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1.
Sex ratios were bimodally distributed in a population of the monogynous and monandrous ant Leptothorax nylanderi during each of 3 study years. The population-wide investment ratios suggested worker control of sex allocation. Nest-level
variation in the proportional investment in virgin queens was not affected by the presence or absence of a queen and only
slightly by collecting year, but was correlated with nest size, total sexual investment and, unexpectedly, with differences
in nestmate relatedness: small, low-investment nests and nests with several worker lineages produced male-biased sex ratios.
Colonies containing several worker lineages arise from usurpation of mature colonies by unrelated founding queens and the
fusion of unrelated colonies under strong nest site limitation. In contrast to facultatively polygynous and polyandrous species
of social insects, where workers can maximize their inclusive fitness by adjusting sex ratios according to the degree of relatedness
asymmetry, workers in mixed colonies of L. nylanderi do not benefit from manipulating sex allocation, as here relatedness asymmetries appear to be the same as in homogeneous
colonies.
Received: 7 December 1999 / Received in revised form: 29 February 2000 / Accepted: 13 March 2000 相似文献
2.
Fertility signaling in queens of a North American ant 总被引:3,自引:0,他引:3
In most species of advanced eusocial insects, the partitioning of reproduction between nestmates is thought to be regulated
by means of primer pheromones or other chemical cues, which presumably influence the behavior of co-queens and workers such
that they maximize their own inclusive fitness. Here we show that in multi-queen colonies of the Nearctic ant, Leptothorax sp. A, physical dominance in concert with chemical cues, which signal the ovarian development of a queen, are used to control
reproduction of competing queens and to influence worker behavior. The analysis of ranks obtained during two fighting periods
in the annual colony cycle revealed a strong link between individual aggressiveness of a queen and her fertility. During the
adoption of newly mated queens in autumn, the resident, egg-laying α-queen was more likely to start aggression first and keep
her high rank position compared to the fighting period after hibernation. We suggest that this is proximately caused by the
α-queen having much stronger developed ovaries in autumn than the young queens, whereas after hibernation, the ovaries of
all queens are similarly inactive. Interactions during the first weeks after the end of hibernation and intrinsic, individual
differences in aggressiveness appear to be crucial for the dominance rank achieved later. Queens which were allowed to become
fertile when their nestmate queens still were kept under prolonged hibernation, were immediately socially dominant over the
latter when all queens were reunited, though no aggression occurred. In another experiment, queen antagonism was prevented
by spatial separation in different parts of the same nest and all queens began to lay eggs. Workers stayed preferentially
with queens with high actual fecundity rather than with those which had had high social status before separation. This and
further evidence suggest that ovarian status is communicated, most likely by a chemical cue perceived by co-queens and workers,
affects the direction of their aggressive behavior, and allows them to discriminate among queens.
Received: 5 May 1998 / Accepted after revision: 29 August 1998 相似文献
3.
Summary. An aphidiid wasp, Paralipsis eikoae, was associated with both Lasius niger and L. sakagamii attending the wormwood root aphid Sappaphis piri. An L. sakagamii worker was observed carrying a winged female P. eikoae to its nest with its mandible, but it did not kill the wasp. Once accepted by the ants, the wasp often mounted and rubbed
against the worker ants and sometimes teased them to regurgitate food to itself. No workers in the colony attacked the wasp.
Conspecific foreign workers, however, viciously attacked the wasp when encountered. Gas chromatography-mass spectrometry analyses
showed that the accepted wasp had complex cuticular hydrocarbons that were very similar to those of its host ants, whereas
the winged wasps collected outside the ant nest showed only a series of n-alkanes. Additionally, the accepted wasp had a hydrocarbon profile closer to that of its host ants than to the conspecific
foreign ants. We believe the wasp mimics ant cuticular hydrocarbons to integrate into the ant nest, acquiring the hydrocarbons
by mounting and rubbing against the ants. In contrast, the cuticular hydrocarbons of the emerged wasp contained larval and
pupal hydrocarbons of L. sakagamii that were also similar to those of L. niger. Both ant species rejected adult workers of the other species but accepted their larvae and pupae. We suggest that the emerged
P. eikoae mimics the cuticular hydrocarbons of these Lasius larvae and pupae, which allows P. eikoae to be accepted by both L. sakagamii and L. niger.
Received 11 March 1998; accepted 22 July 1998. 相似文献
4.
Patrizia D''Ettorre Christine Errard Fernando Ibarra Wittko Francke Abraham Hefetz 《Chemoecology》2000,10(3):135-142
Summary. The dulotic queen ant, Polyergus rufescens, must first penetrate a host colony and kill the resident queen in order to successfully founding a new colony. Successful
usurpation by a newly mated queen predictably depends on a dual strategy. Although, it can sneak in by being “chemically insignificant”
with respect to cuticular hydrocarbons, it may also need to deter prospective host-worker aggressors. Chemical analysis of
Dufour's gland secretion of P. rufescens queens and workers by GS/MS revealed that queen secretion is typified by esters of butanoic acid and acetic acid, of which
decyl butanoate comprises over 80%. Butanoates and acetates are also present in the workers' secretion, but these are of higher
molecular weight, and octadecyl butanoate represents the major compound. Using synthetic mixtures of queen and worker Dufour's
gland, we tested the hypothesis that these secretions modify the aggressive behavior of the host species Formica cunicularia>. The queen-like synthetic mixture significantly reduced aggression of the host workers towards alien conspecifics, but neither
pentane nor the worker-like synthetic mixture showed this effect. Although Dufour's gland content of >Polyergus queens was suggested to function as an appeasement pheromone (Topoff et al. 1988; Mori et al. 2000), we hypothesized that it may in fact act as a repellent. In order to test this hypothesis we exposed starved F. cunicularia workers to a droplet of honey on a glass slide applied with one of the following compounds: decyl butanoate (queen major
compound), octadecyl butanoate (worker main compound), limonene (a reported ant repellent), and pentane (solvent control).
Of these, the workers were repelled only by the decyl butanoate and did not approach the honey. We conclude that during usurpation
the queen actively repels aggressive workers by emitting Dufour's gland repellent, comprising the alternative tactic in the
usurpation dual strategy. This represents another chemical weapon in the diverse arsenal used by parasites to overcome the
host's resistance.
Received 7 April 2000; accepted 17 May 2000 相似文献
5.
Jacques M. Pasteels Arnaud Termonia Donald M. Windsor Ludger Witte Claudine Theuring Thomas Hartmann 《Chemoecology》2001,11(3):113-120
Summary. Field collected exocrine defensive secretions of nine neotropical Platyphora species were analyzed for the presence of plant acquired pyrrolizidine alkaloids (PAs) and pentacyclic triterpene saponins.
All species secrete saponins. In addition, five species feeding on Tournefortia (Boraginaceae), Koanophyllon (Asteraceae, tribe Eupatorieae) and Prestonia (Apocynaceae) were shown to sequester PAs of the lycopsamine type, which are characteristic for species of the three plant
families. The PA sequestering species commonly store intermedine, lycopsamine and their O3′-acetyl or propionyl esters as well as O7- and O9-hydroxyisovaleryl esters of retronecine. The latter as well as the O3′-acyl esters were not found in the beetles’ host plants, suggesting the ability of the beetles to esterify plant derived retronecine
and intermedine or its stereoisomers. Despite the conformity of the beetles’ PA patterns, considerable inconsistencies exist
regarding the PA patterns of the respective host plants. One host plant was devoid of PAs, while another contained only simple
necines. Since the previous history of the field collected beetles was unknown this discrepancy remains obscure. In contrast
to the Palearctic chrysomeline leaf beetles, e.g. some Oreina species which ingest and store PAs as their non-toxic N-oxides, Platyphora leaf beetles absorb and store PAs as the toxic free base (tertiary PA), but apparently avoid to accumulate PAs in the haemolymph.
This suggests that Chrysolina and Platyphora leaf beetles developed different lines of adaptations in their parallel evolution of PA mediated chemical defense.
Received 30 November 2000; accepted 5 February 2001 相似文献
6.
Klaus Peschke Peter Friedrich Uwe Kaiser Stephan Franke Wittko Francke 《Chemoecology》1999,9(2):47-54
Summary. In the rove beetle Aleochara curtula, a male specific sternal gland is described. Isopropyl (Z9)-hexadecenoate has been identified by GC/MS of surface and sternal gland extracts as a male specific compound. Its emission
in the air was demonstrated by closed-loopstripping-analyses. In field experiments, conspecific males and females were attracted
by the odor of carrion, caged males from laboratory cultures, and by the synthetic ester. Isopropyl (Z9)-hexadecenoate or live males, combined with fresh carrion attract more beetles than a fresh carcass alone. Isopropyl hexadecanoate
as a minor compound was not attractive. The term “aggregation” pheromone and the ecological significance of attracting females
to a fresh carcass allowing early copulation and egg-deposition are discussed.
Received 20 August 1998; accepted 15 January 1999. 相似文献
7.
Ana M. M. Viana Anne Frézard Christian Malosse Terezinha M. C. Della Lucia Christine Errard Alain Lenoir 《Chemoecology》2001,11(1):29-36
Summary. Leaf cutting ants live in symbiosis with a basidiomycete fungus that is exploited as a source of nutrients for the ant larvae.
Tests of fungus transport demonstrated that Acromyrmex subterraneus subterraneus workers discriminate concolonial fungus from alien fungus, and rejected the latter. Larvae and pupae of the ant were used
as controls. Chemical analysis of the fungus revealed a great similarity between its hydrocarbon profile and that found on
the ant brood. Experiments with lures showed that chemical extracts from the fungus are responsible for this discrimination
process. Moreover, the presence of brood inside the fungus seemed to be important for discrimination of the fungus by workers.
Resident workers accepted concolonial broodless fungus less than concolonial fungus inoculated with brood odor. Fungus seems
to acquire colonial odor passively, simply by contact with the brood. The impact of fungus volume present in the nest on closure
of the colony is discussed. We show here for the first time the importance of a symbiotic vegetal organism in colonial recognition
in social insects.
Received 14 April 2000; accepted 29 September 2000 相似文献
8.
Induction of host specificity in larvae of Manduca sexta: chemical dependence controlling host recognition and developmental rate 总被引:2,自引:0,他引:2
Summary. The tobacco hornworm, Manduca sexta L. (Lepidoptera: Sphingidae) is a specialist on Solanaceae. This host specificity is induced as the larva feeds on solanaceous
foliage, so that solanaceous-reared larvae will refuse to feed on other plants. Experiments were designed to determine the
role of dietary constituents on the induction of host specificity and the effects of these on development of M. sexta. Choice assays using leaf discs of cowpea, Vigna sinensis (Fabaceae), were used to monitor the isolation of relevant chemical cues from foliage of potato. An aqueous extract of potato
foliage strongly stimulated feeding. This extract was partitioned with n-butanol under alkaline conditions to obtain a highly active butanol extract. Reversed phase flash chromatography with a water-methanol
gradient gave an active fraction that was used as a supplement for wheat germ-based artificial diet. Larvae reared on this
s-diet became dependent on potato allelochemicals for initiation and continuation of feeding activity. These larvae also developed
faster than larvae reared on the control p-diet, but no effect on adult mass was detected. Further flash chromatography of
the active fraction under alkaline conditions provided a highly active sub-fraction, and semi-preparative HPLC using gradients
of water and acetonitrile resulted in the isolation of a single compound. Bioassays indicated that this compound alone can
account for host recognition by solanaceous-reared larvae. The results suggest that the mechanism of induced host specificity
in M. sexta involves development of dependence on this compound.
Received 21 December 1999; accepted 14 March 2000 相似文献
9.
Katrin Strauss Holger Scharpenberg Robin M. Crewe Felix Glahn Heidi Foth Robin F. A. Moritz 《Behavioral ecology and sociobiology》2008,62(9):1523-1531
Queen pheromones interfere with worker reproduction in social insects. However, there is still an unresolved question as to
whether this pheromone acts as an “honest” signal for workers, giving a reliable indication of the queen’s reproductive value,
or as a suppressive agent, inhibiting worker reproduction independent of the queen’s reproductive capacity. In honeybees (Apis mellifera), the queen’s mandibular gland secretion, a mix of fatty acids and some aromatic compounds, is crucial for regulating the
reproductive division of labor in the colony inhibiting ovary development in workers. We quantified the mandibular gland secretions
of virgin, drone-laying, and naturally mated queens using gas chromatography to test whether the queens’ mating, ovary activation,
or the reproductive value for workers correlated with the composition of the secretion. Although the absolute amounts of the
“queen substance” 9-oxo-2(E)-decenoic acid (9-ODA) were similar among the three groups, the proportions of 9-ODA decreased
with increasing reproductive quality. Furthermore, the ratios of queen to worker compounds were similar in all three treatment
groups, irrespective of the reproductive capacity. A multivariate analysis including all six compounds could not separate
drone-laying queens from naturally mated ones, both with active ovaries but only the latter ensuring colony survival. We suggest
that the mandibular gland pheromones are unlikely to function as reliable indicators of queen reproductive value and rather
operate as an agent to suppress worker reproduction. This does not exclude the possibility that other “honest” pheromone signals
exist in the honeybee colony, but these would have to arise from other semiochemicals, which could be produced by both the
queen and the brood. 相似文献
10.
Summary. The African stink ants (Pachycondyla tarsata) lay recruitment trails with secretions from sternal glands. The glandular secretions consist of 10 compounds, 9 of which
have been chemically identified. One of the substances, 9-heptadecanone, elicits trail following behavior in P. tarsata workers that have before been stimulated by a sucessful scout ant.
Received 7 August 1998; accepted 24 November 1998. 相似文献
11.
Testing the limits of social resilience in ant colonies 总被引:4,自引:0,他引:4
Sarah J. Backen A. B. Sendova-Franks Nigel R. Franks 《Behavioral ecology and sociobiology》2000,48(2):125-131
Social resilience is the ability of Leptothorax ant colonies to re-assemble after dissociation, as caused, for example, by an emigration to a new nest site. Through social
resilience individual workers re-adopt their spatial positions relative to one another and resume their tasks without any
time being wasted in worker respecialisation. Social resilience can explain how an efficient division of labour can be maintained
throughout the trials and tribulations of colony ontogeny including the, often substantial, period after the queen dies when
the ability to conserve worker social relationships may be essential for efficiency to be maintained. The mechanism underlying
social resilience is, therefore, expected to be robust even in the absence of many of the colony’s components, such as the
queen, the brood and even a large proportion of the workers. Such losses are likely, given the ecology of this genus. Using
sociotomy experiments, we found that social resilience can occur in the absence of the queen. Furthermore, the spatial component
of social resilience can occur even when the queen, the brood, as well as a large proportion of the workers, are all absent
simultaneously and hence many of the tasks are missing. We conclude, therefore, that social resilience is indeed robust. This
does not, however, preclude worker flexibility in response to changes in task supply and demand. We propose a possible sorting
mechanism based on worker mobility levels which might explain the robustness underlying this phenomenon.
Received: 25 October 1999 / Accepted: 1 April 2000 相似文献
12.
Spread of metals through an invertebrate food chain as influenced by a plant that hyperaccumulates nickel 总被引:6,自引:0,他引:6
Lynsey R. Peterson Victoria Trivett Alan J.M. Baker Carlos Aguiar A. Joseph Pollard 《Chemoecology》2003,13(2):103-108
Summary. Hyperaccumulation of metals in the shoot system of
plants is uncommon, yet taxonomically and geographically widespread. It
may have a variety of functions, including defense against herbivores.
This study investigated the effects of hyperaccumulation on metal
concentrations across trophic levels. We collected plant material, soil,
and invertebrates from Portuguese serpentine outcrops whose vegetation
is dominated by the nickel hyperaccumulator Alyssum pintodasilvae.
Samples were analyzed for nickel, chromium, and cobalt. Grasshoppers,
spiders, and other invertebrates collected from sites where A.
pintodasilvae was common had significantly elevated concentrations of
nickel, compared to nearby sites where this hyperaccumulator was not
found. Chromium and cobalt, occurring in high concentrations in the
serpentine soil but not accumulated by A. pintodasilvae, were not
elevated in the invertebrates. Therefore, it appears likely that a flux
of nickel to herbivore and carnivore trophic levels is specifically
facilitated by the presence of plants that hyperaccumulate this metal.
The results may be relevant to the development of phytoremediation and
phytomining technologies, which use plants to extract metals from the
soil.
Reveived 22 August 2002; accepted 2 April 2003.
R1D="
Correspondence to: A. J. Pollard, e-mail:joe.pollard@furman.edu 相似文献
13.
Aggression and resource sharing among foundresses in the social wasp Polistes dominulus: testing transactional theories of conflict 总被引:3,自引:0,他引:3
Tug-of-war models of within-group conflict predict that the frequency of conflict will be positively related to the degree
of reproductive sharing within the group; in contrast, a negative relationship supports transactional models, in which reproductive
payments among group members limit the degree of within-group selfishness. We tested predictions of the tug-of-war and transactional
models by examining cofoundress interactions during the founding (preworker) phase of colony development in 30 naturally nesting
colonies of the paper wasp Polistes dominulus. We found that the mean rate of foundress aggression and the mean probability of food sharing were significantly negatively
associated, which supports the prediction of the transactional, not the tug-of-war model. Further, cofoundress aggression
significantly increased over the founding phase (independently of temperature), while the fraction of aggression initiated
by the dominant (alpha) foundress significantly decreased over this period. We show that both of these results are predicted
by the transactional model of within-group conflict. Interestingly, the alpha’s rate of aggression was significantly positively
temperature dependent, while the beta’s was not. This indicates that the alpha’s aggression level may often be near her physiological
maximum, while the beta’s aggression is limi- ted by other factors, contradicting the prediction of the tug-of-war model.
Moreover, the alpha’s aggression was significantly positively temperature dependent only in the second half of the founding
period, as predicted by the transactional model since this is when there is least reproductive sharing. Finally, our results
indicate that the alpha’s level of aggression depends on the resources controlled by the beta.
Received: 18 January 2000 / Revised: 19 June 2000 / Accepted: 24 June 2000 相似文献
14.
Summary. Induction of secondary metabolites to herbivore damage is a widespread phenomenon among plants and serves to enhance resistance
by reducing suitability or increasing toxicity of foliage. Post-damage responses of primary metabolites are less well known;
reductions in primary metabolites may increase resistance by decreasing palatability or nutritional suitability for herbivores
or by potentiating toxicity of secondary metabolites. In this study, we examined response to simulated herbivory in Pastinaca sativa, the wild parsnip, in both primary and secondary metabolites. We found that induction of secondary metabolites in response
to damage is largely restricted to a single class of compounds, the furanocoumarins. These prooxidant compounds are known
to be toxic to a wide variety of insect herbivores. The only primary metabolite that responded to damage was total soluble
protein, which increased significantly 24 h after damage. After 24 h, the correlation between total furanocoumarins and total
sugars was significant and negative (r = − 0.697). This correlation likely reflects an independent response of sugar to damage,
rather than a diversion of resources into furanocoumarin production, inasmuch as this correlation at 3 h, after furanocoumarin
induction had taken place, was not significant. In other secondary metabolite pathways, damage produced a significant decline
in farnesene and a C-16 unsaturated fatty acid, 7,10,13-hexadecatrienoic acid, each of which may potentiate the furanocoumarin
defense response. Farnesene may enhance photooxidative activation of the furanocoumarins and 7,10,13-hexadecatrienoic acid
may serve as a precursor to jasmonic acid, a key hormone in regulating induction responses. With few key exceptions, quantities
of both primary and secondary metabolites in wild parsnip foliage are unaffected by damage. Those that are affected may well
play a role in resistance of parsnips to herbivores.
Received 1 July 1998; accepted 28 September 1998. 相似文献
15.
Summary. Analysis of individuals of 17 troidine species demonstrated the presence of aristolochic acids in these butterflies in varying
concentrations. Although aristolochic acids do not occur in Aristolochia galeata leaves, they were present in Battus polydamas larvae reared on these leaves, and thus may be synthesized by the larvae from chemical precursors in the plant.
Received 17 August 1999; accepted 20 January 2000 相似文献
16.
Summary. The Na+, K+-ATPase of the Monarch butterfly (Danaus plexippus) is insensitive to the inhibition by cardiac glycosides due to an amino acid replacement: histidine instead of asparagine
at position 122 of the α-subunit representing the ouabain binding site. By PCR amplification of the DNA sequence of this site,
a PCR product of 270 bp was obtained from DNA extracted from Danainae species (Danaus plexippus, D. chrysippus, D. gillipus, D. philene, D. genutia, Tirumala hamata, Euploea spp., Parantica weiskei, P. melusine), Sphingidae (Daphnis nerii) and mimics of milkweed butterflies (Hypolimnas missipus, Limenitis archippus and L. arthemis, Nymphalidae). Analysis of the nucleotide sequences revealed that the single point mutation in the ouabain binding domain
(AAC-Asn for CAC-His) was present only in Danaus plexippus, but not in the other species investigated. Since these milkweed butterflies also store cardenolides, other structural modifications
of the Na+, K+-ATPase may have occurred or other strategies of cardenolide tolerance have been developed.
Received 15 May 2000; accepted 29 June 2000 相似文献
17.
Deepa S. Pureswaran Regine Gries John H. Borden Harold D. Pierce Jr. 《Chemoecology》2000,10(4):153-168
Summary. The mountain pine beetle, Dendroctonus ponderosae Hopkins, and the pine engraver, Ips pini (Say), often co-exist in lodgepole pine, Pinus contorta var. latifolia Engelmann. Intra- and interspecific semiochemical communication occurs in both species and their complete semiochemical repertoire
and precise dynamics of pheromone production have not been elucidated. Porapak-Q extracts of captured volatiles from beetles
of each species aerated at different attack phases (freshly emerged, pioneer sex alone in the log and both sexes paired in
new galleries), followed by gas chromatographic-electroantennographic detection (GC-EAD) and GC-mass spectroscopic analyses
identified 17 compounds (seven compounds common to both species, six present in D. ponderosae and four present in I. pini) that excited the antennae of either or both species. Seven compounds for D. ponderosae and nine for I. pini had not been assessed for behavioural activity. In field trapping experiments, 2-phenylethanol produced by both species inhibited
the response of D. ponderosae to its aggregation pheromones. exo- and endo-Brevicomin produced by D. ponderosae significantly decreased the response of I. pini to its aggregation pheromone ipsdienol. Nonanal, a ubiquitous compound found in the volatiles of lodgepole pine, various
nonhosts and in both beetle species deterred the response of I. pini to ipsdienol. The occurrence of cis-verbenol, trans-verbenol and verbenone in emergent I. pini, and verbenone and 2-phenylethanol in emergent D. ponderosae suggests that these compounds may inhibit aggregation and induce dispersal following emergence. Termination of aggregation
in D. ponderosae appears to depend on the production of frontalin in combination with changes in the relative ratios of verbenone, exo-brevicomin, trans-verbenol and 2-phenylethanol. In I. pini, the cessation of ipsdienol production by males is probably the main factor in terminating aggregation.
Received 16 November 1999; accepted 7 August 2000 相似文献
18.
Raphaël Boulay Abraham Hefetz Xim Cerdá Séverine Devers Wittko Francke Robert Twele Alain Lenoir 《Behavioral ecology and sociobiology》2007,61(10):1531-1541
Models based on the kin selection theory predict that in social hymenopterans, queens may favor a lower investment in the
production of sexuals than workers. However, in perennial colonies, this conflict may be tuned down by colony-level selection
because of the trade off between colony survival and reproductive allocation. In this study, we present a survey of sexual
production in colonies of Aphaenogaster senilis, a common species of ant in the Iberian Peninsula. Similar to most species that reproduce by fission, males were found in
large excess compared to gynes (172:1). Sexuals were more likely to be found in queenless than in queenright (QR) field colonies.
However, we also found a few gynes and numerous males in very large QR colonies. We compared these data with those available
in the literature for A. rudis, a congeneric species from North America that has independent colony founding. The sex ratio in this species was only five
males for each female, and sexuals were mostly found in QR nests, irrespective of colony size. We confirmed queen inhibition
of sexual production in A. senilis in laboratory experiments and provide evidence that this inhibition is mediated by a nonvolatile pheromone. To seek the potential
source of such a queen pheromone, we analyzed the secretions of two conspicuous exocrine glands, the Dufour’s and postpharyngeal
glands (DG and PPG, respectively) in both queens and workers. Both secretions were composed of hydrocarbons, but that of DG
also contained small quantities of tetradecanal and hexadecanal. The hydrocarbon profile of the DG and PPG showed notable
caste specificity suggesting a role in caste-related behavior. The PPG secretions also differed between colonies suggesting
its role in colony-level recognition. We suggest that in A. senilis, there are two modes of colony fission: First, in very large colonies, gynes are produced, probably because of the dilution
of the queen pheromone, and consequently one or more gynes leave the mother colony with workers and brood to found a new nest.
This is beneficial at the colony level because it avoids the production of costly sexuals in small colonies. However, because
the queen and workers have different optima for sexual production, we hypothesize that queens tend to overproduce the pheromone
to delay their production. This in turn may drive workers to leave the mother colony during nest relocation and to produce
sexuals once they are away from the queen’s influence, creating a second mode of colony fission. 相似文献
19.
Summary. Individuals in an insect colony need to identify one another according to caste. Nothing is known about the sensory process
allowing nestmates to discriminate minute variations in the cuticular hydrocarbon mixture. The purpose of this study was to
attempt to model caste odors discrimination in four species of Reticulitermes termites for the first time by a non-linear mathematical approach using an "artificial neural network" (ANN). Several rounds
of testing were carried out using 1 – the whole hydrocarbon mixtures 2 – mixtures containing the hydrocarbons selected by
principal component analysis (PCA) as the most implicated in caste discrimination. Discrimination between worker and soldier
castes was tested in all four species. For two species we tested discrimination of four castes (workers, soldiers, nymphs,
neotenics). To test cuticular pattern similarity in two sibling species (R. santonensis and R. flavipes), we performed two experiments using one species for training and the other for query. Using whole hydrocarbons mixtures,
worker/soldier discrimination was always successful in all species. Network performance decreased with the number of hydrocarbons
used as inputs. Four-caste discrimination was less successful. In the experiment with the sibling species, the ANN was able
to distinguish soldiers but not workers. The results of this study suggest that non-linear mathematical analysis is a good
tool for classification of castes based on cuticular hydrocarbon mixture. In addition this study confirms that hydrocarbon
mixtures observed are real chemical entities and constitute a true chemical signature or odor. Whole mixtures are not always
necessary for discrimination.
Received 23 July 1998; accepted 9 October 1998. 相似文献
20.
Summary. Larvae of Chrysomela leaf beetles release for defence volatile compounds belonging to various chemical families. This study focuses on the defensive strategy based on the esterification of isobutyric acid and 2-methylbutyric acid with a wide variety of alcohols taken up from the host plant. To date, only two species are known to produce these repellents C. interrupta, which is associated with Betulaceae and C. lapponica which occurs either on Betulaceae or Salicaceae.? In order to know if other species have developed this chemical defence and how the food plant influences the secretion of these toxins, we targeted by mass spectrometry the presence of iso- and 2-methylbutyric acids and esters of them in the defensive secretions of Chrysomela larvae exclusively associated with Betulaceae or Salicaceae. ?Screening analyses reveal that the synthesis of these compounds is a common character restricted to all the members belonging to the C. interrupta group sensu Brown (1956) regardless of the host-plant family. These results suggest that the biochemical mechanism leading to the synthesis of these compounds could be considered as a synapomorphy meaning that the group is probably monophyletic. ?Defensive secretions of the members of the interrupta group are quantitatively assayed for iso- and 2-methylbutyric acids and their (Z)-3-hexenyl esters. Results reveal a chemical plasticity developed by Chrysomela species associated with Salicaceae. The amounts of iso- and 2-methylbutyric acids derivatives and of salicylaldehyde in their larval secretions depend on the food plant and on its content in phenolglucosides. Received 5 October 1998; accepted 25 November 1998. 相似文献