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1.
Background
Wolbachia are endosymbiotic bacteria that commonly infect numerous arthropods. Despite their broad taxonomic distribution, the transmission patterns of these bacteria within and among host species are not well understood. We sequenced a portion of the wsp gene from the Wolbachia genome infecting 138 individuals from eleven geographically distributed native populations of the fire ant Solenopsis invicta. We then compared these wsp sequence data to patterns of mitochondrial DNA (mtDNA) variation of both infected and uninfected host individuals to infer the transmission patterns of Wolbachia in S. invicta. 相似文献2.
Summary Male inhibition of female re-mating is com-mon in many insects. Mating plugs, used by males
to con-trol female re-mating, have been postulated in several ant species. Recent studies of
bumblebees have described re-mating inhibition by male accessory gland secretions. Fire
ants Solenopsis invicta possess accessory glands containing
the same four fatty acids as do the bumblebees. Furthermore it appears that some of these acids
are transferred to the female at mating. Thus, it is possible that single mating of fire ant
females may be enforced by male mating plugs. 相似文献
3.
Nest structure in ants is often designed to optimize the colony’s ability to thermoregulate, and this specialization is most
highly developed in mound-building ant species. Solenopsis invicta invest a large amount of energy in building mounds and transporting their brood up and down in their nests as a means of
thermoregulation. Because few ant species build true mounds, we wanted to determine the effectiveness of these mounds in harvesting
solar heat as well as to distinguish what factors (temperature vs. circadian rhythm) govern where fire ants place their brood
in the mound and when they place it. We measured temperature patterns in the mound over several days at different depths and
under different conditions (under direct sunlight or shade), and then conducted a series of field experiments to manipulate
the orientation and time of heating.
On cool mornings in spring or fall, surface temperatures of the mound rise at the fastest rate on the side receiving the most
direct sunlight (usually the south side). This heating causes a temperature gradient through different depths in the mound,
and shows little difference from outside ground temperature at a depth greater than ~40 cm inside the nest. In the morning,
fire ants move their brood up into the mound on the side most directly heated, and when temperatures exceed optimal (~32°C)
they move their brood down the temperature gradient to lower depths in the nest. In addition to this, mound temperature does
not only increase due to direct sunlight, but temperature also increases higher than ground temperatures when the mound is
in the shade due to its low specific heat.
Experiments in which sunlight was mirrored to the normally shaded side of the mound, or when mounds were heated at night,
revealed that S. invicta primarily track temperature patterns and do not rely on behavioral habits or circadian rhythms for the thermoregulatory transport
of their brood. When mounds were shaded, S. invicta brood was evenly distributed directly under the surface of the mound rather than aggregating towards a specific side. The
fire ant mound is important for thermoregulation because, compared to moundless subterranean nests, it absorbs heat more rapidly
both in direct sunlight and shady conditions. Temperature tracking within the nest is key to understanding thermoregulatory
placement of fire ant brood, as well as insight into the production of sexual brood and reproduction.
Received 9 August 2007; revised 31 January 2008; accepted 7 February 2008. 相似文献
4.
We generated and analyzed microsatellite genotypic data and mtDNA sequence data from the fire ant Solenopsis invicta collected from two separate infested areas (Taoyuan and Chiayi) in Taiwan to infer the population and colony structure of
these recently established populations. These genetic analyses revealed the following patterns: 1) Relatedness among worker
nestmates was significantly greater than zero for both social forms from both populations; 2) No significant isolation by
distance was found among nests within each social form from either population; 3) Significant mtDNA but no nuclear differentiation
occurs between sympatric social forms in Taoyuan; 4) Molecular signatures of genetic bottlenecks associated with recent introductions
are evident in both populations; and 5) The two sampled populations, Taoyuan and Chiayi, are highly genetically differentiated
at both the nuclear or mtDNA genomes and most likely derive from two separate introductions into Taiwan. While results from
these analyses generally were consistent with predictions based on the known biology of these ants and similar studies of
S. invicta in the U.S.A. and South America, some patterns likely reflect the recent introduction and human-mediated inadvertent transport
of ants in Taiwan. This is the first study to investigate the population and colony structure of fire ants in Taiwan and results
from our study represent an important contribution to the ongoing efforts aimed at eradicating this invasive pest in Taiwan.
Received 18 June 2007; revised 11 October 2007; accepted 17 October 2007. 相似文献
5.
6.
Despite the widespread impacts invasive species can have in introduced populations, little is known about competitive mechanisms
and dominance hierarchies between invaders and similar taxa in their native range. This study examines interactions between
the red imported fire ant, Solenopsis invicta, and other above-ground foraging ants in two habitats in northeastern Argentina. A combination of pitfall traps and baits
was used to characterize the ant communities, their dominance relationships, and to evaluate the effect of phorid flies on
the interactions. Twenty-eight ant species coexisted with S. invicta in a gallery forest gap, whereas only ten coexisted with S. invicta in a xerophytic forest grassland. S. invicta was the most numerically dominant species in the richest and complex habitat (gallery forest); however it performed better
as discoverer and dominator in the simpler habitat. S. invicta was active during day and night. In spite of its poor capacity to discover resources, S. invicta showed the highest ecological dominance and the second-best behavioral dominance after Camponotus blandus. S. invicta won 78% of the interactions with other ants, mostly against its most frequent competitor, Pheidole cf. obscurithorax, dominating baits via mass recruitment and chemical aggression. P. cf. obscurithorax was the best food discoverer. S. invicta won 80% of the scarce interactions with Linepithema humile.
Crematogaster quadriformis was one of the fastest foragers and the only ant that won an equal number of contests against S. invicta. The low presence of phorid flies affected the foraging rate of S. invicta, but not the outcome of interspecific interactions. This study revealed that the red imported fire ant ecologically dominated
other terrestrial ants in its native range; however, other species were able to be numerically dominant or co-dominant in
its presence. 相似文献
7.
Ishak HD Plowes R Sen R Kellner K Meyer E Estrada DA Dowd SE Mueller UG 《Microbial ecology》2011,61(4):821-831
Social insects harbor diverse assemblages of bacterial microbes, which may play a crucial role in the success or failure of
biological invasions. The invasive fire ant Solenopsis invicta (Formicidae, Hymenoptera) is a model system for understanding the dynamics of invasive social insects and their biological
control. However, little is known about microbes as biotic factors influencing the success or failure of ant invasions. This
pilot study is the first attempt to characterize and compare microbial communities associated with the introduced S. invicta and the native Solenopsis geminata in the USA. Using 16S amplicon 454 pyrosequencing, bacterial communities of workers, brood, and soil from nest walls were
compared between neighboring S. invicta and S. geminata colonies at Brackenridge Field Laboratory, Austin, Texas, with the aim of identifying potential pathogenic, commensal, or
mutualistic microbial associates. Two samples of S. geminata workers showed high counts of Spiroplasma bacteria, a known pathogen or mutualist of other insects. A subsequent analysis using PCR and sequencing confirmed the presence
of Spiroplasma in additional colonies of both Solenopsis species. Wolbachia was found in one alate sample of S. geminata, while one brood sample of S. invicta had a high count of Lactococcus. As expected, ant samples from both species showed much lower microbial diversity than the surrounding soil. Both ant species
had similar overall bacterial diversities, although little overlap in specific microbes. To properly characterize a single
bacterial community associated with a Solenopsis ant sample, rarefaction analyses indicate that it is necessary to obtain 5,000–10,000 sequences. Overall, 16S amplicon 454
pyrosequencing appears to be a cost-effective approach to screen whole microbial diversity associated with invasive ant species. 相似文献
8.
Freder Medina Haiwen Li S. Bradleigh Vinson Craig J. Coates 《Current microbiology》2009,58(5):478-482
In our previous study we isolated 10 bacterial species from fourth-instar larval midguts of the red imported fire ant, Solenopsis invicta. Here we report the genetic transformation and reintroduction of three species (Kluyvera cryocrescens, Serratia marcescens, and isolate 38) into the fire ant host. All three species were transformed with the plasmid vector, pZeoDsRed. High expression
levels of DsRed were observed and the plasmid is maintained in these bacteria at 37°C in the absence of antibiotic selection
for at least 9 days of subculturing. The transformed bacteria were successfully reintroduced into fire ant larvae and survived
in the fire ant gut for at least 7 days. Upon pupal emergence, 7 days after reintroduction, transformed bacteria can still
be isolated, however, most were passed out in the meconium. We further demonstrated that the engineered bacteria could be
spread within the colony by feeding this meconium to naive larvae with the aid of worker fire ants.
Freder Medina and Haiwen Li have contributed equally to this work. 相似文献
9.
Michael A. D. Goodisman Karen A. Sankovich Jennifer L. Kovacs 《Biological invasions》2007,9(5):571-584
Social insects are among the most successful and damaging of invasive taxa. We studied spatial and temporal variation in two
traits, colony genetic structure and worker mass, associated with social insect success in the introduced fire ant Solenopsis
invicta. Our aim was to determine if changes in social structure occurred over time and if variation in worker size was related to
worker genotype. We sampled 1139 workers from five multiple-queen S. invicta nests on six dates over a one-year period. The genotypes of workers were determined at ten microsatellite loci and at the
selected locus general protein-9 (Gp-9). We found little evidence for genetic differentiation of workers sampled from distinct nests or from different dates at
the microsatellite loci. However, worker Gp-9 genotype frequencies varied among nests and over time. In addition, worker mass was affected by nest-of-origin, sampling
date, ploidy level, and Gp-9 genotype. Our results suggest that large numbers of queens contribute to the production of workers in introduced S. invicta nests throughout the year. Colony boundaries are semi-permeable, although the among-nest variation in Gp-9 genotype frequencies and worker mass does suggest that boundaries are present. In addition, selection operating on Gp-9 genotype depends on nest environment. Finally, worker mass is affected by both endogenous and exogenous factors in S. invicta. Overall, our data suggests that the key traits of colony social structure and worker size reflect the effects of variable
selection in invasive social insects. 相似文献
10.
The phorid fly, Pseudacteon tricuspis is an introduced parasitoid of the red imported fire ant, Solenopsis invicta in the
United States. Previous studies show that phorid flies are attracted to host ant workers at disturbed colonies, to colonies
exhibiting aggressive interspecific interactions, and to fire ant mating flights. In a series of behavioral and electroantennogram
(EAG) experiments, we confirm the possible use of fire ant odor as cues for host location by P. tricuspis. We tested the response
of P. tricuspis of different sex and mating status to several host-related odor stimuli including live fire ant workers, extracts
of worker whole body, head, thorax, and abdomen, and (E,E)-α-farnesene, a trail pheromone component of Solenopsis fire ants.
Results from Y-tube olfactometer bioassays demonstrated the attraction of mated female P. tricuspis to live S. invicta workers.
In addition, extracts of S. invicta worker whole body and thorax elicited strong olfactometer response in female flies (mated
and unmated) and mated males, but not in unmated males. Pseudacteon tricuspis did not show significant attraction to extracts
of S. invicta worker head and abdomen, or to (E,E)-α-farnesene, irrespective of sex and mating status. In EAG experiments,
female and male P. tricuspis showed significant EAG response to extracts of worker whole body, head, and abdomen, and to a
less extent, thorax extract, but not to (E,E)-α-farnesene. Females showed slightly greater EAG response than males, but EAG
response was not affected by mating status. These results suggest that fire ant thorax is likely the source of kairomones
used as host location cues by P. tricuspis, and support the hypothesis that fire ant worker trail pheromones are not likely
used by P. tricuspis for host location. 相似文献
11.
We documented patterns of seasonal abundance and rates of parasitism in introduced populations of Pseudacteon tricuspis Borgmeier, a phorid parasitoid of the red imported fire ant, Solenopsis invicta Buren. Adult P. tricuspis populations were censused at monthly intervals for 1 year at three sites in northern Florida. Censuses were conducted by aspirating phorids attracted to disturbed S. invicta mounds. Pseudacteon tricuspis adults were present in every month at all sites, although abundances varied greatly among sites and over time. The highest densities of flies (up to 453 censused at 10 disturbed S. invicta mounds in 30 min) were observed in November, and changes in abundance over time were positively correlated among sites. Sex ratios were usually male biased. Parasitism rates were evaluated by collecting workers from field colonies and monitoring them in the laboratory for evidence of parasitism. Parasitism rates were very low – always less than 1%. The average parasitism rate per colony over 16 colonies and 2 years was 0.058%. No pupariation occurred within the first 8 days of collection, suggesting parasitism by P. tricuspis induced behavioral changes in parasitized workers that precluded such workers from our collections. If so, true field parasitism rates may be several times higher than measured here, yet still low in an absolute sense. These low parasitism rates can be reconciled with observed adult phorid densities by considering the large number of host ants present at the study sites. 相似文献
12.
Both monogyne and polygyne colonies of Solenopsis invicta now occupy Taiwan. Although venom alkaloids of these ants have been described and synthesized, we here report on a quantitative
analysis of the two social forms for the first time. The alkaloids were studied by gas chromatography coupled to mass spectrometry
(GC-MS), and six major venom alkaloids were detectable in both types of workers. Both C13:C13:1 and C15:C15:1 ratios in alkaloid venom of monogyne workers were statistically higher than that of polygyne workers, but the sum of proportions
of unsaturated alkaloids of polygyne workers was significantly higher than that of monogyne workers, regardless of growth
temperature, sampling seasons or geographic location. Results of this study demonstrate that the difference in the proportions
of unsaturated alkaloids and the ratios of C13:C13:1 and C15:C15:1 alkaloids might be a good indicator for differentiating monogyne and polygyne forms of S. invicta.
Received 20 February 2008; revised 4 July 2008; accepted 5 August 2008. 相似文献
13.
New combinations are proposed in anticipation of the Polygonaceae treatment in the forthcoming volume of Intermountain Flora:
Polygonum kelloggii var. esotericum, P. kelloggii var. watsonii
,
Rumex densiflorus var. pycnanthus
,
R. salicifolius var. utahensis, and R. occidentalis var. tomentellus. Typifications are proposed to facilitate ongoing studies in Polygonaceae and to maintain current usage. 相似文献
14.
We surveyed 165 sites to determine the ecological factors influencing the distribution, abundance, and occurrence of polygyny
in the red imported fire ant (Solenopsis invicta) in Louisiana. On average, sites had 220 nests/ha, 14% of mounds were polygyne, and 22% of sites had ≥ one polygyne mound.
The density of nests and ants per site both increased with the proportion of mounds that were polygyne and the organic and
phosphorous content of the soil but decreased with longitude, latitude, and the silt: clay, calcium and sodium content of
the soil. Ant density also declined with ambient relative humidity. These multivariate models explained ~25% of the variation
in nest and ant density per site. Mean mound size per site increased with the phosphorous content of the soil and the number
of nests at the site suggesting that prospective queens may select sites that are conducive to produce large mounds. Mean
nest size, however, decreased with the proportion of nests that were polygyne and soil potassium while mounds in forests were
typically larger than those in residential areas. Overall, this model accounted for 29% of the variation in mean nest size
per site. Polygyne sites were patchily distributed across Louisiana. The probability of a site being polygyne declined with
mean monthly temperature for 1999 – 2003 and distance to the nearest commercial waterway suggesting that shipping activities
may have played a role in the introduction of polygyne colonists to an area. Forested sites were also less likely to be polygyne
than those in residential areas. Finally, the density of polygyne nests and ants increased with latitude whereas that of the
monogyne form generally declined with latitude. The abundance of both social forms was also greater when they occurred alone.
These data are consistent with the hypothesis that monogyne and polygyne S. invicta compete with one another.
Received 28 July 2006; revised 2 March 2007; accepted 29 May 2007. 相似文献
15.
Background
The Sb supergene in the fire ant Solenopsis invicta determines the form of colony social organization, with colonies whose inhabitants bear the element containing multiple reproductive queens and colonies lacking it containing only a single queen. Several features of this supergene — including suppressed recombination, presence of deleterious mutations, association with a large centromere, and “green-beard” behavior — suggest that it may be a selfish genetic element that engages in transmission ratio distortion (TRD), defined as significant departures in progeny allele frequencies from Mendelian inheritance ratios. We tested this possibility by surveying segregation ratios in embryo progenies of 101 queens of the “polygyne” social form (3512 embryos) using three supergene-linked markers and twelve markers outside the supergene.Results
Significant departures from Mendelian ratios were observed at the supergene loci in 3–5 times more progenies than expected in the absence of TRD and than found, on average, among non-supergene loci. Also, supergene loci displayed the greatest mean deviations from Mendelian ratios among all study loci, although these typically were modest. A surprising feature of the observed inter-progeny variation in TRD was that significant deviations involved not only excesses of supergene alleles but also similarly frequent excesses of the alternate alleles on the homologous chromosome. As expected given the common occurrence of such “drive reversal” in this system, alleles associated with the supergene gain no consistent transmission advantage over their alternate alleles at the population level. Finally, we observed low levels of recombination and incomplete gametic disequilibrium across the supergene, including between adjacent markers within a single inversion.Conclusions
Our data confirm the prediction that the Sb supergene is a selfish genetic element capable of biasing its own transmission during reproduction, yet counterselection for suppressor loci evidently has produced an evolutionary stalemate in TRD between the variant homologous haplotypes on the “social chromosome”. Evidence implicates prezygotic segregation distortion as responsible for the TRD we document, with “true” meiotic drive the most likely mechanism. Low levels of recombination and incomplete gametic disequilibrium across the supergene suggest that selection does not preserve a single uniform supergene haplotype responsible for inducing polygyny.16.
Two repeated DNA sequences isolated from a partial genomic DNA library of Helianthus annuus, p HaS13 and p HaS211, were shown to represent portions of the int gene of a Ty3 /gypsy retroelement and of the RNase-Hgene of a Ty1 /copia retroelement, respectively. Southern blotting patterns obtained by hybridizing the two probes to BglII- or DraI-digested genomic DNA from different Helianthus species showed p HaS13 and p HaS211 were parts of dispersed repeats at least 8 and 7 kb in length, respectively, that were conserved in all species studied. Comparable hybridization patterns were obtained in all species with p HaS13. By contrast, the patterns obtained by hybridizing p HaS211 clearly differentiated annual species from perennials. The frequencies of p HaS13- and p HaS211-related sequences in different species were 4.3x10(4)-1.3x10(5) copies and 9.9x10(2)-8.1x10(3) copies per picogram of DNA, respectively. The frequency of p HaS13-related sequences varied widely within annual species, while no significant difference was observed among perennial species. Conversely, the frequency variation of p HaS211-related sequences was as large within annual species as within perennials. Sequences of both families were found to be dispersed along the length of all chromosomes in all species studied. However, Ty3 /gypsy-like sequences were localized preferentially at the centromeric regions, whereas Ty1/ copia-like sequences were less represented or absent around the centromeres and plentiful at the chromosome ends. These findings suggest that the two sequence families played a role in Helianthusgenome evolution and species divergence, evolved independently in the same genomic backgrounds and in annual or perennial species, and acquired different possible functions in the host genomes. 相似文献
17.
We have investigated the floral ontogeny of Arillastrum, Allosyncarpia, Stockwellia and Eucalyptopsis (of the eucalypt group, Myrtaceae) using scanning electron microscopy and light microscopy. Several critical characters for establishing relationships between these genera and to the eucalypts have been determined. The absence of compound petaline primordia in Arillastrum, Allosyncarpia, Stockwellia and Eucalyptopsis excludes these taxa from the eucalypt clade. Post-anthesis circumscissile abscission of the hypanthium above the ovary in Stockwellia, Eucalyptopsis and Allosyncarpia is evidence that these three taxa form a monophyletic group; undifferentiated perianth parts and elongated fusiform buds are characters that unite Stockwellia and Eucalyptopsis as sister taxa. No floral characters clearly associate Arillastrum with either the eucalypt clade or the clade of Stockwellia, Eucalyptopsis and Allosyncarpia.We gratefully acknowledge Clyde Dunlop and Bob Harwood (Northern Territory Herbarium) for collecting specimens of Allosyncarpia, and Bruce Gray (Atherton) for collecting specimens of Stockwellia. The Australian National Herbarium (CANB) kindly lent herbarium specimens of Eucalyptopsis for examination. This research was supported by a University of Melbourne Research Development Grant to Andrew Drinnan. 相似文献
18.
Hugh D. Wilson 《Economic botany》1990,44(3):92
Traditionally viewed as an Andean grain crop,Chenopodium quinoa Willd. includes domesticated populations that are not Andean, and Andean populations that are not domesticated. Comparative analysis of leaf morphology and allozyme frequencies have demonstrated that Andean populations, both domesticated(quinua) and free-living(ajara), represent an exceptionally homogeneous unit that is well differentiated from allied domesticates of coastal Chile(quingua) and freeliving populations of the Argentine lowlands(C. hircinum). This pattern of relationships indicates that Andean populations represent a monophyletic crop/weed system that has possibly developed through cyclic differentiation (natural vs. human selection) and introgressive hybridization. Relative levels of variation suggest that this complex originated in the southern Andes, possibly from wild types allied withC. hircinum, with subsequent dispersal north to Colombia and south to the Chilean coast. Coastal populations were apparently isolated from post-dispersal differentiation and homogenization that occurred in the Andes. Other data point toward a center of origin in the northern Andes with secondary centers of genetic diversity subsequently developing in the southern Andes and the plains of Argentina. Comparative linkage of South American taxa, all tetraploid, with North American tetraploids of the subsection will eventually clarify this problem. While the possibility of a direct phyletic connection betweenC. quinoa and the Mexican domesticate(C. berlandieri subsp. nuttalliae,) cannot be excluded, available evidence indicates that the latter represents an autonomous lineage that is associated with the basal tetraploid, C. b. subsp.berlandieri, through var.sinuatum, whereas South American taxa show possible affinities to either var. zschackei or var.berlandieri. An extinct domesticate of eastern North America,C. b. subsp.jonesianum, represents either another instance of independent domestication, possibly from subsp. b. var.zschackei, or a northeastern outlier of subsp.nuttalliae. 相似文献
19.
20.
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.
This research was supported in part by a US-Israel Binational Science Foundation Grant (no. 2003367). 相似文献