A new pheromone in the ant Pheidole pallidula (Myrmicinae).

In the dimorphic species Pheidole pallidula, an ethological factor, present on the VIIth abdominal sternite attracts ants from short distances and enhances the linear speed of those having approached it. Added to poison gland extract, it improves the workers' trail following behaviour. This factor is essentially presented by minors, majors' sternite having a much weaker ethological effect. Several functions and a glandular origin are suggested for this hitherto unknown pheromone in Pheidole pallidula.