Pheidole Pallidula Research Articles

New crop, new pest, old ants: Crop colonisation by native ants disrupt biological control of an invasive mealybug in Mediterranean persimmon

Abstract Crop expansion is generally followed by an increase of herbivores. Some of these herbivore species can be favoured by mutualisms with ants that can also colonise introduced crops. Here, we hypothesized that the invasive mealybug Pseudococcus longispinus has established mutualistic relationships with native or exotic ants in Mediterranean persimmon crop. This relationship could negatively impact mealybug natural enemies and facilitate the colonisation of this new crop by the mealybug. To test this hypothesis, we sampled 17 persimmon orchards from the main producing area of the Mediterranean basin across two consecutive years and three different seasons. We identified the ant complex attending Ps. longispinus, calculated the ant attendance ratios and assessed the density dependence between tending ants and Ps. longispinus at mealybug colony level. Finally, we evaluated the effect of ants on the density of Ps. longispinus and its natural enemies at tree level. Fifteen ant species were found foraging in persimmon trees, out of which 11 attended Ps. longispinus colonies. The Mediterranean native species Lasius grandis, Pheidole pallidula and Plagiolepis spp. were the most abundant ant species in the canopies, and La. grandis was the most abundant species attending Ps. longispinus. This ant tended to attend large colonies of the mealybug in spring and summer. Pseudococcus longispinus density was positively correlated with ant activity in persimmon trees, which can be partially explained by the negative effect of ants on the mealybug parasitism and the density of potential predators. This study suggests that the density and damage caused by Ps. longispinus in Mediterranean persimmon are exacerbated by the attendance of native ants that disrupt mealybug biological control. Our results reinforce the hypothesis that ant attendance is a driving factor determining the density of honeydew‐producing herbivores and highlight that native ant species may facilitate the establishment and spread of exotic honeydew‐producing pests in new crops.

Ant Community Is Not Influenced by the Addition of Olive Mill Pomace Compost in Two Different Olive Crop Managements.

Industrial production of olive oil generates large amounts of solid waste called 'alperujo'. Its compost can fertilize many crops, especially olives. Furthermore, superintensive orchards are increasing their surface globally due to higher production and savings in different costs. Ants are considered an important part of the arthropod community in olive orchards and could even play a significant role in pest control. The tree canopy and ground were sampled to compare the ant assemblage in plots fertilized with compost and mineral products in two groves with different types of crop management (superintensive and traditional) over two years. The numbers of ants in both types of fertilization in each grove were not statistically different (p > 0.05), indicating that the type of fertilization did not have a significant impact on its populations in the ground or in the canopy, but the number of individuals was significantly higher in the superintensive grove than in the traditional grove (both in the ground and in the canopy, p < 0.01). The most frequent species in the ground were Pheidole pallidula, Plagiolepis smitzii and Aphaenogaster senilis (superintensive grove) and Pheidole pallidula, Tetramorium gr semilaeve, Plagiolepis pygmaea, and Tapinoma nigerrimum (traditional grove). In the canopy, the most frequent species were Plagiolepis spp. in both groves. Differences in ant densities and species between the groves could be due to the different management, especially of the soil, but it must be confirmed using more replicas and longer periods of study.

Diversity and composition of island insects of the Bejaia region (Algeria).

The study was conducted on four islands located west of Bejaia (north-eastern Algeria) to collect baseline information about diversity and composition of insects. Data were collected during summer and spring of 2015 using traps, sweep nets and the Japanese umbrella sampling methods. A total of 1691 individuals belonging to 112 species were collected. Totals of 72, 56, 41 and 34 species were recorded in Pisans Island, El Euch Island, Sahel Islet and Ail Islet, respectively. Of the 1,691 individuals recorded, 39.85 %, 30.51 %, 18.03 % and 11.59 % were recorded in Pisans Island, El Euch Island, Sahel islet and Ail islet, respectively. Shannon-weaver index ranged from 2.96 to 3.34 and Equitability between 0.77 and 0.87. The composition of the insect community differed between sampled islands (NMDS, Stress =. 0.013). Eleven (11) insect species composed over 50 % of dissimilarity between islands. Two species (Cassida viridis (L.) and Pheidole pallidula (Nyl.) accounted for more than 5% of the diversity on all islands. Sorensen's similarity coefficient showed that Pisans and El Euch islands have the highest similarity (45.37 %), while the lowest similarity was recorded between Pisans Island and Sahel Islet (15.53 %).

The Intranidal Myrmecophiles of the Maltese Islands with Notes on Messor Nests as Repositories of Biodiversity.

The intranidal myrmecophilous arthropod fauna of the Maltese Islands is reviewed. Thirty species from nine orders are found to be obligate myrmecophiles, of which four species are recorded from the Maltese archipelago for the first time: Phrurolithus sp. (Araneae: Phrurolithidae), Pogonolaelaps canestrinii (Berlese, 1904), Gymnolaelaps messor Joharchi, Halliday, Saboori & Kamali, 2011 and G. myrmecophilus (Berlese, 1892) (Mesostigmata: Laelapidae). Phrurolithus also represents the first record of the family Phrurolithidae in Malta. Notes on the biology and local distribution of each species are provided, including ant-myrmecophile associations, of which two appear to be previously unknown: the occurrence of Smynthurodes betae Westwood, 1849 (Hemiptera: Aphididae) in the nest of Plagiolepis pygmaea (Latreille, 1798) and Phrurolithus in the nest of Pheidole pallidula (Nylander, 1849). Fourteen additional species are found to be either only occasionally myrmecophilic, accidental ant-guests or potentially myrmecophilous, the latter remaining ambiguous due to a lack of knowledge of their biology. Of these, the family Caeculidae (Arachnida: Trombidiformes) represents a new record for the Maltese Islands, on the basis of Microcaeculus sp. occurring in a nest of Camponotus barbaricus Emery, 1905. Preliminary results indicate that Messor nests may be repositories of considerable myrmecophile diversity, with the most unique symbionts.

Seed removal decrease by invasive Argentine ants in a high Nature Value farmland

Seed dispersal by ants is an important ecological process that maintains the structure anddiversity of natural communities, however, it is vulnerable to biological invasions. Argentine ants are one of the worst invasive ant species and cause severe changes in ecosystem processes and native ant biodiversity declines in invaded sites. Here, we studied seed removal by ants combining observations and a cafeteria experiment with seeds of four myrmecochorous plant species (Centaurea sphaerocephala, Rosmarinus officinalis, Silybum marianum, and Ulex australis) in two sites (invaded and uninvaded) located in the Mediterranean Montado ecosystem and classified as High Nature Value farmland (HNV). Significant differences in daily seed removal rates were found between the two study sites. In uninvaded sites, several native ant species were attracted to the seeds, resulting in all seeds being removed rapidly. The majority of seed removal events were carried out by two key seed disperses Pheidole pallidula (71%) and Aphaenogaster iberica (26%) with a clear preference for diaspored with larger and heavier elaiosome (i.e., C. sphaerocephala, S. marianum). By contrast, while the Argentine ant showed some interest (68% of seeds were interacted with), no seed removal events were observed. The extirpation of the local ant fauna by the Argentine ant and its inability to ensure seed dispersal services may lead to the interference and eventually to the collapse of seed dispersal of the four studied myrmecochorous plants in the invaded site in the future. We argue that these discrete but severe consequences of an invasive species on a key ecological process may strongly affect the functioning of the Montado ecosystem.

Impact of the Invasive Argentine Ant in Citrus Agroecosystems: Effects on the Diversity and Frequency of Native Ant Species Foraging on Tree Canopy.

Simple SummaryWe aimed at assessing the impact of the Argentine ant invasion on the native ant community in citrus ecosystems. We compared the Argentine ant’s invaded and uninvaded citrus orchards in the south of Portugal, estimating species richness and the frequency of ant assemblages foraging on the tree canopy. The results suggest that the Argentine ant has a negative impact on the native ant community structure, markedly reducing the diversity and frequency of native species. This impact was more or less pronounced depending on the season. Possible implications for citrus pest management are discussed.The invasion of the Argentine ant, Linepithema humile (Mayr) (Hymenoptera, Formicidae) can alter the entire ecosystem with serious impacts on the native community structure (e.g., ant diversity) and processes (e.g., trophic interactions) leading to biodiversity loss and pest outbreaks. Most studies addressing these impacts have been conducted in natural or semi-natural areas, few are those conducted in agricultural ecosystems, such as citrus orchards. These are dominant agricultural ecosystems in Mediterranean landscapes. Furthermore, most studies have been conducted in a short span, not evidencing seasonal fluctuations. In this work, we assessed the ecological impact of the Argentine ant on the native ant communities in citrus orchards, in the region of Algarve, southern Portugal. By using principal response curve, we compared seasonal variation on ant assemblages in invaded and uninvaded citrus orchards foraging on tree canopy from a two-year sampling. The Argentine ant had a marked negative impact on the native ant community foraging on citrus canopy. In the uninvaded orchards, the native ant community had a rich assemblage composed of 16 ant species, in its majority (72%) controlled by the dominant species Lasius grandis Forel, Tapinoma nigerrimum (Nylander) and/or Pheidole pallidula (Nylander). In the invaded orchards, the native ant community was poorer and highly modified, mostly dominated by the Argentine ant (80%). Apparently, the only native ant species not affected by the presence of the Argentine ant was Plagiolepis pygmaea (Latreille). A significant negative effect was found between the proportion of infested trees by L. humile and the number of native ant species per orchard. Differences in the native ant community in the invaded and uninvaded orchards persisted over seasons and years. However, negative impacts were higher in the spring and summer, and less pronounced in the autumn. We discuss implications for citrus pest management.

Mutualistic ants (Hymenoptera: Formicidae) associated with Paracoccus ficus in fig orchards of Fars province, Iran.

Introduction: Ants are the most ubiquitous insects on the earth with more than 12000 species which are classified into 21 subfamilies. Until now, more than 170 ant species have recorded in Iran. Mutualistic relationship between ants and scale insects have been reported in Iran. Such relationships between ants and insects are known as trophobiosis which is due to attraction of ants to honeydew of scale insects. Honeydew is a sugar-rich sticky liquid, secreted by aphids and some scale insects as they feed on plant sap. Ants provide protection from predators and parasitoids by building shelters around scale insect colonies. Such a relationship is mostly facultative and only a few taxa of mostly tropical or subtropical scale insects have obligate mutualism with ants. The coccoids with obligate mutualism display obvious behavioral and morphological adaptations for living with ants. Ants are also able to establish antagonistic interaction with honeydew-producing hemipterans and contribute positively to biological control by the suppression of pests. Materials and Methods: In a study during 2013-2014, colonies of the mealybug Paracoccus ficus Moghaddam, 2014 were investigated for mutualistic ants feeding on honeydew of the mealybug in fig orchards of Neyriz, Estahban and Shiraz cities of Fars province, South Iran. Samples were collected by hand, forceps and soft brush. The specimens were preserved in 75% alcohol in small glass vials and were transferred to the laboratory. The morphological keys were used for identification. Specimens were deposited in Insect and Mite Collection of Ahvaz, at Department of Plant Protection, Shahid Chamran University of Ahvaz. Results and Discussion: Totally, 6 species belonging to 3 subfamilies of ants were identified as follows: Myrmicinae: Monomorium abeillei Andre, 1881; Tetramorium sp.; Pheidole pallidula Nylander, 1849; Crematogaster antaris Forel, 1894; Formicinae: Cataglyphis lividus Andre, 1881; Dolichoderinae: Tapinoma simrothi Krausse, 1911. Among collected species, T. simrothi and P. pallidula were more frequent. T. simrothi has also recorded as most frequent mutualistic ants with aphids in Central Iran. Natural enemies exploit hemipterans which receive ant protection for their benefit. For example, some parasitoid wasps soliciting honeydew directly from aphids by antennation and mimicking ants during foraging in host patches. Researchers believe that preventing ants from colonies of Pseudococcidae scale insects is necessary for success in biological control of such pests. However, not all of ants have negative effects in biological control of pests. Predatory ants are less attracted to the honeydew and mostly feed on egg, larvae and adult insects. Moreover, some ants are important in pollination, soil improvement, and nutrient cycling. Conclusion: Behavioral and ecological should be carried on ants in pest management programs, and only if they have a negative influence on biological control of scale insects, then perform control measures for ants.

Interactional behaviors of the parasitic beetle Paussus favieri with its ant host Pheidole pallidula: the mimetic role of the acoustical signals.

The social parasitic beetle Paussus favieri (Coleoptera, Carabidae, Paussini) performs different types of stridulations, which selectively mimic those emitted by different ant castes of its host Pheidole pallidula (Hymenoptera, Formicidae, Myrmicinae). However, the significance of this acoustical mimicry for the success of the parasitic strategy and the behaviors elicited in the host ants by stridulations was unknown. We reared Paussus favieri in Pheidole pallidula colonies and filmed their interacting behaviors. We analyzed in slow motion the behavior of ants near a stridulating beetle. We analyzed separately trains of pulse (Pa + Pb, produced by repeated rubbings) and single pulse (Pc, produced by a single rubbing) of stridulations, clearly recognizable from the shaking up and down of the beetle hind legs, and associated them with different ant responses. The full repertoire of sounds produced by P. favieri elicited benevolent responses both in workers and soldiers. We found that different signals elicit different (sometimes multiple) behaviors in ants, with different frequency in the two ant castes. However, Pc (alone or in conjunction with other types of pulses) appears to be the type of acoustic signal mostly responsible for all recorded behaviors. These results indicate that the acoustic channel plays a pivotal role in the host-parasite interaction. Finding that a parasite uses the acoustical channel so intensively, and in such a complicated way to trigger ant behaviors, indicates that acoustic signals may be more important in ant societies than commonly recognized.

Integrative biodiversity inventory of ants from a Sicilian archipelago reveals high diversity on young volcanic islands (Hymenoptera: Formicidae)

Islands are fascinating study systems for biogeography, allowing researchers to investigate patterns across organisms on a comparable geographical scale. They are also often important for conservation. Here, we present the first bio-inventory of the ant fauna of the Aeolian Islands, a Sicilian volcanic archipelago formed within the last million years. We documented a total of 40 species, including one first record for Italy (Lasius casevitzi). Mitochondrial DNA barcodes were obtained for all 40 taxa sampled on the islands, 13 of which were studied genetically for the first time. Mitochondrial DNA sequences of island specimens were compared with those of conspecific samples from other Aeolian Islands, Sicily and mainland Italy. Standardized photographical documentation of all sequenced specimens is provided. All but one currently recognized species (97.5%) were recovered as monophyletic. Genetic divergence within species ranged up to 12.4% in Pheidole pallidula, although most species had much lower levels of intraspecific divergence. At the scale of the Aeolian Islands, intraspecific genetic divergence varied significantly between subfamilies, with species of the subfamily Myrmicinae showing higher intraspecific divergences than the Formicinae. Comparison of specimens from the Aeolian Islands with conspecific ones from the putative source populations (Sicily and mainland Italy) suggested that the island of Panarea has the genetically most derived myrmeco-fauna among the seven focal Islands. Overall, DNA barcoding is a useful-albeit not perfect-method for classifying poorly studied groups of organisms and ants in particular.

Ants invading deserts: Non-native species in arid Moroccan oases

The oases of Morocco, located between the Mediterranean and the Sahara ecoregions, constitute the main defence system of the temperate region against desert encroachment. This study aims to determine species richness and distribution of native and non-native ants in the oases of southern Morocco. Survey campaigns were conducted in 11 oases between March and May 2017. Thirty-four ant species belonging to 13 genera and three subfamilies were collected. The regional catalogue of Formicidae is enriched by 27 new species (total 44 species) and five were listed as non-native species (11.4% of diversity). The most frequent species is Pheidole pallidula and the richest oasis is Allogoum (containing 11 species of which two are exotic and three are native and exclusively detected here). Of the 11 studied oases, only four were free from non-native ant species. Regression-based methods indicated that species diversity of non-native ants is related to water availability and total flow rate of sources, and only total flow rate of sources for all species combined. All correlations become non-significant when non-native species are removed from analyses, suggesting a recent colonisation and early invasion. Water availability is necessary to maintain local myrmecological diversity. This study sets the basis for future identification of the impacts of non-native ants on the ecological integrity of oasis ecosystem and to establish conservation measures.

Diet of Cataglyphis bicolor (Hymenoptera-Formicidae) in an insular condition in north-eastern Algeria

A study of the adaptation of the ant Cataglyphis bicolor in terms of feeding under insular conditions was conducted on the north-eastern coast of Algeria. For this, three pairs of stations (island-continent) were chosen. Analyzing fragments of prey species found in C. bicolor nests, the diet in each station pair was studied. The results obtained indicate that C. bicolor has an opportunistic diet characterised by insectivory. Indeed, more than 95% of the prey consumed in the six study stations were insects with a clear preference for other ants, with frequencies ranging from 52 to 87%. Among the latter, Messor barbarus, Camponotus sp., Camponotus laurenti, Pheidole pallidula and Tetramorium biskrense were the ants most predated by C. bicolor. The diversity of continental prey seemed greater than that of island environments. For the two Cap Sigli stations, the prey richness was 94 species for the continent against only 28 species for the island environment. For Boulimat, there were 27 prey species for the mainland and 20 prey species for the islet. Finally, for the Sahel region, C. bicolor was able to harvest 42 prey species on the mainland and 28 species on the island. The diversity of C. bicolor prey in the island environments seems to be a function of insect richness (prey availability) and floral richness.

Biogeography and Cophylogeny of Paussus favieri(Carabidae, Paussinae) and Pheidole pallidula(Hymenoptera, Myrmicinae)

The myrmecophilous carabid beetle, Paussus favieri, has a circum-Mediterranean distribution and it is completely dependent upon its host ant Pheidole pallidula during all stages of its life history. Using molecular sequence data we inferred the phylogenies of the populations of both the beetle and its ant host to determine if there are signs of co-evolution. A total of 34 P. favieri from France, Spain, Portugal, Morocco and Tunisia and 42 Ph. pallidula workers from the same countries, plus Greece and Italy, were collected and analyzed. Many mitochondrial and nuclear markers were sequenced, but only COI was evolving fast enough to infer the population-level phylogenies of the beetles and the ants. Preliminary analyses suggest that the European populations of P. favieri are derived from a single dispersal event from Africa, while several dispersal events are suggested for Ph. pallidula. We found the topologies of host and parasite trees to be generally congruent, as would be expected if the host and parasite have had a history of co-evolution or co-divergence.

How does habitat diversity affect ground-dwelling arthropods assemblages in Douro Demarcated Region terraced vineyards?

We investigated the impact of neighborhood non-crop habitats (NCHs) and cover vegetation in the Douro Demarcated Region terraced vineyards on ground-dwelling arthropods communities. Arthropods were sampled using pitfall traps located either in NCH as inside vineyards, at three distances (5, 25 and 50 m from NCH). Vegetation cover and plant species richness were evaluated around each trap. Omnivores (Formicidae) and detritivores (mainly Collembola), accounted for 42.0% and 33.7% of the sample, respectively. Predators, mainly dominated by Scydmaenidae (Coleoptera) and Araneae, accounted for 19.4% of the sample. The abundance of omnivores and predators was higher in NCH than in vineyards. In Formicidae, the generalist/opportunist group dominated, being highly represented by Pheidole pallidula. This group occurred mainly in NCH and its abundance was positively correlated either with plant richness as with percentage of fresh and total cover vegetation. This study indicates that preserving NCH close to the vineyards, as well as promoting native vegetation, enhances the presence of ground-dwelling arthropods.

A new species of Laelaspis Berlese (Acari: Mesostigmata: Laelapidae) from southeast Iran

ABSTRACTThis paper reports on a new species of mites of the genus Laelaspis from Iran – Laelaspis latisetus sp. nov. was collected clinging to Pheidole pallidula (Nylander) (Hymenoptera, Formicidae) from southeast of Iran. The new species is described and illustrations provided based on morphological characters of the adult female. An updated key to all known Iranian species of the genus is presented.http://www.zoobank.org/urn:lsid:zoobank.org:pub:1C62D92F-8AD6-4C7B-A69E-A7098C2066EEhttp://www.zoobank.org/urn:lsid:zoobank.org:act:C51C83F4-1492-41A3-B6DB-0CECBD002201

The diversity of arthropods community in dunes and a palm grove (Phoenix dactylifera) in the Touggourt region (Septentrionale Sahara)

AbstractAn inventory of arthropods was carried out at locations in the desert area of Touggourt, southeast Algeria. Samples were collected from two diverse habitats, a palm grove (agricultural habitat) and dunes (natural habitat). Using the Barber pitfall trap, 1100 specimens, divided into four classes, 15 orders, 44 families and 99 species were obtained. In the palm grove, 660 arthropods were trapped, belonging to four classes and 12 orders. Of these four classes, Insecta dominated followed by Crustacea, Arachnida and Entognata. Insecta accounted for 59.49% of the total capture and was dominated by two orders: Hymenoptera (41.81%) and Amphipoda (34.55%). In the Hymenoptera, Cataglyphis sp. was the most abundant (38.2%), followed by Pheidole pallidula (2.3%). In the dunes, 440 individuals were trapped. Insecta was the most abundant (90.69%), and Crustacea and Arachnida were scarce. Of the dominance by insects, Hymenoptera was most abundant (68.15%), and within that order, Cataglyphis bombycina (35.5%) was the most abundant followed by Monomorium subopacum (8.9%). In the palm grove, 42 species were recorded, compared to 57 in the dunes. The Shannon–Weaver index and equitability varied in both stations. In the palm grove, the diversity was 2.6, and the equitability was 0.5. By contrast in the dunes, the diversity was equal to 4 and the Equitability equal to 0.7. The differences in vegetation between the two sites reflect the differences in species diversity.

Association between ants (Hymenoptera: Formicidae) and the vine mealybug (Hemiptera: Pseudococcidae) in table-grape vineyards in Eastern Spain.

The vine mealybug, Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae) is a key pest of grapevine in the Mediterranean Basin. Some honeydew collecting ant species are known to increase mealybug populations in other grape-growing regions. However, there is scarce information on either the ant species present in Mediterranean vineyards or their impact on mealybugs. We conducted a study in four commercial vineyards in Eastern Spain in order to i) identify the ant species foraging on the vine canopies, ii) study the association among ant activity, vine mealybug abundance and fruit damage, and iii) test a novel method for ant management, distracting ants from guarding vine mealybugs by providing sugar dispensers. We recorded three ant species native to the Mediterranean foraging on the vine canopies: Lasius grandis (Forel), Pheidole pallidula (Nylander) and Plagiolepis schmitzii (Forel). The mean percentage of damaged fruits per vine was positively correlated with the number of vine mealybugs captured in traps placed at the trunk. We detected a positive but weak relationship between ant activity, vine mealybug abundance and fruit damage. The provisioning of sugar dispensers reduced the number of ants foraging on the vines by 23.4% although this reduction was not statistically significant. Vine mealybug abundance was significantly reduced (72%) after sugar provisioning. Our results suggest that the ant species native to vineyards in eastern Spain induce population increases of the vine mealybug. Moreover, the provisioning of sugars can be a valuable tool for ant management and mealybug control. © 2017 Society of Chemical Industry.

Ant fauna (Hymenoptera: Formicidae) of the Socotra Archipelago (Yemen): zoogeography, distribution and description of a new species

ABSTRACTThe animal fauna of the Socotra Archipelago is influenced by three biogeographical regions, the Afrotropical, the Oriental and the Palaearctic. Consequently, the Archipelago shares faunal elements of these three regions in addition to unique endemic taxa. The ant fauna of Socotra Island was studied and is reviewed based on literature and newly collected material. In total, 28 species, belonging to 10 genera and four subfamilies, were collected from the main island. Eighteen of these (64%) are successful invasive species, seven are native (25%), and three are considered endemic (11%), Cardiocondyla longiceps Seifert, Monomorium elghazalyi sp. nov. and Monomorium nimihil Collingwood et al. Two genera are recorded for the first time from the island, Hypoponera Santschi, and Syllophopsis Santschi. Ten species are recorded for the first time, Cardiocondyla mauritanica Forel, Cardiocondyla minutior Forel, Monomorium atomum Forel, Monomorium dichroum Forel, Monomorium exiguum Forel, Pheidole pallidula (Nylander), Syllophopsis cryptobia (Santschi), Tetramorium pauper Forel, Tetramorium transformans Santschi and Hypoponera punctatissima (Roger). Ten invasive species are recorded from Socotra, reflecting human impacts on the Archipelago. These species are Tapinoma melanocephalum (Fabricius), Cardiocondyla emeryi Forel, Monomorium exiguum Forel, Pheidole indica Mayr, Syllophopsis cryptobia (Santschi), Tetramorium lanuginosum Mayr, Tetramorium simillimum (Smith), Tetramorium caldarium (Roger), Trichomyrmex destructor (Jerdon) and Trichomyrmex mayri (Forel). Our survey indicated a mixture of Afrotropical faunal elements (10 species, 36%), followed by cosmopolitan (nine species, 32%), Palaearctic (five species, 18%) and Oriental (four species, 14%) taxa. Two new synonyms of Monomorium exiguum Forel are proposed: Monomorium exiguum Forel = Monomorium baushare Collingwood & Agosti syn. nov. = Monomorium qarahe Collingwood & Agosti syn. nov. Tetramorium transformans Santschi is removed from synonymy with Tetramorium caldarium (Roger) and elevated to species rank. Ecological and biological notes for each species are given. Distribution maps for all species known from the Socotra Archipelago are provided.http://zoobank/urn:lsid:zoobank.org:pub:89612083-9CE6-48E8-8975-1CE5334E098B

Diversity, spatial distribution, and sampling for ant management decision‐making in integrated pest management programs in citrus groves

AbstractAnts play important ecological roles, such as predation on other arthropods, seed dispersal, and soil structure maintenance. In citrus agroecosystems, ants are considered a secondary pest. The damage they cause is indirect through the disruption of the biological control of pests, especially honeydew producers. In integrated pest management programs, adequate and precise sampling methods are required to accurately determine the need for chemical ant control to minimize the economic and environmental costs of unnecessary chemical treatments and to reduce the risk of crop loss by pests. In Mediterranean citrus groves, eight ant species that differed in abundance and frequency have been found foraging on citrus trees: Lasius grandis Forel, Pheidole pallidula (Nylander), Plagiolepis pygmaea (Latreille), Formica gerardi Bondroit, Formica rufibarbis Fabricius, Camponotus sylvaticus (Olivier), Linepithema humile (Mayr), and Tapinoma erraticum (Latreille) (all Hymenoptera: Formicidae). The trunk was selected as the most efficient sampling unit to establish the monitoring method. Aggregation indices on the trunk of these species were calculated, and enumerative and binomial sampling methods were developed for the most frequent species, L. grandis and Ph. pallidula. Ant species differed in spatial distributions within citrus orchards, and required different sample sizes to estimate population abundance. The minimum sample size required, taking into account the maximum average abundance found – 44.1 L. humile, 17.3 L. grandis, and 3.5 Ph. pallidula per trunk per min –, would be 28, 25, and 54 trees, respectively.

Social Structure and Genetic Distance Mediate Nestmate Recognition and Aggressiveness in the Facultative Polygynous Ant Pheidole pallidula.

In social insects, the evolutionary stability of cooperation depends on the privileged relationships between individuals of the social group, which is facilitated by the recognition of relatives. Nestmate recognition is based on genetically determined cues and/or environmentally derived chemical components present on the cuticle of individuals. Here, we studied nestmate recognition in the ant Pheidole pallidula, a species where both single-queen (monogyne) and multiple-queen (polygyne) colonies co-occur in the same population. We combined geographical, genetic and chemical analyses to disentangle the factors influencing the level of intraspecific aggressiveness. We show that encounters between workers from neighbouring colonies (i.e., nests less than 5 m away) are on average less aggressive than those between workers from more distant colonies. Aggressive behaviour is associated with the level of genetic difference: workers from monogyne colonies are more aggressive than workers from polygyne colonies, and the intensity of aggressiveness is positively associated with the genetic distance between colonies. Since the genetic distance is correlated with the spatial distance between pairs of colonies, the lower level of aggression toward neighbours may result from their higher relatedness. In contrast, the analysis of overall cuticular hydrocarbon profiles shows that aggressive behaviour is associated neither with the chemical diversity of colonies, nor with the chemical distances between them. When considering methyl-branched alkanes only, however, chemical distances differed between monogyne and polygyne colonies and were significantly associated with aggressiveness. Altogether, these results show that the social structure of colonies and the genetic distances between colonies are two major factors influencing the intensity of agonistic behaviours in the ant P. pallidula.

Inconvenient hyperdiversity - the traditional concept of "PheIdole pallIdula" includes four cryptic species (Hymenoptera: Formicidae)

Results of a pilot study are presented suggesting that Edward Wilson’s guess of some 1500 species in the hyperdiverse genus Pheidole Westwood, 1839 is likely to turn out as rather moderate estimate. Investigation of 112 nest samples containing 287 major workers of Westpalaearctic ants currently named Pheidole pallidula (Nylander, 1849) was performed by the explorative data analyses NC-Ward and NC-k-means clustering in combination with cross-validated linear discriminant analysis. Seventeen primary morphometric data were recorded by high-resolution stereomicroscopy. Allometric variance of shape variables was removed. Four cryptic species, forming the Ph. pallidula complex, were resolved: Ph. pallidula, Ph. balcanica nov. sp., Ph. koshewnikovi Ruzsky, 1905 and Ph. cicatricosa Stitz, 1917. The classification error varied between 0 and 2.8 % in NC clustering of nest samples and between 1.6 and 3.7 % in cross-validated linear discriminant analysis of individuals. Ph. cicatricosa has a North African distribution whereas Ph. pallidula, Ph. balcanica nov. sp. and Ph. koshewnikovi are Eurasian species with large sympatric ranges in the Balkans and Asia Minor. Colonization of urban regions north of the Alps and of offshore islands in the Mediterranean Sea indicates an invasive potential of the supercolonial social type of Ph. pallidula. There are no indications that any of these four taxa might represent an intraspecific polymorphism and signals for putative interspecific hybridization are not significant. The following synonymies were established: Ph. subdentata Mayr, 1853, Ph. pallidula var. obscura Santschi, 1936 and Xenoaphaenogaster inquilina Baroni Urbani, 1964 are junior synonyms of Ph. pallidula, Ph. pallidula var. arenarum Ruzsky, 1905 and Ph. pallidula ssp. orientalis Muller, 1923 are junior synonyms of Ph. koshewnikovi and Ph. pallidula var. recticeps Menozzi, 1932 is a junior synonym of Ph. cicatricosa. The senior synonymy of the following seven Westpalaearctic taxa with any member of the Ph. pallidula complex was excluded by type investigation and diagostic statements in the original descriptions: Ph. sinaitica Mayr, 1862, Ph. jordanica Saulcy, 1874, Ph. teneriffana Forel, 1893, Ph. laticeps Mayr, 1904, Ph. schmitzi Forel, 1911, Ph. obtusa Stitz, 1917 and Ph. pallidula selenia Ozdikmen, 2010. Species delimitation in the less differentiated caste of minor workers was not tested but seems possible when accessory morphological characters are included.