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.

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.

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.

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.

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.

Visual associative learning in wood ants.

Wood ants are a model system for studying visual learning and navigation. They can forage for food and navigate to their nests effectively by forming memories of visual features in their surrounding environment. Previous studies of freely behaving ants have revealed many of the behavioural strategies and environmental features necessary for successful navigation. However, little is known about the exact visual properties of the environment that animals learn or the neural mechanisms that allow them to achieve this. As a first step towards addressing this, we developed a classical conditioning paradigm for visual learning in harnessed wood ants that allows us to control precisely the learned visual cues. In this paradigm, ants are fixed and presented with a visual cue paired with an appetitive sugar reward. Using this paradigm, we found that visual cues learnt by wood ants through Pavlovian conditioning are retained for at least 1 h. Furthermore, we found that memory retention is dependent upon the ants' performance during training. Our study provides the first evidence that wood ants can form visual associative memories when restrained. This classical conditioning paradigm has the potential to permit detailed analysis of the dynamics of memory formation and retention, and the neural basis of learning in wood ants.

Widespread hybridization within mound-building wood ants in Southern Finland results in cytonuclear mismatches and potential for sex-specific hybrid breakdown.

Hybridization and gene flow between diverging lineages are increasingly recognized as common evolutionary processes, and their consequences can vary from hybrid breakdown to adaptive introgression. We have previously found a population of wood ant hybrids between Formica aquilonia and F. polyctena that shows antagonistic effects of hybridization: females with introgressed alleles show hybrid vigour, whereas males with the same alleles show hybrid breakdown. Here, we investigate whether hybridization is a general phenomenon in this species pair and analyse 647 worker samples from 16 localities in Finland using microsatellite markers and a 1200-bp mitochondrial sequence. Our results show that 27 sampled nests contained parental-like gene pools (six putative F. polyctena and 21 putative F. aquilonia) and all remaining nests (69), from nine localities, contained hybrids of varying degrees. Patterns of genetic variation suggest these hybrids arise from several hybridization events or, instead, have backcrossed to the parental gene pools to varying extents. In contrast to expectations, the mitochondrial haplotypes of the parental species were not randomly distributed among the hybrids. Instead, nests that were closer to parental-like F. aquilonia for nuclear markers preferentially had F. polyctena's mitochondria and vice versa. This systematic pattern suggests there may be underlying selection favouring cytonuclear mismatch and hybridization. We also found a new hybrid locality with strong genetic differences between the sexes similar to those predicted under antagonistic selection on male and female hybrids. Further studies are needed to determine the selective forces that act on male and female genomes in these newly discovered hybrids.

Differential scaling within an insect compound eye.

Environmental and genetic influences cause individuals of a species to differ in size. As they do so, organ size and shape are scaled to available resources whilst maintaining function. The scaling of entire organs has been investigated extensively but scaling within organs remains poorly understood. By making use of the structure of the insect compound eye, we show that different regions of an organ can respond differentially to changes in body size. Wood ant (Formica rufa) compound eyes contain facets of different diameters in different regions. When the animal body size changes, lens diameters from different regions can increase or decrease in size either at the same rate (a 'grade' shift) or at different rates (a 'slope' shift). These options are not mutually exclusive, and we demonstrate that both types of scaling apply to different regions of the same eye. This demonstrates that different regions within a single organ can use different rules to govern their scaling, responding differently to their developmental environment. Thus, the control of scaling is more nuanced than previously appreciated, diverse responses occurring even among homologous cells within a single organ. Such fine control provides a rich substrate for the diversification of organ morphology.

Acquisition and expression of memories of distance and direction in navigating wood ants.

Wood ants, like other central place foragers, rely on route memories to guide them to and from a reliable food source. They use visual memories of the surrounding scene and probably compass information to control their direction. Do they also remember the length of their route and do they link memories of direction and distance? To answer these questions, we trained wood ant (Formica rufa) foragers in a channel to perform either a single short foraging route or two foraging routes in opposite directions. By shifting the starting position of the route within the channel, but keeping the direction and distance fixed, we tried to ensure that the ants would rely upon vector memories rather than visual memories to decide when to stop. The homeward memories that the ants formed were revealed by placing fed or unfed ants directly into a channel and assessing the direction and distance that they walked without prior performance of the food-ward leg of the journey. This procedure prevented the distance and direction walked being affected by a home vector derived from path integration. Ants that were unfed walked in the feeder direction. Fed ants walked in the opposite direction for a distance related to the separation between start and feeder. Vector memories of a return route can thus be primed by the ants' feeding state and expressed even when the ants have not performed the food-ward route. Tests on ants that have acquired two routes indicate that memories of the direction and distance of the return routes are linked, suggesting that they may be encoded by a common neural population within the ant brain.

Study and Development of an Anthroposophical Formula Based on Phosphorus and Formica rufa for Onychomycosis´s Treatment.

Onychomycosis is a fungal infection of the nail plate or nail bed that leads to the gradual destruction of the nail. The main difficulties in the treatment of onychomycosis refer to the duration of treatments and their side effects. Thus, it becomes relevant to look for new therapeutic alternatives in the treatment of such common diseases that are efficient without causing the undesirable side effects on the patient's body. In this way, the objective of this study was to develop an anthroposophical formula for the treatment of onychomycosis, based on Phosphorus and Formica rufa, from an extensive bibliographic survey on the functions of these components, evaluating within the principles of Anthroposophy. Considering the set of knowledge and practices on the use of these components, it was possible to arrive at a proposal therapy that can be effective for the treatment of onychomycosis. After an extensive review of several existing patents, it was observed that formulations containing Phosphorus and Formica rufa together have not been described in other studies. Subsequently, our research group published a patent of the anthroposophical formula using these two components, with the number BR1020180750755, which will be efficient to help the recovery of nails, and facilitate normal growth.

Mushroom Bodies Are Required for Learned Visual Navigation, but Not for Innate Visual Behavior, in Ants.

Visual navigation in ants has long been a focus of experimental study [1-3], but only recently have explicit hypotheses about the underlying neural circuitry been proposed [4]. Indirect evidence suggests the mushroom bodies (MBs) may be the substrate for visual memory in navigation tasks [5-7], while computational modeling shows that MB neural architecture could support this function [8, 9]. There is, however, no direct evidence that ants require MBs for visual navigation. Here we show that lesions of MB calyces impair ants' visual navigation to a remembered food location yet leave their innate responses to visual cues unaffected. Wood ants are innately attracted to large visual cues, but we trained them to locate a food source at a specific angle away from such a cue. Subsequent lesioning of the MB calyces using procaine hydrochloride injection caused ants to revert toward their innate cue attraction. Handling and saline injection control ants still approached the feeder. Path straightness of lesioned and control ants did not differ from each other but was lower than during training. Reversion toward the cue direction occurred irrespective of whether the visual cue was ipsi- or contralateral to the lesion site, showing this is not due simply to an induced motor bias. Monocular occlusion did not diminish ants' ability to locate the feeder, suggesting that MB lesions are not merely interrupting visual input to the calyx. The demonstrated dissociation between innate and learned visual responses provides direct evidence for a specific role of the MB in navigational memory.

The heavy metals cadmium, lead and mercury in raw materials of animal origin: evaluation of data from practice.

Raw materials from animal origin are widely used in homoeopathy. Due to the lack of dedicated limits, the quality requirements for herbal drugs of the European Pharmacopoeia (Ph. Eur.) and/or the German Homoeopathic Pharmacopoeia (Homöopathisches Arzneibuch, HAB), including limits for heavy metals such as cadmium, lead and mercury, have been applied. A recent database evaluation shows that for some raw materials of animal origin the Ph. Eur. limits for herbal drugs cannot be met in practice. For this reason proposals for new limits for cadmium, lead and mercury are made based on recent experiences from the companies' daily practice. These specific limits are suggested to be included in the individual monographs of the Ph. Eur. or at least the German HAB, respectively, for Ambra grisea, Euspongia officinalis, Formica rufa and Sepia officinalis.

Ant assemblages in the taiga biome: testing the role of territorial wood ants.

Ants were collected with sets of pitfall traps in four coniferous-forest habitats in southern Finland. A three-level competition hierarchy concept was used to generate predictions on ant community structure. The levels of the hierarchy, and the respective predictions, from top to bottom were: (1) The dominant territorial wood ants (Formica rufa-group species), expected to exclude each other. (2) The other aggressive species, likely to be excluded by the F. rufa-group. (3) The submissive species, non-aggressive and defending only their nest, and thus likely to coexist with the dominants but in reduced numbers. As expected, the species of the F. rufa-group excluded each other, and the species number of the other aggressive ants was significantly cut down in the presence of the F. rufa-group. The aggressive species F. sanguinea and Camponotus herculeanus showed complementary occurrences with the F. rufa-group, and Lasius niger reduced occurrences. The number of the submissive species was not significantly affected by the F. rufa-group. However, pairwise correlation coefficients were significantly more often negative than positive between presence of the F. rufa-group and average proportion of pitfalls per set with a submissive species, each analyzed in turn. The result indicates that the F. rufa-group also reduced the colony densities of the submissive species. We conclude that in the taiga biome territorial wood ants are, after adjusting for physical vicissitudes of the environment, the major structuring force of ant species assemblages.

GeoBioScience: Red Wood Ants as Bioindicators for Active Tectonic Fault Systems in the West Eifel (Germany).

In a 1.140 km² study area of the volcanic West Eifel, a comprehensive investigation established the correlation between red wood ant mound (RWA; Formica rufa-group) sites and active tectonic faults. The current stress field with a NW-SE-trending main stress direction opens pathways for geogenic gases and potential magmas following the same orientation. At the same time, Variscan and Mesozoic fault zones are reactivated. The results showed linear alignments and clusters of approx. 3,000 RWA mounds. While linear mound distribution correlate with strike-slip fault systems documented by quartz and ore veins and fault planes with slickensides, the clusters represent crosscut zones of dominant fault systems. Latter can be correlated with voids caused by crustal block rotation. Gas analyses from soil air, mineral springs and mofettes (CO2, Helium, Radon and H2S) reveal limiting concentrations for the spatial distribution of mounds and colonization. Striking is further the almost complete absence of RWA mounds in the core area of the Quaternary volcanic field. A possible cause can be found in occasionally occurring H2S in the fault systems, which is toxic at miniscule concentrations to the ants. Viewed overall, there is a strong relationship between RWA mounds and active tectonics in the West Eifel.