Honey bees are important pollinators and are essential in agriculture; as such they get exposed to a wide range of pesticides while foraging in contaminated fields or during the spray of chemical on crops. It is therefore important to know the toxicity and evaluate the impacts of bees' exposure to these molecules. Acetamiprid and cypermethrin are two pesticides widely used in Cameroon and other countries. The objective of this study was to determine the toxicity of acetamiprid and cypermethrin on the native subspecies of Apis mellifera L. in agricultural areas in Adamaoua-Cameroon and to evaluate the impact on honeybee foragers exposed to lethal and sublethal doses of these two insecticides. The results obtained in laboratory conditions show that acetamiprid and cypermethrin are toxic to A. mellifera. The symptoms of neurotoxicity and first mortality appear 15 min after the ingestion of the high concentrations and about 30 to 45 min after the inoculation of the pesticides through contact route and the mortality increases with the concentration and time. The LC50 of acetamiprid obtained after 24 h are respectively 5.26 ng/μl for the topical application and 4.70 μg/μl by the oral route. At the same time, the LC50 of cypermethrin are respectively 2.27 ng/μl for topical application and 2.68 ng/μl for oral toxicity. For a sustainable agriculture and beekeeping, it is, therefore, important to establish quality measures on these insecticides in the ecosystem and to set up a phyto-pharmacovigilance and awareness system to the population.
To evaluate the impact of the foraging behaviour of Apis mellifera in increasing boll and seed yields of Gossypium hirsutum, its pollination activities were studied in Garoua for two seasons, from September through October 2018 and 2019. Observations were made on 540 flowers divided into four treatments of which two were differentiated according to the presence or absence of flower protection regarding insect visits; the third was made of protected and opened flowers, to allow Apis mellifera visits and the fourth made of opened flowers then closed without any visit. The bee's daily rhythm of activity, their foraging and pollination activities were evaluated. Results showed that, on Gossypium hirsutum flowers, Apis mellifera intensely collected pollen and nectar. Data obtained allow the classification of this Malvaceae as a highly polliniferous and nectariferous bee plant species. Through its pollination efficiency, Apis mellifera has increased the fruiting rate by 29.66% and 13.95%, the mean number of seeds per boll by 24.53% and 14.89% and the percentage of normal seeds by 3.89% and 8.87% in 2018 and 2019 respectively. Hence, the conservation of Apis mellifera colonies close to Gossypium hirsutum fields is recommended to improve its boll and seed yields.
Les investigations ont été faites sur les fleurs de Cajanus cajan en vue d’estimer l’impact de l’activité de Dactylurina staudingeri sur la pollinisation, la production en gousses et en graines à Dang, en 2016 et 2017. Pour chacune de ces années, 540 boutons floraux ont été étiquetés sur 120 plantes réparties en quatre traitements: 120 fleurs laissées en libre pollinisation, 120 fleurs protégées des insectes, 200 fleurs protégées, puis découvertes, visitées exclusivement par D. staudingeri et de nouveau protégées et 100 fleurs protégées, découvertes et à nouveau protégées, sans visite d’insectes ou de tout autre organisme. Le taux de fructification, le nombre moyen de graines par gousse et le pourcentage de graines normales ont été comparés entre ces traitements. Sur 33 espèces d’insectes recensées, D. staudingeri était majoritaire avec 12,19% de 6037 visites. Cette abeille prélevait fortement le nectar et récoltait faiblement le pollen au niveau des fleurs de C. cajan. La vitesse moyenne de butinage était de 7,14 fleurs/min. Via l’efficacité pollinisatrice d’une visite florale, D. staudingeri a augmenté le taux de fructification de 14,71%, le nombre moyen de graines par gousse de 35,29% et le pourcentage de graines normales de 17,31%. La conservation des colonies de D. staudingeri à proximité des exploitations de C. cajan est recommandée pour assurer la hausse des rendements de cette culture et favoriser une bonne pratique de la méliponiculture dans la région.Abstract Investigations were made on the flowers of Cajanus cajan in order to estimate the impact of the activity of Dactylurina staudingeri on pollination and yields at Dang, in 2016 and 2017. For each of these years, 540 flowers buds labeled on 120 plants were divided into four treatments: 120 open-pollinated flowers, 120 bagged flowers, 200 flowers protected, then unbagged, exclusively visited once by D. staudingeri and rebagged, and 100 flowers bagged, unbagged and rebagged without insect or any other organism visit. The fruiting rate, the mean number of seeds per pod and the percentage of normal seeds were compared between these treatments. Among 33 insect species recorded, D. staudingeri was prominent with 12.19% of 6037 visits. This bee harvested intensely nectar and collected slightly pollen from C. cajan flowers. The mean foraging speed was 7.14 flowers/min. Through the pollinating efficiency of a single flower visit, D. staudingeri increased the fruiting rate by 14.71%, the mean number of seeds per pod by 35.29% and the percentage of normal seeds by 17.31%. The conservation of D. staudingeri colonies close to C. cajan farms is recommended to improve yields of the crop and to promote the good meliponiculture in the region.
The investigations were carried out from September 10 through October 13, 2017 at Tchabbal-Mounguel. On Gossypium hirsutum flowers, investigations were done on many aspects of the pollination services of Amegilla calens and Apis mellifera. G. hirsutum flowers were observed to study the activity of A. calens and A. mellifera and to evaluate their impacts on fruits and seed yields of this Malvaceae. The treatments consisted of 120 flowers left for free pollination, 120 flowers protected from insects using gauze bag nets, 200 protected flowers and visited exclusively by A. calens and A. mellifera and 100 protected flowers then opened and closed without any visit of insects or any other organisms. The results show that on cotton flowers, foragers of A. calens and A. mellifera highly collect nectar and pollen on its flowers. The highest mean number of individuals simultaneously active per 1000 flowers is 587 for A. calens and 526 for A. mellifera. Through their pollinating efficiency, A. calens and A. mellifera caused a significant increase in the fruiting rate by 7.00% and 17.33%, the number of seeds per fruit by 44.20% and 18.32% and the normal seeds by 47.78% and 5.66% respectively. Therefore, the conservation of the nests of A. calens and colonies of A. mellifera around G. hirsutum plantations are to be recommended to improve the fruit and seed yields of this Malvaceae.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.