Abstract:
Honeybee queens produce a number of pheromones that influence the behaviour and physiology of worker bees. The mandibular gland secretion of queens, the major pheromone source, suppresses the formation of emergency queen cells, worker reproduction and coordinates the social organisation of the colony. A study of analytical procedures for honeybee queen mandibular gland pheromone was undertaken, with the aim of doing multiple analyses of the same individual over a period of time. Attention was given to developing new non-destructive sampling methods that would help to characterize signal changes. This study involves the characterisation of non-destructive sampling devices that are highly selective and sensitive towards extraction of mandibular pheromone. Two polymer based sampling techniques, solid phase micro extraction and silicone rubber tubing, compatible with gas chromatography were studied. A solvent extract, of mandibular pheromone was analysed by gas chromatography (GC) and employed as a tested reference method for the two newly developed techniques. Direct sampling with solid phase micro extraction fibres at the glandular openings at the base of the mandibles is a non-destructive method that met our objectives. Mandibular gland secretions from living honeybee queens were sampled with polar and non-polar fibres. Non-polar fibres were saturated with Bis(trimethylsilyl)triflouroacetamide (BSTFA) prior to mandibular pheromone extraction. Treatment of the polymer devices with derivatising agent enhances extraction of polar components of the mandibular pheromone. BSTFA saturated non-polar fibres with a low-polarity column gave consistent results compared to polar fibres with a mid-polar column. The results confirmed that the solid phase micro extraction technique is a sensitive and non-destructive method that can ideally be used to analyse insect secretions particularly in tracking temporal changes in the secretion composition during an individual’s life. Silicone rubber tubing consisting of polydimethylsiloxane was explored as an alternative sampling technique for pheromones from living individuals. Prepared One cm long silicone rubber tubing was saturated with BSTFA prior to mandibular pheromone extraction to enhance extraction of polar components. Preliminary studies done on mandibular pheromone standards sampled with this method showed promising results. However, queen mandibular secretion analyses were characterized by low recovery of pheromonal compounds. The new polymer based techniques that we employed isolated the mandibular pheromones from living honeybee queens directly from the mandibles. The pheromonal components of the mandibular gland secretion were successfully analysed. Copyright
