Volatile exudates from the oribatid mite, Platynothrus peltifer

Gas chromatographic-mass spectrometric analysis of whole body extracts of Platynothrus peltifer, a desmonomatan oribatid mite that belongs to the family Camisiidae, exhibited a basic profile of seven compounds, comprising the monoterpenes neral, geranial, and nerylformate; the aromatics 3-hydroxybenzene-1,2-dicarbaldehyde (= gamma-acaridial) and 2-formyl-3-hydroxybenzyl formate (= rhizoglyphinyl formate), and two unsaturated Cl7-hydrocarbons, 6,9-heptadecadiene and 8-heptadecene. Neryl formate, gamma-acaridial, and rhizoglyphinyl formate were the main components and amounted to 80% of the extracts. With the exception of y-acaridial (relative abundance varied considerably among samples), this chemical profile was consistently present in extracts of P. peltifer from nine different localities in SE-Austria. In addition, two further components, 2,3-dihydroxy benzaldehyde and 7-hydroxyphthalide, both probably of non-oil gland origin, infrequently were detected in the extracts. The aromatic compound rhizoglyphinyl formate, also known from Astigmata, was found for the first time in extracts of Oribatida, whereas all other compounds have already been reported from other oribatid species. The hydrocarbons are generally considered to represent plesiomorphic characters of mite oil gland secretions, whereas the monoterpenes and y-acaridial form a part of the so-called "astigmatid compounds" that are thought to be characteristic for middlederivative Mixonomata and all more highly derived oribatid groups (including Astigmata).