Behavioral and olfactory antennal responses of Solenopsis geminata (Fabricius) (Hymenoptera: Formicidae) workers to their dufour gland secretion

Behavioral and electrophysiological tests were performed to evaluate the responses of workers of the ant Solenopsis geminata (Fabricius) from different size categories to Dufour gland extracts. Morphometric measures based in head widths across eyes were used to determine worker sizes. Trail following response of different worker sizes to Dufour gland extract from workers of different sizes was assessed. For each worker size category olfactory responses to Dufour gland extracts were determined using electroantennography (EAG). Gas chromatography and mass spectrometry (GC-MS) were used to determine the chromatographic profile of Dufour gland secretion for each worker size. Morphometric measures permitted to classify the workers of S. geminata as large, medium and small workers. Medium S. geminata workers displayed a significantly higher behavioral response to Dufour gland extracts produced by medium size workers. Similarly, medium workers showed a significantly higher EAG response to Dufour gland extracts produced by medium sized workers. Chromatographic profile of Dufour gland secretions produced by workers showed that each size category exhibited a characteristic profile of the three main components considered as potential trail pheromone constituents. This work showed that medium workers of S. geminata exhibited a high trail-following behavior as well as a high antennal response to Dufour gland secretion. This and their relative abundance in field foraging areas, suggest that medium-sized workers are specialized in foraging activities. Se efectuaron pruebas comportamentales y electrofisiológicas para evaluar las respuestas de obreras de Solenopsis geminata (Fabricius) de diferentes tamaños a extractos de la glándula de Dufour. Se usaron medidas del ancho de la cabeza para determinar el tamaño de las obreras. Se evualuó la respuesta de seguimiento de ruta de obreras de diferentes tamaños a extractos de la glándula de Dufour proveniente de obreras de diferentes tamaños. Para cada grupo de obrera de determinado tamaño se le determinó la respuesta olfatoria por medio de electroantenografía (EAG). Se utilizó Cromatografía de Gases acoplada a Espectrometría de Masas (GC-EM) para determinar el perfil cromatográfico de la secreción de la glándula de Dufour para cada grupo de obreras. Las medidas morfométricas permitieron clasificar a las obreras de acuerdo a su tamaño en grandes, medianas y pequeñas. Las obreras medianas de S. geminata exhibieron una respuesta co