Changes in the Morphology and Ultrastructure of the Dufour's Gland During the Life Cycle of the Bumble Bee Queen, Bombus Terrestris L. (Hymenoptera: Bombini)

Abstract

The Dufour's gland is found closely associated with the sting apparatus of all female hymenopterans, playing multiple roles among bees. In some species of Bombus the gland may be involved in production of nestmate recognition pheromones, but in B. terrestris its function is not certain yet. The morphology of the Dufour's gland of B. terrestris queens and the ultrastructural features of its cells were studied in different ages and behavioural stages using routine transmission electron microscopy. Measurements of the length and the diameter of the gland in the same conditions were also made. The Dufour's gland of the queen increases signi cantly in size (both in length and in diameter) with age and reproductive activity. The ultrastructural features of the gland show electrondense material that comes from the haemolymph. This material is also present in the intercellular spaces, and is conducted to the subcuticular space, to be released directly into the glandular lumen. Hence at least part of the secretion is probably taken up directly from the haemolymph. The ultrastructural features indicate a more active phase of the gland corresponding to the period of egg-laying of the queen, and a decrease in activity when the queen is in hibernation as well as after the competition point. In conclusion, the gland is probably involved in reproduction, more speci cally, in the marking of eggs.

Age and time related pheromone production in coffee leafminer Leucoptera coffeella Guérin-Méneville (Lepidoptera: Lyonetiidae)

“…This hypothesis can be tested by subjecting the population to high amounts of pheromone in a way that pheromone traps with the right dose of pheromone can compete with feral females. 28 In our study, the quantification of 1 was done taking in account a stereoisomeric mixture because the absolute configuration of the natural pheromone still remains unknown. [28][29][30] However, in field experiments using all the four possible stereoisomers synthesized by Kuwahara et al 29 it was observed that the traps baited with pure stereoisomers were poor attractive 30 while the binary mixture of the 5S,9S-(1) and 5R,9S-(1) isomers were attractive comparable to a stereoisomeric mixture of (1).…”

Function of the Dufour’s gland in solitary and social Hymenoptera

“…In bumble bees (Bombini), the Dufour's gland has been found to increase in size and activity with the reproductive activity and age of queens, and queen worker differences in gland size have also been reported, implying a possible role as an egg marking pheromone (Abdalla et al 1999). Queen signaling and nestmate recognition through Dufour's gland has also been implied (Tengö et al 1991, Oldham et al 1994, Ayasse et al 1999.…”

“…It is partially covered by a muscular layer and is associated with tracheoles and nerves (Hermann and Blum 1967a, 1967b, Landolt and Akre 1979, Downing and Jeanne 1983, Billen 1986a, 1986b, Abdalla et al 1999. Since there is a single layer of glandular epithelium, the Dufour's gland is a "class I" epidermal gland, as described by Noirot and Quennedy (1974).…”

A Comparative Cytochemical Study of the Dufour Gland in the Eusocial Bee Apis mellifera Linne, 1758 and Melipona bicolor Lepeletier, 1836

“…This phase is of short duration and in A. mellifera the mechanism of secretion release is very curious, since the secretion is released in blocks constituted by aggregations of granules, which accumulate in the cuticle, before being released to the lumen [4]. In A. mellifera and B. terrestris the secretory phases are related with the age and fecundity condition of the bee [1,2,4]. The same may occur in M. bicolor, the physogastric queen gland cells being more active than the virgin queen gland cells (data not shown).…”

“…According to Katzav-Gozansky et al [11], only the esters are synthesized by the gland, the hydrocarbons being taken up probably from the hemolymph. In fact, the Dufour gland cells of A. mellifera [4] and Bombus terrestris [1,2] present, in both castes, many invaginations of the basal plasmic membrane, which ramify or form loops, with many mitochondria associated on the cytosolic surface. Such structures form a cell basal labyrinth that constitutes an apparatus for absorption of exogenous substances [4][5][6].…”