In almost all cases, a gland normally utilized for other functions has been converted into a social organ, presumably as a consequence of the ﬁnite number of exocrine organs available for communicative functions of the best pheromones.
Butler et al. (1969) have demonstrated that both honey bees and wasps lay trails with footprints in the vicinity of the hive or nest, and the pheromones appear to be derived from dermal glands. These footprint trails are apparently employed by workers to orient to the nest entrance and it has been suggested that such trails may be present in the vicinity of the nests of other hymenopterans such as ants. Indeed, there is evidence that ants can lay trails with their feet (tarsi) and this phenomenon may be widespread in eusocial insects. Workers of the ant Eciton hamatum (Fab.) generate trails with a hind gut secretion (table 12.1) but nevertheless are able to lay weak footprint trails after their abdomens have been removed (Torgerson and Akre 1970). Leuthold (1968) has also reported that, if a well-established trail of the myrmicine Crematagaster ashmeadi Mayr is interrupted, the ants will re-establish the trail without exhibiting typical trail-laying behavior involving the hind legs (table 12.1). He interprets this ‘passive’ trail laying as a function of the deposition of normal footprint material which is less stimulatory than the recruitment phero- mone but nevertheless suffices as a low level trail-following stimulus. Although the footprint trails developed by ants, bees, and wasps could not in themselves be completely responsible for the specific odors that the members of each colony possess, they may still serve as an important component of the aromas that accom- pany the individuals of a nest.
It is only in the stingless bees that the mandibular glands are known to be employed in dispensing trail pheromones (table 12.1). Lindauer and Kerr (1958) demonstrated that these trails are especially distinctive since they actually function as ephemeral aerial ﬂyways accurately followed by airborne bees. These trails devel- op from a series of droplets deposited at specific intervals from a food source back to the nest. These chemically-developed ﬂyways are particularly well adapted for use in tropical rain forests, and, as they are functional in both the horizontal and vertical component, they can guide bees to the rich ﬂora at the top of the forest canopy. Learn more about the best pheromones at http://pheromones-planet.com/mens-pheromones/.
However, it is among the ants that the independent development of trail organs by different phyletic lines is so clearly expressed (table 12.1). Formicid trail sub- stances are present in glands: 1) secondarily adapted to function as social organs (poison gland and Dufour’s gland); 2) extensively hypertrophied to produce trail pheromones (tibial glands); and 3) which arose de novo to play the role as dispen- sers of chemical releasers of trail following (Pavan’s gland). Since members‘ of both the poneroid (Ponerinae and Dorylinae) and myrmecioid (Forrnicinae) complex (Brown 1954) utilize the hind gut for a source of trail pheromones, the social function of this organ has arisen independently in the two main lines of formicid evolution, ln contrast, the poison gland is restricted as a trail organ to species in two subfamilies in the poneroid complex, the Myrmicinae and the Ponerinae.