Secretion of the Dufour Glands of Two African Desert Ants, Camponotus aegyptiacus and Cataglyphis savignyi (Hymenoptera: Formicidae)

-Dufour glands of minor workers of Camponotus aegyptiacus contain a mixture of linear and methyl branched hydrocarbons and a trace of dodecyl acetate. Major workers contain a similar mixture of hydrocarbons but also large quantities of dodecyl acetate, some other long chain acetates and traces of propionates and farnesyl acetate. Cataglyphis savignyi has pentadecane as the most abundant compound with traces of ketones, alcohols and an aldehyde. Camponotus vagus, a Mediterranean species, has a more b/pical formicine mixture with undecane being the major compound. A summary of Camponotus Dufour substances demonstrates the species-specificity of this secretion. Introduction The Dufour glands of ants have been shown to be the source of a wide variety of aliphatic hydrocarbons, and related oxygenated compounds, the diversity being greatest in species of the Formicinae. From the evidence so far accumulated, it would appear that the composition of this secretion is species-specific. The purpose of this specificity is far from clear, though we have been able to show that in the genus Myrmica the secretion acts as a homerange marking pheromone for each species [1]. In some other species, the trail pheromone is found in the Dufour gland secretion [2]. Nearly all of the studies of the formicine Dufour glands have concentrated on European or North American species [3]. Few or none have dealt with tropical species, including the dry desert areas of Northern Africa. We have therefore turned our attention to the two common formicines of Egypt, Camponotus aegyptiacus Emery, which is found frequently inside and outside dwellings, foraging individually and mainly active at night, and Cataglyphis §Author to whom correspondence should be addressed. (Received 30 August 1988) savignyi (Dufour) which is highly adapted to the dry conditions, living near agricultural areas in the Nile valley. Workers forage individually, running across stones and soil during the heat of the day and returning to the nest before sunset. In addition, the dimorphic aspect of the worker caste in C. aegyptiacus offered the opportunity to investigate this dimorphism from a chemical aspect. Such a caste-related analysis of Dufour gland contents has not previously been attempted among the Formicinae, and is restricted among other subfamilies to a report on the difference in chemical content between major and minor workers of the myrmicine species Pheidole pallidula [4]. The only casterelated studies on Dufour glands of Formicinae deal with a comparison between females and workers of Camponotus aethiops [5] and of Formica sanguinea [6], in which only slight differences were found. The Dufour glands of formicine ants are characterized by the presence of long chain alkanes and alkenes, together with related oxygenated compounds, chiefly acetates and alcohols. The dominant component, often representing over two thirds of the total mass, is undecane. In just a few species there may be more tridecane than undecane. The oxygenated