Fig 1.
Nutrient intakes and survival of honey bees under the influence of THX.
Each panel represents a different THX dose, noted on the bottom-right corner. On each panel, the different rails are the different diets signified by numbers or letters: (1) P:C ratio [0:1]; (2) [1:100]; (3) [1:30]; (4) [1:3]; and (ch), for choice experiment, representing the regulated intake close to the P:C ratio 1:6.5 (see S3 Table). Dotted lines refer to different days, also showing the different intakes and survival rates between diets. For the sake of clarity, we chose to represent only four days (4, 7, 10 and 14). Survival rate is colour-scaled. For values and statistical data, refer to Table 1 and S1 Table.
Table 1.
Survival Rates and Nutrient Consumption at days 7 and 14.
Fig 2.
PER response levels to different sucrose concentrations and influence of THX.
During choice experiment, THX had no effect at day 7 (A) and influenced PER response to high sucrose concentrations at day 14 (B), with lower levels for medium and high doses of THX. During no-choice experiment, THX influenced PER response to high sucrose concentrations at both day 7 (C) and day 14 (D), again with lower levels for medium and high doses of THX. Kruskal-Wallis significance (* p<0.05; ** p<0.01; *** p<0.005) indicates where PER response are influenced by THX. Letters represent post hoc Mann-Whitney pairwise comparisons, and different letters mean significant differences between THX groups. Grey boxes represent a significant correlation between groups. Refer to Table 2 for related PER values. For all statistical data, refer to S1 Table.
Table 2.
Response Levels to 10% and 30% Sucrose Concentrations.
Fig 3.
PER response levels to different sucrose concentrations and influence of dietary protein.
During the no-choice experiment, the dietary protein from the different P:C ratio diets affects PER response to lower sucrose concentrations at both day 7 (A) and day 14 (B): the higher the dietary protein concentration in diet, the higher the PER response rate. Kruskal-Wallis significance (* p<0.05; ** p<0.01; *** p<0.005) indicates where PER response are influenced by dietary protein. Letters represent post hoc Mann-Whitney pairwise comparisons, and different letters mean significant differences between dietary protein groups. Grey boxes represent a significant correlation between groups. Refer to Table 3 for related PER values. For all statistical data, refer to S1 Table.
Table 3.
Response Levels to Low Sucrose Concentrations.
Fig 4.
Schematic diagram of the effects of dietary protein and THX on sucrose sensitivity.
Both protein and pesticide affect sucrose sensitivity, but not at the same levels, and in opposite directions. Consider the plain line as the regular expected response to sucrose from control bees. When dietary protein concentration increases, the sucrose sensitivity increases too. Whereas the first detectable sucrose concentrations (0.30%–1%) elicit a very low response rate in control bees, dietary protein increases their response rate by improving detection of these low sucrose concentrations. In contrast, when dietary THX dose increases, the sucrose sensitivity decreases. Acting on higher sucrose concentrations (10%–30%), dietary THX impedes the normal rate of response compared to control bees, leading to taste attenuation.