Diversité de l’entomofaune floricole de Sesamum indicum (L.) 1753 (Pedaliaceae) et son impact sur les rendements fruitiers et grainiers à Bambui (Nord-Ouest, Cameroun)

De mai à juin 2013 et 2014 respectivement, les fleurs de Sesamum indicum ont été observées en vue de l’étude de l’activité des insectes et de la détermination de l’impact de celle-ci sur les rendements fruitiers et grainiers de cette plante. Deux traitements ont été formés à partir du marquage de 1347 et 5480 boutons floraux pour chacune des périodes d’investigation selon la présence ou l’absence de protection de ces bouquets floraux. Le comportement de butinage des insectes, le taux de fructification, le nombre moyen de graines par fruit et le pourcentage de graines normales ont été évalués. Les résultats montrent que 15 espèces d’insectes ont visité les fleurs de sésame en 2013 et 2014. Amegilla sp. était l’espèce la plus fréquente, suivie de Camponotus flavomarginatus et Apis mellifera adansonii. En comparant les rendements des deux traitements, il est apparu que les insectes ont augmenté le taux de fructification de 27,35%, le nombre de graines par fruit de 15,99% et le pourcentage de graines normales de 12,26%. Cette étude a fourni une certaine connaissance sur la diversité des insectes floricoles du sésame, qui peut être exploitée pour améliorer la production fruitière.© 2016 International Formulae Group. All rights reserved.Mots clés: Insectes floricoles, Sesamum indicum, fleurs, pollinisation, rendementsEnglish Title:  Diversity of flowering insect fauna on Sesamum indicum (L.) 1753 (Pedaliaceae) and its impact on fruit and seed yields in Bambui (North-West, Cameroon)English AbstractFrom May to June 2013 and 2014 respectively, Sesamum indicum flowers have been observed for the study of insect activity and determination of the impact of it on pod and seed yields of this plant. 1347 and 5480 flower clusters for each studied year were labeled and divided in to two treatments, differentiated according to the presence or absence of protection against insect’s activities. Insects foraging activities, the fruiting rate, the percentage of normal seeds and the mean number of seeds per pod were recorded. Results have shown that 15 species of flower-visiting insects were recorded on S. indicum flower within the two years.  Amegilla sp. was the most frequent, followed by camponotus flavomarginatus and Apis mellifera adansonii. The comparison of yields of the two treatments showed that insects significantly increased the fruiting rate by 27.35%, as well as the number of seeds per pod by 15.99% and the percentage of normal seeds by 12.26%. This study provided some knowledge about the anthophilous insect’s diversity of this Pedaliaceae, which canbe exploited to improve fruit production.© 2016 International Formulae Group. All rights reserved.Keywords: Anthophilous insects, Sesamum indicum, flowers, pollination, yield

AGRO-MORPHOLOGICAL CHARACTERIZATION OF TWO RICE VARIETIES FROM JAPAN; ORYSA SATIVA L. AND FOUR NERICAS VARIETIES IN AN AGRO-ECOLOGICAL ZONE OF THE TOWN OF YAOUNDE (CAMEROON); COMPARATIVE STUDY OF THEIR PERFORMANCES

International audienceThe performances of two rice species of the genus Oryza were evaluated by considering parameters such as the number of panicle per rice plant, the number of primary branches of the panicles, panicle length, the plant height, the number of grains and empty balls per panicle. It appears that O. sativa from Japan has a number of empty balls less than NERICA’s varieties from Africa. We also noted that O. sativa has the highest number of panicles per rice plant (a mean of 14.05 ± 6.14). However, the number of grains per panicle NERICA’s varieties was very high (a mean of 164 ± 38.82) and therefore they shows more attractive characters than Orysa sativa lines. The differences were statistically significant above all the parameters considered in both African and Japan rice studied. A significant correlation that was negative has been observed between the number of panicles per rice plant and the number of primary branches per panicle within the NERICA 9 variety (P <0.05). The correlation was highly significant and positive (P <0.001) between the number of primary branches per panicle and the number of grain per panicle. These results suggest another demonstration of the hybrid vigor of NERICA varieties

Biodiversity of Freshwater Shrimp of the Genus Macrobrachium (Decapoda Palaemonidae) in the Nyong Basin of Cameroon

The population of shrimps, especially the macrobrachium genus, has been affected with habitat pollution and overexploitation. Shrimps provide a major protein source to animals higher in the food chain. The importance of studying the ecology of shrimps in their different habitats helps in their preservation and provides possibilities of carcinoculture. This study examines diversity, ecology and reproduction parameters of fresh water shrimps of the genus macrobrachium in the basins of Lepmassoun and Ondoamedza rivers. Lepmassoun and Ondoamedza rivers form part of the larger Nyong river basin in Cameroon. In situ water physicochemical parameters were determined on site, preserved water samples used in mineral analysis and subsequent ecological health assessment. Shrimps were sampled using the scoop method with hand nets and analyzed. Sampling was done in 5 seasons distributed from January 2017 to February 2018. The results of physicochemical parameters indicate that water in the two rivers was slightly mineralized, sufficiently oxygenated and slightly turbid. It was generally a non-polluted ecological zone for shrimps. A total of 113 shrimps distributed among 14 species were collected. The shrimp population included Macrobrachium macrobrachion Macrobrachium idae, Macrobrachium rude, Macrobrachium niloticus , Macrobrachium dux Macrobrachium sp1, Macrobrachium sp2, Macrobrachium sp3,Macrobrachium sp4, Macrobrachium sp4, Macrobrachium sp5, Macrobrachium sp6, Macrobrachium sp7, Macrobrachium sp8 and Macrobrachium sp9.In the river Odoameza 11 species were collected among which Macrobrachium sp8 (26.02%) is abundant, though,in the river Lepmassoun we collected 10 species dominanced by Macrobrachium macrobrachion (22,5%). The species Macrobrachium macrobrachion is most ubiquiste throughout river Lepmassoun (%O = 83.33%) The river basin of Lepmassoun had a higher population of Macrobrachium macrobrachion with a percentage occurrence of 66.67%. then It is concluded that the water in the two river basins is of good ecological quality for shrimp survival with species Macrobrachium macrobrachion dominating in the river lepmassoun. In the river Ondoameza Macrobrachium sp8, Macrobrachium idea, Macrobrachium macrobrachion,Macrobrachium sp4 having all the percentage of occurrence (%O) of 66.67% are relatively represented. Only Macrobrachium dux have Ovigerous females in our study. This Ovigerous females ranged from 50.38 to 64.18 mm and egg size varied from 1.7 to 2 mm. The prawn attained a maximum total length and weight of 64,18 m and 2,96 g respectively. In our basins slope the Macrobrachium dux reproduces twice year during the big dry season and small dry season since production is early and the eggs are rather broad by consequence the larval development is shortened

Structure des communautés de fourmis arboricoles tropicales (implications évolutives et économiques)

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

Data from: The evolution of communication in two ant-plant mutualisms

Myrmecophytes are plants that provide nesting sites and food to ants that protect them against herbivores. Plant signals function to synchronize ant patrolling with the probability of herbivory. We compared the communication signals in two symbioses involving ant and plant pairs that are closely related. The two plants emitted the same volatile compounds upon damage. These compounds are simple molecules common in the plant kingdom. Electroantennography revealed that the two symbiotic ants, as well as several other ant species, were able to perceive these compounds. However, workers of one species responded only to hexanal, while those of the other species responded mostly to methyl salicylate. The two signals involved in the focal symbioses are ‘cheap’ (low metabolic cost), which is consistent with theoretical predictions for the evolution of signalling between partners with convergent interests. They are also not specific, which is expected between plants and broad-spectrum predators such as ants. The fact that different signals are used in the two sister symbioses suggests different mechanisms underlying similar adaptations in the evolution of communication

Facteurs environnementaux et répartition spatiale des crustacés dans un cours d'eau peu anthropisé à Makak (Région du Centre Cameroun)

This study examines the influence of environmental factors on the spatial distribution of crustaceans in the Matourou stream, located in a forest area of the District of Makak (Center Region of Cameroon). The physico-chemical analyses reveal good ecological conditions : waters slightly basic (average pH value of 7.28 ± 0.81), well oxygenated (saturation rate = 82.54 ± 8.22 %), slightly mineralized (electrical conductivity = 25.89 ± 6.13 µS/cm) and with low organic matter loads (oxydisability = 1.42 ± 1.70 mg/l). Concerning crustaceans, two freshwater shrimp species known as Caridina sp. (Atyidae) and Macrobrachium sp. (Palaemonidae), and an undetermined species of crab belonging to the genus Soudanonautes (Potamidae), were identified. A total number of 2132 individuals were collected. Caridina sp. is the dominant species with 90.43 % of relative abundance, followed by Soudanonautes spp. (7.83 %) and Macrobrachium sp. (1.74 %). Macrobrachium sp. is absent in the upper stream