Quantitative trait loci influencing honeybee alarm pheromone levels

Quantitative trait loci (QTL) mapping procedures were used to identify loci that influence the levels of alarm pheromones found in the stinging apparatus of worker honeybees. An F₁ queen was produced from a cross between a queen of European origin and a drone descended from an African subspecies. Haploid drones from the hybrid queen were individually backcrossed to European queens to produce 172 colonies. Samples of stings were taken from backcross workers of these colonies. Alarm pheromone levels were determined by gas chromatography, RAPD markers were scored from the haploid drone fathers of these colonies. The multiple-QTL model (MQM) of MapQTL was used to identify QTLs that influence the levels of four alarm pheromone components. Seven independent, potential QTLs were identified with LOD scores greater than two, and one at LOD 1.88. We identified one QTL for n-decyl acetate, three for n-octanol, four for isopentyl acetate, and one for hexyl acetate. One region of linkage group XI shows a strong influence on body size and the levels of three alarm pheromone components. This locus explained 40% of the variance for the amount of n-decyl acetate (LOD 6.57). In general, the QTLs influencing alarm pheromone levels were independent of previously identified loci that influenced the stinging behavior of these colonies. The only exception was a potential locus influencing levels of n-octanol, which was inversely correlated with stinging behavior.