Biodiversité des mouches des fruits (Diptera : Tephritidae) en vergers de manguiers de l'ouest du Burkina Faso : structure et comparaison des communautés de différents sites

Introduction. Un inventaire des espèces de Tephritidae dans des vergers de l'ouest du Burkina Faso a été effectué entre décembre 2007 et décembre 2009. Matériel et méthodes. Un piégeage de détection a été mené dans sept vergers de manguiers en utilisant comme appât de la levure de Torula placée dans des pièges Mac Phail. Résultats et discussion. L'identification et le dénombrement des Tephritidae capturées a permis de recenser 18 espèces : neuf du genre Ceratitis, sept du genre Dacus et deux du genre Bactrocera. Ceratitis cosyra et Bactrocera invadens (respectivement 53,02 % et 36,19 % de l'ensemble des captures) se sont révélées être les espèces dominantes. Nous avons mis en évidence une forte similarité des communautés de Tephritidae au niveau des différents sites étudiés (coefficients de similitude entre 42,86 % et 100 %); cette similarité pourrait être expliquée d'une part par l'homogénéité des conditions climatiques, d'autre part par celle de la végétation de la zone d'étude. La proximité des parcelles de cultures maraîchères et la diversité des fruitiers locaux hôtes des Tephritidae autour des vergers de manguiers pourraient être à l'origine de la richesse spécifique élevée que nous avons constatée. Conclusion. Notre étude a révélé une diversité de Tephritidae dans la zone d'investigation qui présente des communautés d'espèces homogènes. Ces résultats seront complétés par l'identification des espèces associées aux dégâts sur manguier et à l'évaluation de leur importance. Ils suggèrent dès à présent la possibilité de développer, contre ces ravageurs, une stratégie de lutte commune à toutes les localités de la zone d'étude de l'ouest du Burkina Faso. (Résumé d'auteur

Description d'une nouvelle espèce de termites du genre Macrotermes originaire de la forêt du Mayombe (Rép. Congo) (Isoptera, Termitidae)

In this study, we describe a new termite species from Congo, belonging to the subfamily Macrotermitinae. Its biology is also studiedDans cette étude sont décrites la morphologie et la biologie d'une nouvelle espèce de termite du genre Macrotermes, originaire de la forêt du Mayombe en République du Congo.Rouland-lefèvre Corinne. Description d'une nouvelle espèce de termites du genre Macrotermes originaire de la forêt du Mayombe (Rép. Congo) (Isoptera, Termitidae). In: Bulletin de la Société entomologique de France, volume 98 (2), juin 1993. pp. 109-115

Nematodes, indicators of the origin of the soil used by termites to construct biostructures

In Sahelian savannas, fungus-growing termites form biogenic structures made of soil or sheetings, on the soil surface and inside the soil, to protect themselves against heat, desiccation and predators while collecting food. The purpose of this study was to determine if analysis of the nematofauna can show differences in the way termites construct sheetings according to termite species or organic material harvested. In this study, soil nematodes, which were inactive during the experiment, were passively transported in soil. pellets by termites when they built sheetings. Composition of the soil nematofauna was analyzed in sheetings produced when harvesting the four different types of different organic matter and in the soil around which these structures were produced. Three of the four organic materials were applied on soil as mulch whereas wood Logs were inserted in the soil. Nematode density and diversity in sheetings produced by the three different termite species present (Ancistrotermes guineensis, Ondontotermes nilensis and Macrotermes subhyalinus) were similar in the four organic treatments except for sheetings constructed within the wood by A. guineensis. Nematode densities in sheetings were about ten-fold lower than in the 0-10 cm upper soil layer. Moreover, the composition of the nematofauna in sheetings was very different from that of the upper 10cm, except for the sheetings built on wood. A finer comparison of the soil nematofauna in the top 7cm of soil (separated in 0-0.25, 0.25-3.0 and 3.0-7.5cm), and of fresh surface sheetings (produced within 24h) showed that nematode composition of sheetings was very similar to that of the soil. in the superficial strata (0-3 cm). Analysis of the nematofauna led us to conclude that the soil. used by termites to construct biogenic structures when harvesting organic matter originates from soil layers as close as possible to the area where the organic resource is located. Moreover, there were no differences in the soil or the three type of surface-applied organic matter used for the three fungus-growing termites

Biodiversité des mouches des fruits (Diptera : Tephritidae) en vergers de manguiers à l'ouest du Burkina Faso : structure et comparaison des communautés de différents sites

Introduction. Un inventaire des espèces de Tephritidae dans des vergers de l'ouest du Burkina Faso a été effectué entre décembre 2007 et décembre 2009. Matériel et méthodes. Un piégeage de détection a été mené dans sept vergers de manguiers en utilisant comme appât de la levure de Torula placée dans des pièges Mac Phail. Résultats et discussion. L_identification et le dénombrement des Tephritidae capturées a permis de recenser 18 espèces : neuf du genre Ceratitis, sept du genre Dacus et deux du genre Bactrocera. Ceratitis cosyra et Bactrocera invadens (respectivement 53,02 % et 36,19 % de l_ensemble des captures) se sont révélées être les espèces dominantes. Nous avons mis en évidence une forte similarité des communautés de Tephritidae au niveau des différents sites étudiés (coefficients de similitude entre 42,86 % et 100 %) ; cette similarité pourrait être expliquée d'une part par l'homogénéité des conditions climatiques, d'autre part par celle de la végétation de la zone d'étude. La proximité des parcelles de cultures maraîchères et la diversité des fruitiers locaux hôtes des Tephritidae autour des vergers de manguiers pourraient être à l'origine de la richesse spécifique élevée que nous avons constatée. Conclusion. Notre étude a révélé une diversité de Tephritidae dans la zone d'investigation qui présente des communautés d'espèces homogènes. Ces résultats seront complétés par l'identification des espèces associées aux dégâts sur manguier et à l'évaluation de leur importance. Ils suggèrent dès à présent la possibilité de développer, contre ces ravageurs, une stratégie de lutte commune à toutes les localités de la zone d'étude de l'ouest du Burkina Faso

Gut-specific actinobacterial community structure and diversity associated with the wood-feeding termite species, Nasutitermes corniger (Motschulsky) described by nested PCR-DGGE analysis

This comprehensive survey studied the actinobacterial community structure and putative representative members associated with the gut of the wood-feeding termite, Nasutitermes corniger (Motschulsky), using nested PCR-DGGE and 16S rDNA sequences analyses. The closest relatives of the actinobacteria inhabiting the gut of Nasutitermes corniger were in five families, regardless of the geographical origin of the termite colony: Propionibacteriaceae, Streptomycetaceae, Cellulomonodaceae, Corynebacteriaceae and Rubrobacteraceae. Feeding termites on beech wood did not result in substantial changes in the actinobacterial community structure as revealed by DGGE banding patterns. Most of the 16S rDNA sequences obtained after excision and sequencing of DGGE bands clustered with those previously retrieved in termite guts. These results confirm the presence of gut-specific actinobacteria. Except for the 16S rDNA sequences affiliated to Streptomycetaceae and Cellulomonodaceae, no sequence had more than 97% similarity with the closest isolated strains, indicating the presence of microorganisms that have not yet been cultivated. These results suggest that members of the Actinomycetales order account for the largest proportion of the Actinobacteria phylum inhabiting the gut of the termite N. corniger

Molecular diversity and host specificity of termite associated Xylaria

International audiencePrevious studies have revealed that some Xylaria species were closely associated with fungus-growing termite nests. However, this relationship had been very rarely investigated and the host-specificity of termite-associated Xylaria was not yet clearly established. 18 Xylaria rDNA-ITS sequences were obtained from fungus combs belonging to 11 Macrotermitinae species from 8 regions. There was low diversity between isolates and 9 different sequences were retrieved. Termite-associated Xylaria were shown to be monophyletic, with three main clades, all including strains from various termite hosts and geographical localities. This new molecular study shows that there is no species specificity with respect to fungus-growing termites which suggests that there may be substrate specialization

Effects of earthworms on the fungal community and microbial activity in root-adhering soil of Lantana camara during phytoextraction of lead

Earthworms are known to stimulate soil microorganisms and to enhance phytoextraction of metals. This study was designed to test the hypothesis that the positive effect of earthworms on phytoextraction performance results from the stimulation of soil fungi that are known to be tolerant to heavy metals in contaminated soils. It set out to assess the relationships between lead phytoextraction and the changes in soil fungi in response to earthworm activity. The experiment was performed in outdoor microcosms combining: earthworms (Pontoscolex corethrurus), Spanish Flag (Lantana camara) and soil spiked with 500 and 1000 mg Pb kg(-1). Cultivable fungi were enumerated using plate counts. PCR-DGGE analysis targeting the 28S rRNA gene was used to determine the structure of the fungal community. Total microbial activity was measured by fluorescein diacetate (FDA) hydrolysis assay. Plant Pb uptake by L. camara increased by about 2.5-fold in the presence of earthworms, regardless of the Pb concentration. This was significantly correlated with the increase in total microbial activity, abundance of cultivable fungi and richness index of the fungal community calculated from DGGE banding patterns. In the presence of earthworms, there was a significant positive correlation between microbial activity, plant biomass and plant Pb uptake. There was no correlation for the control without earthworms. These results provide evidence that interactions between earthworms and soil microorganisms have a positive effect on Pb-phytoextraction yield. The study of the ecological context of phytoremediation should be broadened by considering the interactions between plants, microorganisms and earthworms that affect heavy metal uptake by plants

Melissotarsus ants are likely able to digest plant polysaccharides

Melissotarsus ants have an extremely specialized set of behaviours. Both workers and gynes tunnel galleries in their host tree bark. Workers walk with their mesothoracic legs pointing upwards and tend Diaspididae hemiptera for their flesh. The ants use their forelegs to plug the galleries with silk that they secrete themselves. We hypothesised that the ants' energetic needs for nearly constant gallery digging could be satisfied through the absorption of host tree tissues; so, using basic techniques, we examined the digestive capacities of workers from two species. We show that workers are able to degrade oligosaccharides and heterosides as well as, to a lesser degree, polysaccharides. This is one of the rare reports on ants able to digest plant polysaccharides other than starch