Fragmented landscapes affect honey bee colony strength at diverse spatial scales in agroecological landscapes in Kenya

Abstract

Landscape fragmentation and habitat loss at multiple scales directly affect species abundance, diversity, and productivity. There is a paucity of information about the effect of the landscape structure and diversity on honey bee colony strength in Africa. Here, we present new insights into the relationship between landscape metrics such as patch size, shape, connectivity, composition, and configuration and honey bee (Apis mellifera) colony strength characteristics. Remote-sensing-based landscape variables were linked to honey bee colony strength variables in a typical highly fragmented smallholder agroecological region in Kenya. We examined colonies in six sites with varying degrees of land degradation during the period from 2017 to 2018. Landscape structure was first mapped using medium resolution bitemporal Sentinel-1 and Sentinel-2 satellite imagery with an optimized random forest model. The influence of the surrounding landscape matrix was then constrained to two buffer distances, i.e., 1 km representing the local foraging scale and 2.5 km representing the wider foraging scale around each investigated apiary and for each of the six sites. The results of zero-inflated negative binomial regression with mixed effects showed that lower complexity of patch geometries represented by fractal dimension and reduced proportions of croplands were most influential at local foraging scales (1 km) from the apiary. In addition, higher proportions of woody vegetation and hedges resulted in higher colony strength at longer distances from the apiary (2.5 km). Honey bees in moderately degraded landscapes demonstrated the most consistently strong colonies throughout the study period. Efforts towards improving beekeeper livelihoods, through higher hive productivity, should target moderately degraded and heterogeneous landscapes, which provide forage from diverse land covers.

Effective pest management approaches can mitigate honey bee (Apis mellifera) colony winter loss across a range of weather conditions in small-scale, stationary apiaries

“…This suggests that in colonies where Varroa was managed in a more integrated manner, using multiple-treatment types, the relative importance of weather versus landscape variables may have shifted, allowing the relationships between landscape and colony survival to be illuminated, although it should be noted that the treatment quantity and frequency is not known, and that treatment diversity may not be related to treatment intensity. Predicted survival increased with forage score for spring, summer, and fall in our study, which is consistent with previous work establishing links between forage availability in the landscape improving honey bee colony health ( Donkersley et al, 2014 , St Clair et al 2020 , Ochungo et al 2022 ). Increased nutrition can mitigate the impacts of Varroa infestation as well ( Aronstein et al 2012 , DeGrandi-Hoffman and Chen 2015 , Dolezal and Toth 2018 ).…”