A supergene-controlling social structure in Alpine ants also affects the dispersal ability and fecundity of each sex.

Social organization, dispersal and fecundity coevolve, but whether they are genetically linked remains little known. Supergenes are prime candidates for coupling adaptive traits and mediating sex-specific trade-offs. Here, we test whether a supergene that controls social structure in Formica selysi also influences dispersal-related traits and fecundity within each sex. In this ant species, single-queen colonies contain only the ancestral supergene haplotype M and produce MM queens and M males, while multi-queen colonies contain the derived haplotype P and produce MP queens, PP queens and P males. By combining multiple experiments, we show that the M haplotype induces phenotypes with higher dispersal potential and higher fecundity in both sexes. Specifically, MM queens, MP queens and M males are more aerodynamic and more fecund than PP queens and P males, respectively. Differences between MP and PP queens from the same colonies reveal a direct genetic effect of the supergene on dispersal-related traits and fecundity. The derived haplotype P, associated with multi-queen colonies, produces queens and males with reduced dispersal abilities and lower fecundity. More broadly, similarities between the Formica and Solenopsis systems reveal that supergenes play a major role in linking behavioural, morphological and physiological traits associated with intraspecific social polymorphisms.

Coexistence of territorial competitor ants in fragmented boreal forest landscape.

The distribution of species in a patchy habitat may be influenced by competitive interactions. The dominant and highly competitive boreal ant species belong to the Formica rufa group. A pair of species, Formica aquilonia and Formica polyctena, require extensive territories due to their multi-nest breeding habits. The coexistence and habitat patterns of these two wood ant species in the boreal forest landscape were investigated. Forest characteristics in the vicinity of nests in forest patches were similar for both species, but they did not coexist in the same sampling plots of 0.79 ha in forest patches, indicating competitive exclusion. The sampling plots in large forest patches were more occupied by F. aquilonia, while no such association was found for F. polyctena. At a larger spatial scale (78.5 ha), we found that F. polyctena was more tolerant of smaller forest patches than F. aquilonia suggesting that these two ant species can coexist in moderately fragmented forest landscapes. However, forest habitat loss, fragmentation and climate-induced changes in forest tree structure may shift the species balance in favour of F. polyctena over F. aquilonia in the future.

"The Reference Genome Of The Kidnapper Ant, Polyergus Mexicanus".

Polyergus kidnapper ants are widely distributed, but relatively uncommon, throughout the Holarctic, spanning an elevational range from sea level to over 3000 m. These species are well known for their obligate social parasitism with various Formica ant species, which they kidnap in dramatic, highly coordinated raids. Kidnapped Formica larvae and pupae become integrated into the Polyergus colony where they develop into adults and perform nearly all of the necessary colony tasks for the benefit of their captors. In California, Polyergus mexicanus is the most widely distributed Polyergus, but recent evidence has identified substantial genetic polymorphism within this species, including genetically divergent lineages associated with the use of different Formica host species. Given its unique behavior and genetic diversity, Polyergus mexicanus plays a critical role in maintaining ecosystem balance by influencing the population dynamics and genetic diversity of its host ant species, Formica, highlighting its conservation value and importance in the context of biodiversity preservation. Here, we present a high-quality genome assembly of P. mexicanus from a sample collected in Plumas County, CA, USA, in the foothills of the central Sierra Nevada. This genome assembly consists of 364 scaffolds spanning 252.31 Mb, with contig N50 of 481,250 kb, scaffold N50 of 10.36 Mb, and BUSCO completeness of 95.4%. We also assembled the genome of the Wolbachia endosymbiont of P. mexicanus - a single, circular contig spanning 1.23 Mb. These genome sequences provide essential resources for future studies of conservation genetics, population genetics, speciation, and behavioral ecology in this charismatic social insect.

Impact of Aphis pomi-tending Formica rufa (Hymenoptera: Formicidae) on biological parameters of Hippodamia variegata (Coleoptera: Coccinellidae).

One of the key reasons for the poor performance of natural enemies of honeydew-producing insect pests is mutualism between ants and some aphid species. The findings demonstrated that red wood ant, Formica rufa Linnaeus (Hymenoptera: Formicidae) had a deleterious impact on different biological parameters of the lady beetle, Hippodamia variegata Goeze (Coleoptera: Coccinellidae). H. variegata laid far fewer eggs in ant-tended aphid colonies, laying nearly 2.5 times more eggs in ant absence. Ants antennated and bit the lady beetle eggs, resulting in significantly low egg hatching of 66 per cent over 85 per cent in ant absent treatments. The presence of ants significantly reduced the development of all larval instars. The highest reduction was found in the fourth larval instar (31.33% reduction), and the lowest in the first larval instar (20% reduction). Later larval instars were more aggressively attacked by ants than earlier instars. The first and second larval instars stopped their feeding and movement in response to ant aggression. The third and fourth larval instars modified their mobility, resulting in increased ant aggression towards them. Adult lady beetles were shown to be more vulnerable to ant attacks than larvae. However, H. variegata adults demonstrated counterattacks in the form of diverse defensive reaction behaviours in response to F. rufa aggression.

Ants act as olfactory bio-detectors of tumours in patient-derived xenograft mice.

Early detection of cancer is critical in medical sciences, as the sooner a cancer is diagnosed, the higher are the chances of recovery. Tumour cells are characterized by specific volatile organic compounds (VOCs) that can be used as cancer biomarkers. Through olfactory associative learning, animals can be trained to detect these VOCs. Insects such as ants have a refined sense of smell, and can be easily and rapidly trained with olfactory conditioning. Using urine from patient-derived xenograft mice as stimulus, we demonstrate that individual ants can learn to discriminate the odour of healthy mice from that of tumour-bearing mice and do so after only three conditioning trials. After training, they spend approximately 20% more time in the vicinity of the learned odour than beside the other stimulus. Chemical analyses confirmed that the presence of the tumour changed the urine odour, supporting the behavioural results. Our study demonstrates that ants reliably detect tumour cues in mice urine and have the potential to act as efficient and inexpensive cancer bio-detectors.

Semipermeable species boundaries create opportunities for gene flow and adaptive potential.

Hybridisation and gene flow can have both deleterious and adaptive consequences for natural populations and species. To better understand the extent of hybridisation in nature and the balance between its beneficial and deleterious outcomes in a changing environment, information on naturally hybridising nonmodel organisms is needed. This requires the characterisation of the structure and extent of natural hybrid zones. Here, we study natural populations of five keystone mound-building wood ant species in the Formica rufa group across Finland. No genomic studies across the species group exist, and the extent of hybridisation and genomic differentiation in sympatry is unknown. Combining genome-wide and morphological data, we demonstrate more extensive hybridisation than was previously detected between all five species in Finland. Specifically, we reveal a mosaic hybrid zone between Formica aquilonia, F. rufa and F. polyctena, comprising further generation hybrid populations. Despite this, we find that F. rufa, F. aquilonia, F. lugubris and F. pratensis form distinct gene pools in Finland. We also find that hybrids occupy warmer microhabitats than the nonadmixed populations of cold-adapted F. aquilonia, and suggest that warm winters and springs, in particular, may benefit hybrids over F. aquilonia, the most abundant F. rufa group species in Finland. In summary, our results indicate that extensive hybridisation may create adaptive potential that could promote wood ant persistence in a changing climate. Additionally, they highlight the potentially significant ecological and evolutionary consequences of extensive mosaic hybrid zones, within which independent hybrid populations face an array of ecological and intrinsic selection pressures.

Impact of central complex lesions on innate and learnt visual navigation in ants.

Wood ants are excellent navigators, using a combination of innate and learnt navigational strategies to travel between their nest and feeding sites. Visual navigation in ants has been studied extensively, however, we have little direct evidence for the underlying neural mechanisms. Here, we perform lateralized mechanical lesions in the central complex (CX) of wood ants, a midline structure known to allow an insect to keep track of the direction of sensory cues relative to its own orientation and to control movement. We lesioned two groups of ants and observed their behaviour in an arena with a large visual landmark present. The first group of ants were naïve and when intact such ants show a clear innate attraction to the conspicuous landmark. The second group of ants were trained to aim to a food location to the side of the landmark. The general heading of naïve ants towards a visual cue was not altered by the lesions, but the heading of ants trained to a landmark adjacent food position was affected. Thus, CX lesions had a specific impact on learnt visual guidance. We also observed that lateralised lesions altered the fine details of turning with lesioned ants spending less time turning to the side ipsilateral of the lesion. The results confirm the role of the CX in turn control and highlight its important role in the implementation of learnt behaviours that rely on information from other brain regions.

Injury shortens life expectancy in ants and affects some risk-related decisions of workers.

The Formica cinerea ants are known to be highly territorial and aggressively defend their nest and foraging areas against other ants. During the foraging, workers engage in large-scale battles with other colonies of ants and injuries often occur in the process. Such injuries open the body up to pathologies and can lead to costs expressed in lower survival. Here, we addressed the significance of injury in dictating decisions related to engagement in risky behavior in ants (i.e., rescue and aggression). We manipulated the life expectancies of F. cinerea workers by injury and found that the survival of injured workers was shorter compared to the intact individuals. Furthermore, we found that injured workers discriminated between the intact and injured nestmates and showed more rescue behavior toward intact individuals. These rescue actions were expressed as digging around the trapped ant in need of rescue, pulling at its body parts, transporting the sand covering it, and biting the thread entrapping it. In turn, intact and injured workers showed similar and high levels of aggression toward heterospecifics. Our findings highlight the role of behavioral context in the studies devoted to the decision-making processes among social insects and the importance of life expectancy in their behavioral patterns.

Formica fusca ants use aphid supplemented foods to alleviate effects during the acute phase of a fungal infection.

The modulation of nutritional intake by animals to combat pathogens is a behaviour that is receiving increasing attention. Ant studies using isolated compounds or nutrients in artificial diets have revealed a lot of the dynamics of the behaviour, but natural sources of medicine are yet to be confirmed. Here we explored whether Formica fusca ants exposed to a fungal pathogen can use an artificial diet containing foods spiked with different concentrations of crushed aphids for a medicinal benefit. We show that pathogen exposed colonies adjusted their diet to include more aphid supplemented foods during the acute phase of the infection, reducing the mortality caused by the disease. However, the benefit was only attained when having access to a varied diet, suggesting that while aphids contain nutrients or compounds beneficial against infection, it is a part of a complex nutritional system where costs and benefits of compounds and nutrients need to be moderated.

Whole-genome analysis of multiple wood ant population pairs supports similar speciation histories, but different degrees of gene flow, across their European ranges.

The application of demographic history modelling and inference to the study of divergence between species has become a cornerstone of speciation genomics. Speciation histories are usually reconstructed by analysing single populations from each species, assuming that the inferred population history represents the actual speciation history. However, this assumption may not be met when species diverge with gene flow, for example, when secondary contact may be confined to specific geographic regions. Here, we tested whether divergence histories inferred from heterospecific populations may vary depending on their geographic locations, using the two wood ant species Formica polyctena and F. aquilonia. We performed whole-genome resequencing of 20 individuals sampled in multiple locations across the European ranges of both species. Then, we reconstructed the histories of distinct heterospecific population pairs using a coalescent-based approach. Our analyses always supported a scenario of divergence with gene flow, suggesting that divergence started in the Pleistocene (c. 500 kya) and occurred with continuous asymmetrical gene flow from F. aquilonia to F. polyctena until a recent time, when migration became negligible (2-19 kya). However, we found support for contemporary gene flow in a sympatric pair from Finland, where the species hybridise, but no signature of recent bidirectional gene flow elsewhere. Overall, our results suggest that divergence histories reconstructed from a few individuals may be applicable at the species level. Nonetheless, the geographical context of populations chosen to represent their species should be taken into account, as it may affect estimates of migration rates between species when gene flow is spatially heterogeneous.

Challenges and a call to action for protecting European red wood ants.

Red wood ants (RWAs) are a group of keystone species widespread in temperate and boreal forests of the Northern Hemisphere. Despite this, there is increasing evidence of local declines and extinctions. We reviewed the current protection status of RWAs throughout Europe and their International Union for the Conservation of Nature (IUCN) threat classification. Only some RWA species have been assessed at a global scale, and not all national red lists of the countries where RWAs are present include these species. Different assessment criteria, inventory approaches, and risk categories are used in different countries, and data deficiency is frequent. Legislative protection is even more complex, with some countries protecting RWAs implicitly together with the wildlife fauna and others explicitly protecting the whole group or particular species. This complexity often occurs within countries, for example, in Italy, where, outside of the Alps, only the introduced species are protected, whereas the native species, which are in decline, are not. Therefore, an international, coordinated framework is needed for the protection of RWAs. This first requires that the conservation target should be defined. Due to the similar morphology, complex taxonomy, and frequent hybridization, protecting the entire RWA group seems a more efficient strategy than protecting single species, although with a distinction between autochthonous and introduced species. Second, an update of the current distribution of RWA species is needed throughout Europe. Third, a protection law cannot be effective without the collaboration of forest managers, whose activity influences RWA habitat. Finally, RWA mounds offer a peculiar microhabitat, hosting a multitude of taxa, some of which are obligate myrmecophilous species on the IUCN Red List. Therefore, RWAs' role as umbrella species could facilitate their protection if they are considered not only as target species but also as providers of species-rich microhabitats.

Las hormigas rojas de la madera (HRM) conforman un grupo de especies clave con amplia distribución en los bosques templados y boreales del Hemisferio Norte. A pesar de lo anterior, cada vez hay más evidencia de su declinación y extinción local. Revisamos el estado actual de protección de las HRM en toda Europa y su clasificación en la Lista Roja de la Unión Internacional para la Conservación de la Naturaleza (UICN). Sólo se han evaluado algunas especies de HRM a escala mundial y no todas las listas rojas nacionales de los países con presencia de HRM incluyen a estas especies. Los diferentes países usan criterios de evaluación, estrategias de inventario y categorías de riesgo distintos, además de que la información deficiente es habitual. La protección legislativa es todavía más compleja pues algunos países protegen implícitamente a las HRM junto con la fauna silvestre y otros protegen explícitamente a todo el grupo o a una especie particular. Esta complejidad ocurre a menudo en los países (por ejemplo: Italia) en donde, fuera de los Alpes, sólo se protege a las especies introducidas, mientras a las especies nativas, que están declinando, no se les protege. Por lo tanto, se requiere un marco de trabajo internacional y coordinado para proteger a las HRM. Esto necesita primero que se defina el objetivo de conservación. Ya que las HRM tienen similitudes morfológicas, una taxonomía compleja e hibridación frecuente, la protección del grupo completo, con la distinción entre las especies autóctonas y las introducidas, parece ser una estrategia más eficiente que la protección de una sola especie. Segundo, se debe actualizar la distribución actual de las HRM en Europa. Tercero, una ley de protección no puede ser efectiva sin la colaboración de los gestores forestales, cuya actividad influye sobre el hábitat de las HRM Finalmente, los montículos de las HRM ofrecen un microhábitat peculiar pues hospedan a una multitud de taxones, algunos de los cuales son especies mirmecófilas obligadas presentes en la Lista Roja de la UICN. Así, el papel de las HRM como especie paraguas podría facilitar su protección si se les considera no sólo como especies diana sino también como proveedoras de microhábitats con riqueza de especies.

Dissecting the costs of a facultative symbiosis in an isopod living with ants.

The balance between costs and benefits is expected to drive associations between species. While these balances are well understood for strict associations, we have no insights to which extent they determine facultative associations between species. Here, we quantified the costs of living in a facultative association, by studying the effects of red wood ants on the facultatively associated isopod Porcellio scaber. Porcellio scaber frequently occurred in and near hostile red wood ant nests and might outnumber obligate nest associates. The facultative association involved different costs for the isopod. We found that the density of the isopod decreases near the nest with higher ant traffic. Individuals in and near the nest were smaller than individuals further away from the nest. Smaller individuals were also found at sites with higher ant traffic. A higher proportion of wounded individuals was found closer to the nest and with higher ant traffic. We recorded pregnant females and juveniles in the nest suggesting that the life cycle can be completed inside the nests. Lab experiments showed that females died sooner and invested less in reproduction in presence of red wood ants. Porcellio scaber rarely provoked an aggression response, but large numbers were carried as prey to the nest. These preyed isopods were mainly dried out corpses. Our results showed that the ant association incurred several costs for a facultative associate. Consequently, red wood ant nests and their surrounding territory act as an alternative habitat where demographic costs are offset by a stable resource provisioning and protection.

Innate visual attraction in wood ants is a hardwired behavior seen across different motivational and ecological contexts.

Ants are expert navigators combining innate and learnt navigational strategies. Whereas we know that the ants' feeding state segregates visual-navigational memories in ants navigating along a learnt route, it is an open question if the motivational state also affects the ants' innate visual preferences. Wood ant foragers show an innate attraction to conspicuous visual cues. These foragers inhabit cluttered woodland habitat and feed on honeydew from aphids on trees. Hence, the attraction to 'tree-like' objects might be an ecologically relevant behavior that is tailored to the wood ants' foraging ecology. Foragers from other ant species with different foraging ecologies show very different innate attractions. We investigated here the innate visual response of wood ant foragers with different motivational states, i.e., unfed or fed, as well as males that show no foraging activity. Our results show that ants from all three groups orient toward a prominent visual cue, i.e., this intrinsic visuomotor response is not context-dependent, but a hardwired behavior seen across different motivational and ecological contexts. Supplementary Information: The online version contains supplementary material available at 10.1007/s00040-022-00867-3.

Avoidance of ant chemical traces by spider mites and its interpretation.

Spider mites become easy prey for ants when they leave their protective webs; therefore, the ability to avoid traces of ongoing ant activity should confer a selective advantage to mites. We examined avoidance of ant traces by the spider mites Tetranychus kanzawai and Tetranychus urticae. Both mite species avoided host plant leaves with active traces of Pristomyrmex punctatus or Formica japonica ants. Pristomyrmex punctatus trace avoidance by T. kanzawai lasted for more than 1 h, but not more than 3 h. Tetranychus kanzawai also avoided P. punctatus traces on plant stems, along which the mites access leaves. Moreover, T. kanzawai avoided hexane extracts of P. punctatus or F. japonica applied to a filter paper pathway. This study represents the first demonstration of a repellent effect of ant chemical traces on spider mites. Considering the substantial abundance and global distribution of ants in nature, such repellent effects may help to answer the long-standing question of why only a small fraction of available plant resources is used by herbivores. Although spider mites have developed resistance against many synthetic pesticides, natural compounds that simulate ant chemical traces may repel spider mites from agricultural crops.

Disentangling the mechanisms linking dispersal and sociality in supergene-mediated ant social forms.

The coevolution between dispersal and sociality can lead to linked polymorphisms in both traits, which may favour the emergence of supergenes. Supergenes have recently been found to control social organization in several ant lineages. Whether and how these 'social supergenes' also control traits related to dispersal is yet unknown. Our goal here was to get a comprehensive view of the dispersal mechanisms associated with supergene-controlled alternative social forms in the ant Formica selysi. We measured the production and emission of young females and males by single-queen (monogyne) and multiple-queen (polygyne) colonies, the composition of mating aggregations, and the frequency of crosses within and between social forms in the wild. We found that males and females from alternative social forms did not display strong differences in their propensity to leave the nest and disperse, nor in their mating behaviour. Instead, the social forms differed substantially in sex allocation. Monogyne colonies produced 90% of the females flying to swarms, whereas 57% of the males in swarms originated from polygyne colonies. Most crosses were assortative with respect to social form. However, 20% of the monogyne females did mate with polygyne males, which is surprising as this cross has never been found in mature monogyne colonies. We suggest that the polygyny-determining haplotype free rides on monogyne females, who establish independent colonies that later become polygyne. By identifying the steps in dispersal where the social forms differ, this study sheds light on the behavioural and colony-level traits linking dispersal and sociality through supergenes.

Comparative analysis of a geometric and an adhesive righting strategy against toppling in inclined hexapedal locomotion.

Animals are known to exhibit different walking behaviors in hilly habitats. For instance, cats, rats, squirrels, tree frogs, desert iguana, stick insects and desert ants were observed to lower their body height when traversing slopes, whereas mound-dwelling iguanas and wood ants tend to maintain constant walking kinematics regardless of the slope. This paper aims to understand and classify these distinct behaviors into two different strategies against toppling for climbing animals by looking into two factors: (i) the torque of the center of gravity (CoG) with respect to the critical tipping axis, and (ii) the torque of the legs, which has the potential to counterbalance the CoG torque. Our comparative locomotion analysis on level locomotion and inclined locomotion exhibited that primarily only one of the proposed two strategies was chosen for each of our sample species, despite the fact that a combined strategy could have reduced the animal's risk of toppling over even more. We found that Cataglyphis desert ants (species Cataglyphis fortis) maintained their upright posture primarily through the adjustment of their CoG torque (geometric strategy), and Formica wood ants (species Formica rufa), controlled their posture primarily by exerting leg torques (adhesive strategy). We further provide hints that the geometric strategy employed by Cataglyphis could increase the risk of slipping on slopes as the leg-impulse substrate angle of Cataglyphis hindlegs was lower than that of Formica hindlegs. In contrast, the adhesion strategy employed by Formica front legs not only decreased the risk of toppling but also explained the steeper leg-impulse substrate angle of Formica hindlegs which should relate to more bending of the tarsal structures and therefore to more microscopic contact points, potentially reducing the risk of hindleg slipping.

The Scent of Ant Brood: Caste Differences in Surface Hydrocarbons of Formica exsecta Pupae.

Chemical communication is common across all organisms. Insects in particular use predominantly chemical stimuli in assessing their environment and recognizing their social counterparts. One of the chemical stimuli used for recognition in social insects, such as ants, is the suite of long-chain, cuticular hydrocarbons. In addition to providing waterproofing, these surface hydrocarbons serve as a signature mixture, which ants can perceive, and use to distinguish between strangers and colony mates, and to determine caste, sex, and reproductive status of another individual. They can be both environmentally and endogenously acquired. The surface chemistry of adult workers has been studied extensively in ants, yet the pupal stage has rarely been considered. Here we characterized the surface chemistry of pupae of Formica exsecta, and examine differences among sexes, castes (reproductive vs. worker), and types of sample (developing individual vs. cocoon envelope). We found quantitative and qualitative differences among both castes and types of sample, but male and female reproductives did not differ in their surface chemistry. We also found that the pupal surface chemistry was more complex than that of adult workers in this species. These results improve our understanding of the information on which ants base recognition, and highlights the diversity of surface chemistry in social insects across developmental stages.

Value-added switchgrass extractives for reduction of Escherichia coli O157:H7 and Salmonella Typhimurium populations on Formica coupons.

Recurring outbreaks linked to Escherichia coli O157:H7-contaminated lettuce and Salmonella enterica-contaminated sprouts highlight the need for improved food safety measures. The aim of this study was to determine the ability of a bio-based antimicrobial extract prepared from switchgrass, a dedicated energy crop, to reduce E. coli O157:H7 and S. Typhimurium populations on Formica coupons, a model food-contact surface. Overnight cultures of ~7 log CFU/mL E. coli O157:H7 and S. Typhimurium, air-dried on Formica coupons were treated with 0.625% NaClO, 70% ethanol, sterile water or different batches of switchgrass extractives (SE1, SE2, and SE3) for up to 30 min. E. coli O157:H7 was reduced by 4.43 log CFU/mL after 1 min by SE3, and to non-detectable levels after 1 min by all other treatments. Populations of S. Typhimurium LT2 (15-min drying) were reduced by 3.30 log CFU/mL with 70% ethanol, 5.38 log CFU/mL with SE1, and to non-detectable levels with 0.625% NaClO after 1 min, while S. Typhimurium ATCC 23564 (1-h drying) was non-detectable after 1 min by all treatments. Under soiled conditions, 10-min treatment with SE1 and 70% ethanol reduced both bacteria to non-detectable levels. Studies with concentrated switchgrass extractives combined with various other natural disinfectants or in hurdle approaches warrant further investigation.

Dynamic multimodal interactions in navigating wood ants: what do path details tell us about cue integration?

Ants are expert navigators, using multimodal information to navigate successfully. Here, we present the results of systematic studies of multimodal cue use in navigating wood ants, Formica rufa Ants learnt to navigate to a feeder that was defined by an olfactory cue (O), visual cue (V) and airflow (A) presented together. When the feeder, olfactory cue and airflow were all placed at the centre of the visual cue (VOACentre), ants did not directly approach the learnt feeder when either the olfactory or visual cue was removed. This confirms that some form of cue binding has taken place. However, in a visually simpler task with the feeder located at the edge of the visual cue (VOAEdge), ants still approached the feeder directly when individual cue components were removed. Hence, cue binding is flexible and depends on the navigational context. In general, cues act additively in determining the ants' path accuracy, i.e. the use of multiple cues increased navigation performance. Moreover, across different training conditions, we saw different motor patterns in response to different sensory cues. For instance, ants had more sinuous paths with more turns when they followed an odour plume but did not have any visual cues. Having visual information together with the odour enhanced performance and therefore positively impacted on plume following. Interestingly, path characteristics of ants from the different multimodal groups (VOACentre versus VOAEdge) were different, suggesting that the observed flexibility in cue binding may be a result of ants' movement characteristics.

The first draft genomes of the ant Formica exsecta, and its Wolbachia endosymbiont reveal extensive gene transfer from endosymbiont to host.

BACKGROUND: Adapting to changes in the environment is the foundation of species survival, and is usually thought to be a gradual process. However, transposable elements (TEs), epigenetic modifications, and/or genetic material acquired from other organisms by means of horizontal gene transfer (HGTs), can also lead to novel adaptive traits. Social insects form dense societies, which attract and maintain extra- and intracellular accessory inhabitants, which may facilitate gene transfer between species. The wood ant Formica exsecta (Formicidae; Hymenoptera), is a common ant species throughout the Palearctic region. The species is a well-established model for studies of ecological characteristics and evolutionary conflict. RESULTS: In this study, we sequenced and assembled draft genomes for F. exsecta and its endosymbiont Wolbachia. The F. exsecta draft genome is 277.7 Mb long; we identify 13,767 protein coding genes, for which we provide gene ontology and protein domain annotations. This is also the first report of a Wolbachia genome from ants, and provides insights into the phylogenetic position of this endosymbiont. We also identified multiple horizontal gene transfer events (HGTs) from Wolbachia to F. exsecta. Some of these HGTs have also occurred in parallel in multiple other insect genomes, highlighting the extent of HGTs in eukaryotes. CONCLUSION: We present the first draft genome of ant F. exsecta, and its endosymbiont Wolbachia (wFex), and show considerable rates of gene transfer from the symbiont to the host. We expect that especially the F. exsecta genome will be valuable resource in further exploration of the molecular basis of the evolution of social organization.