Male Alates Research Articles

Colony Structure of the Weaver Ant, Oecophylla smaragdina (Fabricius) (Hymenoptera: Formicidae)

The colony structure of Oecophylla smaragdina within the compound of Universiti Sains Malaysia, Penang Island, Malaysia was determined. The current study involved a total of twelve nests which were taken from two different locations. Each nest was dissected and the specimens were separated according to their caste. Results show that the colony structure of O. smaragdina consisted of a dealate queen, eggs, larvae of female alates, pupae of major and minor workers, pupae of female alates, major workers, minor workers, female alates and male alates. Our present study shows that O. smaragdina had a distinct caste system and the numbers of individuals in each caste reflect their respective functions which contributed to the success of their colony.

Alate susceptibility in ants.

Pathogens are predicted to pose a particular threat to eusocial insects because infections can spread rapidly in colonies with high densities of closely related individuals. In ants, there are two major castes: workers and reproductives. Sterile workers receive no direct benefit from investing in immunity, but can gain indirect fitness benefits if their immunity aids the survival of their fertile siblings. Virgin reproductives (alates), on the other hand, may be able to increase their investment in reproduction, rather than in immunity, because of the protection they receive from workers. Thus, we expect colonies to have highly immune workers, but relatively more susceptible alates. We examined the survival of workers, gynes, and males of nine ant species collected in Peru and Canada when exposed to the entomopathogenic fungus Beauveria bassiana. For the seven species in which treatment with B. bassiana increased ant mortality relative to controls, we found workers were significantly less susceptible compared with both alate sexes. Female and male alates did not differ significantly in their immunocompetence. Our results suggest that, as with other nonreproductive tasks in ant colonies like foraging and nest maintenance, workers have primary responsibility for colony immunity, allowing alates to specialize on reproduction. We highlight the importance of colony-level selection on individual immunity in ants and other eusocial organisms.

Dynamics of sex ratio, fresh weight and nutrient contents at five developmental stages of alates in the subterranean termite Reticulitermes chinensis

Sex ratio, fresh weight and nutrient contents were examined at five developmental stages of alates in the subterranean termite Reticulitermes chinensis Snyder, including sixth-instar nymphs, callow alates, dark alates, flying alates and dealates. The results showed that the sex ratio of callow alates and dark alates was highly female biased, but there were no significant differences in the percentage of females and males at sixth-instar nymphs, flying alates, and dealates. The fresh weights of alates declined with the developmental stages, suggesting a dynamic process in which the termites continue to shrink and harden. Meanwhile, the weights of female alates were significantly higher than weights of male alates in all five stages. There were no significant differences in the protein titers of the five developmental stages of alates. Flying alates were observed to have the highest triglyceride level, but a low glucose titer. This suggested that the main energy for flight of alates is provided by the breakdown of triglyceride reserves. Alates regardless of developmental stages, workers and soldiers had no significant differences in the cholesterol titers for the two extraction methods. Interestingly, there was a significantly negative linear correlation between the titer of glucose and the titer of triglyceride in both female alates and male alates during the five developmental stages, suggesting that the indirect mutual transformation between glucose and triglyceride might occur in the energy metabolism of all alates in R. chinensis.

Trehalase activity in fungus-growing termite, Odontotermes feae (Isoptera: Termitideae) and inhibitory effect of validamycin.

Trehalase is the hydrolytic enzyme that catalyzed the hydrolysis of trehalose to glucose. In this study, trehalase activity in the fungus-growing termite, Odontotermes feae Wasmann had been examined. Trehalase activity in digestive tract and carcass of O. feae was higher than that in wood-feeding termite, Coptotermes gestroi Wasmann. The intestinal tract of worker caste of O. feae was the main source of trehalase compared with that in salivary, fat body, and carcass. In particular, the highest activity was found in the midgut and hindgut parts. More specifically, the contents of midgut and hindgut had higher enzyme activity compared with that trehalase prepared from their epithelial tissue. The enzyme activity of gut trehalase in three different termite castes, worker, soldier, and reproductive, had been determined. The result showed that female alate had the highest activity, followed by worker, male alate, and soldier castes. Trehalose concentration in the reproductive caste was at lowest level, while soldier and worker contained the high trehalose concentration. This study indicates that high trehalase activity locates in the midgut and hindgut contents and change in trehalase activity in fungus-growing termite is caste-specific. Validamycin inhibited trehalase activity of O. feae in vivo and caused high mortality, indicating that this trehalase inhibitor is valuable tools for termite control.

A new Shivaphis species (Hemiptera: Aphididae) on the Chinese endemic plant, Pteroceltis tatarinowii.

A new species of aphid in subfamily Calaphidinae, Shivaphis pteroceltis sp. n., is described from China. This aphid feeds on Pteroceltis tatarinowii, an endemic tree commonly planted as an ornamental in China and used in the production of Xuan paper. The life cycle is described, and the descriptions of fundatrices, apterous and alate viviparae, oviparae and males are provided. COI sequences have been deposited in Genbank, and the type specimens are deposited in the National Zoological Museum of China, Institute of Zoology, Chinese Academy of Sciences, Beijing and Forestry Bureau of Central District, Zaozhuang City, Shandong Province, China.

Polygyny in the nest-site limited acacia-ant Crematogaster mimosae

Polygyny is common in social insects despite inevitable decreases in nestmate relatedness and reductions to the inclusive fitness returns for cooperating non-reproductive individuals. We studied the prevalence and mode of polygyny in the African acacia-ant Crematogaster mimosae. These ants compete intensively with neighboring colonies of conspecifics and with three sympatric ant species for resources associated with the whistling-thorn acacias in which they all obligately nest. We used the genotypes of alate males at ten microsatellite loci to reconstruct queen genotypes and found that C. mimosae colonies are frequently secondarily polygynous, in that they include multiple closely related (and sometimes full-sib) queens, and (more rarely) unrelated queens. We also found that individual queens in both monogynous and polygynous colonies had mated with multiple males, making C. mimosae an interesting example of simultaneous polygyny and polyandry. The presence of polygyny in C. mimosae and the intense competition for nest-sites between C. mimosae and its conspecifics support the association between nest-site limitation and polygyny. Polygyny may allow for increased worker populations and a competitive advantage, as inter-colony conflicts are typically won by the colony with the larger number of workers.

Toxicity of formic acid to red imported fire ants, Solenopsis invicta Buren

Ants often compete with other ants for resources. Although formic acid is a common defensive chemical of formicine ants, it does not occur in any other subfamilies in Formicidae. No information on toxicity of formic acid to red imported fire ants, Solenopsis invicta, is available. This study examined its contact and fumigation toxicity to S. invicta in the laboratory. In a contact toxicity bioassay, 24 h LD50 values of formic acid for workers ranged from 124.54 to 197.71 µg ant(-1) . Female alates and queens were much less sensitive to formic acid than workers. At a concentration of 271.72 µg ant(-1) , which killed 81.09 ± 16.04% of workers, the 24 h mortality was up to 39.64% for female alates and 38.89% for queens. In fumigation bioassays, 24 h LC50 values ranged from 0.26 to 0.50 µg mL(-1) for workers, 0.32 µg mL(-1) for male alates and 0.70 µg mL(-1) for female alates. Complete mortality (100%) in queens occurred 24 h after they had been exposed to 1.57 µg mL(-1) of formic acid. At a concentration of 2.09 µg mL(-1) , KT50 values ranged from 23.03 to 43.85 min for workers, from 37.84 to 58.37 min for male alates, from 86.06 to 121.05 min for female alates and from 68.00 to 85.92 min for queens. When applied topically, formic acid was significantly less toxic than bifenthrin to red imported fire ants. Although its fumigation toxicity was lower than that of dichlorvos, formic acid had about an order of magnitude higher toxicity to S. invicta than to other insects studied so far. It may be worth investigating the use of formic acid for managing imported fire ants.

Sexual morphs and colour variants of Aphis (formerly Toxoptera) odinae (Hemiptera, Aphididae) in Japan

Recent molecular studies have shown that the genus Toxoptera is polyphyletic, and in particular that the name of the aphid known since 1952 as Toxoptera odinae (van der Goot) should revert to Aphis odinae (van der Goot), stat. rev. In this paper oviparae, alate males and fundatrices of A. odinae are described for the first time, from Japan. A. odinae is common as a grey-brown or rust-brown aphid on numerous plant species of shrubby habit throughout the Old World tropics and subtropics, but in temperate east Asia much darker forms occur, and Japanese populations of A. odinae include a dark green form not found elsewhere in the world. Multivariate morphometrics were used to confirm that both colour forms of the aphid in Japan were conspecific with samples from other parts of the world. Pergandeida kalopanacis Hori 1927 is a new synonym of A. odinae.

Chemical communication in termites: syn-4,6-dimethylundecan-1-ol as trail-following pheromone, syn-4,6-dimethylundecanal and (5 E)-2,6,10-trimethylundeca-5,9-dienal as the respective male and female sex pheromones in Hodotermopsis sjoestedti (Isoptera, Archotermopsidae)

The trail-following pheromone and sex pheromones were investigated in the Indomalayan termite Hodotermopsis sjoestedti belonging to the new family Archotermopsidae. Gas chromatography coupled to mass spectrometry (GC–MS) after solid phase microextraction (SPME) of the sternal gland secretion of pseudergates and trail-following bioassays demonstrated that the trail-following pheromone of H. sjoestedti was syn-4,6-dimethylundecan-1-ol, a new chemical structure for termite pheromones. GC–MS after SPME of the sternal gland secretion of alates also allowed the identification of sex-specific compounds. In female alates, the major sex-specific compound was identified as (5 E)-2,6,10-trimethylundeca-5,9-dienal, a compound previously identified as the female sex pheromone of the termite Zootermopsis nevadensis. In male alates, the major sex-specific compound was identified as syn-4,6-dimethylundecanal, a homolog of syn-4,6-dimethyldodecanal, which has previously been confirmed as the male sex pheromone of Z. nevadensis. The presence of sex-specific compounds in alates of H. sjoestedti strongly suggests for this termite the presence of sex-specific pairing pheromones which were only known until now in Z. nevadensis. Our results showed therefore a close chemical relationship between the pheromones of the taxa Hodotermopsis and Zootermopsis and, in contrast, a clear difference with the taxa Stolotermes and Porotermes, which is in total agreement with the recent creation of the families Archotermopsidae and Stolotermitidae as a substitute for the former family Termopsidae.

Sex-pairing pheromones and reproductive isolation in three sympatric Cornitermes species (Isoptera, Termitidae, Syntermitinae)

The species-specificity of pairing has been studied in three sympatric Neotropical termites: Cornitermes bequaerti, Cornitermes cumulans and Cornitermes silvestrii (Termitidae, Syntermitinae). Bioassays showed that sex attraction was highly species-specific between C. bequaerti and C. cumulans but not between C. cumulans and C. silvestrii. The sex-pairing pheromone of the three species is secreted by the tergal glands of female alates. It consists of a common compound (3Z,6Z,8E)-dodeca-3,6,8-trien-1-ol. In C. bequaerti, this polyunsaturated alcohol is the only compound of the sex-pairing pheromone, whereas it is associated with the oxygenated sesquiterpene (E)-nerolidol in C. cumulans, and with (E)-nerolidol and (Z)-dodec-3-en-1-ol in C. silvestrii. (3Z,6Z,8E)-Dodeca-3,6,8-trien-1-ol is responsible for sexual attraction, whereas (E)-nerolidol, which is inactive in eliciting attraction of male alates, is responsible for the species-specificity of the attraction. This is the first time that a multicomponent sex-pairing pheromone has been identified in termites. The role of (Z)-dodec-3-en-1-ol present on the surface of the tergal glands of the female alates of C. silvestrii could not be definitively determined, but it is suggested that this compound could be involved in the species-specificity of sex attraction with other sympatric species of Cornitermes. Our study shows that the reproductive isolation in termites is due to a succession of factors, as the chronology of dispersal flights, the species-specificity of sex-pairing pheromones and the species-specific recognition.

Mites (Acari) Associated with the Desert Seed Harvester Ant,Messor pergandei(Mayr)

Mites (Acari) associated with the seed harvester antMessor pergandeiwere investigated in the Sonoran desert of Arizona. At least seven representatives of the mite generaArmacarus, Lemanniella, Petalomium, Forcellinia, Histiostoma, Unguidispus, andCosmoglyphusare phoretically associated withM. pergandei. Most of these morphospecies show preference for specific phoretic attachment sites and primarily use female alates rather than male alates for dispersal. Five mite morphospecies were found in low numbers inhabiting the chaff piles: Tydeidae sp.,Procaeculussp., Anystidae sp.,Bakerdaniasp., and Tetranychidae sp. The phoreticPetalomiumsp. was observed consuming fungus growing on a dead queen, but the roles of the other mite species remain mostly unresolved.

PBAN gene architecture and expression in the fire ant, Solenopsis invicta

The PBAN/pyrokinin peptides are a major neuropeptide family characterized by a common FXPRLamide at the C-termini. These peptides are distributed ubiquitously in the Insecta and are involved in many essential endocrine functions, e.g. pheromone production. We report the gene architecture of the fire ant Solenopsis invicta PBAN (Soi-PBAN) gene, including the exon and intron boundaries. Furthermore, we quantified expression of the Soi-PBAN mRNA in the head, thorax and abdomen of the fire ant. The Soi-PBAN gene is comprised three exons and two introns, all composed of 13,358 nucleotides, which is 2–4 times larger than lepidopteran PBAN genes. The overall pattern of the PBAN immunoreactive neuron number and localization was similar for female and male alates, inseminated female delates, workers and queens. The Soi-PBAN mRNA expression level was highest in the head, followed by the thorax, and abdomen of adult ants. Expression in the abdominal tissues was expected to be similar to the head, or at least higher than thorax because strong PBAN immunoreactive neurons were detected previously in brain–subesophageal and abdominal ganglia. This result suggests that another FXPRL gene could be dominant in the abdomen rather than Soi-PBAN gene.

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.

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.

Life Cycle of Cryptomyzus Leonuri Bozhko, 1961 in Lithuania with the Description of previously unknown Morphs

Cryptomyzus leonuri is the least investigated species of this genus in Europe. So far, the description of one morph, an apterous viviparous female, has been published (Bozhko 1961), and its life cycle remains unclear. This paper presents descriptions of previously unknown alate viviparous females, males and oviparous females of C. leonuri and the redescription of an apterous viviparous female, which has been also compared with the original description (Bozhko 1961) and character values indicated in the identification key of European species of the genus Cryptomyzus (Guldemond 1991a). Results of experimental cloning and the test on the possible host plant range are also summarised and measurements of both clonal and field samples are presented.

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.

PBAN/pyrokinin peptides in the central nervous system of the fire ant, Solenopsis invicta

The pyrokinin/pheromone-biosynthesis-activating neuropeptide (PBAN) family of peptides found in insects is characterized by a 5-amino-acid C-terminal sequence, FXPRLamide. The pentapeptide is the active core required for diverse physiological functions, including the stimulation of pheromone biosynthesis in female moths, muscle contraction, induction of embryonic diapause, melanization, acceleration of puparium formation, and termination of pupal diapause. We have used immunocytochemical techniques to demonstrate the presence of pyrokinin/PBAN-like peptides in the central nervous system of the fire ant, Solenopsis invicta. Polyclonal antisera against the C-terminal end of PBAN have revealed the location of the peptide-producing cell bodies and axons in the central nervous system. Immunoreactive material is detectable in at least three groups of neurons in the subesophageal ganglion and corpora cardiaca of all adult sexual forms. The ventral nerve cord of adults consists of two segmented thoracic ganglia and four segmented abdominal ganglia. Two immunoreactive pairs of neurons are present in the thoracic ganglia, and three neuron pairs in each of the first three abdominal ganglia. The terminal abdominal ganglion has no immunoreactive neurons. PBAN immunoreactive material found in abdominal neurons appears to be projected to perisympathetic organs connected to the abdominal ganglia. These results indicate that the fire ant nervous system contains pyrokinin/PBAN-like peptides, and that these peptides are released into the hemolymph. In support of our immunocytochemical results, significant pheromonotropic activity is found in fire ant brain-subesophageal ganglion extracts from all adult fire ant forms (queens, female and male alates, and workers) when extracts are injected into decapitated females of Helicoverpa zea. This is the first demonstration of the presence of pyrokinin/PBAN-like peptides and pheromonotropic activity in an ant species.

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.

Metabolic Influx and Energy Investment in Macrotermes convulsionarius (könig)

Although a considerable amount of information is available on termite caste differentiation, much less is known about metabolic influx and energy investment among castes, those would presumably play a pivotal role in termite physiology. In this study, nutritional metabolites among the major castes of Macrotermes were compared and the data illustrated that the worker caste holds considerable amount of energy, whereas the soldier caste enjoys huge reserves. Reproductive alates also showed higher metabolic turn over but we have concluded that energy allocation to reproduction is secondary and the energy investment in colony defense seems primary. Higher levels of glucose, cholesterol, creatinine, and fatty acids were observed in soldier caste, suggesting colony defense is an energydemanding phenomenon. Since Uric acid formation without xanthine oxidase (XO) is unlikely, exogenous uric acid source from other nest mates may be possible, because negligible XO activity and considerable amount of uric acid content is observed in soldier caste. Observed uric acid content and xanthine oxidase activity both were descending in the order of female, male, worker, and soldier castes. Alates have huge reserves of ATP, triglyceride, fatty acids, and uric acid. Maximum fatty acids reserve was observed in male alates and predominant gross fatty acids measured by GC-MS were stearic and oleic.

Role of (3Z,6Z,8E)-Dodecatrien-1-ol in Trail Following, Feeding, and Mating Behavior of Reticulitermes hesperus

Trail pheromones mediate communication among western subterranean termites, Reticulitermes hesperus Banks. Repetitive passages of >or=28 termites were required to establish a pheromone trail and trails needed to be reinforced because they lasted <48 hr. The minimal threshold concentration for inducing responses from termite workers and secondary reproductives was between 0.01 and 0.1 fg/cm of (3Z,6Z,8E)-dodecatrien-1-ol (henceforth, dodecatrienol). Workers showed optimal trail-following behavior to dodecatrienol at a concentration of 10 fg/cm. Trails with concentrations >10 pg/cm were repellent to workers. Workers did not detect pheromone gradients, responding equally to increasing or decreasing gradients of dodecatrienol, and termite workers were not able to differentiate between different concentrations of dodecatrienol. Termites preferred dodecatrienol trails to 2-phenoxyethanol trails. Antennae played a key role in trail pheromone perception. Dodecatrienol acted as an arrestant for worker termites (10 fg/cm2) and male alates (5 ng/cm2), whereas sternal gland extracts from females attracted male alates. Workers and alates, upon contact with filter paper disks treated with higher doses (10 fg/cm2 and 5 ng/cm2, respectively) of dodecatrienol, were highly excited (increased antennation and palpation) and repeatedly returned to the treated disks. Dodecatrienol did not act as a phagostimulant when offered on a paper towel disk. Reticulitermes hesperus is highly responsive to dodecatrienol, and it may play an important role in orientation of workers and alates.