Figure 1.
Cage containing bees exposed to QMP from the time of adult emergence.
(A) Water feeder with small holes at the base. (B) Spare feeder. (C) Foundation comb that was replaced when cages were cleaned between sets of bees (D) Food feeder covered with a fine wire mesh to prevent bees from becoming coated with food. Arrow indicates a strip impregnated with QMP (Bee Boost) attached to the inside of the cage with a fine piece of wire. Cage dimensions (100/100/1350 mm).
Table 1.
F values and degrees of freedom (shown in brackets) obtained by two-way ANOVA of the behaviour of 2-day old QMP-exposed control and JH-treated bees towards a control strip or QMP strip.
Figure 2.
Photo of a QMP attraction assay test arena.
A 2-day old bee can be seen contacting the QMP strip located at the centre of the arena.
Figure 3.
Effects of JH on aversive learning (A) and memory recall (B) in 2-day old worker bees raised with QMP.
Learning performance in control bees injected with vehicle alone (n = 42) was compared with learning in bees treated with JH (n = 42). Bees were conditioned using differential conditioning of the sting extension reflex. Each bee received 12 pseudo-randomised conditioning trials. In six trials, eugenol was paired with an electric shock (CS+) in the remaining trials 2-hexanol was presented without reinforcement (CS−). (A) The percentage of control bees displaying a sting extension response (SER) to CS+ did not change significantly across successive trials (GLMM, P = 0.7355, z = −0.338). However, the percentage of bees displaying sting extension in response to the CS− odour significantly decreased (GLMM, P = 0.0258, z = −2.228). The slopes of the CS+ and CS− response curves of the control bees were significantly different (GLMM, P≤0.05). In contrast to controls, JH-treated bees showed clear evidence of learning with a significant increase in the % of bees displaying SER over successive conditioning trials with CS+ (GLMM, P≤0.001, z = 3.784). These bees also displayed a significant decrease in responses to CS− (GLMM, P≤0.001, z = −3.964). The slopes of the CS+ and CS− response curves of the JH treated bees were also significantly different (GLMM, P≤0.001). Significant differences in responses to CS+ and CS− are indicated by plots that do not share a letter (GLM, P≤0.01). (B) The percentage of bees responding to CS+ with sting extension during the retention test was significantly higher in JH-treated bees than in controls, as indicated by an asterisk (P≤0.01). (C) Percentage of bees responding to electric shock at intensities ranging between 0.25 and 8 volts. Responses of control bees injected with vehicle alone did not differ from those of JH treated bees at any of the voltages tested. (D) Neither group of bees responded significantly with sting extension in response to placement alone.
Figure 4.
Behaviour of 2-day old controls (n = 25) and JH-treated bees (n = 23) towards a control strip versus a QMP strip.
(A) Mean number of contacts/min with the test strip (2-WAY ANOVA, treatment, P = 0.0037, test strip, P = 0.0548, interaction, P = 0.0796). (B) Average area occupied (cm2) during the four minute test period when in the presence of either a control strip or a QMP strip (2-WAY ANOVA, treatment, P = 0.0033, strip, P = 0.5142, interaction, P = 0.2266). The percentage of total counts/area for control (C) and JH treated (D) bees in the presence of either a control strip or a QMP strip. F values and degrees of freedom are provided in Table 1.
Figure 5.
Amine receptor gene expression in the MB of 2-day old bees 3-hours following treatment with vehicle only (Control) or JH.
All bees were exposed to QMP from the time of adult emergence. Statistics: (two-tailed t-test) (A) Amdop1 (t(8) = 3.033) (B) Amdop2 (t(8) = 1.091) (C) Amdop3 (t(8) = 0.3248) (D) Amgpcr19 (t(8) = 1.732) (E) Amoa1 (t(8) = 2.299). Expression levels were normalised using the geometric mean of Rpn2 and Rps8 (F) (t(8) = 0.1073).
Figure 6.
Amine receptor gene expression in the antennae of 2-day old bees 3-hours after treatment with vehicle alone (Control) or JH.
Expression levels were normalised using the geometric mean of Rpn2 and Rps8. Statistics (A) Amdop1 (t8 = 1.649; P = 0.1377) (B) Amdop2 (t8 = 0.5836) (C) Amdop3 (t8 = 0.5239) (D) Amgpcr19 (t8 = 1.921) (E) Amoa1 (t8 = 2.389) (F) Amtyr1 (t8 = 1.982).