Chez le palmier à huile, le taux de nouaison des fruits est fortement lié à la densité des populations d'insectes pollinisateurs. Les populations du principal pollinisateur, Elaeidobius kamerunicus, ont été suivies dans le but d'identifier les facteurs influençant leurs fluctuations. Des prélèvements d'épillets ont été effectués sur les inflorescences mâles et des captures ont été réalisées sur les inflorescences femelles dans trois localités pendant 24 mois. Les résultats ont montré qu'à La Mé, le nombre d'inflorescences mâles influence positivement le nombre d'E. kamerunicus/épillet (r = 0,81 ; p ˂ 0,0001) et le nombre d'E. kamerunicus visitant les fleurs femelles (r = 0,77 ; p ˂ 0,0001). A Grand-Béréby, le nombre d'E. kamerunicus/épillet est corrélé négativement (r =-0,46 ; p = 0,027) avec le nombre de jours de pluies et positivement (r = 0,51; p = 0,012) avec l'insolation. A Iboké, les densités sur les inflorescences mâles et femelles sont influencées négativement par le nombre de jours de pluies (r =-0,45 ; p = 0,028 et r =-0,51 ; p = 0,027). Ainsi, l'abondance d'E. kamerunicus dans les plantations dépend en partie du nombre d'inflorescences mâles, de la pluie et de l'insolation.

Abstract:Mango is the third largest export fruit in Côte d'Ivoire. However, its yield is limited by the damage caused by fruit flies (Diptera: Tephritidae). This study aimed at assessing the trapping system for fruit fly detection and monitoring in mango orchards in Northern Côte d'Ivoire. Four sites were selected in Northern Côte d'Ivoire in mango production area and in timber yard areas. Five trapping systems were tested: two food attractants (torula yeast, CeraTrap) and three sex attractants (methyl eugenol, trimedlure, cue-lure). Plastic bottles were used for food attractants and commercial traps for sex attractants. Five traps per treatment with three repetitions per site were set up. Ten species of flies have been identified: Bactrocera dorsalis, B. cucurbitae, Ceratitis anonae, C. bremii, C. capitata, C. cosyra, C. punctata, Dacus ciliatus, D. punctatifrons and Dacus spp.. Among these species, B. dorsalis was dominant. It was captured by 94.04% and 90.94%, respectively, in mango orchards and forest areas included wild fruits. The average number of individuals captured varied from one species to another, depending on the attractants. This average was estimated to 379.91, 27.58, 25.55, 15.1 and 11.93, respectively, for méthyl eugénol, torula yeast, CeraTrap, cue-lure, trimedlure. The attractants have shown their specificity in capturing fly species. Methyl eugenol had the highest capture and was the most effective.

West African savanna ecosystems and biodiversity are severely threatened by intensified land use and increasing degradation of natural habitats. Despite the importance of bees for pollinating crops and native plant species little information is available regarding the importance of savanna woody plant species to provide bees with food resources. Flora inventories were carried out on 48 subplots laid out across three land use types. The number of bee morphospecies and their abundance as flower visitors were recorded from inflorescences of plants during the different flowering periods. Out of a total diversity of 82 woody plant species, 53 species (64.63%) from 38 genera and 21 families were melliferous. These plants were visited by bees for foraging nectar and/or pollen. Species of the Combretaceae family were the most visited by bees in terms of individuals (53.85%). Combretum glutinosum alone accounted for 36% of visits. More than half of the melliferous plants (50.94%) were visited for both nectar and pollen. About 32.08% of plants were visited for nectar only (32.08%), while 16.98% were visited for pollen only (16.98%). The majority of savanna plants are flowering in the dry season, but few flowering species can be found throughout the whole year. Savanna woody plant species constitute important food resources for bees, therefore providing a wide range of applications for the development of beekeeping activities in the Sudanian region of West Africa.

Cashew nut represents the third most exported agricultural product of Côte d'Ivoire. However, the yield production of cashew is still low likely due to many factors including under-pollination. This study aims to identify the insects visiting cashew tree inflorescences at Niofoin in northern Côte d'Ivoire. Observations were made in a cashew orchard measuring two hectares. Insects visiting the inflorescences were captured and identified. A total of four cashew nut varieties (Yellow Benin, Henry, Costa Rica, and James) were observed. The daily activity of honey bee Apis mellifera, considered here as the number of flower visits made by a bee in one minute to an inflorescence, was evaluated on the inflorescences from 5 a.m. to 6 p.m. The findings showed 16 families belonging to 7 orders. Among the insect families, Apidae emerged as the most abundant family (32.15%). Apis mellifera (Apidae) was the main visitor of cashew tree inflorescences. His activity was stronger on "Yellow Benin" and "Henry" varieties compared to "James" and "Costa Rica" varieties. For all varieties of cashew trees, honey bee activity varied throughout the day with two peaks, one between 7 a.m. and 8 a.m. and the other between 5 p.m. and 6 p.m. It was inversely proportional to temperature (p < 0.05; r = -0.59) and evolved in the same direction with relative humidity (p < 0.05; r = 0.49). This study, although preliminary, remains quite relevant because it will help to boost cashew production in northern Côte d'Ivoire through the pollinators' involvement.

Natural and protected area degradation constitutes a threat to bee communities and could decrease crop yield by reducing bee pollination effectiveness. For West Africa, changes in bee communities across disturbance gradients from savannah to agricultural land are mainly unknown. Our study aimed to assess the impact of land use patterns on bee communities in the department of Korhogo. We chose three sites of varying disturbance intensity (low, medium and high disturbance). Bees were caught using pan traps. Abundance, richness, evenness and community structure of bees were assessed. During 6 months of sampling, 3176 bee specimens belonging to three families (Apidae, Halictidae and Megachilidae) were caught, comprising 18 species and 15 genera. Species richness of Halictidae and abundance of Apidae were highest (F = 93.86; p = 0.0051). The station with low disturbance was more diversified (H′ = 2.75). Bee average abundance was higher in sites with medium disturbance. Our findings are relevant to biodiversity conservation. They show that bee diversity is high where the disturbance level is still low.