Species-Specific Chemical Signatures in Scale Insect Honeydew

The quantity and chemical composition of honeydew produced by scale insects may influence wider community structure, but little is known about the detailed chemical composition of the honeydew found in forest ecosystems. We used gas chromatography–mass spectrometry to examine the amino acid and carbohydrate composition of honeydew from three New Zealand communities. Low molecular weight carbohydrates (mono-, di-, and tri-saccharides) were derivatized using a modified trimethylsilyl (TMS) method, and amino and non-amino organic acids were derivatized using methylchloroformate (MCF). These recently developed derivatization methods allowed us to detect atypical compounds such as sugar alcohols, fatty acids, and non-amino organic acids, in addition to the more routinely studied compounds such as sugars and amino acids. Some compounds could not be identified and may be novel. Multivariate analysis showed that honeydew from each scale insect species had a distinctive amino acid and carbohydrate signature. We suggest these chemical signatures may influence the types of consumers that are attracted to different honeydews and may explain the characteristic communities associated with these honeydews.