Mating Flight Research Articles

Genome-wide analysis of brain transcriptional changes in honey bee (Apis mellifera L.) queens exposed to carbon dioxide and physical manipulation

Mating is a complex process causing many behavioural and physiological changes, but the factors triggering them and the underlying molecular processes are not well characterized. In the present study we examine the effects of CO(2) (a commonly used anaesthetic in instrumental insemination that causes changes similar to those occurring after mating) and physical manipulation (which may mimic certain aspects of copulation) on the behavioural, physiological and brain transcriptional changes in honey bee queens. We show that while CO(2) causes cessation of mating flights and ovary activation, physical manipulation has additional effects on ovary activation and brain transcriptional changes. Comparisons with previous studies of honey bees and female Drosophila indicate that common molecular mechanisms may be responsible for regulating reproductive changes across different mating regimes and insect orders.

Environmental and biological determinants of Termitomyces species seasonal fructification in central and southern Côte d’Ivoire

The Macrotermitinae subfamily is characterized by its symbiosis with fungi of the genus Termitomyces. The most common and presumably primitive mode of reproduction for these fungi is to produce basidiocarps on the mounds of the host termite colony. The seasonal fructification pattern of the fungi seems to depend on the habitat type and termite ecology. We examined Termitomyces diversity and distribution in two phytogeographic zones in central and southern Cote d’Ivoire. Data were collected in different habitats in exhaustive searches with standardized methods for termites and basidiocarps as well. The respective findings were complemented with behavioral and life cycle data of the associated termite species. Basidiocarps occur species-specifically either during the long or the short rainy season in wooded habitats. The diversity and abundance of termites and their associated basidiocarps were significantly correlated only with woody plant species richness. Nuptial flight of termites, comb biomass and Termitomyces fructification periods were correlated. Termitomyces appear to fructify during (1) the period of strong precipitation, (2) in habitats with appropriate microclimatic characteristics.

Coffee Farm Diversity and Landscape Features Influence Density of Colonies of Atta cephalotes (Hymenoptera: Formicidae)

The density of colonies of leaf-cutting ants, Atta cephalotes L. (Hymenoptera: Formicidae), was measured and compared among coffee (Coffea arabica L.) plantations in five management categories: monoculture conventional, diversified conventional, diversified organic, highly diversified conventional, and highly diversified organic. Twenty-four small farms (<4 ha) in Turrialba, Costa Rica, were included in this study. Within-farm and off-farm (landscape) variables were measured and tested for their relationship with A. cephalotes colony density. Total ant colony density (colonies per ha) and density of new colonies shortly after a nuptial flight were significantly greater in the coffee monoculture conventional system, compared with all other systems. Total ant colony density and density of new colonies were inversely related to percentage of shade within the farms. Within farms, colony density was greater near edges adjacent to riparian forest than those adjacent to nonforested land. Regardless of edge type, plots closer to the edge (0-30 m) had greater colony density than those furthest from the edge. At the landscape scale, density of new colonies was positively related to fallow land use coverage within a 2,000-m buffer radius and to forest coverage within a 500-m radius. Results indicate that coffee farm management practices and landscape level factors can affect A. cephalotes colony densities. Understanding such practices and factors could assist in the development of better management methods of these injurious insects in coffee farms. Increased diversification in coffee farms, possibly due to the greater shade associated with it, may reduce colonization by the ants, which are considered forest gap specialists.

Systematics of the mealybug tribe Xenococcini (Hemiptera: Coccoidea: Pseudococcidae), with a discussion of trophobiotic associations with Acropyga Roger ants

The mealybug tribe Xenococcini (Hemiptera: Pseudococcidae) comprises three genera, Eumyrmococcus Silvestri, Neochavesia Williams &amp; Granara de Willink and Xenococcus Silvestri, trophobiotically associated with ants of the genus Acropyga Roger (Hymenoptera: Formicidae). Alate Acropyga queens vertically transmit trophobionts by carrying them along on the nuptial flight, a unique behaviour termed trophophoresy. Xenococcine mealybugs have never been collected without ant associates, and putatively only associate with Acropyga. Xenococcine mealybugs are characterized by the absence of dorsal ostioles, presence of distally cup‐shaped circuli and a female pupal instar rather than a third feeding instar. The phylogeny of this tribe is derived for the first time using morphological data from adult females (53 characters) through Bayesian inference and maximum parsimony methods. Monophyly of the clade is strongly supported and a discussion of their taxonomy is included. The Neotropical genus Neochavesia was recovered as monophyletic. Eumyrmococcus, as previously defined, was recovered as paraphyletic, and thus two species are transferred to Xenococcus: Xenococcus kinomurai (Williams &amp; Terayama) comb.n. and Xenococcus neoguineensis (Williams) comb.n. Two species groups are recognized within Eumyrmococcus: the Eumyrmococcus scorpioides species group, restricted to the eastern Mediterranean and Afrotropics, and the Eumyrmococcus smithii species group, restricted to the Orient and Indo‐Australasia. Six new species are described: Eumyrmococcus adornocapillussp.n. from Australia; Eumyrmococcus sarnatisp.n. from Fiji; Eumyrmococcus ordinotersussp.n. and Xenococcus baryglobosussp.n. from the Solomon Islands; Neochavesia cephalonodussp.n. from French Guiana; and Neochavesia linealumasp.n. from Guyana. The systematics and biology of the xenococcine mealybugs is discussed in the context of obligate ant symbiosis.

Phenology of mating flight in Ecitoninae (Hymenoptera: Formicidae) in a Brazilian Atlantic Forest location

The mating flight of Ecitoninae ants was studied using four light traps inspected daily during the whole year of 2004. A total of 1285 males belonging to 15 species was collected, the species number varying monthly from two to 11. For most species, the beginning of the reproductive period occurred in November or in February. Synchronism of the flight activity among species was observed in the genera Neivamyrmex and Eciton, while segregation occurred in two Labidus species. In the model tested to explain male abundance over the year, including rainfall, temperature and interaction between both factors, only temperature was significant.

The mating sign of queen bees originates from two drones and the process of multiple mating in honey bees

SummaryQueens return from successful mating flights with the mating sign, which consists of chitinized plates of drone endophallus filled with mucus. The orange membranes covering both sides of the mating sign do not touch the hairy rim of the bursa copulatrix. The thin thread at the end of the mating sign is pushed forward on the surface of the sign in most queens. This makes the end of the sign look blunt. Simulated stages of natural mating showed that it is impossible for the orange membranes covering the cornua of the endophallus to become stuck to the mating sign of the same drone. Mating signs with additional pairs of orange membranes were found. In some queens, the semen or additional second mating signs were found at the end of the sign protruding from queen's sting chambers. Those three additional parts originated from drones, which attempted to mate, but failed to remove the mating sign of the predecessor. The thin thread at the end of the mating sign was pushed to the surface of the sign, because the next drone attempted to mate, but failed to remove the sign of its predecessor. The last drone, which failed to mate, left the orange membranes of his endophallic cornua at the mating sign of his predecessor. Thus, the mating sign originates from two drones. The chitinized plates and the mucus originate from one drone, but the orange membranes originate from the last drone/s, which attempted to mate, but failed to remove the sign of his predecessor.

Colony founding and social parasitism in Lasius (Acanthomyops)

We investigated colony foundation behavior of three species of the Lasius claviger group, L. latipes, L. interjectus and L. claviger, using field observations and laboratory experiments. Laboratory studies included observing gyne behavior prior to interaction with host colonies (e.g. grouping, overwintering, feeding) and experiments in which gynes were introduced to putative host colonies. Observations of gyne parasitic behavior immediately after mating flights in the field and the discovery of mixed colonies both confirm the parasitic behavior of these species and point toward a wide host species range including two cases of hyperparasitism. L. interjectus and L. latipes enter the host colony immediately after the nuptial flight, while L. claviger may hibernate and enter in the spring. Laboratory experiments showed that L. interjectus gynes prefer to group and suffer lower mortality when in a group, which is consistent with field observations of L. interjectus gynes entering host colonies in large numbers. Details on behavior of L. latipes alpha and beta form gynes are also given.

Societies Drifting Apart? Behavioural, Genetic and Chemical Differentiation between Supercolonies in the Yellow Crazy Ant Anoplolepis gracilipes

BackgroundIn populations of most social insects, gene flow is maintained through mating between reproductive individuals from different colonies in periodic nuptial flights followed by dispersal of the fertilized foundresses. Some ant species, however, form large polygynous supercolonies, in which mating takes place within the maternal nest (intranidal mating) and fertilized queens disperse within or along the boundary of the supercolony, leading to supercolony growth (colony budding). As a consequence, gene flow is largely confined within supercolonies. Over time, such supercolonies may diverge genetically and, thus, also in recognition cues (cuticular hydrocarbons, CHC's) by a combination of genetic drift and accumulation of colony-specific, neutral mutations.Methodology/Principal FindingsWe tested this hypothesis for six supercolonies of the invasive ant Anoplolepis gracilipes in north-east Borneo. Within supercolonies, workers from different nests tolerated each other, were closely related and showed highly similar CHC profiles. Between supercolonies, aggression ranged from tolerance to mortal encounters and was negatively correlated with relatedness and CHC profile similarity. Supercolonies were genetically and chemically distinct, with mutually aggressive supercolony pairs sharing only 33.1%±17.5% (mean ± SD) of their alleles across six microsatellite loci and 73.8%±11.6% of the compounds in their CHC profile. Moreover, the proportion of alleles that differed between supercolony pairs was positively correlated to the proportion of qualitatively different CHC compounds. These qualitatively differing CHC compounds were found across various substance classes including alkanes, alkenes and mono-, di- and trimethyl-branched alkanes.ConclusionsWe conclude that positive feedback between genetic, chemical and behavioural traits may further enhance supercolony differentiation through genetic drift and neutral evolution, and may drive colonies towards different evolutionary pathways, possibly including speciation.

Differential flight muscle development in workers, queens and males of the eusocial bees, Apis mellifera and Scaptotrigona postica.

The flight capability of the adult eusocial bees, Apis mellifera L. and Scaptotrigona postica Latreille (Hymenoptera: Apidae), is intrinsically linked to their colonial functions, such as the nuptial flight for mating in the case of queens and males, and the exploration of new habitats for nesting and food sources in the case of workers. Flight is achieved by the contraction of indirect flight muscles that produce changes in thoracic volume and, therefore, wing movement. The purpose of this work is to examine possible differences in muscle development that may be associated with the flying activity of individuals in a given life stage considering the behavioral and physiological differences among the stages and between the two species studied. Measurements of the muscle fibers obtained from light microscopy preparations of muscle were submitted to statistical analysis in order to detect the differences at a given time, or throughout the life of the individual. The results show that muscle morphology is similar in both species, but in A. mellifera the muscle fibers are thicker and more numerous than in S. postica. Differences in the fiber thickness according to life stage in all classes of individuals of both species were detected. These results are discussed in relation to the need for flying in each life stage.

Filamentous fungi found on foundress queens of leaf‐cutting ants (Hymenoptera: Formicidae)

AbstractQueens of the leaf‐cutting ant species Atta laevigata and Atta capiguara were collected soon after their mating flight and maintained in the laboratory until death. Ant corpses showing signs of contamination by insect pathogenic fungi were selected for fungal identification. Filamentous fungi such as Beauveria bassiana and Paecilomyces lilacinus actively sporulated in the ant’s corpses. This is the first report of the latter fungus on reproductives of leaf‐cutting ants. The fact that queens may acquire filamentous fungi including saprophytic and potential insect pathogens after their mating event is especially interesting regarding the impacts of such microbes on the establishment of a new nest.

Dopamine enhances locomotor activity for mating in male honeybees ( Apis mellifera L.)

Dopamine plays multiple roles in the regulation of reproduction in female honeybees where it appears to act independently of juvenile hormone (JH). In males the role of dopamine and its relationship to JH control have not been elucidated. In the present study we determined hemolymph levels of dopamine and its metabolite ( N-acetyldopamine) in males at post-emergence days 0–16. The development of locomotor and flight activities were recorded over the same period. Hemolymph levels of dopamine and N-acetyldopamine were found to increase at the time of onset of mating flight activity and those of dopamine decreased thereafter. Both locomotor and flight activities increased in parallel with hemolymph dopamine levels but the increased activity levels were maintained following decline of dopamine levels. Brain and meso-metathoracic ganglia levels of dopamine showed a similar developmental profile to hemolymph dopamine levels. Locomotor activities were temporarily inhibited by injection of a dopamine-receptor antagonist (cis( Z)-flupenthixol) into the thorax, and were enhanced by injection of a dopamine-receptor agonist (6,7-ADTN). These results suggest that dopamine regulates locomotor activities for mating and plays a role downstream of JH in premature males in honeybees.

Microgynous Queens in the Paleartic Ant,Manica rubida: Dispersal Morphs or Social Parasites?

In many ant species, queen size is dimorphic, with small microgynes and large macrogynes, which differ, for example, in size, insemination rate, ovary development, and dispersal tactics. These polymorphic queens often correspond with alternative reproductive strategies. The Palearctic ant, Manica rubida (Latreille) (Hymenoptera: Formicidae), lives mostly in mountainous regions in either monogynous colonies, containing one macrogynous queen or polygynous colonies, containing a few large macrogynous queens. In 1998, a colony of M. rubida was discovered containing macrogynes and many small alate microgynes that did not engage in a nuptial flight but, instead, stayed in the home nest the following winter. These microgynes were studied more closely by investigating their size, behavior, and spermatheca in relation to M. rubida macrogynes and workers. Mitochondrial DNA of macrogynes, microgynes and workers from four nests was sequenced to detect possible genetic differences between them. The microgynes were significantly smaller than the macrogynes, and the head width of the gynes was completely bimodal. The microgynes behaved like workers of the macrogynes in every experiment tested. Furthermore, the microgynes had a normal spermatheca and could be fecundated, but rarely (only one in several years). Finally, all the individuals were genetically identical, except three workers that differed by only one codon position. Because these microgynes have features of both queens and workers, their functional significance in the colony is not yet clear.

Changes in reproductive roles are associated with changes in gene expression in fire ant queens

In species with social hierarchies, the death of dominant individuals typically upheaves the social hierarchy and provides an opportunity for subordinate individuals to become reproductives. Such a phenomenon occurs in the monogyne form of the fire ant, Solenopsis invicta, where colonies typically contain a single wingless reproductive queen, thousands of workers and hundreds of winged nonreproductive virgin queens. Upon the death of the mother queen, many virgin queens shed their wings and initiate reproductive development instead of departing on a mating flight. Workers progressively execute almost all of them over the following weeks. To identify the molecular changes that occur in virgin queens as they perceive the loss of their mother queen and begin to compete for reproductive dominance, we collected virgin queens before the loss of their mother queen, 6 h after orphaning and 24 h after orphaning. Their RNA was extracted and hybridized against microarrays to examine the expression levels of approximately 10,000 genes. We identified 297 genes that were consistently differentially expressed after orphaning. These include genes that are putatively involved in the signalling and onset of reproductive development, as well as genes underlying major physiological changes in the young queens.

Isolation of a Pyrazine Alarm Pheromone Component from the Fire Ant, Solenopsis invicta

Alarm pheromones in social insects are an essential part of a complex of pheromone interactions that contribute to the maintenance of colony integrity and sociality. The alarm pheromones of ants were among the first examples of animal pheromones identified, primarily because of the large amount of chemical produced and the distinctive responses of ants to the pheromone. However, the alarm pheromone of the fire ant, Solenopsis invicta, eluded identification for over four decades. We identified 2-ethyl-3,6-dimethylpyrazine as an alarm pheromone component of S. invicta. Worker fire ants detect the pyrazine alarm pheromone at 30 pg/ml, which is comparable to alarm pheromone sensitivities reported for other ant species. The source of this alarm pheromone are the mandibular glands, which, in fire ants, are not well developed and contain only about 300 pg of the compound, much less than the microgram quantities of alarm pheromones reported for several other ant species. Female and male sexuals and workers produce the pyrazine, which suggests that it may be involved in fire ant mating flight initiation, as well as the typical worker alarm response. This is the first report of 2-ethyl-3,6-dimethylpyrazine from a Solenopsis species and the first example of this alkaloid functioning as an alarm pheromone.

Intranidal mating, gyne polymorphism, polygyny, and supercoloniality as factors for sympatric and parapatric speciation in ants

1. The syndrome of intranidal mating, morpho‐ethological gyne polymorphism, and polygyny is found in less than 5% of European ant species, but is considered as an important precondition for sympatric and parapatric speciation.2. This idea is discussed in three cases that represent example of evolution below the species level: (1) the polygynous—polydomous form of Lasius turcicus as a model of how speciation of the supercolonial Lasius neglectus could have taken place; (2) the microgyne form of Myrmica rubra as a model for sympatric speciation of socially parasitic species; and (3) hybridisation and rapid genotype selection in supercolonial wood ants of the Formica rufa group as a model for hybrid speciation.3. The first step of the evolutionary scenario is transition to polygyny followed by development of morpho‐ethological gyne polymorphism: smaller gynes with weaker wing muscles and body reserves shift to intranidal mating and reduce dispersal flight, while larger gynes with bigger wing muscles and body reserves retain nuptial and dispersal flight. This scenario leads to mating place separation and facilitates further genotype divergence.4. There is much less gene flow between conspecific supercolonies of Formica rufa group ants with dominance of intranidal or intracolonial mating than between conspecific monogynous colonies performing a nuptial flight. If two supercolonial species occasionally hybridise and if landscape structure provides some isolation of the resulting hybrid supercolony, very strong selection for genotypes takes place within this cohesive system of thousands of reproductive females eventually leading to novel genotypes and new species.

Nest Relocation and Colony Founding in the Australian Desert Ant,Melophorus bagotiLubbock (Hymenoptera: Formicidae)

Even after years of research on navigation in the Red Honey Ant,Melophorus bagoti, much of its life history remains elusive. Here, we present observations on nest relocation and the reproductive and founding stages of colonies. Nest relocation is possibly aided by trail laying behaviour, which is highly unusual for solitary foraging desert ants. Reproduction occurs in synchronised mating flights, which are probably triggered by rain. Queens may engage in multiple matings, and there is circumstantial evidence that males are chemically attracted to queens. After the mating flight, the queens found new colonies independently and singly. Excavation of these founding colonies reveals first insights into their structure.

Two potential host plants and notes on the habitat of the Haitian tailed blue,Pseudochrysops bornoi(Comstock and Huntington 1943) (Lycaenidae, Lepidoptera) in Guánica, Puerto Rico, USA

The natural history of Pseudochrysops bornoi, native to Santo Domingo, Puerto Rico and Cuba, is poorly known. Based on observations of a population of P. b. escobioi made in March 2006 and March 2007 near Guánica, Puerto Rico, we describe likely host plants, flight behavior, mating flight and oviposition. On multiple occasions P. b. escobioi laid eggs in the developing inflorescences of acacia (Acacia farnesiana) and cinazo Pithecellobium circinale.

The Potential for Gene Flow in a Dependent Lineage System of a Harvester Ant: Fair Meiosis in the F1 Generation

We investigated the potential for gene flow in a dependent lineage (DL) system of the harvester ant Pogonomyrmex. Each DL system is composed of 2 reproductively isolated lineages that are locked in an obligate mutualism. The genetic components that produce the worker phenotype are acquired by hybridizing with the partner lineage. In the mating flight, queens of both lineages mate with multiple males from each lineage. During colony growth and reproduction, eggs fertilized by partner-lineage sperm produce F(1) hybrid workers with interlineage genomes, whereas eggs fertilized by same-lineage sperm result in the development of new queens with intralineage genomes. New males are typically produced from unfertilized eggs laid by the pure-lineage queen but in her absence may be produced by interlineage F(1) workers. We investigated the potential for interlineage gene flow in this system using 2 classes of lineage-specific nuclear markers to identify hybrid genome combinations. We confirmed the production of viable interlineage F(1) reproductive females in field colonies, the occurrence of which is associated with the relative frequencies of each lineage in the population: interlineage F(1) queens occurred only in the rare lineage of the population with dramatically skewed lineage frequencies. In laboratory colonies, we detected fair meiosis in interlineage F(1) workers leading to the production of viable and haploid interlineage F(2) males. We conclude that the genomes of each lineage recombine freely, suggesting that extrinsic postzygotic selection maintains the integrity of each lineage genome. We compare our findings with those of the H1/H2 DL system.

Mating flights select for symmetry in honeybee drones (Apis mellifera)

Males of the honeybee (Apis mellifera) fly to specific drone congregation areas (DCAs), which virgin queens visit in order to mate. From the thousands of drones that are reared in a single colony, only very few succeed in copulating with a queen, and therefore, a strong selection is expected to act on adult drones during their mating flights. In consequence, the gathering of drones at DCAs may serve as an indirect mate selection mechanism, assuring that queens only mate with those individuals having a better flight ability and a higher responsiveness to the queen's visual and chemical cues. Here, we tested this idea relying on wing fluctuating asymmetry (FA) as a measure of phenotypic quality. By recapturing marked drones at a natural DCA and comparing their size and FA with a control sample of drones collected at their maternal hives, we were able to detect any selection on wing size and wing FA occurring during the mating flights. Although we found no solid evidence for selection on wing size, wing FA was found to be significantly lower in the drones collected at the DCA than in those collected at the hives. Our results demonstrate the action of selection during drone mating flights for the first time, showing that developmental stability can influence the mating ability of honeybee drones. We therefore conclude that selection during honeybee drone mating flights may confer some fitness advantages to the queens.

Temporal and geographic variations in the morphology and chemical composition of the frontal gland in imagoes of Prorhinotermes species (Isoptera: Rhinotermitidae)

Although the frontal gland has long been known as a prominent defensive device for termite soldiers in many Rhinotermitidae and Termitidae, almost nothing is known about its function in imagoes. In the present study, we show that the frontal gland of imagoes in Prorhinotermes species is well developed at the time of the nuptial flight, and is filled with a complex mixture of sesquiterpene hydrocarbons and nitroalkenes. The sesquiterpene composition varies between Prorhinotermes simplex and Prorhinotermes canalifrons, between geographically distant colonies of P. simplex (Cuba versus Florida), and even between different flights of closely-related subcolonies. The ratio between (E)-1-nitropentadec-1-ene and sesquiterpenes is sex-specific. The volume of secretory cells decreases in functional kings and queens after colony foundation, and the subcellular organization changes into a form resembling unmodified epidermal cells. Dealate reproductives lose the ability for biosynthesis, and their frontal gland is devoid of volatile compounds found in swarming imagoes. The results obtained in the present study clearly show that the frontal gland is only temporarily active at the time of the dispersal flight. The most likely function of this gland is defence by the toxic nitroalkenes. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98, 384–392.