Top Trail Pheromones
There is no information on the chemical identity of the trail pheromone. It has been shown that bees are attracted to an ethanol extract of glass beads on which bees have stood to forage (Lecomte, 1957) and a dichloromethane extract of the deposit left by bees that gathered on empty dishes (Ferguson and Free, 1979).
Chauvin (1962) thought that trail pheromone is probably produced by the Arnhart’s gland located on the tarsal extremities but it now seems that the trail pheromone is widely distributed on a bee’s body. The odour of head, thorax or abdomen alone is attractive and will elicit an alighting response of bees searching for food, although the thorax and dorsal surface of the abdomen are especially effective. (Butler et al., 1969; Ferguson and Free, 1979). The increased response to the dorsal surface of the abdomen possibly reﬂects the presence there of Nasonov pheromone. Irrespective of its origin, the trail pheromone must move to the feet from whence it is deposited, as other parts of a walking bee’s body (with the possible exception of the tip of the abdomen (Butler, 1969)) rarely touch the substrate. Because bees leave a trail odour on glass it is likely they do so even more readily when trampling over the petals of a ﬂower. When foraging on ﬂowers all parts of a bee’s body often rub against the petals, stamens and stigma so a rapid rate of deposition would be possible. Learn more about the top pheromones at http://buy-pheromones.org and http://pheromones-planet.com/mens-pheromones/.
Free and Williams (1974) found that wire gauze on which A. ﬂorea foragers had stood to reach sucrose syrup below induced other foragers to alight on it, so it is likely that A. ﬂorea workers also produce an attractive trail pheromo- ne. It is probably of special signiﬁcance in the communication of rewarding ﬂoral sources to other A. ﬂorea foragers as, unlike A. mellzfera, they do not release Nasonov pheromone (page 118) in such circumstances.
Although the trail pheromone is very effective in releasing alighting responses of bees conditioned to a source of forage, and by bees recruited to the area, it is not known at what distance it is perceived and responded to. If foragers are attracted from a distance, it would be worth exploring the possibility of using a synthetic preparation of the pheromone to apply to crops needing insect pollination.
Pheromones do not make orientated communication dances, but deposit scent marks every few metres between the nest and food to form a trail that alerted nestmates follow (Lindauer, 1956; Lindauer and Kerr, 1958; Nedel, 1960). When a scout bee has discovered a food source it usually makes several trips between its nest and food before it lays down a pheromone trail. Scent marks are deposited on leaves, branches, pebbles and even clumps of earth. Distances between adjacent scent marks vary according to the species concerned from 2 m or less (T. bipunctata) to between 10 and 30 m (T. mnidadensis) (Kerr et al. , 1963).
Workers of T. subterranea place their scent marks in an irregular manner and the distance separating adjacent marks is very variable. The ﬁrst mark is placed at the food source and the second only 30—50 cm from it. Thereafter marks are placed 1-5 m apart in the direction of the nest. Individual bees have their own characteristic marking patterns (Blum et al., 1970). Different species also have their own preferred height at which to deposit scent trails (Kerr et al., 1981).
Trail odours last only 8-19 minutes without reinforcement (Kerr et al., 1963). However, it is possible that the odour released by T. cupira is strong enough to form an aerial odour trail in the calm conditions of a tropical forest (Kerr, 1969). While foraging on ﬂowers workers of T. spinipes produce a strong odour from their mandibular glands that may attract recruits (Kerr, 1973).