232 Final formatted article © Institute of Entomology, Biology Centre, Czech Academy of Sciences, České Budějovice. An Open Access article distributed under the Creative Commons (CC-BY) license (http://creativecommons.org/licenses/by/4.0/). EUROPEAN JOURNAL OF ENTOMOLOGY EUROPEAN JOURNAL OF ENTOMOLOGY ISSN (online): 1802-8829 http://www.eje.cz affected by several factors, such as, reproductive status (Sledge et al., 2001; Howard & Blomquist, 2005), sex, age (Gibbs & Markow, 2001; Kuo et al., 2012), food (Carvalho et al., 2012; Fedina et al., 2012), temperature, social ex- perience (Belenioti & Chaniotakis, 2020) and photoperiod (Gershman et al., 2014; Belenioti & Chaniotakis, 2020). Cuticular hydrocarbons not only protect insects against en- vironmental factors such as desiccation (Gibbs et al., 2003) and entomopathogens (Blomquist et al., 1987), but also play a major role in chemical communication, including aggregation, mating, alarm and recognition signals (How- ard, 1982; Yew & Chung, 2015). Several studies have used analytical methods to de- termine the qualitative and quantitative aspects of insect hydrocarbons (Bagneres & Morgan, 1990; Cvacka et al., 2006; Dossey et al., 2006; Blomquist, 2010b; Yew et al., 2008, 2011a, b). Currently, chromatographic separation combined with mass spectrometry (GC-MS) is the main method used to identify hydrocarbons (Blomquist, 2010b). There is several extraction procedures for determining ei- Effect of solvent extraction time on the hydrocarbon profile of Drosophila suzukii (Diptera: Drosophilidae) and behavioural effects of 9-pentacosene and dodecane MARIA BELENIOTI 1 , EMMANOUIL RODITAKIS 2 , MANOLIS SOFIADIS 3 , MARIA FOUSKAKI 1 , MARIA APOSTOLAKI 4 and NIKOs CHANIOTAKIS 1 1 Laboratory of Analytical Chemistry, Department of Chemistry, University of Crete, Panepistimioupoli Vouton, 70013 Heraklion, Crete, Greece; e-mails: maria.belenioti@uoc.gr, fouskakm@uoc.gr, chaniotakis@uoc.gr 2 Department of Agriculture, Hellenic Mediterranean University, Stavromenos PC 71410, Heraklion, Crete, Greece; e-mail: eroditakis@hmu.gr 3 Laboratory of Organic Chemistry, Department of Chemistry, University of Crete, Panepistimioupoli Vouton, 70013 Heraklion, Crete, Greece; e-mail: msofiadis@gmail.com 4 Laboratory of Environmental Chemistry, Department of Chemistry, University of Crete, Panepistimioupoli Vouton, 70013 Heraklion, Crete, Greece; e-mail: apostolm@uoc.gr Key words. Cuticle hydrocarbons, bioassays, extraction steady state Abstract. Hydrocarbons play a major role in the life cycle of insects. Their composition and concentration can be affected by several factors. Hydrocarbons are biosynthesized in oenocytes and subsequently transported to the cuticle of insects, such as Drosophila suzukii (Matsumura) (Diptera: Drosophilidae). As the extraction procedure markedly affects the type and amount of hy- drocarbon obtained we determined the association between the time taken to extract the maximum amounts of these compounds and the behaviour of D. suzukii. The required extraction time to reach a steady state is different for each hydrocarbon, which in most cases is more than one hour. On the other hand, if the entire hydrocarbon profile of D. suzukii needs to be investigated, extraction times significantly longer than one hour were required. By extending the extraction time 5 additional hydrocarbons were detected in D. suzukii for the first time. One of them, dodecane proved to be repulsive to D. suzukii. In addition, it took 3 h of extraction to determine the maximum value of 9-pentacosene, which is responsible for triggering mating behaviour in D. suzukii. INTRODUCTION The outermost layer of the insect cuticle, the epicu- ticle, is composed of a mixture of lipids. These lipids consist of branched and unbranched, saturated and un- saturated hydrocarbons, free fatty acids, sterols and al- dehydes (Blomquist et al., 1987). Hydrocarbons are also present in the inner cuticle as well as in epidermal tissue, fat body, other organs and especially in lipophorin in the haemolymph (Blomquist et al., 2010a). Hydrocarbons are mainly biosynthesized in oenocytes and then transported by high-density lipoproteins in the haemolymph to the in- sect cuticle (cuticular hydrocarbons) via specialized pore canals (Haruhito & Haruo, 1982; Schal et al., 2001; Holze et al., 2021). Internal hydrocarbons in many insects, such as Drosophila spp. are qualitatively similar to cuticular hy- drocarbons (Schal et al., 1998; Tillman et al., 1999; Ever- aerts et al., 2010; Choe et al., 2012). However, the cuticular hydrocarbon profiles may be quantitatively different from those of other tissues (Choe et al., 2012). Hydrocarbons occur in all insect life stages and their production can be Eur. J. Entomol. 119: 232–241, 2022 doi: 10.14411/eje.2022.025 ORIGINAL ARTICLE