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The sampling behavior of the Colorado potato beetle Leptinotarsa decemlineata Say (CPB) involves examination of the surface of potato leaves. It has been suggested that leaf surface compounds (volatiles and cuticular waxes) may be involved in host-plant recognition, acceptance or discrimination. Here we report on the effect of leaf surface extracts of six Polish commercial potato varieties on CPB feeding. We tested the influence of potato leaf surface extracts on CPB adult and larval feeding, then separated the extracts with HPLC, and finally tested the effect of the HPLC-separated fractions on CPB feeding. The bioassays were performed using potato leaf discs deprived of their original surface compounds. Applied to test discs at concentrations ten times higher than natural (10 leaf area equivalent), the extracts deterred CPB adults and larvae from feeding. HPLC-separated fractions composed of alkanes, sesquiterpene hydrocarbons, wax esters, benzoic acid esters, fatty acid methyl, ethyl, isopropyl and phenylethyl esters, aldehydes, ketones, methyl ketones, fatty acids, primary alcohols, b-amyrin and sterols did not affect adult CPB feeding. Similarly, alkanes, sesquiterpene hydrocarbons, wax esters, methyl ketones, sesquiterpene alcohols and secondary alcohols had no effect on larval CPB feeding. The sterol fraction (cholesterol, b-sitosterol and stigmasterol) acted as a phagostimulant to CPB larvae. We isolated a fraction demonstrating a phagodeterrent effect on CPB adults and larvae. The qualitative composition of the deterrent fraction was quite similar in all potato extracts, but there were quantitative differences between the varieties. Much further work is needed to identify the compounds that can produce the deterrent effect.

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Recently, ionic liquids (ILs) have been regarded as an attractive water-immiscible phase in liquid-liquid extraction. Because ILs have a wide range of polarity irrespective of their miscibility with water, the possibility of using them as an effective extraction phase for a broad range of contaminants means they are starting to be of particular interest. In this study we investigated a wide variety of ionic liquids, which are known to be hydrolytically stable and of a hydrophobic character, for their potential suitability as passive-sampling media for monitoring selected polyaromatic hydrocarbons. Preliminary research in this field has indicated very promising results using these novel extraction media. Because there is an enormous number of possible cation-anion combinations offering tuneable properties of ionic liquids with the potential for effective passive extraction, we hope this paper will encourage the scientific community to undertake further studies verifying the undoubted usefulness of these alternative solvents as passive samplers for many other groups of analytes. Additionally, because of the unusual solubility properties that have already been proved for ILs, it is very probable that it would soon be possible to deliver a very effective system able to extract analytes differing widely in polarity.