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See detailKeep the nest clean: survival advantages of corpse removal in ants
Diez, Lise; Lejeune, Philippe ULg; Detrain, Claire

in Biology Letters (2014), 10(7),

Sociality increases exposure to pathogens. Therefore, social insects have developed a wide range of behavioural defences, known as ‘social immunity’. However, the benefits of these behaviours in terms of ... [more ▼]

Sociality increases exposure to pathogens. Therefore, social insects have developed a wide range of behavioural defences, known as ‘social immunity’. However, the benefits of these behaviours in terms of colony survival have been scarcely investigated. We tested the survival advantage of prophylaxis, i.e. corpse removal, in ants. Over 50 days, we compared the survival of ants in colonies that were free to remove corpses with those that were restricted in their corpse removal. From Day 8 onwards, the survival of adult workers was significantly higher in colonies that were allowed to remove corpses normally. Overall, larvae survived better than adults, but were slightly affected by the presence of corpses in the nest. When removal was restricted, ants removed as many corpses as they could and moved the remaining corpses away from brood, typically to the nest corners. These results show the importance of nest maintenance and prophylactic behaviour in social insects. [less ▲]

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See detailWho brings out the dead ? Necrophoresis in the red ant, Myrmica rubra
Diez, Lise; Le Borgne, Hélène; Lejeune, Philippe ULg et al

in Animal Behaviour (2013)

The division of labour plays a major role in the success of social insects. For instance, through social prophylaxis, the spread of pathogens within the colony can be reduced if corpse removal is the ... [more ▼]

The division of labour plays a major role in the success of social insects. For instance, through social prophylaxis, the spread of pathogens within the colony can be reduced if corpse removal is the concern of a specialized group of ants. However, in relatively small colonies, the number of dead individuals and the amount of waste may be too low to justify a specialized group of corpse carriers. We examined the corpse removal habits of the common red ant, Myrmica rubra. Ants acting as corpse carriers were not strictly specialized in corpse management, but split their time between disposing of the dead and foraging. Some corpse-carrying individuals, however, developed a short-term specialization by making several successive corpse transports. Corpse carriers limited cross-contamination by remaining mostly outside the nest and congregating near the nest entrance when resting inside. [less ▲]

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See detailTissu social, coopérations et conflits entre les acteurs de la filière soie de landibe dans la région d’Itasy
Diez, Lise; Poncelet, Marc ULg; Rakotoniaina, Naritiana et al

in Verheggen, François; Bogaert, Jan; Haubruge, Eric (Eds.) Les vers à soie malgaches : Enjeux écologiques et socio-économiques (2013)

Wild silk in Madagascar is made by endemic silk moths of the genus Borocera and locally named landibe. In this study, we tried to shed light on the social aspects of the wild silk sector, by understanding ... [more ▼]

Wild silk in Madagascar is made by endemic silk moths of the genus Borocera and locally named landibe. In this study, we tried to shed light on the social aspects of the wild silk sector, by understanding the interactions between the actors of the sector. We interviewed different professionals such as weavers and cocoon harvesters in the country and in the city. The study area was located in villages of the Itasy region, situated 50 km West of the capital, Antananarivo. Moreover, people working in the silk sector were also interviewed in Antananarivo. Analysis of the wild silk’s sector revealed complex dynamics. Each player has his own purpose, not the least of which is finding additional revenues with silk. In the country, cocoon harvesting and weaving are complementary activities to agriculture. The collective actors of the silk sector are the VOI (Local Communities) who are managing tapia woods, weaving women associations, and NGOs who try to develop silk sector in the region. These collective actors cooperate with the local population, but it appears that some conflicts and misunderstandings arise between individuals and associations, which could hamper meeting the shared goals of silk sector development and preservation of the natural environment. [less ▲]

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See detailPlace de la soie de landibe dans l’économie rurale de la région d’Arivonimamo
Diez, Lise; Poncelet, Marc ULg; Rakotoniaina, Naritiana et al

in Verheggen, François; Bogaert, Jan; Haubruge, Eric (Eds.) Les vers à soie malgaches : Enjeux écologiques et socio-économiques (2013)

Wild silk in Madagascar is produced by endemic silk moths of the genus Borocera, locally named landibe. Wild silk is used to produce shrouds and clothes, and provides a great added value. In this document ... [more ▼]

Wild silk in Madagascar is produced by endemic silk moths of the genus Borocera, locally named landibe. Wild silk is used to produce shrouds and clothes, and provides a great added value. In this document, we describe the silk sector in the Arivinimamo region, and we analyze the importance of silk production and transformation as a source of income for rural populations, as observed in 2008. First, the harvest of cocoons does not require any investment and weaving pays more than working as a field hand. In the study area, wild silk brings significant profits to households. In Antananarivo, workshops employ many weavers. Consequently, wild silk is quite important for the region’s employment. However, these activities still belong to the informal sector and it is quite difficult to know the real impact of the sector on the national economy. Wild silk products are mostly sold in Antananarivo, at outdoor marketplaces or in specialized shops. Nowadays, the principal problem of the wild silk enterprise is finding markets. The economic crisis in the country diminishes demand as well as investment possibilities for weavers and enterprises. [less ▲]

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See detailLa soie de landibe : connaissances biologiques et savoir-faire des populations rurales de la région d’Arivonimamo
Diez, Lise; Poncelet, Marc ULg; Rakotoniaina, Naritiana et al

in Verheggen, François; Bogaert, Jan; Haubruge, Eric (Eds.) Les vers à soie malgaches : Enjeux écologiques et socio-économiques (2013)

Wild silk in Madagascar is made by endemic silk moths of the genus Borocera, locally named landibe. For centuries, wild silk has been woven in Madagascar to dress the more powerful islanders or shroud the ... [more ▼]

Wild silk in Madagascar is made by endemic silk moths of the genus Borocera, locally named landibe. For centuries, wild silk has been woven in Madagascar to dress the more powerful islanders or shroud the ancestors at the time of first and second burials. Nowadays, it is mostly wealthy malagasy and foreigners who buy and wear wild silk. By interviewing the cocoon harvesters in the rural region of Arivonimamo, we aimed at a better understanding of their knowledge of the butterflies’ biology and rearing methods. We also interviewed persons implied in the silk sector to describe the techniques that are presently used in silk transformation. In Arivonimamo region, Borocera cocoons are directly harvested in tapia (Uapaca bojeri) forests, and wild silk is still processed in a traditional way. [less ▲]

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See detailChoosing an aphid partner: a matter of taste and smell
Detrain, Claire; Fischer, Christophe ULg; Lognay, Georges ULg et al

Conference (2012, August 27)

Honeydew is the keystone upon which ants and aphids build their mutualistic relationship. We have investigated how sugar and volatile compounds from honeydew are involved in the discovery, the recognition ... [more ▼]

Honeydew is the keystone upon which ants and aphids build their mutualistic relationship. We have investigated how sugar and volatile compounds from honeydew are involved in the discovery, the recognition and the exploitation of aphid colonies by the black garden ant Lasius niger. In addition to semiochemicals produced by aphids, honeydew volatile compounds are used by ant scouts to orient themselves and distantly recognize myrmecophilous species. Once discovered, aphid colonies producing sugars which are the most beneficial to the ants are preferentially tended. In this respect, the ways each sugar acts upon the feeding behavior of ant foragers and triggers the laying of a recruitment trail are essential to understand how their collective exploitation of aphid colonies proceeds and why mutualistic interactions between ants and aphids are maintained. Sensitivity of ant scouts to honeydew sugars was also investigated. Dose-response curves revealed between-sugar differences with foragers being very sensitive even to small amounts of melezitose, a sugar specifically produced by aphid colonies. We discuss about the relevance of honeydew cues used by ants in the selection of sugary resources, the recognition of their honeydew-producing partners as well as in the assessment of size and nutritive value of exploited aphid colonies. [less ▲]

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See detailAphid Alarm Pheromone as a Cue for Ants to Locate Aphid Partners
Verheggen, François ULg; Diez, Lise; Sablon, Ludovic ULg et al

in PLoS ONE (2012)

The mutualistic relationships that occur between myrmecophilous aphids and ants are based on the rich food supply that honeydew represents for ants and on the protection they provide against aphid natural ... [more ▼]

The mutualistic relationships that occur between myrmecophilous aphids and ants are based on the rich food supply that honeydew represents for ants and on the protection they provide against aphid natural enemies. While aphid predators and parasitoids actively forage for oviposition sites by using aphid semiochemicals, scouts of aphid-tending ant species would also benefit from locating honeydew resources by orienting toward aphid pheromone sources. The present study aims to provide additional information on the use of Aphis fabae alarm pheromone, i.e. (E)-β-farnesene (EβF), by ant scouts. The perception and behavioral impact of EβF on Lasius niger were investigated using electroantennography and two bio-assays measuring their attraction and orientation towards aphid semiochemicals. Pronounced electrical depolarizations were observed from L. niger scout antennae to stimulations of A. fabae alarm pheromone, while other sesquiterpenes elicited weak or no responses. L. niger scouts were significantly attracted toward EβF in a four-arm olfactometer, as well as in an two-choice bioassay. These laboratory results suggest for the first time that low amounts of aphid alarm pheromone can be used by L. niger scouts as a cue indicating the presence of aphid colonies and could therefore mediate the aphid-ant partnership in the field. [less ▲]

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See detailAphid-ant mutualism: how honeydew sugars influence the behaviour of ant scouts
Detrain, Claire; Verheggen, François ULg; Diez, Lise et al

in Physiological Entomology (2010), 35(2), 168-174

Honeydew is the keystone on which ant-aphid mutualism is built. The present study investigates how each sugar identified in Aphis fabae Scopoli honeydew acts upon the feeding and the laying of a ... [more ▼]

Honeydew is the keystone on which ant-aphid mutualism is built. The present study investigates how each sugar identified in Aphis fabae Scopoli honeydew acts upon the feeding and the laying of a recruitment trail by scouts of the aphid-tending ant Lasius niger Linnaeus, and thus may enhance collective exploitation by the ant mutualists. The feeding preferences shown by L. niger for honeydew sugars are: melezitose = sucrose = raffinose > glucose = fructose > maltose = trehalose = melibiose = xylose. Although feeding is a prerequisite to the launching of trail recruitment, the reverse is not necessarily true: not all ingested sugar solutions elicit a trail-laying behaviour among fed scouts. Trail mark laying is only triggered by raffinose, sucrose or melezitose, with the latter sugar being specific to honeydew. By comparing gustatory and recruitment responses of ant foragers to sugar food sources, the present study clarifies the role of honeydew composition both as a source of energy and as a mediator in ant-aphid interactions. Lasius niger feeding preferences can be related to the physiological suitability of each sugar (i.e. their detection by gustatory receptors as well as their ability to be digested and converted into energy). Regarding recruitment, the aphid-synthesized oligosaccharide (melezitose) could be used by ant scouts as a cue indicative of a long-lasting productive resource that is worthy of collective exploitation and defence against competitors or aphid predators. [less ▲]

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See detailAnts’ survival and waste management in Myrmica rubra nests
Diez, Lise; Lejeune, Philippe ULg; Detrain, Claire

Poster (2010)

Sociality increases risks of disease transmission as genetically related individuals live in a confined environment. Therefore, social insects developed specific defences against pathogens by showing ... [more ▼]

Sociality increases risks of disease transmission as genetically related individuals live in a confined environment. Therefore, social insects developed specific defences against pathogens by showing hygienic behaviours such as the rejection of cadavers and other wastes. We investigated if the undertaking and waste management is actually an efficient way of increasing ants’ survival and of limiting pathogens transmission. First, we observed the survival curve of ant colonies that were prevented from rejecting their dead nestmates outside the nest. Colonies that were forced to keep their dead inside the nest showed increased mortality of both adults and larvae in comparison to control nests, confirming that undertaking is an effective way for improving colony’s survival. Then, we compared the rejection dynamics of single waste items (ant cadavers, preys and clay pellet) introduced into ant nests. Clay pellets were quickly rejected within 12 ± 4 minutes, cadavers were dumped outside after 139 ± 28 min and preys were eaten and rejected only after 17.3 ± 0.3 hours. Spatial localisation inside the nest also differs between different items, as most cadavers stayed far from ants’ aggregate and larvae while preys were long-eaten close to larvae and inside ants’ aggregate. These results show that cadavers and preys are managed differently before becoming contagious, thus preventing effectively pathogens transmission inside the nest. [less ▲]

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See detailSpatio-temporal patterns of preys and wastes moved by ants within the nests
Diez, Lise; Lejeune, Philippe ULg; Deneubourg, Jean-Louis et al

Poster (2010)

Living in society in a restricted and confined nest implies important organisational issues. Ants have to control food supply for the whole colony as well as nest defence but they also have to manage ... [more ▼]

Living in society in a restricted and confined nest implies important organisational issues. Ants have to control food supply for the whole colony as well as nest defence but they also have to manage everyday life tasks such as waste rejection. Within the nest, ants are faced with different items that have to be used or rejected regarding colony needs. We study whether they can discriminate between three types of items (building material, nestmate cadaver or prey) and accordingly adapt the spatio-temporal distribution of these items. Therefore, we used colonies of the ant Myrmica rubra settled in a 2-dimensional space and introduced different items in the nest centre. We show that each item triggers a specific cascade of behaviour. We observed important differences in rejection time: building items were removed within a few minutes and cadavers after a few hours while preys could be kept in the nest for a day or more. Furthermore, the movement of items by ants leads to specific spatio-temporal patterns. Building items were removed with a straight trajectory from the centre to the exit of the nest. Ant cadavers that could bear pathogens showed a trajectory avoiding and moving away from larvae that are potentially more sensitive to diseases. The moving of preys headed an oscillating pattern: these items were alternatively taken on larvae for consumption and then moved away from them, until final rejection. This specific pattern may be due to the coupled effects of groups of ants acting alternatively to feed larvae and reject waste. In the case of cadavers and building items, only undertaking ants may be active. These results suggest that each ant is able to discriminate and interact with each other leading at the collective level to a complex cascade of behaviour. [less ▲]

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See detailDynamique spatiale de rejet des déchets au sein des fourmilières Myrmica rubra
Diez, Lise; Lejeune, Philippe ULg; Detrain, Claire

Conference (2010)

La vie en société de milliers d’individus apparentés dans un milieu confiné augmente le risque de transmission des pathogènes. Par le biais de comportements hygiéniques collectifs tels quel le rejet des ... [more ▼]

La vie en société de milliers d’individus apparentés dans un milieu confiné augmente le risque de transmission des pathogènes. Par le biais de comportements hygiéniques collectifs tels quel le rejet des déchets, les insectes sociaux ont développé des défenses spécifiques contre les pathogènes. Nous avons comparé la dynamique de rejet de différents types de déchets (cadavres, proies et morceaux de vermiculite) introduits dans des nids de Myrmica rubra. L’analyse vidéo, réalisée grâce à un programme original de suivi du déchet et de digitalisation des zones de couvain, a permis un suivi précis du déplacement de ces déchets au sein du nid. La vermiculite a été rapidement rejetée après 12 ± 4 minutes, les cadavres ont été éliminés après 139 ± 28 min et les proies ont été consommées puis rejetées après 17,3 ± 0,3 heures. L’analyse spatiale des déchets a montré un déplacement rapide des cadavres loin du couvain alors que les proies étaient fréquemment apportées près des larves pour la consommation. L’efficacité de la gestion des déchets a été testée par ailleurs en comparant la survie de colonies de fourmis ayant ou non la possibilité de rejeter leurs cadavres. La mortalité des adultes et des larves vivant dans des nids contraints de garder leurs cadavres est significativement supérieure à celle observée dans les colonies contrôles, confirmant l’importance de ce rejet pour la survie et le bon état sanitaire de la fourmilière. [less ▲]

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See detailAphid-ant mutualism: How do aphids focus ant foraging?
Verheggen, François ULg; Detrain, Claire; Diez, Lise et al

Conference (2009, August)

The mutualistic relationships that occur between myrmecophilous aphids and ants are based on the rich food supply that honeydew represents for ants and on the protection they provide against aphid natural ... [more ▼]

The mutualistic relationships that occur between myrmecophilous aphids and ants are based on the rich food supply that honeydew represents for ants and on the protection they provide against aphid natural enemies. While aphid predators and parasitoids actively forage for oviposition sites by using aphid semiochemicals, scouts of aphid-tending ant species would also benefit from locating honeydew resources by orienting toward aphid pheromone sources. The present study aims to identify the chemical factors that attract ants and that maintain their mutualistic relationships with aphids. The perception and behavioral impact of Aphis fabae alarm pheromone, namely (E)-β-farnesene, on Lasius niger were firstly investigated using electroantennography and a four-arm olfactometer. Aphis fabae honeydew sugar composition was subsequently analyzed while the foraging and recruiting behaviour of L. niger scouts towards each of the identified sugars was studied. Clear electrical depolarisations were observed from L. niger scout antennae to stimulations of A. fabae alarm pheromone. Scouts were significantly attracted toward (E)-β-farnesene in the four-arm olfactometer, suggesting for the first time that the latter compound is a key chemical in the establishment of the mutualism. Aphis fabae honeydew consisted of 9 identified mono-, di- and tri-saccharides and 8 hydrocarbons that could not be identified. The main identified sugars were sucrose, fructose, glucose and melezitose. L. niger scouts showed the following drinking preferences for the tested sugars: melezitose = sucrose = raffinose > glucose = fructose > maltose = trehalose = melibiose = xylose, with a recruitment launched toward the first three sugars. Therefore, ant scouts may use aphid semiochemicals to locate at distance an aphid colony and subsequently estimate honeydew quality by tasting it before recruiting conspecifics and establishing a mutualistic relationship. [less ▲]

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See detailMutualisme pucerons-fourmis : étude des bénéfices retirés par les colonies d’Aphis fabae en milieu extérieur
Verheggen, François ULg; Diez, Lise; Detrain, Claire et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2009), 13

La relation de coopération entre pucerons-fourmis est un bel exemple de mutualisme dans le règne animal, les premiers cherchant protection et hygiène, les seconds une source de sucres nécessaires à la ... [more ▼]

La relation de coopération entre pucerons-fourmis est un bel exemple de mutualisme dans le règne animal, les premiers cherchant protection et hygiène, les seconds une source de sucres nécessaires à la survie de la colonie. La présente étude s’est intéressée à recenser les bénéfices retirés par Aphis fabae Scopoli (Homoptera, Aphididae) de ses relations de mutualisme avec Lasius niger L. (Hymenoptera : Formicidae). Plusieurs paramètres ont été observés en milieu extérieur sur des plants de fèves des marais infestés initialement par 100 individus en présence ou non d’une colonie de L. niger. En présence de fourmis, les plantes étaient constamment infestées par un nombre de pucerons plus important, et la proportion d’individus ailés y était également similaire ou plus grande, selon la date d’observation. Un nombre moins important de prédateurs aphidiphages sur les plantes en présence de fourmis a permis d’expliquer en partie ces observations. Les nombres moyens de pucerons parasités ne différaient pas que les plantes soient explorées ou non par les fourmis suggérant que L. niger est peu efficace face aux attaques de parasitoïdes. Par contre, très peu de pucerons appartenant à des espèces différentes d’A. fabae ont été observés sur les plants mis en présence des fourmis. Ces observations suggèrent que L. niger adopte un comportement de prédation sur les pucerons avec lesquels elle n’entretient aucune relation mutualiste. Les observations menées n’ont pas permis de mettre en évidence un quelconque effet des fourmis sur la vigueur des plantes hôtes des pucerons, bien que sensiblement moins d’exuvies et de tâches de miellat étaient présentes sur les plantes dont les colonies de pucerons étaient visitées par L. niger. L’ensemble de ces résultats confirme que L. niger améliore les conditions de vie des colonies de pucerons d’Aphis fabae dont elle exploite le miellat, principalement grâce à la protection qu’elle apporte contre les prédateurs et la réduction de la pression de compétition exercée par les autres espèces non myrmécophiles de pucerons. [less ▲]

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See detailMutualisme pucerons-fourmis : étude des bénéfices retirés par les colonies d’Aphis fabae en milieu extérieur
Verheggen, François ULg; Detrain, Claire; Diez, Lise et al

Conference (2008)

Aphid-Ant relationships are common examples of mutualism. Aphids are indeed submitted to predation and therefore require protection, while ants are continuously looking for new sugar sources. The present ... [more ▼]

Aphid-Ant relationships are common examples of mutualism. Aphids are indeed submitted to predation and therefore require protection, while ants are continuously looking for new sugar sources. The present work aimed to study the benefits that a mutualistic relationship with Lasius niger (Hymenoptera : Formicidae) could bring to the black bean aphid Aphis fabae (Homoptera, Aphididae). Several parameters were observed in the field, on broad bean plants infested with an initial amount of 100 A. fabae and in presence or not of a L. niger colony. More aphids were observed on plants being visited by ants as well as a higher proportion of winged individuals. One explanation is that fewer predators were observed on plants being visited by ants, demonstrating their protective role. However, the number of parasitized aphids was not reduced in presence of L. niger. On the other hand, fewer different aphid species were present on plants foraged by ants, what suggests that they could exert a predation on unattended aphids. Our observations do not allow to conclude on any impact of L. niger on the fitness of the aphid host plant, although fewer exuvia and honeydew spots were observed when they were present. All these results confirm that L. niger increase the fitness of A. fabae colonies mainly by decreasing the number of predators and by reducing competition from aphid species unattended by ants. [less ▲]

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See detailAphid-ant mutualism: an outdoor study of the benefits for Aphis fabae
Verheggen, François ULg; Detrain, Claire; Diez, Lise et al

Conference (2008)

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See detailAphid-ant mutualism: How do aphids focus ant foraging?
Verheggen, François ULg; Detrain, Claire; Diez, Lise et al

Conference (2008)

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See detailAphid – ant mutualism : How do aphids focus ant foraging ?
Verheggen, François ULg; Diez, Lise; Detrain, Claire et al

Poster (2008)

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