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The ant genus Monomorium is one of the most species-rich but taxonomically problematic groups in the hyperdiverse subfamily Myrmicinae. An East Asian species, M. triviale Wheeler, produces both reproductive queens and sterile workers via obligate thelytokous parthenogenesis. Here, we describe the immature forms of M. triviale based on light and scanning electron microscopy observations, with a note on the striking caste dimorphism in the last larval instar. The last-instar queen larvae were easily recognized by their large size, “aphaenogastroid” body shape, and rows of doorknob-like tubercles on the lateral and dorsal body surface. This type of queen-specific structure has not been found in ants in general, let alone congeneric species found in Japan. In stark contrast to the queen larvae, worker larvae showed a “pheidoloid” body shape and a body surface similar to other ants. The worker larvae were estimated to have three instars, consistent with previously described congeners. The pupae of both castes had no cocoon, a characteristic commonly described in other Myrmicinae species. In total, the developmental period from egg to adult worker averaged 59 days under 25°C. We discuss possible functions of the tubercles of queen larvae based on previous studies.

The effectiveness of insecticidal baits based on chlorfenapyr and hydramethylnone against colonies of the Pharaoh ant has been studied. Sugar baits containing 0.1–1.0 % chlorfenapyr are ineffective because after 4 weeks of the experiment, the viability of the colonies was not changed. Sugar baits based on 1 % hydramethylnon effectively destroyed workers, the effect on queens was weak, and depletion of the colony was achieved. Commercially produced baits effectively and completely destroy ant colonies both in the absence and in the presence of alternative food. Keywords: Pharaoh ant, baits, chlorfenapyr, hydramethylnon.

The discovery in the Netherlands in a shipping container of the ant Monomorium sahlbergi Emery, 1898, a species similar to the invasive pharaoh ant M. pharaonis (Linnaeus, 1758), led to a quest to better define the distribution of this species, which was initially obscure due to uncertain specimen identifications. Here it is shown that M. sahlbergi, like M. pharaonis, is found worldwide, almost certainly as a result of introductions. Including quarantine interceptions, this species is recorded from seven global biogeographic regions, but its established outdoor distribution is currently limited to the tropics and subtropics. Monomorium dichroum Forel, 1902 is here presented as a junior synonym of M. sahlbergisyn. nov. based on morphometric and CO1 analyses.

Проведены исследования эффективности пищевых приманок в отношении колоний рыжих домовых муравьев лабораторного содержания. Изучены промышленно выпускаемые и приготовленные в лабораторных условиях приманки на основе соединений бора, неоникотиноидов, оксадиазинов, фенилпиразолов, карбаматов, пирролов, амидиногидразонов, авермектинов, регуляторов развития насекомых. Установлено, что при пищевой привлекательности основы приманки гибель колоний наступает в срок от 1 до 4 недель для действующих веществ – инсектицидов и в срок до 8 недель при использовании регуляторов развития насекомых. Сделан вывод о необходимости снабжать каждый опыт двумя контрольными вариантами, в которых колонии содержатся при отсутствии источника пищи и при наличии углеводного питания (мед)., Studies on the effectiveness of food baits in relation to laboratory colonies of the Pharaoh ant have been carried out. Commercially produced and laboratory-prepared baits based on boron compounds, neonicotinoids, oxadiazines, phenylpyrazoles, carbamates, pyrroles, amidinohydrazones, avermectins, and insect growth regulators have been studied. It has been established that in the case of nutritional attractiveness of the base of the bait, the death of colonies occurs within 1 to 4 weeks for the most insecticides, but up to 8 weeks for insect growth regulators. It is necessary to make in two control options in each experiment, i.e. colonies are kept in the absence of a food source and in the presence of carbohydrate food (honey)., ПЕСТ-МЕНЕДЖМЕНТ, Выпуск 3 (123) 2022, Pages 37-40

We report comprehensive evidence for obligatory thelytokous parthenogenesis in an antMonomorium triviale. This species is characterized by distinct queen–worker dimorphism with strict reproductive division of labor: queens produce both workers and new queens without mating, whereas workers are completely sterile. We collected 333 nests of this species from 14 localities and three laboratory-reared populations in Japan. All wild queens dissected had no sperm in their spermathecae. Laboratory observation confirmed that virgin queens produced workers without mating. Furthermore, microsatellite genotyping showed identical heterozygous genotypes between mothers and their respective daughters, suggesting an extremely low probability of sexual reproduction. Microbial analysis detected no bacterial genera that are known to induce thelytokous parthenogenesis in Hymenoptera. Finally, the lack of variation in partial sequences of mitochondrial DNA among individuals sampled from across Japan suggests recent rapid spread or selective sweep.M. trivialewould be a promising model system of superorganism-like adaptation through comparative analysis with well-studied sexual congeners, including the pharaoh antM. pharaonis.

Background Ants with complex societies have fascinated scientists for centuries. Comparative genomic and transcriptomic analyses across ant species and castes have revealed important insights into the molecular mechanisms underlying ant caste differentiation. However, most current ant genomes and transcriptomes are highly fragmented and incomplete, which hinders our understanding of the molecular basis for complex ant societies. Findings By hybridizing Illumina, Pacific Biosciences, and Hi-C sequencing technologies, we de novo assembled a chromosome-level genome for Monomorium pharaonis, with a scaffold N50 of 27.2 Mb. Our new assembly provides better resolution for the discovery of genome rearrangement events at the chromosome level. Analysis of full-length isoform sequencing (ISO-seq) suggested that ∼15 Gb of ISO-seq data were sufficient to cover most expressed genes, but the number of transcript isoforms steadily increased with sequencing data coverage. Our high-depth ISO-seq data greatly improved the quality of gene annotation and enabled the accurate detection of alternative splicing isoforms in different castes of M. pharaonis. Comparative transcriptome analysis across castes based on the ISO-seq data revealed an unprecedented number of transcript isoforms, including many caste-specific isoforms. We also identified a number of conserved long non-coding RNAs that evolved specifically in ant lineages and several that were conserved across insect lineages. Conclusions We produced a high-quality chromosome-level genome for M. pharaonis, which significantly improved previous short-read assemblies. Together with full-length transcriptomes for all castes, we generated a highly accurate annotation for this ant species. These long-read sequencing results provide a useful resource for future functional studies on the genetic mechanisms underlying the evolution of social behaviors and organization in ants.

Wolbachia is a widespread group of maternally-transmitted endosymbiotic bacteria that often manipulates the reproductive strategy and life history of its hosts to favor its own transmission. Wolbachia mediated phenotypic effects are well characterized in solitary hosts, but effects in social hosts are unclear. The invasive pharaoh ant, Monomorium pharaonis, shows natural variation in Wolbachia infection between colonies and can be readily bred under laboratory conditions. We previously showed that Wolbachia-infected pharaoh ant colonies had more queen-biased sex ratios than uninfected colonies, which is expected to favor the spread of maternally-transmitted Wolbachia. Here, we further characterize the effects of Wolbachia on the short- and longer-term reproductive and life history traits of pharaoh ant colonies. First, we characterized the reproductive differences between naturally infected and uninfected colonies at three discrete time points and found that infected colonies had higher reproductive investment (i.e. infected colonies produced more new queens), particularly when existing colony queens were three months old. Next, we compared the long-term growth and reproduction dynamics of infected and uninfected colonies across their whole life cycle. Infected colonies had increased colony-level growth and early colony reproduction, resulting in a shorter colony life cycle, when compared to uninfected colonies.

Morocco has a rich ant fauna with 237 known species, of which 14 (5.9%) are widespread tramp ants considered non-native in Morocco. In the present study, we collected ants in urban areas of 13 Moroccan regions to examine the spread of non-native species. We found that the known distribution of non-native ants is expanding along the Mediterranean and Atlantic coasts of Morocco. We confirmed the presence of the pharaoh ant, Monomorium pharaonis, in Morocco, after many years of omission from the lists of Moroccan ants.

BACKGROUND Historically, inert insecticidal powders such as diatomaceous earth were researched for pest management applications, and it was revealed that these types of powders killed insects by desiccation. However, data on the critical material properties that affect their efficacy are sparse. The present study investigated the insecticidal effect of powdered materials on the pharaoh ant, a notorious domestic pest. RESULTS The insecticidal activity of 24 porous materials was tested. Eight of these materials performed better than the benchmark, diatomaceous earth. Zeolite Y and carbon black II performed best, inducing 50% mortality within 40 and 55 minutes, respectively. Statistical analysis of seven material properties revealed that macroporous surface area and Brunauer-Emmett-Teller (BET) specific surface area were most predictive of insecticidal activity. For zeolites and ordered mesoporous silica materials, the most important parameters were, respectively, BET and large mesopore surface area. Finally, gas chromatography-mass spectrometry (GC-MS) analysis confirmed the adsorption of epicuticular hydrocarbons onto the zeolite powders. CONCLUSION This study shows clear potential for the use of environmentally friendly, inert porous materials as insecticides against the pharaoh ant and identified the key material properties influencing insecticidal activity. The GC-MS data support the hypothesis that the mortality was caused by the removal of the protective epicuticular hydrocarbons. © 2017 Society of Chemical Industry.

In social insects, cuticular hydrocarbons function in nest-mate recognition and also provide a waxy barrier against desiccation, but basic evolutionary features, including the heritability of hydrocarbon profiles and how they are shaped by natural selection are largely unknown. We used a new pharaoh ant ( Monomorium pharaonis ) laboratory mapping population to estimate the heritability of individual cuticular hydrocarbons, genetic correlations between hydrocarbons, and fitness consequences of phenotypic variation in the hydrocarbons. Individual hydrocarbons had low to moderate estimated heritability, indicating that some compounds provide more information about genetic relatedness and can also better respond to natural selection. Strong genetic correlations between compounds are likely to constrain independent evolutionary trajectories, which is expected, given that many hydrocarbons share biosynthetic pathways. Variation in cuticular hydrocarbons was associated with variation in colony productivity, with some hydrocarbons experiencing strong directional selection. Altogether, this study builds on our knowledge of the genetic architecture of the social insect hydrocarbon profile and indicates that hydrocarbon variation is shaped by natural selection.

Wolbachiais a widespread group of maternally-transmitted endosymbiotic bacteria that often manipulates the reproductive strategy and life history of its solitary hosts to enhance its own transmission.Wolbachiaalso commonly infects eusocial insects such as ants, although the effects of infection on social organisms remain largely unknown. We tested the effects of infection on colony-level reproduction and life history traits in the invasive pharaoh ant,Monomorium pharaonis. First we compared the reproductive investment of infected and uninfected colonies with queens of three discrete ages, and we found that infected colonies had increased reproductive investment. Next, we compared the long-term growth and reproduction of infected and uninfected colonies across their life cycle, and we found that infected colonies had increased colony-level growth and early colony reproduction. These colony-level effects ofWolbachiainfection seem to result because of a ‘live fast, die young’ life history strategy of infected queens. Such accelerated colony life cycle is likely beneficial for both the host and the symbiont and may have contributed to success of the highly invasive pharaoh ant.

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...

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.

The division of labour between reproductive queens and mostly sterile workers is among the defining characteristics of social insects. Queen-produced chemical signals advertising her presence and fertility status, i.e. queen pheromones, are normally used to assert the queen's reproductive dominance in the colony. Most queen pheromones identified to date are chemicals that stop the daughter workers from reproducing. Nevertheless, it has long been suggested that queen pheromones could also regulate reproduction in different ways. In some multiple-queen ants with obligately sterile workers, for example—such as fire ants and pharaoh ants—queen pheromones are thought to regulate reproduction by inhibiting the rearing of new sexuals. Here, we identify the first such queen pheromone in the pharaoh ant Monomorium pharaonis and demonstrate its mode of action via bioassays with the pure biosynthesized compound. In particular, we show that the monocyclic diterpene neocembrene, which in different Monomorium species is produced solely by fertile, egg-laying queens, strongly inhibits the rearing of new sexuals (queens and males) and also exerts a weakly attractive ‘queen retinue’ effect on the workers. This is the first time that a queen pheromone with such a dual function has been identified in a social insect species with obligately sterile workers.

Non-toxic and environmentally friendly insecticidal powders have grown in popularity as pest control products to substitute traditional pesticide-based methods. The pharaoh ant is an ideal test species for insecticidal dusts and it is an indoor pest, mostly found in heated buildings where it can pose severe risks because of its ability to destroy electrical equipment and transfer diseases in hospitals. The use of commercially available activated carbon and carbon black materials as insecticidal dust is of great interest, since these types of materials proved effective in previous research and they have been little researched in the past. In the present study, we compared the effectiveness of 11 different carbon materials to reveal the key material properties defining the insecticidal action. All of the materials, with the exception of Printex U, performed better than the benchmark diatomaceous earth, which is presently the most widely used insecticidal dust. The shortest median survival time, 25 min, was observed upon exposure to activated carbon powder, which was significantly shorter than the 95 min observed for diatomaceous earth. Model selection revealed that particle size was the most important parameter determining insecticidal activity for activated carbon materials. Overall, our findings highlight the potential for the use of carbon materials as insecticidal agents, not just for the control of the pharaoh ant, but potentially also to control other domestic or agricultural pests in confined spaces, such as stored grain pests or bed bugs. ispartof: JOURNAL OF PEST SCIENCE vol:92 issue:2 pages:1-10 status: Published online

The success of social insect colonies is dependent upon efficient and dynamic allocation of resources to alternate queen and worker castes. The developmental and molecular mechanisms regulating the caste fate of individual larvae in response to environmental cues have been the focus of intense study. However, the mechanisms regulating colony-level resource allocation into alternate castes (i.e., caste allocation ratios) are less well studied. Here, we systematically manipulate colony demography to elucidate the social regulatory mechanisms of caste allocation in the ant Monomorium pharaonis. By measuring the effects of demographic manipulation on colony productivity, we infer that caste allocation results from differences in timing and efficiency of culling of very young reproductive-destined larvae, which are always present in colonies. Based on our results, we develop a conceptual model depicting how colonies integrate numerous individual-level caste determination decisions to regulate colony-level caste allocation. We propose that adult workers make decisions about culling larvae based on the ratio of the number of workers to the number of eggs contained in colonies, likely signaled by pheromone present on eggs. This strategy enables the dynamic alteration of colony demography in response to internal and external conditions, which is likely key to the ability of M. pharaonis and similar ants to thrive in disturbed habitats and to become widespread invasive species. The defining feature of social insect societies is the presence of alternate queen (reproductive) and worker (non-reproductive) castes of individuals. The fitness of social insect colonies is dependent upon efficient allocation of resources to alternate castes, particularly in the case of highly polygynous (multiqueen) societies. However, the mechanisms by which such societies regulate caste allocation are largely unknown. In this study, we perform a range of manipulative studies to disentangle social mechanisms of caste allocation in polygynous ant societies. Based on our results, we develop a model in which colonies manipulate their production of queens (and also males) versus workers according to the present density of eggs in the colony, a reliable indicator of queens’ fertility. Provided egg density is high, colonies kill queen- and male-destined larvae; when egg density falls, colonies begin to rear queens and males. This flexible resource allocation strategy is key to the ability of highly polygynous species to thrive in marginal (often human-associated) habitats.

Division of labor within and between the worker and queen castes is thought to underlie the tremendous success of social insects. Colonies might benefit if subsets of nurse workers specialize further in caring for larvae of a certain stage or caste, given that larval nutritional requirements depend on stage and caste. We used short- (Monomorium pharaonis) exhibit such specialization. We found that nurses were behaviorally specialized based on larval instar but not on larval caste. This specialization was widespread, with 56% of nurses in the short-term and between 22-27% in the long-term showing significant specialization. Additionally, we identified ∼200 genes that were differentially expressed in nurse head and abdominal tissues between nurses feeding young versus old larvae. These included 18 genes predicted to code for secreted proteins, which may be passed from nurses to larvae via trophallaxis, as well as vitellogenin and major royal jelly protein-1, which have previously been implicated in the transfer of nutrition from nurse to larvae and the regulation of larval development and caste in social insects. Altogether, our results provide the first evidence in any social insect for a division of labor among nurse workers based on larval stage, and our study begins to elucidate the molecular mechanisms underlying this specialization.

The success of social insect colonies is dependent upon efficient and dynamic allocation of resources to alternate queen and worker castes. The developmental and molecular mechanisms regulating the caste fate of individual larvae in response to environmental cues have been the focus of intense study. However, the mechanisms regulating colony-level resource allocation into alternate castes (i.e. caste allocation ratios) are less well studied. Here, we systematically manipulate colony demography to elucidate the social regulatory mechanisms of caste allocation in the antMonomorium pharaonis. We find that differences in caste allocation result from differences in timing and efficiency of culling of very young reproductive-destined larvae, which are always present in colonies. Based on our results, we develop a conceptual model depicting how colonies integrate numerous individual-level caste determination decisions to regulate colony-level caste allocation. We propose that adult workers make decisions about culling larvae based on the ratio of the number of workers to the number of eggs contained in colonies, likely signalled by pheromone present on eggs. This strategy is a bet-hedging strategy which enables the dynamic alteration of colony demography in response to internal and external conditions. The strategy is likely key to the ability ofM. pharaonisand similar ants to thrive in disturbed habitats and to become widespread invasive species.Significance StatementThe defining feature of social insect societies is the presence of alternate queen (reproductive) and worker (non-reproductive) castes of individuals. The fitness of social insect colonies is dependent upon efficient allocation of resources to alternate castes, particularly in the case of highly polygynous (multi-queen) societies. However, the mechanisms by which such societies regulate caste allocation are largely unknown. In this study, we show that colonies manipulate their production of queens (and also males) versus workers according to the present density of eggs in the colony, which serves as a reliable indicator of queens’ fertility. Provided egg density is high, colonies kill queen-and male-destined larvae; when egg density falls, colonies begin to rear queens and males. This flexible resource allocation strategy is key to the ability of highly polygynous species to thrive in marginal (often human-associated) habitats.

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.

On West Indian islands, as elsewhere in the world, ants are a very important component of virtually every terrestrial ecosystem. Nonetheless, the ants of most West Indian islands have remained largely unknown and unstudied. Now several destructive exotic ant species are spreading through the region, threatening native biodiversity. Here, we have compiled published and unpublished ant records and collected new specimens to document the diversity of ants on the island of Grenada. Our investigations increased the list of ant taxa known from the island to 82 (65 New World and 17 Old World species). Of these, 71 species are represented among specimens we collected, whereas 11 are New World species known from Grenada solely on the basis of earlier records. Some species recorded earlier, including at least nine not seen for more than 100 years, may now be extinct on Grenada. Grenada has more New World ant species than are known for Barbados (46), a neighboring island that has 34% more land area. Factors that may contribute to this difference include: 1) during low sea levels 15,000 years ago, Grenada was part of a larger island about 10 times Grenada's current size; 2) Grenada is more mountainous than Barbados; and 3) Grenada has more remaining forest cover than Barbados (50.0% vs. 14.7%). Conversely, Grenada has fewer Old World ant species than are known for Barbados (24). Factors that may contribute to this difference include: 1) lower human population density, 2) lower levels of imported lumber products, and 3) lower tourism levels. Records for only four of the 17 Old World exotic ants found in Grenada date to before 1995. Major tramp ant species that are known from the West Indies but have not yet been recorded from Grenada include Old World species such as the pharaoh ant (Monomorium pharaonis), the African big-headed ant (Pheidole megacephala), and the difficult white-footed ant (Technomyrmex difficilis), as well as the red imported fire ant (Solenopsis invicta).

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 statement Pheromones 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 material The online version of this article (doi:10.1007/s00265-016-2187-y) contains supplementary material, which is available to authorized users.

Multiple mating by queens has been shown to enhance disease resistance in insect societies, because higher genetic diversity among nestmates improves collective immune defences or offers a certain level of herd immunity. However, it has remained ambiguous whether polygynous societies with large numbers of queens also benefit from increased genetic diversity. 2. We used one of the very few ant species that can be reared across generations, the pharaoh ant, Monomorium pharaonis Linnaeus, to create experimental colonies with two types of enhanced genetic diversity: (i) mixed workers from three divergent inbred lineages representing the 'polygyny-equivalent' of multiple mating by queens (i.e. increased between-worker variation); and (ii) uniform workers whose overall heterozygosity was increased by two subsequent generations of crossing between the same divergent inbred lineages (i.e. increased within-worker variation). 3. We found significant differences in worker survival among the three inbred lineages, with exposure to conidiospores of the fungal pathogen Beauveria bassiana causing significant mortality to the workers independently of their diversity type. Increased diversity did not improve the resistance to Beauveria. 4. Enhanced heterozygosity colonies had worker survival rates similar to the most resistant inbred lineage, whereas colonies with mixed workers from the three inbred lineages had lower worker and larval survival. Workers did not show any infection- avoidance behaviour. 5. Average larval survival appeared unaffected by the presence of conidiospores. It benefitted from increased heterozygosity but was reduced in mixed colonies independent of infection. This suggests that negative, but cryptic social interactions in mixed colonies may affect overall survival. 6. The present results do not provide evidence for or against a link between increased genetic variation and increased disease resistance in pharaoh ants, but show that colonies differ considerably in general survival. Thus, increasing the genetic diversity of pharaoh ant colonies may not provide survival advantages in the face of pathogen exposure, and polygyny and polyandry may not be directly comparable mechanisms for creating adaptive resistance towards pathogens.

The success of an ant colony depends on the simultaneous presence of reproducing queens and non-reproducing workers in a ratio that will maximize colony growth and reproduction. Despite its presumably crucial role, queen–worker caste ratios (the ratio of adult queens to workers) and the factors affecting this variable remain scarcely studied. Maintaining polygynous pharaoh ant (Monomorium pharaonis) colonies in the laboratory has provided us with the opportunity to experimentally manipulate colony size, one of the key factors that can be expected to affect colony level queen–worker caste ratios and body size of eclosing workers, gynes and males. We found that smaller colonies produced more new queens relative to workers, and that these queens and workers both tended to be larger. However, colony size had no effect on the size of males or on the sex ratio of the individuals reared. Furthermore, for the first time in a social insect, we confirmed the general life history prediction by Smith and Fretwell (Am Nat 108:499–506, 1974) that offspring number varies more than offspring size. Our findings document a high level of plasticity in energy allocation toward female castes and suggest that polygynous species with budding colonies may adaptively adjust caste ratios to ensure rapid growth.

The pharaoh ant is a notorious and hard to eradicate pest, which poses a threat in hospitals, spreading pathogens and contaminating sterile equipment. When applied on ants, zeolites adsorb part of their epicuticular wax layer. The ants are then vulnerable to desiccation, since this layer regulates water exchange. We analyzed the chemical composition of this wax layer using GC-MS (Gas Chromatography-Mass Spectrometry). A hexane wash of M. pharaonis foragers resulted in the identification of 53 components, four of which were not previously defined in Monomorium species. Selective adsorption of specific compounds on zeolites assisted in the identification of compounds which could not be separated on the GC column and allowed for the identification of three additional compounds. Zeolites show different affinities for the wax compounds depending on pore structure and chemical composition. Selective adsorption of alkanes on zeolites is also investigated in the fields of refinery processes and catalysis. Pore mouth and key lock adsorption mechanisms and selectivity according to molecular weight and branching, investigated in these fields, are also involved in adsorption processes of epicuticular waxes. The insecticidal activity of a zeolite is related to adsorption selectivity rather than capacity. One of the best adsorbing zeolites showed limited insecticidal activity and can be considered as a non-lethal alternative for epicuticular wax sampling. ispartof: International Journal Of Molecular Sciences vol:19 issue:9 ispartof: location:Switzerland status: published

( S )-4-Methyl-3,6-dihydro-2 H -pyran-2-carbaldehyde ( 3 ), the common intermediate in the syntheses of the C17–C27 subunit of laulimalide ( 4 ) and (+)-faranal ( 5 ), the trail pheromone of the pharaoh ant, Monomorium pharaonis , were obtained via transformation of methyl 3-bromomethyl-3-butenoate ( 1 ) into allylstannane 2 and subsequent allylation of (benzyloxy)acetaldehyde ( 6 ) in accordance with the Keck procedure as the key steps.

To advance our understanding of the causes and the consequences of budding (colony multiplication by fragmentation of main nests), we investigated nest movement in the facultatively polydomous Pharaoh ant, Monomorium pharaonis. Demographic data revealed that Pharaoh ants are highly polygynous and have a relatively low worker to queen ratio of 12.86. Budding experiments demonstrated that the number of available bud nests has a significant effect on colony fragmentation and increasing the number of bud nests resulted in smaller colony fragments. The overall distribution among bud nests was uneven, even though there was no evidence that the different life stages and castes partitioned unevenly among the bud nests and the analysis of individual colonies revealed no evidence of an uneven split in any of the colonies. This demonstrates that Pharaoh ants have the ability to exert social control over colony size and caste proportions during budding, which may contribute to their success as an invasive ant. The intensity of nest disturbance had a significant effect on whether or not the ants migrated into bud nests. Major disturbance resulted in the ants abandoning the source nest and migrating to bud nests and minor disturbance did not stimulate the ants to abandon the source nest. The results of the successive budding experiment which allowed the ants the opportunity to bud into progressively smaller nest fragments demonstrate that Pharaoh ants maintain a preferred minimum group size of 469 28 individuals. Food allocation experiments utilizing protein marking revealed that nest fragmentation in Pharaoh ants has no negative impact on intracolony food distribution. Overall, our results suggest that nest units in the Pharaoh ant behave like cooperative, rather than competitive, entities. Such cooperation is most likely facilitated by the fact that individuals in all bud nests are genetically related, remain in close proximity to each other, and may continue to exchange individuals after budding.

Background:The widespread house ant, Monomorium pharaonis (pharaoh ant, PA), was recently identified as a potential cause of respiratory allergies. However, there are no reports of the distribution of PA allergens in various environments. We developed specific ELISA inhibition assays and measured the distribution and amount of PA antigens in household dust samples. Methods:Floor dust was collected at 3-month intervals from 56 homes in Seoul over a 1-year period. PA antigens in fine dusts were quantified by ELISA inhibition assays using rabbit anti-PA sera, and specific IgE to PA antigens in residents’ serum was measured by ELISA. Results: In 18 of the 56 homes (32.1%), PA antigen was detected in at least 1 floor dust sample either from the living room or the kitchen. Levels of PA antigens showed seasonal variations with peaks in autumn and winter. The detection rate of PA antigens was significantly higher in homes with visual evidence of PA infestations (70%) than in homes without such infestations (23.9%; p < 0.05). However, a significant amount of PA antigens was still detected in uninfested homes. Thirteen of 113 (11.5%) residents were positive for PA-specific IgE. PA-specific IgE was detected more frequently in residents living in PA antigen-positive homes (19.6%) than in antigen-negative homes (4.8%; p < 0.05). Conclusion: A considerable level of PA antigens is distributed in the indoor environment. Therefore, inhalant exposure to PA antigens can occur during domestic activities. These results suggest that PAs might be a significant source of aeroallergens in households.

Five selected insecticides were applied to four substrates and evaluated in laboratory studies for repellency and toxicity against the Pharaoh ant, Monomorium pharaonis (L.). We tested both repellent and nonrepellent formulations on outdoor (concrete and mulch) and indoor (ceramic and vinyl) substrates. Repellency was evaluated using a behavioral bioassay in which colonies were given a choice to leave the treated zone and move into empty nests provided in the untreated zone. We used a novel experimental design whereby ants walked on a Slinky coil suspended from a metal support frame, thus permitting a long foraging distance with a minimum use of space and resources. Cypermethrin, a repellent pyrethroid insecticide, resulted in colony budding, although the response was delayed. Toxicity of insecticides was evaluated as worker, queen, and brood mortality. The most effective treatment was fipronil, which provided 100% reduction in pretreatment activity by 2 d posttreatment on both concrete and mulch. Chlorfenapyr was highly effective on both outdoor and indoor substrates. Significant substrate effects were observed with insecticides applied to nonabsorbent substrates (ceramic tile), which performed better than insecticides applied to absorbent substrates (vinyl tile). Other highly absorbent materials (mulch and concrete), however, did not reduce insecticide efficacy. This is because ants relocated nests into and/or under these attractive nesting materials, thus increasing their exposure to toxic insecticide residues. Our results demonstrate efficacy of nonrepellent liquid insecticides as indoor treatments for the control of Pharaoh ants and possibly as exterior perimeter treatments.

Background Many studies are available on systemic reactions to ant sting, but few have described the direct role of ants in respiratory allergy. The nonstinging house ant, Monomorium pharaonis (pharaoh ant), is a highly infesting species in indoor environments. Objective To determine whether the pharaoh ant is an indoor source of aeroallergens. Methods Two patients with asthma who lived in homes with ant infestation were enrolled. Pharaoh ants were collected at the patients' homes, and crude extracts were prepared. Skin prick tests with ant extracts were performed. Specific IgE to pharaoh ant was measured by enzyme-linked immunosorbent assay (ELISA), and the allergenic components were determined by using immunoblot analysis. Cross-reactivity among pharaoh ant, imported fire ant, Pachycondyla chinensis ant, and other indoor allergens was evaluated by ELISA inhibition tests. Specific bronchial challenge testing was performed using pharaoh ant extracts. Results Both patients had positive skin test reactions to pharaoh ant extract and high levels of specific IgE antibodies to pharaoh ant. The ELISA inhibition test results demonstrated significant inhibition by pharaoh ant; however, P chinensis , cockroach, and house dust mite showed no inhibition of the IgE binding to pharaoh ant. Two important IgE-binding components, 9.4 and 34 kDa, were identified by using immunoblot analysis. Pharaoh ant bronchial challenge test results showed typical early asthmatic reactions in 1 patient and dual asthmatic reactions in the other patient. Conclusions Ants can induce IgE-mediated bronchoconstriction regardless of sting in sensitized patients. Ants should be taken into consideration as a cause of respiratory allergy in patients living in homes with visual evidence of infestation.

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

Pyriproxyfen, a juvenile hormone analog, was formulated into 2 types of baits and applied to the exterior of buildings for control of natural infestations of the Pharaoh ant, Monomorium pharaonis (L.). Pyriproxyfen baits were formulated at 0.5 and 1% by weight in an unprocessed peanut oil attractant applied to a pregel defatted corn grit carrier and at 0.25% in a composite bait consisting of unknown ingredients. Both baits effectively controlled the ants. Worker numbers were reduced between 84.5 and 94.3% at 2.5 wk after the 2nd bait application when the 0.25% pyriproxyfen composite bait was applied to apartment buildings with separate apartments. Outdoor worker numbers were reduced 84% 2 wk after the 2nd bait application when 0.5% pyriproxyfen bait was applied to a large building with separate wings. A reduction of >85% in worker number was not observed in the 1% pyriproxyfen treatment until 8 wk after the 2nd bait application; however, no ants were ever found indoors in this treatment. Dyes in the pyriproxyfen oil treatments were used to determine if ants foraged from one treatment area to the next. Calco oil dyes used as markers in the oil bait were detectable in the postpharyngeal gland of the queens and workers for up to 14 wk after baiting in the field and 17 wk after baiting in the laboratory. A perimeter treatment applied to large buildings with separate wings was more difficult to evaluate than treatments applied to separate buildings containing multiple apartments because contaminated ants from treated areas, as indicated by the presence of dye, were found in the controls.

The distribution (between adult workers and worker larvae) and storage of dyed foods (one protein, two lipids, and three carbohydrates) were investigated in standardized Pharaoh ant, Monomorium pharaonis (L.), colonies (n = 250 workers, 2 queens, and 25–30 mg worker brood) in the laboratory. Two foods were in liquid form (peanut oil and 1 M sucrose) and four were in solid form (egg yolk, beef fat, table sugar, and corn starch). Workers did not actively recruit to table sugar, but in a concurrent study it was used as building material to fill nest openings. Moistened corn starch was ignored by foraging workers with little storage. Workers became satiated on 1 M sucrose before any solution was given to larvae. Peanut oil, like the 1 M sucrose solution, was rapidly distributed among and stored internally by adult workers. Unlike the 1 M sucrose solution given primarily to older larvae, peanut oil was distributed rapidly to all larval stadia. Workers showed weak recruitment to beef fat even after 7 d of starvation. Only a few workers showed evidence of feeding on beef fat and none was distributed to larvae. Storage of solid lipid (beef fat) was variable. Workers in two of five colonies stored large quantities of beef fat in piles inside their nests. In three colonies only trace amounts of beef fat were stored after 24 h. In contrast, workers consistently stored large quantities of excess solid protein (moist egg yolk powder) in piles inside their nests. Solid protein was fed to and consumed primarily by older larvae, and none was detected in young larvae or adult workers. Workers actively recruited to liquid carbohydrate (1 M sucrose) and solid protein (moist egg yolk powder) foods after 2 d of starvation. A 7-d starvation period was necessary for active recruitment to lipids (peanut oil and beef fat), but caused extremely rapid recruitment (too fast for accurate observation) to carbohydrate and protein foods. Thus, colonies were starved for 2 d prior to the introduction of protein or carbohydrate foods, and 7 d prior to lipid foods. Our results suggest that lipids may not be rapidly depleted in the metabolism of the Pharaoh ant. Thus, protein and liquid carbohydrates (using simple sugars) may play a more important role as components of insecticidal baits that are important in Pharaoh ant management. However, in field colonies that may be stressed for lack of food (which may commonly occur), an insecticidal bait formulated from oil may be readily accepted and effective.

Boonen, S., Eelen, D., Borgesen, L. and Billen, J. 2012. Functional morphology of the mandibular gland of queens of the ant Monomorium pharaonis (L.). — Acta Zoologica (Stockholm) 00: 1–9. In this study, the functional morphology of the mandibular glands of pharaoh ant queens is investigated through histological and behavioural observations. The mandibular glands of queens of different age stages and mating status were examined at the light microscopical as well as the ultrastructural level. The results clearly show a high activity of the gland at the time of hatching, followed by a rapid degeneration independent of the queens’ mating status. We therefore hypothesize the glandular secretion serves to stimulate workers to remove the queens’ pupal skin. Experiments to compare hatching ability of isolated pupae and pupae assisted by workers confirmed the necessity of worker assistance, which is even more crucial to allow proper wing formation in queens and males. Together with the histological data, this suggests that the mandibular gland may indeed play a role in the social facilitation of hatching, although bioassays are required to give decisive answers about the mandibular gland’s function.

The insect growth regulator fenoxycarb was very effective against a natural infestation of the Pharaoh ant, Monomorium pharaonis (L.). A large building (7,841 m2) containing four separate wings was used to evaluate two concentrations of fenoxycarb (0.5 and 1%) in oil on a corn grit bait. Raid Max Ant Bait was used as a standard for comparative purposes. A separate wing was used for each treatment. One wing received no bait and functioned as a control Our study demonstrated that 0.5% fenoxycarb in peanut butter oil was more effective than a 1% fenoxycarb bait and Raid Max Ant Bait; this treatment completely eliminated the ants

Fenoxycarb, an insect growth regulator, was highly effective against the Pharaoh ant, Monomorium pharaonis (L.). Fenoxycarb acts by reducing egg production in the queens; the colonies eventually die because of worker attrition. The best laboratory results were obtained using concentrations of 0.25, 0.5, and 1% in peanut oil. These concentrations significantly reduced worker numbers by 12 wk and quantity of brood by 5 wk, if not sooner; however, more than one baiting was necessary to eliminate the colonies completely. Also, in some tests, colonies fed fenoxycarb baits at concentrations of 0.1, 0.25, and 0.5% significantly delayed the production of winged reproductives. Intermediate castes (individuals that were larger than workers yet smaller than queens) were produced at lower concentrations (0.05, 0.1, and 0.25%). Higher concentrations of 2.5 and 5% were not effective, probably because of repellency of the chemical. These results demonstrate that fenoxycarb is as effective as the commercially available bait, Pharorid (methoprene), for the control of the Pharaoh ant.

In colonies of the pharaoh's ant Monomorium pharaonis (L), new males and queens can be produced at any time by the removal of the inhibitory effect of the presence of existing fertile queens. When queens are absent, workers rear sexual larvae and will also accept sexual larvae introduced from other nests. However, in the presence of fertile queens workers cannibalize sexual brood, and will not accept male or queen larvae or pre-pupae from other nests, although worker brood is always accepted and reared. Worker larvae are covered in bifurcated hairs, whereas sexual larvae are essentially hairless. Workers may use these morphological cues to distinguish between sexual and worker brood stages.

Two juvenile hormone analogs (JHAs), pyriproxyfen and S-methoprene, were impregnated into dried tuna fish and fed to colonies of Monomorium pharaonis (L.) at very low concentrations (1.0, 2.0, 3.0, 4.0, and 5.0 microg/ml). Its effects on the production of sexuals and colonial growth were observed. Colonies treated with pyriproxyfen yielded sexuals with physical abnormalities. Both female and male sexuals developed bulbous wings, decreased melanization, and died shortly after emergence. Sexuals emerged from colonies treated with S-methoprene did not possess anomalous characteristics. Both pyriproxyfen and S-methoprene did not have significant effects on colonial growth because of the low concentrations of the baits. A commercial bait containing 0.3% S-methoprene (Bioprene-BM) also was evaluated for its efficacy on Pharaoh's ant colonies. Results showed that Pharaoh's ant colonies succumbed to the lethal effects of S-methoprene. Colony members were reduced significantly. Production of queens also decreased significantly in treated colonies and treated queens were unable to lay eggs. JHAs are slow acting and eliminate ant colonies at a relatively slow rate. At low concentrations, pyriproxyfen recorded baffling results, i.e., bulbous wings and demelanized exoskeleton, and it is vital that further studies are initiated to solidify these findings.

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.

Pharaoh ant, Monomorium pharaonis (L.), infestations often consist of several colonies located at different nest sites. To achieve control, it is desirable to suppress or eliminate the populations of a majority of these colonies. We compared the trophallactic distribution and efficacy of two ant baits, with different modes of action, among groups of four colonies of Pharaoh ants. Baits contained either the metabolic-inhibiting active ingredient hydramethylnon or the insect growth regulator (IGR) pyriproxyfen. Within 3 wk, the hydramethylnon bait reduced worker and brood populations by at least 80%, and queen reductions ranged between 73 and 100%, when nests were in proximity (within 132 cm) to the bait source. However, these nest sites were reoccupied by ants from other colonies located further from the bait source. The pyriproxyfen bait was distributed more thoroughly to all nest locations with worker populations gradually declining by 73% at all nest sites after 8 wk. Average queen reductions ranged from 31 to 49% for all nest sites throughout the study. Even though some queens survived, brood reductions were rapid in the pyriproxyfen treatment, with reductions of 95% at all locations by week 3. Unlike the metabolic inhibitor, the IGR did not kill adult worker ants quickly, thus, more surviving worker ants were available to distribute the bait to all colonies located at different nest sites. Thus, from a single bait source, the slow-acting bait toxicant provided gradual, but long-term control, whereas the fast-acting bait toxicant provided rapid, localized control for a shorter duration.

Pharaoh ant, Monomorium pharaonis (L.), colonies were effectively controlled following ingestion of pyriproxyfen formulated in peanut butter oil. Pyriproxyfen, a juvenile hormone analog, reduced egg production in the queens, decreased the amount of brood due to delayed death in the eggs and larvae, caused death of pupae about 3 wk after treatment, and decreased the number of workers due to attrition and toxic effects. Queens, which continued to produce a small amount of eggs, eventually died. Queen death may have been caused by lack of workers required to tend them, old age or toxic effects. At concentrations of 0.25, 0.5 and 1%, pyriproxyfen was more effective than the once commercially available bait, Pharorid (methoprene) for the control of the Pharaoh ant.

Background Ants typically distinguish nestmates from non-nestmates based on the perception of colony-specific chemicals, particularly cuticular hydrocarbons present on the surface of the ants' exoskeleton. These recognition cues are believed to play an important role in the formation of vast so-called supercolonies that have been described for some invasive ant species, but general conclusions about the role of these cues are hampered by only few species being studied. Here we use data on cuticular hydrocarbons, aggression and microsatellite genetic markers to investigate the interdependence of chemical recognition cues, genetic distance and nestmate discrimination in the pharaoh ant (Monomorium pharaonis), a widespread pest species, and ask whether introduced populations of this species are genetically differentiated and exhibit intraspecific aggression. Results Microsatellite analyses of a total of 35 colonies from four continents revealed extremely high levels of genetic differentiation between almost all colonies (FST = 0.751 ± 0.006 SE) and very low within-colony diversity. This implies that at least 34 and likely hundreds more independent lineages of this ant have spread worldwide. Aggression tests involving workers from 14 different colonies showed only low levels of aggression, even between colonies that were geographically and/or genetically very distant. Chemical analyses of groups of worker ants showed that all colonies had the same cuticular compounds, which varied only quantitatively among colonies. There was a positive correlation between geographical and genetic distance, but no other significant relationships were detected between aggression, chemical profile, genetic distance and geographical distance. Conclusions The pharaoh ant has a global invasion history of numerous independent introductions resulting in genetically highly differentiated colonies typically displaying surprisingly low levels of intraspecific aggression, a behaviour that may have evolved in the native range or by lineage selection in the introduced range.

The nonstinging house ant, Monomorium pharaonis (pharaoh ant), was recently identified as a cause of respiratory allergy. This study was performed to evaluate the extent of sensitization to pharaoh ant, and its clinical significance in asthmatic patients. We carried out skin prick tests in 318 patients with asthma. Specific IgE (sIgE) to pharaoh ant was measured by ELISA, and cross-reactivity was evaluated by ELISA inhibition tests. Bronchial provocation testing was performed using pharaoh ant extracts. Fifty-eight (18.2%) of 318 patients showed positive skin responses to pharaoh ant, and 25 (7.9%) had an isolated response to pharaoh ant. Positive skin responses to pharaoh ant were significantly higher among patients with non-atopic asthma than among those with atopic asthma (26.0% vs. 14.9%, p