New components of the honey bee (Apis mellifera L.) queen retinue pheromone

Abstract

The honey bee queen produces pheromones that function in both releaser and primer roles such as attracting a retinue of workers around her, attracting drones on mating flights, preventing workers from reproducing at the individual (worker egg-laying) and colony (swarming) level, and regulating several other aspects of colony functioning. The queen mandibular pheromone (QMP), consisting of five synergistic components, is the only pheromone chemically identified in the honey bee (Apis mellifera L.) queen, but this pheromone does not fully duplicate the pheromonal activity of a full queen extract. To identify the remaining unknown compounds for retinue attraction, honey bee colonies were selectively bred to have low response to synthetic QMP and high response to a queen extract in a laboratory retinue bioassay. Workers from these colonies were then used in the bioassay to guide the isolation and identification of the remaining active components. Four new compounds were identified from several glandular sources that account for the majority of the difference in retinue attraction between synthetic QMP and queen extract: methyl (Z)-octadec-9-enoate (methyl oleate), (E)-3-(4-hydroxy-3-methoxyphenyl)-prop-2-en-1-ol (coniferyl alcohol), hexadecan-1-ol, and (Z9,Z12,Z15)-octadeca-9,12,15-trienoic acid (linolenic acid). These compounds were inactive alone or in combination, and they only elicited attraction in the presence of QMP. There was still unidentified activity remaining in the queen extract. The queen therefore produces a synergistic, multiglandular pheromone blend of at least nine compounds for retinue attraction, the most complex pheromone blend known for inducing a single behavior in any organism.

Figure 1

RP-HPLC of partitioned queen head extract. Workers in the bioassay were from a wild-type (not selectively bred) colony with a low QMP response. One-way ANOVA: F = 11.1, P < 0.0001, n = 10. In Figs. 1–5, treatments with the same letter are not significantly different (P < 0.05, by Tukey–Kramer test).

Figure 2

QMP with MO and other esters. EO, ethyl oleate; MP, methyl palmitate; EP, ethyl palmitate; MPL, methyl palmitoleate; EPL, ethyl palmitoleate; ES, ethyl stearate. One-way ANOVA: F = 59.3, P < 0.0001, n = 60.

Figure 3

Retinue activity of PA. One-way ANOVA: F = 30.2, P < 0.0001, n = 40.

Figure 4

Synergy of QMP with the three new components. One-way ANOVA F = 51.6, P < 0.0001, n = 20.

Figure 5

Retinue activity of LEA. One-way ANOVA: F = 5.4, P = 0.006, n = 30.

Figure 6

Dose–response. The bioassay results from two wild-type and two selectively mated colonies were combined (n = 48; n = 12 per colony). Treatments at each dose with the same letter are not significantly different (P < 0.05, by Tukey–Kramer test).