Alate Females Research Articles

Gaeolaelaps invictianus, a new and unusual species of hypoaspidine mite (Acari: Mesostigmata: Laelapidae) phoretic on the red imported fire ant Solenopsis invicta Buren (Hymenoptera: Formicidae) in Louisiana, USA

ABSTRACT A new species of hypoaspidine laelapid mite, Gaeolaelaps invictianus, associated with the red imported fire ant Solenopsis invicta Buren in the southern United States of America is described. This new species is unusual among the gamasine Mesostigmata in lacking a postanal seta in adults of both sexes and among species of Gaeolaelaps in being phoretic on dispersing male and female alate ants, lacking dorsal shield setae z3 and J1, and in having a separate anal shield in the adult male. The chelicerae of this new species are similar to free-living forms, suggesting that it may be a predator of small invertebrates in the ant colony.

Caste-specific visual adaptations to distinct daily activity schedules in AustralianMyrmeciaants

Animals are active at different times of the day and their activity schedules are shaped by competition, time-limited food resources and predators. Different temporal niches provide different light conditions, which affect the quality of visual information available to animals, in particular for navigation. We analysed caste-specific differences in compound eyes and ocelli in four congeneric sympatric species of Myrmecia ants, with emphasis on within-species adaptive flexibility and daily activity rhythms. Each caste has its own lifestyle: workers are exclusively pedestrian; alate females lead a brief life on the wing before becoming pedestrian; alate males lead a life exclusively on the wing. While workers of the four species range from diurnal, diurnal-crepuscular, crepuscular-nocturnal to nocturnal, the activity times of conspecific alates do not match in all cases. Even within a single species, we found eye area, facet numbers, facet sizes, rhabdom diameters and ocelli size to be tuned to the distinct temporal niche each caste occupies. We discuss these visual adaptations in relation to ambient light levels, visual tasks and mode of locomotion.

Histiostoma blomquisti n. sp. (Acari: Astigmata: Histiostomatidae), a phoretic mite of the red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae)

The new species Histiostoma blomquisti n. sp., associated with the Red Imported Fire Ant, Solenopsis invicta, is described by its deutonymph. A putative adult female is depicted. The deutonymphs only attach to female alates, dealates and queens of S. invicta. While queens may be covered by more than 200 deutonymphs over their entire bodies, the numbers of deutonymphs substantially differed between alates, dealates and queens, which are the preferred carriers, and the males and workers, which are usually not the phoretic hosts of these deutonymphs. It is assumed that the large amount of deutonymphs on queens may be a consequence of special conditions during nest foundings of monogyne colonies. Presence of deutonymphs apparently stimulates the cleaning behavior in workers; however deutonymphs are not removed during this procedure. This may be a consequence of chemical components produced in the opisthonotal glands of astigmatid mites that allow the mite to repel cleaning workers and remain strongly adhered to its carrier. It is unknown whether or not these mites affect the vitality of fire ant colonies.

Sex-Ratio Bias in Alates of Polygyne Colonies of the Red Imported Fire Ant Solenopsis invicta Buren (Hymenoptera: Formicidae) in China

A sex-ratio bias was studied in alates of natural polygyne colonies of Solenopsis invicta Buren in southern China. The results showed that at the population level, the numbers of male and female alates were nearly equal, even though there was a strong bias toward producing one particular sex at the nest level. For example, 88.89% of the nests sampled were strongly biased toward males or females. In particular, three bias types were observed: extreme female bias, extreme male bias, and a moderate bias. Future studies should address the factors that lead queens to produce strongly biased sex ratios.

Reproductive Characteristics of Imagos ofReticulitermes flavipes(Isoptera: Rhinotermitidae)

AbstractTermite alates presumably do not mate in their natal nest or during a swarming event. Rather, after flight, females and males lose their wings, pair, and select a nest site, with mating typically taking place in the incipient nest. In this study of Reticulitermes flavipes (Kollar) (Isoptera: Rhinotermitidae), histology and other techniques were used to assess reproductive features of female and male imagos, including unflown alates, flown alates, and the primary pair in incipient and well-established (5-yr-old) colonies. The spermathecae of female flown alates were devoid of spermatozoa, as expected, but the lumen contained a mucus-like substance. Histochemical tests revealed that this substance was intensely stained by periodic acid-Schiff, which is diagnostic for mucopolysaccharides. This is the first study to confirm that termites possess a mucopolysaccharide secretion in the spermathecal lumen. The secretion may serve as a sperm energy source as has been suggested for some other insects. Transmission electron microscopy subsequently revealed the presence of a semiopaque secretory material in the spermathecal lumen and associated ductules of flown and unflown alates as well as queens. Unflown female alates showed the least reproductive development in terms of spermathecal diameter and terminal oocyte size. Unflown male alates similarly possessed less developed reproductive organs than the kings.

Arginine kinase: Differentiation of gene expression and protein activity in the red imported fire ant, Solenopsis invicta

Arginine kinase (AK), a primary enzyme in cell metabolism and adenosine 5′-triphosphate (ATP)-consuming processes, plays an important role in cellular energy metabolism and maintaining constant ATP levels in invertebrate cells. In order to identify genes that are differentially expressed between larvae and adults, queens and workers, and female alates (winged) and queens (wingless), AK cDNA was obtained from the red imported fire ant. The cDNA sequence of the gene has open reading frames of 1065 nucleotides, encoding a protein of 355 amino acid residues that includes the substrate recognition region, the signature sequence pattern of ATP:guanidino kinases, and an “actinin-type” actin binding domain. Northern blot analysis and protein activity analysis demonstrated that the expression of the AK gene and its protein activity were developmentally, caste specifically, and tissue specifically regulated in red imported fire ants with a descending order of worker> alate (winged adult) female> alate (winged adult) male> larvae> worker pupae ≈ alate pupae. These results suggest a different demand for energy-consumption and production in the different castes of the red imported fire ant, which may be linked to their different missions and physiological activities in the colonies. The highest level of the AK gene expression and activity was identified in head tissue of both female alates and workers and thorax tissue of workers, followed by thorax tissue of female alates and abdomen tissue of male alates, suggesting the main tissues or cells in these body parts, such as brain, neurons and muscles, which have been identified as the major tissues and/or cells that display high and variable rates of energy turnover in other organisms, play a key role in energy production and its utilization in the fire ant. In contrast, in the male alate, the highest AK expression and activity were found in the abdomen, suggesting that here energy demand may relate to sperm formation and reproduction.

Ant colony size and the scaling of reproductive effort

1 Reproductive effort typically scales as mass0·75 in unitary organisms, but less is known about such scaling in colonial organisms. 2 I compiled data on worker and reproductive number at maturity for 65 ant species and found an interspecific allometry (alate number = worker number0·73) whose exponent was significantly < 1, even after a phylogenetic correction. 3 When I analyzed 15 species for which biomass data were available, I found an interspecific isometry (alate biomass = worker biomass0·89) whose exponent was not significantly different from 1. Analysis of maximum species biomass values, rather than averages, strengthened this isometry, yielding a slope b = 1·01 that was also not distinguishable from 1. 4 Species with larger colony size at reproduction tended to couple investment in proportionately fewer alates with investment in larger male and female alates. 5 This comparative analysis suggests a trade-off between alate size and number, and provides a framework for studying the diversity of colony life histories and the mechanisms generating allometries.

A bird-parasitic fly, Carnus hemapterus Nitzsch(Diptera, Carnidae) in Japan : Avian hosts, infestations, and a case of human dermatitis caused by adult

A bird-parasitic fly, Carnus hemapterus Nitzsch was found from three avian hosts in Japan. A total of 42, 35, and 2 adults of C. hemapterus was collected from nestlings of Eurytomus orientalis (Linnaeus), Dendrocopus major (Linnaeus), and Corvus corone Linnaeus, respectively. Eurytomus orientalis is a new host for C. hemapterus. Almost all flies obtained were dealate, but one alate male and two alate females were found from D. major and E. orientalis, respectively. Two deformed-wing flies were collected from a new nest box of E. orientalis. In 51 females, abdomens of 48 flies were distended or slightly distended, and those of 3 flies were not distended. A case of human dermatitis caused by a male adult fly was also reported from a survey of nesting ecology of D. major.

A new species and first stage associations in Crinitella (Ephemeroptera: Ephemerellidae: Ephemerellinae)

The alates of Crinitella coheri (Allen and Edmunds) are described for the first time, and morphological variability of the species is discussed. Male adults have penes with dorsal projections at the base of the gonopores and forceps with a relatively straight lateral profile. Crinitella coheri female alates and associated eggs have been misidentified as those of a Hyrtanella species. Crinitella coheri is reported from Vietnam for the first time. We describe C. lacuna, new species, based on male and female subimagoes and larvae, and the species is included in Crinitella on the basis of genitalia morphology. Alates of C. lacuna are distinguished from C. coheri by the presence of a prominent dorsal longitudinal stripe, and larvae are distinguished by having paired median spines on abdominal terga, mouthparts that are not greatly reduced, and gills 3 that are relatively larger than those of C. coheri. Crinitella lacuna is reported from India, Thailand and Vietnam. The structures of Crinitella and Hyrtanella gill cavities are different and do not represent a synapomorphy for the two genera.

Alternative mating behaviors of the queen polymorphic ant Temnothorax longispinosus

Mating behaviors of ants fall into two categories: female calling, in which a female alate releases pheromones that attract males, and male swarming, in which large male aggregations attract females. Female calling is common in species with queens that return to their natal nest to found colonies dependently after mating, while male swarming is common in species with queens that disperse to found independently. In some species that display both founding strategies, a queen-size polymorphism has evolved in which dependent-founding queens are smaller than independent-founding queens. Dependent founding is likely difficult if gynes (virgin queens) are mating in distant swarms. Therefore, a queen may adopt one or the other mating strategy based on its size and founding behavior. We investigated mating behaviors in the queen-polymorphic ant, Temnothorax longispinosus. Observations in laboratory mating arenas indicated that small gynes exhibited significantly lower flight activity than large gynes. Both forms mated in male swarms, and neither form exhibited female calling. The reduced flight activity of the small morph may facilitate returning to the natal nest after mating, provided the mating swarm is located nearby. Therefore, alternative colony-founding behaviors may be possible without the evolution of female-calling behavior; however, the reduced flight activity of small morphs may require that mating swarms are not distant from the natal nest.

Life table parameters affecting the population development of the woolly beech aphid, Phyllaphis fagi

AbstractA detailed study of the basic biological parameters affecting the population development of the woolly beech aphid, Phyllaphis fagi L. (Homoptera: Drepanosiphidae), was performed under field and laboratory conditions in order to obtain information about factors responsible for outbreak situations in forest nurseries. In the nurseries, the aphid eggs have found to hatch before budburst. The newly hatched nymphs were highly active in searching for feeding places, which resulted in higher nymph mortality in the first generation than in the following generations. Ten aphid generations were recorded in the nursery during one growing season. In the laboratory, development time, nymph mortality, reproduction, and adult lifetimes were assessed for P. fagi at four constant temperatures, i.e., 12, 15, 20, and 25 °C through four successive generations. Both temperature and aphid generation were found to affect life table parameters. The first generation, however, was less susceptible to changing temperatures than the following generations. Phyllaphis fagi reproductive effort was more dependent on temperature than on aphid generation. No significant difference was found in reproductive effort between apterous and alate females. The potential for outbreak situations therefore exists throughout the summer. The formation of winged morphs was not restricted to a few generations but rather continued for several months, with activity peaking in all years in mid‐June. This had implications for migration to new seedlings in the nurseries. The highest rm value was obtained at 20 °C. Nymphs born at higher temperatures were sometimes born deformed and unable to survive.

Mating Flight Activity as Dealation Factors for Red Imported Fire Ant (Hymenoptera: Formicidae) Female Alates

Queens of the red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae), release a primer pheromone that inhibits dealation (wing removal) of nestmate female alates by presumably suppressing endogenous concentrations of juvenile hormone (JH). Alates cast their wings once separated from the queen; however, the point of initiating dealation varies upon conditions. Alates are stimulated to shed their wings after several days of the death or removal of the queen, whereas newly mated alates dealate within 1 h after the mating flight. We found no single premating behavior or combination of behaviors associated with the nuptial flight that induces dealation rates comparable with that of newly mated queens. Copulation by itself or in conjunction with other behavioral signals and environmental prompts seems to be critical in causing rapid dealation in newly inseminated alates. In addition, colonies containing alates treated with precosene would not initiate mating flights nor could they be induced to fly. We suggest that precosene treatment affects the corpora allata (CA), but CA products other than juvenile hormone (JH) or in combination with JH are responsible for rapid dealation after mating. Dealation in the two contexts, within the colony and after mating flights, seems to occur via separate mechanisms.

Prevalence of Thelohania solenopsae infected Solenopsis invicta newly mated queens within areas of differing social form distributions

Newly mated queens (NMQs) originating from monogyne red imported fire ant ( Solenopsis invicta) colonies and following a mating flight, initiate new colonies by sealing themselves in a nuptial chamber and relying solely on their own fat and crop reserves, as well as no longer needed wing muscles to rear their first workers (claustral colony foundation). This method of colony-founding is rarely successful for polygyne-derived NMQs, whose low weight critically limits the number of first workers they are able to produce. However, this observation may be confounded by the parasitic microsporidium, Thelohania solenopsae, thus far found to persist only in association with polygyne colonies. Infections of this microsporidium reduce the weight of female alates and may explain why polygyne NMQs are unlikely to successfully found colonies claustrally. NMQs collected following mating flights in Gainesville and Ocala, Florida were sorted by weight, checked for insemination and T. solenopsae infection. Insemination levels were greater than 90% for all weight classes at both collection sites and were not related to infection. Infection levels were lower in Gainesville than Ocala, averaging 1.67% and 14.14%, respectively. Polygyne-derived NMQs collected in Ocala, defined here as weighing ⩽12 mg (social form correctly assigned in 85% of samples examined by PCR), had the highest infection levels, 25.37% (17/67) in 2003 and 21.43% (6/28) in 2004. We conclude that infection by T. solenopsae cannot be completely responsible for the inability of polygyne NMQs to claustrally establish colonies.

A novel hypothesis for the origin of the sexual division of labor in termites: which sex should be soldiers?

Sexual specialization and skewed sex ratios of the altruistic castes, especially soldiers, are common in many termite taxa. However, no theoretical or empirical studies have explained the origin of the sexual division of labor in termites. In most termite species, female alates are larger than male alates, and mature queens are much larger than kings, with females under consistent selection for high fertility. Therefore, females usually have the potential to be larger than males. Here, I present a novel preadaptation hypothesis that potential sexual differences in the suitability for the caste give rise to the sexual division of labor, and I provide the first evidence in support of this hypothesis in termites. Defense in Reticulitermes is typically performed by soldiers via mandibular and phragmotic defense in which soldiers with pluglike heads block openings, thus preventing enemies from invading the nest. Phragmotic defense requires that soldiers have heads wide enough to plug nest openings. Therefore, a size threshold for workers that develop into soldiers is a likely adaptation for effective defense. I show that sexual size dimorphism (SSD) and a size threshold for soldiers promote skewed sex ratios. A female-biased soldier sex ratio was observed in species with SSD, whereas there was no bias in soldier sex ratio in species without SSD. Thus, SSD and soldier sex ratio data from several Reticulitermes species support the preadaptation hypothesis.

A Taxonomie Note on Sclerodermas harmandi, Ectoparasite of Stem and Wood Boring Insect Larvae (Hymenoptera: Chrysidoidea'-Bethylidae) in South Korea

As a result of natural enemy survey against the Japanese pine sawyer (Monochamus alternates (Hope 1842)), the major vector of pine wood nematode (Bursaphelenchus xylophilus (Steiner & Buhrer 1934)), many samples of the ectoparasitic wasp, Sclerodermas harmandi (Buysson 1903) were collected nationwide in Korea from June to October in 2005. It is redescribed with the figures and biométrie data of apterous and alate females.

Early Emergence of Males in the Termite &lt;I&gt;Reticulitermes speratus&lt;/I&gt; (Isoptera: Rhinotermitidae): Protandry as a Side Effect of Sexual Size Dimorphism

The early emergence (protandry) of males is common in a variety of insects. Most studies to date have explained protandry as an adaptive reproductive strategy. Sexual selection favors males that emerge before females because this maximizes the number of encounters with females. However, protandry may be a side effect of female-biased sexual size dimorphism (SSD) because larger females need a longer developmental time than males. Despite the plausibility of the adaptive protandry hypothesis, determining whether protandry is adaptive or incidental is difficult because size and developmental time are interdependent. Female-biased SSD is a common trend among insects and has been most frequently attributed to fecundity selection favoring large females. Reticulitermes speratus Kolbe alates showed significant SSD with female alates that were consistently heavier than male alates. A significant tendency was observed that SSD increased as body size increased among the colonies. A sexual difference in eclosion timing should be disadvantageous in this termite species because male and female alates perform swarming (nuptial flight) synchronously. Alates of an early emerging sex must use reserve nutrition while they wait for eclosion of the other sex in the colony. Nevertheless, significant protandry was found in R. speratus, and this tendency was detected even at the molt of the earlier nymphal stage. Therefore, the early emergence of males in this termite species is clearly incidental protandry due to the SSD. The occurrence of incidental protandry or protogyny as a side effect of sexual size dimorphism may be as common as adaptive protandry.

Mating Flight Initiation and Nutritional Status (Protein and Lipid) of &lt;I&gt;Solenopsis invicta&lt;/I&gt; (Hymenoptera: Formicidae) Alates Infected with &lt;I&gt;Thelohania solenopsae&lt;/I&gt; (Microsporidia: Thelohaniidae)

Female alates of the red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae), infected with Thelohania solenopsae Knell, Allen, and Hazard (Microsporidia: Thelohaniidae) were found to be significantly less likely to be among the early alates to initiate a mating flight. If a flight was initiated, the infected females were significantly more likely to initiate the flight later in comparison with uninfected alates. In addition, many infected female alates seemed not to fly as a significantly greater proportion of the remaining females. Furthermore, infected females exhibited a significantly reduced body weight and a significantly reduced lipid titer, in comparison with uninfected individuals. However, there was no difference between the infected and uninfected alates in the amount of soluble protein. These results suggest that the low-weight, late flying-infected females may be less likely to reach a male mating swarm and less likely to outcompete uninfected females in mating and dispersing. Last, if mated or not, upon landing, the infected females may less likely have the needed energy to initiate a colony.

Sex Pheromone of the Soybean Aphid,Aphis glycinesMatsumura, and Its Potential Use in Semiochemical-Based Control

The newly invasive soybean aphid, Aphis glycines Matsumura, has seriously threatened soybean production in North America, after having spread to 20 states in the United States and several southern provinces of Canada. Control ofA.glycines has focused on applications of insecticides, which are not a long-term solution to soybean aphid pest management. In autumn, soybean aphids start producing alate females (gynoparae) that search for their overwintering host plants, the common buckthorn, Rhamnus cathartica. The gynoparae then produce pheromone-emitting wingless female offspring (oviparae) that attract male aphids. In this study, we report the chemical identiÞcation of the soybean aphid sex pheromone using gas chromatographyÐ electroantennogram, gas chromatog- raphyÐmass spectrometry, and nuclear magnetic resonance spectroscopy. Behavioral activities of males and gynoparous females in the Þeld were also characterized. The potential applications using formulations containing speciÞc soybean aphid pheromone compositions for reducing overwintering populations are discussed.

THE EFFECT OF AGE AND SOCIAL ENVIRONMENT ON DEALATION IN SOLENOPSIS INVICTA (HYMENOPTERA:FORMICIDAE) FEMALE ALATES

The fire ant (Solenopsis invicta Buren) queen produces a primer pheromone that prevents dealation (wing removal) of cohabiting female alates presumably by suppressing endogenous titers of juvenile hormone (JH). Alates are released from the effects of this primer pheromone when they are separated from the queen by physical disturbance, queen death, or mating flights. We investigated whether maturity influences the time at which female alates shed their wings. Results indicated that dealation rates were not different for newly-eclosed (sexually immature) or sexually mature alates. The dealation inhibitory pheromone did not suppress the casting of wings in newly-eclosed female alates that were relieved of their antennae. Dealation normally occurs within 1 h of a mating flight, whereas uninseminated alates isolated from colony members shed their wings significantly later. Therefore, dealation in the context of the colony and after mating flights appears to occur via separate mechanisms.

Persistence conditions of symmetric social hybridogenesis in haplo-diploid hymenoptera

In eusocial Hymenoptera species, females variably develop into either alate females (queens) or workers, and in most cases, caste differentiation is determined environmentally. Recently, however, female castes in two harvester ant species, Pogonomyrmex rugosus and P. barbatus, were found to be determined genetically in hybrid zones of these two species. In the hybrid populations, homozygous females (e.g. AA or BB) and heterozygous females ( AB) develop into alate females and workers, respectively. This genetic caste determination system is called symmetric social hybridogenesis (SSH). It is clear that populations with SSH can persist only if all four genotypes ( AA and BB females, and A and B males) coexist simultaneously. However, it is not obvious that these populations are always persistent when the four genotypes simultaneously exist. Here, we examined the stability and persistence of an SSH population using a simple mathematical model. According to the analysis of the model, the SSH population persists only when some conditions are satisfied: (1) each female mates with more than two males, and (2) male production increases less steeply than linearly with increasing numbers of workers in a colony, and alate female production increases more steeply than linearly with increasing numbers of workers, or (2′) male production increases more steeply than linearly with increasing numbers of workers in a colony, and alate female production increases much more steeply than male production. Therefore, it is not obvious that SSH populations are maintained and are stable for long periods. We discuss whether these conditions are satisfied in real SSH populations.