Impact of human disturbance on bee pollinator communities in savanna and agricultural sites in Burkina Faso, West Africa

Abstract

All over the world, pollinators are threatened by land‐use change involving degradation of seminatural habitats or conversion into agricultural land. Such disturbance often leads to lowered pollinator abundance and/or diversity, which might reduce crop yield in adjacent agricultural areas. For West Africa, changes in bee communities across disturbance gradients from savanna to agricultural land are mainly unknown. In this study, we monitored for the impact of human disturbance on bee communities in savanna and crop fields. We chose three savanna areas of varying disturbance intensity (low, medium, and high) in the South Sudanian zone of Burkina Faso, based on land‐use/land cover data via Landsat images, and selected nearby cotton and sesame fields. During 21 months covering two rainy and two dry seasons in 2014 and 2015, we captured bees using pan traps. Spatial and temporal patterns of bee species abundance, richness, evenness and community structure were assessed. In total, 35,469 bee specimens were caught on 12 savanna sites and 22 fields, comprising 97 species of 32 genera. Bee abundance was highest at intermediate disturbance in the rainy season. Species richness and evenness did not differ significantly. Bee communities at medium and highly disturbed savanna sites comprised only subsets of those at low disturbed sites. An across‐habitat spillover of bees (mostly abundant social bee species) from savanna into crop fields was observed during the rainy season when crops are mass‐flowering, whereas most savanna plants are not in bloom. Despite disturbance intensification, our findings suggest that wild bee communities can persist in anthropogenic landscapes and that some species even benefitted disproportionally. West African areas of crop production such as for cotton and sesame may serve as important food resources for bee species in times when resources in the savanna are scarce and receive at the same time considerable pollination service.

Diversity of Eusocial Bees in Natural and Anthropized Areas of a Tropical Dry Forest in the Parque da Sapucaia (Montes Claros, Minas Gerais, Brazil)

“…According to Souza et al (2015) this species is widely distributed in Brazil, being frequent in anthropized habitats, such as urban environments. Our results corroborate previous studies indicating that habitat modification has negative effects on the diversity of native bee communities (Winfree et al, 2009;Ferreira et al, 2015;Stein et al, 2018).…”

Impact of hiking trails on the diversity of flower-visiting insects in Wadi Telah, St. Katherine protectorate, Egypt

“…Furthermore, the results that were consistent with the previous study reveal that disturbance resulting from degradation of seminatural habitats often leads to lowered pollinator abundance and/or diversity (Stein et al, 2018). Also, butterflies and bees both exert strong negative responses to land-use change and extreme land-use causes a strong decrease in species richness and/or abundance (Winfree et al, 2009).…”

“…Anthropogenic activates such as land-use alteration, pathogens, pesticides, and climate change can have critical impacts on insect pollinators and the pollination services they provide (Cariveau & Winfree, 2015). Globally, pollinators are threatened by land-use change including degradation of seminatural habitats and several studies are concerned that insect pollinators are in decline (Stein et al, 2018;Winfree et al, 2009). Hiking trails and nature-based tourism might have negative impacts on faunal biodiversity within protected areas (Huhta & Sulkava, 2014).…”

Reliability of the Tanzania river scoring system (TARISS) macroinvertebrate index of water quality: a case study of the river Mpanga system, Uganda

“…Whittaker et al (1973) argue that organisms survive in their optimum and suboptimum range, which may indicate that moderately disturbed sites support tax from undisturbed and highly disturbed niches. Thus moderate anthropogenic disturbance tends to offer better condition for a more varied community structure (Townsend et al1997;Stein et al 2018;Willig and Presley 2018) whereas extremes favour dominant better adapted taxa.…”