Pheromone Producing Dorsal Abdominal Glands in Leptocoris augur

Abstract

Morphology of the scent (pheromone) glands is the first and basic step in understanding the mechanism of working of this highly evolved and integrated system of communication in insects. Leptocoris augur contains a pair of large and distinct symmetric exocrine dorsal abdominal glands (DAGs) found in the dorsal abdominal segments. The glands are simple, voluminous, sac-like and bright orange that turn brown and downsized with age. They are invested with a large and dense network of trachea and open to the exterior via minute slit shaped openings in the form of ostioles that remain permanently open to the outside. The functional specificity of these glands can be associated with the activities ranging from aggregation to sexual behaviours like courtship and mating. The mating is not restricted to a specific season, being distributed all-round the year; however, the insect prefers low and humid temperature for mating and they can be seen congregating in huge numbers when the hot summers subside and the rainy season arrives. We didn’t observe any considerable variation in size of these glands with respect to the body size in between the instars and the adults. Further, there were no significant difference between males and females in terms of the size of these DAGs.