Ant (Hymenoptera: Formicidae) to Trail and its Tvvo Alarm Substmcesl

Electsoantennograms (EAGs) were recorded from major workers, queens, and males of the Texas leaf cutting, Attu texana (BucMey) wpenoptera: Forrnicidae) in response to serial dilutions of two alarm subsbnces, 2-hephone and 4-methyl-3-heptanone, and its trail pheromone, 4-methylpynole-2-carboxylate. The lower EAG threshold for major workers relative to queens and males for both alarm substances correlated well with previously reported behavioral bioassays which showed workers to be most responsive to these odorants. Although Iaboratory behavioral bioassays showed minor workers, queens, and males to have a similar behavioral threshold for the trail pheromone, minor workers were more responsive to higher concentrations of the trail pheromone. However, EAGs revealed queens si~iflicantly more sensitive and responsive to the trail pheromone than the other castes. These seedngly eniwatic results are discussed with regard to A. texana biology and receptor physiology.