Foraging behaviour of Apis mellifera adansonii and its impact on pollination, fruit and seed yields of Citrullus lanatus at Nkolbisson (Yaoundé, Cameroon)

Honeybee (Apis mellifera adansonii Latreille (Hymenoptera: Apidae)) foraging activity was observed to evaluate its impact on pollination, fruit and seed yields of Citrullus lanatus (Thunb) Mansf (Cucurbitaceae) in the area of Yaoundé (Cameroon). Two lots of 775 female flowers were marked according to the presence or the absence of a protection for insect visits. The honey bees’ activity, the fruit set, the number of seeds per fruit were recorded. A. m. adansonii primarily foraged for nectar on C. lanatus throughout the whole blooming period of each plant and pollen collection was low. The mean maximum number of workers foraging at the same time was 331 ± 173 (n= 41) per 1000 flowers. The mean foraging speed was 10.20 ± 2.75 (n = 154) flowers per minute. The fruit set and the number of seeds per fruit of unprotected female flowers were significantly higher than those of female flowers protected from insects. A. m. adansonii pollination contributed 70.14% to the fruit set and seed yields. The conservation of A. m. adansonii colonies near C. lanatus population must be encouraged.Key words: Citrullus lanatus, Apis mellifera adansonii, pollination, yields, Cameroon.L’activité de butinage d’Apis mellifera adansonii Latreille (Hymenoptera : Apidae) a été étudiée afin d’évaluer son impact sur la pollinisation, les rendements fruitiers et grainiers de Citrullus lanatus (Thunb) Mansf (Cucurbitaceae) à Yaoundé (Cameroun). Deux lots ont été déterminés par le marquage de 775 fleurs femelles différant selon la présence ou l’absence de protection vis-à-vis des visites d’insectes. Le rythme saisonnier d’activité des abeilles domestiques, le taux de fructification des fleurs femelles et le nombre de graines par fruit ont été évalués. A. m. adansonii butinait les fleurs de C. lanatus tout au long de la période de floraison de chaque plante. Les butineuses prélevaient intensément le nectar pendant que la collecte du pollen était réduite. Le plus grand nombre d’ouvrières butinant simultanément était de 331 ± 173 (n = 41)par 1000 fleurs. La vitesse moyenne de butinage était de 10.20 ± 2.75 (n = 154) fleurs par minute. Le taux de fructification et le nombre moyen de graines matures par fruit des fleurs non protégées de l’activité des insectes étaient significativement élevés que ceux des fleurs femelles protégées. La contribution d’A. m. adansonii sur les rendements fruitiers et grainiers de C. lanatus était de 70.14% grâce à l’action pollinisatrice des ouvrières. La conservation des colonies d’A. m. adansonii à côté des populations de C. lanatus en fleurs doit être encouragée.Mots clés: Citrullus lanatus, Apis mellifera adansonii, pollinisation, rendements, Camerou

Nectar palatability can selectively filter bird and insect visitors to coral tree flowers

Secondary compounds in nectar may play a decisive role in determining the spectrum of floral visitors on plants. Flowers of the African coral tree Erythrina caffra are visited mainly by generalist passerine nectarivores, such as weavers and bulbuls. As the nectar of this species tastes very bitter to humans, it was hypothesized that secondary compounds may repel sunbirds and honeybees which are common in the same habitats yet seldom consume the nectar. We conducted choice tests using fresh nectar and both sucrose and hexose (glucose/fructose) solutions of the same concentration as the nectar. Whitebellied Sunbirds (Cinnyris talatala) were repelled by nectar of both E. caffra and a related species Erythrina lysistemon, but Dark-capped Bulbuls (Pycnonotus tricolor) did not discriminate between the Erythrina nectar and control sugar solution in terms of amounts consumed. Honeybees (Apis mellifera scutellata) probed exposed droplets of E. caffra nectar and a control sugar solution at the same rate, suggesting that there is no volatile deterrent, but they immediately withdrew their proboscis far more often from the droplets of Erythrina nectar than they did from the sugar solution, suggesting that they find Erythrina nectar distasteful. These results contribute to a growing awareness that non-sugar components of nectar can play important functional roles in plant pollination systems.South African National Research Foundation (NRF)http://link.springer.com/journal/106822016-03-31hb201

Activité de butinage et de pollinisation de Apis mellifera adansonii Latreille (Hymenoptera: Apidae) sur les fleurs de Helianthus annuus (Asteraceae) à Ngaoundéré (Cameroun)

Afin de déterminer la valeur apicole de Helianthus annuus L. (Asteraceae) et d’évaluer l’impact de Apis mellifera adansonii Latreille (Hymenoptera: Apidae) sur les rendements en graines de H. annus au Cameroun, les activités de butinage et de pollinisation des fleurons par les abeilles ont été observées dans la région de Ngaoundéré. De septembre à novembre, en 2004 et 2006 respectivement, 66 et 104 capitules divisés en deux lots selon la présence ou l’absence de protection de ces capitules vis-à-vis des insectes ont été étiquetés. Les rythmes journaliers, le comportement de butinage de l’abeille domestique sur les fleurs, l’indice de fructification et le pourcentage des akènes avec graine des capitules marqués ont été évalués. Les résultats ont montré que A. m. adansonii butinait H. annuus toute la journée et pendant toute la période de floraison de cette plante. Sur les fleurons de tournesol, les ouvrières récoltaient intensément et régulièrement le pollen et le nectar. Le plus grand nombre moyen d’ouvrières simultanément en activité sur un capitule était de 14 en 2004 et 15 en 2006. La vitesse moyenne de butinage a été de 24,70 fleurons par minute en 2004 et de 24,04 fleurons par minutes en 2006. Les données obtenues indiquent que H. annuus est une plante apicole fortement nectarifère et fortement pollinifère. Le pourcentage des akènes avec graine des infrutescences issues des capitules non protégés des insectes était significativement supérieur à celui des infrustescences issues des capitules protégés des insectes. La contribution numérique de A. m. adansonii dans les rendements en graine a été de 62,07 % en 2004 et 74,70 % en 2006. L’installation des colonies de A. m. adansonii dans les plantations de tournesol est recommandée pour augmenter la production du miel, du pollen et des graines.   To determine the apicultural value of Helianthus annuus L. (Asteraceae) and to evaluate Apis mellifera adansonii Latreille (Hymenoptera: Apidae) impact on seeds yields of H. annuus species in Cameroon, bee foraging and pollination activities were observed in the area of Ngaoundere. From September to November, in 2004 and 2006 respectively, 66 and 104 capitula divided in two lots differentiated according to the presence or absence of the capitula protection regarding insect visits were labelled. The honey bee’s daily rhythm of activity, its foraging behaviour on flowers and the percentage of fruits with seeds were evaluated. Results showed that A. m. adansonii foraged on sunflower all day long and throughout the whole blooming period of this plant. Worker bees intensely harvested pollen and nectar. The greatest number of workers foraging simultaneously was 14 per capitula in 2004 and 15 per capitula in 2006. The mean foraging speed was 24.70 florets/min in 2004 and 24.04 florets/min in 2006. Data obtained allow the classification of H. annuus as a highly nectariferous and highly polliniferous bee plant. The percentage of fruits with full seeds of unprotected capitula was significantly higher than that of capitula protected from insects. A. m. adansonii contributed 62.07 % and 74.70 to the seeds yields in 2004 and 2006 respectively. The installation of A. m. adansonii colonies in the plantation of sunflower should be recommended to increase honey, pollen and seeds production

Foraging behaviour of Apis mellifera adansonii Latreille (Hymenoptera : Apidae) on Daniellia oliveri, Delonix regia, Hymenocardia acida and Terminalia mantaly flowers in Ngaoundéré (Cameroon)

To determine the apicultural value of Daniellia oliveri, Delonix regia, Hymenocardia acida and Terminalia mantaly, the foraging activity of the honey bee, Apis mellifera adansonii was studied on flowers in the area of Ngaoundéré, from December 2001 to May 2002 and from December 2002 to May 2003. At Dang, flowers of each plant species were prospected at least four days per month, between 07.00 and 18.00 h, for recording of the nectar and/or pollen foraging behaviour of A. m. adansonii workers. Results showed that A. m. adansonii harvested nectar and pollen of each plant species. The greatest number of workers foraging simultaneously on a plant varied from 230 (H. acida) to 3500 (De. Regia). A. m. adansonii workers that visited flowers of a given plant species once generally remained with this nectar and/or pollen sources throughout the observation period. Thus Da. oliveri, De. regia, H. acida and T. mantaly could be cultivated and protected to increase honey production. Each of the four plant species could enable beekeepers to increase their pollen production as a hive product. On each plant species, A. m. adansonii workers carried pollen from one flower to another and can thus be considered as pollinators.© 2010 International Formulae Group. All rights reserved.Keywords: Nectar, pollen, bee plant, apicultural value, honey, pollination, Dang