Potential application of a Gulf Coast Tick, Amblyomma maculatum Koch, Aggregation-Attachment-Pheromone for surveillance of free-living adults

The aggregation-attachment-pheromone (AAP) of two geographic strains of the \nGulf Coast tick, Amblyomma maculatum Koch, was investigated to evaluate practicality \nof using solid-phase-microextraction (SPME) in an AAP study of Gulf Coast tick. \nSolid-phase microextraction was used to compare the AAP production in two strains of \nfed male Gulf Coast tick and demonstrate and confirm the presence of AAP in bioassays. \nA solid-phase-microextraction (SPME) headspace collection technique was \nsufficient to capture volatile organic compounds produced by fed and unfed male Gulf \nCoast ticks. Gas chromatography analysis revealed three major volatile organic \ncompounds were produced in significantly greater amounts (p < 0.05) by fed males than \nthose produced by unfed males. These volatile compounds were produced in \nsignificantly higher amount by the third day of feeding by male ticks. However, two of \nthese volatiles remained relatively constant in their production while the primary volatile \ncompound increased in its production until the eighth day of feeding by male Gulf Coast \nticks. Also, the relative abundances of these three volatile organic compounds were \ndifferent between Oklahoma and Texas strains of Gulf Coast ticks. \nThe activity of AAP from fed male Gulf Coast ticks was confirmed using two \nbioassay techniques. A petri dish bioassay revealed significantly higher numbers of \nfemale Gulf Coast ticks attracted to fed-males which also produced significantly greater \namounts (p < 0.001) of volatile organic compounds detected by GC analysis. The Ytube \nolfactometer bioassay revealed that significantly higher numbers of females \nresponded to fed-males or to CO2 when compared to purified air (p < 0.001), but the \ndifferences in female response to fed-males and CO2 were not significant (p < 0.391 in \nOklahoma strain and p < 0.458 in Texas strain). However, female responses to stimuli \ncontaining both fed-males and CO2 were significantly higher when compared to either \nstimulus alone (p < 0.001).