Other cephalic glands

The function of the hypopharyngeal glands is known only in the honey bee. In nurse worker bees, they secrete a portion of the bee milk , the food given to larvae which is a complex mixture of lipids, vitamins and proteins. They also secrete invertase and an enzyme that oxidizes glucose to an acid (Cruz Landim and Hadek, 1969). 

Female Colletidae and Andrenidae possess a pair of depressed areas, densely covered by short setae, on the face between the eyes and antennae. These areas, the facial foveae, are lined by enlarged epidermal cells that appear to be 

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Whiie the esters (and lactones) mentioned above may (or may not) be mixtures, the farnesyl and geranyl esters found in Andrena are not. They appear to all be of all-tra/is-farnesol and devoid of esters of the other farnesol isomers. Simiiarly the geranyl esters are free of their neryl counterparts. The specific isomer of dihydrofarnesyl acetate from Melissodes is unknown although 2,3-dihydro-6-tra 5-farnesol has been found in a Bombus jonellus cephalic gland (Bergstrom and Svensson, 1973a). 

Defensive substances are often general irritants that can be used in a variety of contexts. For example, the alloxystine wasps (Cynipoidea), all hyperpara-sitoids of other hymenopteran parasitoids, produce a large number of compounds in their cephalic (mainly mandibular) glands. These compounds include m/p-xylol, 6-methylhept-5-en-2-one 16, various iridoids 21 and frans-dihydro-nepetalactone 22 [46,73]. 

All- m 5-farnesyl hexanoate (190) was the main component of the female Dufour s gland secretion of eleven Andrena species, while ger-anyl octanoate (191) was the main component of the secretion from two other species. One or another of these two compounds is also the dominant component in the cephalic secretion of male Nomada bees. Apparently, Nomada bees prey only on a single Andrena host species. All-rm 5-famesyl hexanoate (190) is the dominant component... 

On the other hand, the cephalic secretion of the cleptoparasitic bee Holcopasites calliopsides produces two main substances, 6-methyl-5-hepten-2-one (62) and geranyl acetone (63), whereas the mandibular gland secretion of its host Caliopsis andreniformis contains neral (199) and geranial (200). Thus in this case no evidence was found to support the hypothesis that H. calliopsides uses host mandibular gland secretion as a kairomone to locate C. andreniformis nests (579). 

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