant mortality, with temperature 50.C being fatal to all species after 1h of exposition. The least tolerant species to temperatures below 20.C was T. bicarinatum. Low temperatures tested were not fatal to any of the tested species.

Structure-Invading Pest Ants in Healthcare Facilities in Singapore

A survey of structure-invading pest ants was conducted at 17 healthcare facilities (HFs) in Singapore using the index card method. A total of 18 species (Anoplolepis gracilipes (Fr. Smith), Meranoplus sp., Monomorium destructor ( Jerdon), Monomorium floricola ( Jerdon), Monomorium pharaonis (L.), Monomorium sp., Odontomachus sp., Oecophylla smaragdina (F.), Pachycondyla sp., Paratrechina bourbonica (Forel), Paratrechina longicornis (Latreille), Paratrechina pubens (Forel), Pheidole megacephala (F.), Pheidole parva (Mayr), Pheidole sp., Tapinoma indicum (Forel), Tapinoma melanocephalum (F.) andTetramorium bicarinatum (Nylander)) were trapped. Of these, the most common species were P. parva (25.9%), P. megacephala (25.2%), P. longicornis (14.1%), M. pharaonis (9.6%), and T. indicum (8.1%). Most of these ant species were found in and around the premises.

Influences of pyriproxyfen on fecundity and reproduction of the Pharaoh ant (Hymenoptera: Formicidae).

The effects of the juvenile hormone analog pyriproxyfen (at concentrations of 0.1, 0.5, and 1%) on egg production, number of ovarioles, and length of oocytes were examined in queens of the Pharaoh ant Monomorium pharaonis (L.). Pyriproxyfen significantly reduced egg production in queens from week 3 onwards. Queens that were exposed to 1% pyriproxyfen stopped producing eggs at week 8. After 8 wk, ovaries were dissected from all queens, and the number of ovarioles and the length of the largest oocytes were recorded. The ovaries of queens in treated colonies were smaller than those in untreated queens, and the number of ovarioles in the ovaries was significantly lower in all pyriproxyfen-treated queens. Queens treated with the highest concentrations of pyriproxyfen tended to have significantly shorter oocytes than untreated queens. Histological studies of the ovaries revealed that pyriproxyfen caused vacuolation in the ovarioles, thickening of the tunica propria, development of small eggs, and underdevelopment of nurse cells and the follicular epithelium. Exposure to pyriproxyfen reduced egg production and induced severe morphological changes in the ovaries of queens, and the effects increased with increased concentration of pyriproxyfen.

ChemInform Abstract: Ruthenium—NHC‐Catalyzed Asymmetric Hydrogenation of Indolizines: Access to Indolizidine Alkaloids.

Indolizidine alkaloids constitute a very important class of natural products. These metabolites derived from lysine can be isolated from diverse sources, like fungi, bacteria, higher plants, invertebrates, and vertebrates. Their core structure is characterized by fused sixand five-membered rings, with a bridgehead nitrogen atom, and is found in 25–30% of all naturally occurring alkaloids. The most important types of indolizidines are plant-derived polyhydroxylated indolizidines, like swainsonine and castanospermine, which are glycosidase inhibitors with activity against HIV, as well as alkylindolizidines, like monomorine (3), which is isolated from ants (Monomorium pharaonis) and from the skin of amphibians (Melanophryniscus stelzneri), and is believed to serve in their defense against predators (Scheme 1).

Parsimonious use of foraging pheromones during nest migration in ants

Decision making is vital to the fitness of all animals, with many social species making consensus decisions that require efficient communication. Chemical signals are the most important tools for many animals, and are used notably by social insects in a wide variety of contexts, from foraging for food to recognition of nestmates. However, chemical cues may be biosynthetically limited and costly to produce, making their use in multiple contexts potentially beneficial. In this study we examined the role of foraging pheromones during nest migrations in the Pharaoh's ant, Monomorium pharaonis. Using a Y-shaped bridge apparatus, we tested whether ants would prefer migrating to a novel nest site along branches coated with attractive foraging pheromones rather than to a nest site reached via a control branch. We found that ants preferred to migrate to nest sites reached via branches with attractive foraging pheromones, and that there were more queens and workers in those nests at the end of the migration than in nests at the end of control branches. The results show that attractive foraging pheromones are utilized during nest migrations in the Pharaoh's ant, highlighting the evolutionary pressure to use signals in a parsimonious manner to improve communication during decision making.

Multilocus genetic characterization of two ant vectors (Group II "Dirty 22" species) known to contaminate food and food products and spread foodborne pathogens.

The U.S. Food and Drug Administration utilizes the presence of filth and extraneous materials as one of the criteria for implementing regulatory actions and assessing adulteration of food products of public health importance. Twenty-two prevalent pest species (also known as the ''Dirty 22'' species) have been considered by this agency as possible vehicles for the spread of foodborne diseases, and the presence of these species is considered an indicator of unsanitary conditions in food processing and storage facilities. In a previous study, we further categorized the Dirty 22 species into four groups: group I includes four cockroach species, group II includes two ant species, group III includes 12 fly species, and group IV includes four rodent species. Here, we describe the development of three nested PCR primer sets and multilocus genetic characterization by amplifying the small subunit rRNA, elongation factor 1-alpha, and wingless (WNT-1) genes of group II Dirty 22 ant species Monomorium pharaonis and Solenopsis molesta. These novel group II Dirty 22 species-specific nested PCR primer sets can be used when the specimens cannot be identified using conventional microscopic methods. These newly developed assays will provide correct identification of group II Dirty 22 ant species, and the information can be used in the control of foodborne pathogens.