RESUMEN
Conventional gas chromatography with electroantennographic detection (GC-EAD) and two-dimensional (GCxGC) gas chromatography using a time-of-flight mass spectrometric detector (TOFMS), were combined to analyse the female sex pheromone gland extract of the persimmon bark borer, Euzophera batangensis. GC-EAD analysis produced two EAD responses in GC areas where no compounds were detected by FID detection. GCxGC/TOFMS analysis of this area indicated the presence of several chemicals, including (Z9,E12)-tetradeca-9,12-dien-1-ol and (Z9)-tetradec-9-en-1-ol, pheromone components of closely related Euzophera species. Spectral characteristics, retention behaviour and the ability to elicit GC-EAD responses imply that both identified unsaturated alcohols are candidates for E. batangensis sex pheromone components. GCxGC/TOFMS facilitated the analysis of complex matrices on a subnanogram level and was shown to have great potential as a powerful tool in the analysis of insect pheromones.
RESUMEN
An insect neuropeptide leucopyrokinin (LPK) (pQTSFTPRLamide) accelerates pupariation in wandering larvae of the fleshfly Sarcophaga bullata. The period of sensitivity to the action of LPK begins approximately 4 h before pupariation. Within this period the degree of acceleration of contraction into the shape of a puparium is practically independent of the age at which the larvae are injected, while acceleration of tanning is distinctly more age dependent. From ligation experiments we conclude that intact central innervation is essential for the action of LPK on puparial contraction, whereas central neurones take no part in mediation of LPK action on tanning of the cuticle. An analysis of tensiometric recordings of muscular activity revealed that the actual time of LPK accelerated puparial contraction coincides with the beginning of the immobilisation/retraction phase. LPK accelerates the switch from wandering behaviour to immobilisation/retraction behaviour but has no effect on the onset and duration of motor patterns that normally underlie puparial contraction in controls. The morphology of an accelerated puparium is normal but its formation is temporally dissociated from normal 'contraction patterns' that are performed a long time after the puparium has contracted. It means that neuromuscular activity of larvae accelerated by LPK does not cease upon formation of the white puparium, but continues until the whole motor programme of pupariation behaviour is completed. Apparently the peptide acts on the integument by stimulating it to contract and shrink, and no specific patterns of muscular contractions are needed to properly shape the puparium. This finding sheds a new light on our understanding of the mechanism of puparium formation.
