# Bioaccumulation of Trace Elements along the Body Longitudinal Axis in Honey Bees
## 3 Results  
The survey at Alviano Lake (sites 1, 2), carried out in 2019 and 2020, was based on 72 honey bee samples (24 for each sample type, i.e., B, B\(-\)G, and G) collected on four sampling occasions at three different hives for each site. The element concentrations in the whole bee tissues (body) of Alviano Lake were not significantly different (Mann-Whitney U test, \(p>0.05\)) among the three hives (a, b, and c), both at site 1 and site 2. No significant differences were detected also between the two sites (1, 2). As a result, all the Alviano samples were subsequently processed comprehensively as Alviano Lake area samples. At the four control sites (sites C3-C6), located close to the city of Perugia (Umbria, Central Italy), 12 samples (4 for each sample type, i.e., B, B\(-\)G, and G), collected in September 2020, were processed comprehensively as Perugia Control area samples. The mean concentrations of the 30 trace elements (single values, means, and standard deviations are reported in the Supplementary Material, Table S1a-c) for the Alviano and control areas were grouped into 8 classes (with a variation of a 10 factor), from concentrations lower than 0.001 mg kg\({}^{-1}\) to concentrations higher than 1000 mg kg\({}^{-1}\). This analysis was carried out separately for the three different sample types, i.e., whole honey bee body (B), abdominal segments after the petiole (G), and the remaining part of the body (B\(-\)G) (Table 1a,b). The trace elements showing the lowest mean concentrations (class \(<\) 0.001) in Alviano honey bee tissues were, for B and B\(-\)G, Be (0.0008 mg kg\({}^{-1}\) and 0.0002 mg kg\({}^{-1}\), respectively), and Ag (0.0008 mg kg\({}^{-1}\) and 0.0009 mg kg\({}^{-1}\), respectively), while for gaster the elements Ag (0.002 mg kg\({}^{-1}\)) and Be (0.002 mg kg\({}^{-1}\)) were in the superior class (0.001-0.01), together with Hg (0.007 mg kg\({}^{-1}\)) and Ga (0.009 mg kg\({}^{-1}\)). In the control area, the first class (\(<\)0.001) was always empty for gaster tissues, while the lowest values were of Tl (0.0004 mg kg\({}^{-1}\)) and Be (0.0009 mg kg\({}^{-1}\)) for B, and Tl (0.0002 mg kg\({}^{-1}\)), Be (0.0004 mg kg\({}^{-1}\)), Ag (0.0005 mg kg\({}^{-1}\)), and Cs (0.0008 mg kg\({}^{-1}\)) for B\(-\)G.  
On the other hand, the trace elements in Alviano showing the highest levels in honey bee tissues (class \(>\)1000) for B and B\(-\)G were S (2625.77 mg kg\({}^{-1}\) and 3087.50 mg kg\({}^{-1}\), respectively), P (4157.22 mg kg\({}^{-1}\) and 4055.21 mg kg\({}^{-1}\), respectively) and K (4407.09 mg kg\({}^{-1}\) and 4259.24 mg kg\({}^{-1}\), respectively), while for gaster tissues these elements (S, 2153.56 mg kg\({}^{-1}\); P, 5055.63 mg kg\({}^{-1}\); and K, 5598.33 mg kg\({}^{-1}\)) were accompanied by Ca (1200.03 mg kg\({}^{-1}\)). The conditions in the control area sites were similar. The elements showing the highest levels (class \(>\)1000) for B, G, and B\(-\)G were S (2323.33 mg kg\({}^{-1}\), 1875.13 mg kg\({}^{-1}\), and 2649.64 mg kg\({}^{-1}\), respectively), P (3859.63 mg kg\({}^{-1}\), 4565.84 mg kg\({}^{-1}\)and 3675.06 mg kg\({}^{-1}\), respectively), and K (3964.07 mg kg\({}^{-1}\), 4294.02 mg kg\({}^{-1}\), and 3829.48 mg kg\({}^{-1}\), respectively), for gaster tissues; also, Ca is included (1317.58 mg kg\({}^{-1}\)).