Fragmented landscapes affect honeybee colony strength at diverse spatial scales in agro-ecological landscapes in Kenya

Standard Langstroth hives were used for this study. Each of the hives were labeled randomly from 1 to 10 in each apiary and subsequently the frames in the hives labeled 1 to 10 with each side of the frame labeled A or B. Initially, 60 hives were setup for this study, i.e., 10 hives per site. However, throughout the study period, we only inspected and sampled 30 hives (i.e., colonies) which were the only ones occupied by natural swarms as observed during our first field data collection. Visual estimates from two observers were used, as this method is less disruptive compared to using empirical measurements such as weight of the honeybees (Delaplane et al, 2013a). All the data measurements were conducted during the early hours around 07h00 and 08h00 local time (Greenwich Mean Time: GMT + 3) of the day to control for the foraging activities of honeybees, which might affect the observations, especially of the adult honeybee population. Each of the occupied hives was lightly smoked, opened and frames containing combs were sequentially removed and examined. The estimated percentage coverage of each frame side by the target resource (adult population, sealed and open brood, eggs, honey and pollen) was visually done. Honeybee colony strength was estimated following Delaplane et al. (2013) and Imdorf and Gerig (2001) Liebefeld protocol. In order to generate the landscape fragmentation indices, a honeybee habitat map was generated from a fused bi-temporal Sentinel-1 and a single season Sentinel-2 dataset ((European Space Association (ESA), 2017), which had an overall accuracy of 86% (Ochungo et al., 2019), (Figure 1). Fragmentation indices were thereafter generated from the habitat map at various spatial scales ranging from 0.5 km to 3 km.