Differences in cuticular lipid composition of the antennae of Helicoverpa zea, Heliothis virescens, and Manduca sexta Katalin Bo ¨ro ¨ czky a, *, Kye Chung Park a,1 , Robert D. Minard b , Tappey H. Jones c , Thomas C. Baker a , James H. Tumlinson a a Center for Chemical Ecology, Department of Entomology, The Pennsylvania State University, University Park, PA 16802, USA b Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA c Virginia Military Institute, Chemistry Department, Lexington, VA 24450, USA 1. Introduction The major components of the cuticular lipid coating of adult insects are often hydrocarbons, among which methyl-branched alkanes are the most abundant (Lockey, 1988). Nevertheless, a wide range of more polar lipids have been identified as constituents of the cuticle, including fatty acids, alcohols, aldehydes, ketones, wax esters, and esters of primary and secondary alcohols (references cited in Buckner, 1993). Little is known about the distribution and the function of various compound groups on the surface of adult insects. Two characteristics of the free cuticular lipids have been investigated thoroughly in insect species: the melting temperature and the critical temperature at which the cuticle becomes more permeable to water (Noble-Nesbitt, 1991). While in recent years substantial efforts have been made to prove that the correlation between these two physical parameters is true over a wide range of insect species (Gibbs, 2002), the transport of organic molecules (pheromones, plant volatiles, pesticides) through the cuticle has gained less attention (Theisen et al., 1991; Steinbrecht, 1992). Moreover, it has become apparent that lipid classes may not mix when they form the outer epicuticular layer (Gibbs, 2002) resulting in separate phases with different chemical and physical properties. Since the role of the epicuticular lipids on the olfactory sensilla has never been studied, an investigation to analyze the surface lipids of the antenna of selected moth species was conducted. Two heliothine species, Helicoverpa zea (Boddie) and Heliothis virescens (Fabricius), and the hawkmoth, Manduca sexta (Linnaeus) were chosen due to the extent to which their pheromone systems (Klun et al., 1980a, 1980b; Teal and Tumlinson, 1986; Tumlinson et al., 1989; Baker et al., 2004) and olfactory mechanisms (Matsumoto and Hildebrand, 1981; Vickers et al., 1991; Mustaparta, 1996; Vickers et al., 2005) have been studied. The pheromone systems of these moths are similar in that the male antenna holds thousands of trichoid sensilla that contain neurons finely tuned to the components of the female produced pheromone blend. Further, unsaturated 16-carbon aldehydes play a major role in the pheromone of each species. This report describes the cuticular coatings of the antennae and the forelegs of H. zea, H. virescens, and M. sexta and includes the identification of esters of short-chain Journal of Insect Physiology 54 (2008) 1385–1391 ARTICLE INFO Article history: Received 26 May 2008 Received in revised form 11 July 2008 Accepted 21 July 2008 Keywords: Moth antenna Polar lipids Cuticular hydrocarbons Sexual dimorphism ABSTRACT Analyses of the hexane washes of antennae, forelegs and whole bodies of Helicoverpa zea, Heliothis virescens, and Manduca sexta revealed notable differences in the components of the cuticular coatings of each species. Most striking were the differences between the cuticular coatings of male and female antennae of both H. zea and H. virescens. Novel esters of short-chain acids (C2–C4) and long-chain secondary alcohols (C25–C32) were identified in the hexane washes of the male antenna and forelegs of H. zea and H. virescens. These compounds were found in only small amounts or were completely absent on the female antennae of both species. In H. zea, butyrates of 7- and 8-pentacosanol and 8- and 9- heptacosanol were found, whereas, in the foreleg extracts of H. virescens, acetates and propionates were detected in addition to butyrates. While cholesterol is a major component of antennal washes (10–15%), only traces were found in the foreleg extracts. Although the composition of the cuticular coating of M. sexta differed greatly from that of the other two species, the extractable coatings of the antennae of male and female M. sexta were nearly identical. ß 2008 Elsevier Ltd. All rights reserved. * Corresponding author at: 117 Chemical Ecology Lab, University Park, PA 16802, USA. Tel.: +1 814 863 1791; fax: +1 814 863 4439. E-mail addresses: katalin_by@yahoo.com, kub13@psu.edu (K. Bo ¨ro ¨ czky). 1 Current address: Horticulture and Food Research Institute, Lincoln 7640, New Zealand. Contents lists available at ScienceDirect Journal of Insect Physiology journal homepage: www.elsevier.com/locate/jinsphys 0022-1910/$ – see front matter ß 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.jinsphys.2008.07.010