RESUMES

17- Behavioural Interactions Between Crematogaster brevispinosa rochai Forel (Hymenoptera: Formicidae) and Two Nasutitermes Species (Isoptera: Termitidae).
16- Defensive behaviour and biological activities of the abdominal secretion in the ant Crematogaster scutellaris (Hymenoptera: Myrmicinae).
15- Ovarian activity correlates with extreme changes in cuticular hydrocarbon profile in the highly polygynous ant, Linepithema humile.
14- New 1-alk(en)yl-1,3,5-trihydroxycyclohexanes from the Dufour gland of the African ant Crematogaster nigriceps.
13- Chemical defense in Platyphora kollari and Leptinotarsa behrensi(Coleoptera : Chrysomelidae). Hypotheses on the origin and evolution of leaf beetles toxins.
12 - Furanocembranoid diterpenes as defensive compounds in the Dufour's gland of the ant Crematogaster brevispinosa rochai.
11 - Five new furanocembrenoids from the venom of a Brazilian Crematogasterant.
10 - Response thresholds to recruitment signals and the regulation of foraging intensity in the ant Myrmica sabuleti (Hymenoptera : Formicidae).
9 - Hydroxypentacosa-13,15,18,20-tetraen-11-yn-4-one
1-acetate, from the venom of a Brazilian Crematogasterant.
8 - Venom constituents of three species of Crematogasterants from Papua New Guinea.
7 - Food recruitment as a component of the trunk-trail foraging behaviour of Lasius fuliginosus(Hymenoptera : Formicidae).
6 - Explosive food recruitment as a competitive strategy in the ant Myrmica sabuleti(Hymenoptera : Formicidae).
5 - Regulated food recruitment through individual behavior of scouts in the ant Myrmica sabuleti(Hymenoptera : Formicidae).
3 -Respective contributions of leader and trail during group recruitment to food in Tetramorium bicarinatum(Hymenoptera : Formicidae).
2 - Mechanisms of food recruitment in the ant Myrmica sabuleti: an experimental and theoretical approach.
In : Biology and Evolution of Social Insects(J. Billen, Ed.), Leuven University Press, Leuven.
1 -Collective flexibility during mass recruitment in the ant Myrmica sabuleti(Hymenoptera : Formicidae).
Psyche.

Demande de tiré à part pour les textes complets...

.....................................Haut

Résumés des publications

1- COLLECTIVE FLEXIBILITY DURING MASS RECRUITMENT IN THE ANT MYRMICA SABULETI (Hym., Form.).

This paper describes the recruitment strategy of the ant Myrmica sabuleti and the collective behavior of the colonies when two sources of sucrose are offered. Our experiments show that this species uses an explosive mass recruitment to exploit large sources. A colony is able to select the richer source out of two simultaneously offered ones and, to some extent, to shift its main foraging activity toward a richer source discovered after a poor one. The role of the modulation of the chemical signals on the collective decisions is analyzed with the help of a mathematical model of recruitment and trail following. Our results are compared to those obtained with two other species. They suggest that modulating the deposition of the trail pheromone is sufficient to obtain a collective flexibility during mass recruitments.

Demande de tiré à part pour le texte complet.....................................Haut

2- MECHANISMS OF FOOD RECRUITMENT IN THE ANT MYRMICA SABULETI :
AN EXPERIMENTAL AND THEORETICAL APPROACH.

Some aspects of the recruitment strategy of Myrmica sabuleti were investigated.
The analysis of the dynamic of the recruitment reveals an explosive strategy when sucrose solutions are discovered by the foragers. The trail of the first recuiter is very strong and suffices to conduct 20-40 recruits to the food without the presence of a leader worker.
When foragers of this species have a choice of reaching food by two paths of the same length, the favoured path does not remain fixed over the course of time. The opposite was found to be true in the other species tested (Iridomyrmex humilis, Lasius niger, Lasius flavus). The consequences of these results have been studied by application of a mathematical model which has allowed us to propose hypotheses about the caracteristics and organization of recruitment in this species, namely duration of the chemical signal, idiosynchratic or collective behaviour during communication, and intensity of trail marking in relation to the concentration of the sucrose solutions.

Demande de tiré à part pour le texte complet......... ...... ... .... ... .. ....Haut

3- RESPECTIVE CONTRIBUTIONS OF LEADER AND TRAIL DURING RECRUITMENT TO FOOD IN TETRAMORIUM BICARINATUM (HYMENOPTERA, FORMICIDAE)

This paper describes the food recruitment strategy of the ant Tetramorium bicarinatum, at both the individual and collective levels. The general organisation of recruitment used by this species during the exploitation of sucrose solutions shows similarities with group recruitment described for other species. However, our experiments demonstrate that in T. bicarinatum, the first trail laid by a recruiter during its return trip to the nest is more efficient than in other species using group recruitment, for example Tetramorium impurum. Moreover, the efficiency of the first trail of a T. bicarinatum recruiter is comparable with that of Tapinoma erraticum, a species that uses mass recruitment. Despite the efficiency of the trail, choice experiments show that the recruited workers prefer to follow the leader rather than the first trail, suggesting the emission of a more attractive signal by the leader on its way back to the food. The function of the leader in this strategy is discussed in terms of collective decisions.

Demande de tiré à part pour le texte complet.....................................Haut

5 - REGULATED FOOD RECRUITMENT THROUGH INDIVIDUAL BEHAVIOR OF SCOUTS IN THE ANT, MYRMICA SABULETI (HYMENOPTERA, FORMICIDAE)

By presenting different kinds of food sources to colonies of M. sabuleti, we have demonstrated that this species regulates its foraging activity by altering the proportion of scouts that return to the nest to recruit nestmates after discovering a food source and by varying the number of nestmates recruited by a scout. These two parameters are related to the kind of food discovered. Our behavioral experiments showed that the probability that a scout returned to the nest decreased with a decreasing quantity of sucrose solution. In contrast, the number of returned scouts that elicited recruitment from the nest and the mean number of nestmates recruited by one of these scouts were independent of the quantity of the sucrose solution. Recruitment even occurred toward a 1- or 0.25-mul droplet of sucrose solution. When a scout discovered a large dead prey, a large drop of prey juice, a cluster of 30 dead fruit flies, or 1 isolated fruit fly, it always went back to the nest, but it elicited recruitment only when the food source was a large dead prey or a large drop of prey juice. No recruitment occurred when the food source was a single fruit fly and recruitment occurred only once in 30 trials when a cluster of 30 fruit flies was discovered.

Demande de tiré à part pour le texte complet.....................................Haut

6- EXPLOSIVE FOOD RECRUITMENT AS A COMPETITIVE STRATEGY IN THE ANT MYRMICA SABULETI (HYMENOPTERA, FORMICIDAE)

Myrmica sabuleti forms mature colonies of about one thousand workers and a few queens. Although living in dry and sunny biotopes, this species avoids foraging during the warmer hours of the day which correspond to the period of the maximum foraging activity of two sympatric species, Formica fusca and F. cunicularia. M. sabuleti is the most frequently observed species on the extrafloral nectaries of Vicia sativa, even during the warmer hours of the day, whereas F. fusca is the most frequent species during those hours at tubes of 1 M sucrose solutions placed on the ground. In spite of this temporal segregation, the foraging activity of M. sabuleti and F. fusca overlaps two times a day (10:00-11:00 am and 5:00-8:00 pm). Newly discovered large food sources are exploited by M. sabuleti through an explosively increasing recruitment, whereas workers of F. fusca forage mainly individually. Interference between M. sabuleti and F. fusca was studied when offering sucrose solutions, large dead insects unretrievable by individual foragers of either species (cockroaches), medium-sized insects retrievable by single foragers of F. fusca but not by single M. sabuleti (larvae of Calliphora erythrocephala) and small insects (Drosophila) retrievable by individual foragers of both species. Owing to its rapid recruitment, M. sabuleti is able to displace F. fusca from sucrose solution and large dead prey during the overlaping of the activity cycles of both species. When medium-sized corpses are offered, the issue depends on the speed of the events. F. fusca is able to take the prey away only if it discovers it before M. sabuleti has recruited nestmates. Small dead prey do not lead to interference, but is taken by the first worker that finds it.

Demande de tiré à part pour le texte complet.....................................Haut

7- FOOD RECRUITMENT AS A COMPONENT OF THE TRUNK-TRAIL FORAGING BEHAVIOUR OF LASIUS FULIGINOSUS (HYMENOPTERA: FORMICIDAE)

Field investigations showed that the ant Lasius fuliginosus combines stable foraging behaviour based on long-term memory and spatial specialization with more flexible actions, based on food recruitment. The use of food recruitment varies according to the season and the type of food. Baits of meat or large prey elicited recruitment during the major part of the year, except in the autumn, while baits of sugar elicited recruitment only in early spring, before the aphid colonies developed. A permanent trunk trail was established after a recruitment towards a newly discovered and stable source of carbohydrate food. This happened in early spring when the food sources were scarce or when spring migrating aphids were produced. (C) 1997 Elsevier Science B.V.

Demande de tiré à part pour le texte complet.....................................Haut

8- VENOM CONSTITUENTS OF THREE SPECIES OF CREMATOGASTER ANTS FROM PAPUA NEW GUINEA

Fourteen new long-chain derivatives (1j-1l, 2j-2l, 4a-4f, 6, and 7) have been isolated, together with the known 4-oxo-2,5-dienyl acetates 1g-1i and 4-oxo-2,5-dienals 2g-2i, from the defensive secretions of three species of Crematogaster ants from Papua-New Guinea. Their structures have been established by HREIMS and H-1-NMR studies, and by MS-MS analyses of the dimethyl disulfide derivatives 3a-3f, 5a-5f and 8a-8f. These results, together with those already reported on the three European Crematogaster species, suggest that the production of long-chain electrophilic contact poisons is a characteristic feature of this ant genus.

Demande de tiré à part pour le texte complet.....................................Haut

9- (13E,15E,18Z,20Z)-1-HYDROXYPENTACOSA-13,15,18,20-TETRAEN-11-YN-4-ONE 1-ACETATE, FROM THE VENOM OF A BRAZILIAN CREMATOGASTER ANT

(13E,15E,18Z,20Z)-1-hydroxypentacosa-13,15,18,20-tetraen-11-yn-4-one 1-acetate, a new polyfunctionalized long chain derivative, was isolated from the venom of an as yet undetermined Crematogaster ant species from Brazil, and its structure established by a detailed high-field 1D and 2D NMR study. (C) 1998 Elsevier Science Ltd. All rights reserved.

Demande de tiré à part pour le texte complet.....................................Haut

10 - RESPONSE THRESHOLDS TO RECRUITMENT SIGNALS AND THE REGULATION OF FORAGING INTENSITY IN THE ANT MYRMICA SABULETI (HYMENOPTERA, FORMICIDAE)

The optimal foraging theory predicts that colonies of social insects must be able to adjust the intensity of their foraging behaviour as a function of the quality of the food discovered. Here. the mechanisms allowing the regulation of recruitment as a function of food concentration in the ant Myrmica sabuleti were analyzed. Although the total number of foragers engaged in food collection during recruitments increased with increasing concentration of sucrose solutions (0.1 vs. 1 M), neither the proportion of recruiting scouts nor the invitation behaviour performed by the scouts in the nest can explain this relationship. Foragers trail more when coming back from a 1 M than from a 0.1 M sucrose solution. However, this alone cannot explain the collective patterns observed since the mean numbers of workers leaving the nest after the entry of a scout coming back from either 0.1 or 1 M sources were not significantly different. We suggest-that a spatial distribution of the foragers in the nest as a function of their motivational state could be part of the regulation process. The ants located near the nest entrance would respond to both low and high trail pheromone signals, but those located deeper in the nest would respond only to high level signals, resulting in higher recruitment rate towards richer sources. (C) 2000 Elsevier Science B.V. All rights reserved.

Demande de tiré à part pour le texte complet.....................................Haut

11- FIVE NEW FURANOCEMBRENOIDS FROM THE VENOM OF THE ANT CREMATOGASTER BREVISPINOSA AMPLA FROM BRAZIL

Five new furanocembrenoids (3-7) were isolated from the Dufour gland secretion of the Brazilian ant Crematogaster brevispinosa ampla. The structure of the major component was established by a detailed high-field 1D and 2D NMR study as the dibutanoate 3. Compounds 4 and 5 were shown to be the two isomeric monoacetate monobutanoates corresponding to 3, whereas 6 and 7 are the two isomeric monohydroxy monobutanoates. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.

Demande de tiré à part pour le texte complet.....................................Haut

12 - FURANOCEMBRANOID DITERPENES AS DEFENSIVE COMPOUNDS IN THE DUFOUR GLAND OF THE ANT CREMATOGASTER BREVISPINOSA ROCHAI

Two new furanocembranoid diterpenes, crematofuran [(1R*,11R*,12R*)-6,19:11,12-bisepoxycembra-3,6,8(19),15-tetraene] (1) and isocrematofuran [(1R*,3S*,4S*)-3,4:6,19-bisepoxycembra-6, 8(19), 11, 15-tetraene] (2), have been isolated from the Dufour gland secretion of the Brazilian ant Crematogaster brevispinosa rochai. Their structures, including the relative configuration, have been determined by a combination of NMR and molecular mechanics methods. The toxicity of 1 towards other ants is on the same level as that of nicotine. This is the first report of cembranoid diterpenes as defensive compounds in an ant. (C) 2000 Elsevier Science Ltd. All rights reserved.

Demande de tiré à part pour le texte complet.....................................Haut

13 - CHEMICAL DEFENSE IN PLATYPHORA KOLLARI BALY AND LEPTINOTARSA BEHRENSI HAROLD

The defensive secretions of Platyphora kollari beetles (Chrysomelidae) from Brazil contained one oleanene glycoside. This was identified as 3-0-beta -D-glucopyranosyl-(1 --> 4)-beta -D-glucuronopyranosyl-hederagenin (8), by a combination of 1D and 2D NMR methods (COSY, HMQC, HMBC) and SIMS. There were also several amino acid derivatives, including the known non-protein amino acid (Z)-2-amino-3,5-hexadienoic acid (1), the new dipeptide L-gamma -glutamyl-2-amino-(3Z)-hexenoic acid (4), ethanolamine (7), and a mixture of phosphatidylcholines. Compounds 1 and 7 have already been identified in several leaf beetle taxa. Secretions of Leptinotarsa behrensi contained as major triterpene glycoside 3-O-beta -D-glucopyranosyl-(1 -->3)-beta -D-glucuronopyranosyl-oleanolic acid-28-O-beta -D-ghlcopyranoside (9), already isolated from Platyphora opima. Although the host plants of these beetles were devoid of these triterpene glycosides, beta -amyrin was shown to be present in three plants on which different species of triterpene-producing chrysomelids had been fed (Mikania micrantha, Ipomoea batatas and Convolvulus arvensis). This suggests that these insects are able to use beta -amyrin from their food plant as a precursor to their oleanolic- and hydroxyoleanolic acid glycosides. The distribution of toxins already identified in leaf beetles suggests that amino acid derivatives could be a plesiomorphic character, considering their wide distribution, whereas the secretion of triterpene saponins, probably derived from ubiquitous plant triterpenes, could be an apomorphic character shared by some Doryphorina. The secretion of cardenolides derived from ubiquitous plant phytosterols would be another apomorphic character shared by other Doryphorina and Chrysolinina.

Demande de tiré à part

....................................Haut

14 - New 1-alk(en)yl-1,3,5-trihydroxycyclohexanes from the Dufour gland of the African ant Crematogaster nigriceps

The Dufour gland of the African ant Crematogaster nigriceps contains a mixture of at least eight 1-heptadec(en)yl- and 1-nonadec(en)yl-1,3,5-trihydroxycyclohexane derivatives, the mono-unsaturated components being the major ones (about 65%). They are accompanied by small amounts of ( Z,Z)-dienic derivatives (<10%). The structures, the relative and absolute configurations, and the preferred conformation of these new compounds have been established by spectroscopic and chemical methods, whereas the positions of the double bond in the alkenyl chains were determined by DMDS derivatisation followed by linked scan EIMS.