Water loss in three species of tiger beetles ( Cicindela): Correlations with epicuticular hydrocarbons

• Published in: Journal of insect physiology Vol. 33; no. 10; pp. 677 - 682
• Main Authors: Hadley, Neil F, Schultz, Thomas D
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 1987; Elsevier
• Subjects: Biochemistry. Physiology. Immunology; Biological and medical sciences; Chemotaxonomy; Cicindela; cicindela obsoleta; cicindela oregona; cicindela tranquebarica; Coleoptera; cuticle; dry environmental conditions; Fundamental and applied biological sciences. Psychology; hydrocarbons; Insecta; Invertebrates; lipids; losses; Physiology. Development; tiger beetles; water; water excretion; water loss; Arizona; water loss; lipids; hydrocarbons; cuticle; Chemotaxonomy; tiger beetles; Cicindela; Gas chromatography; Water loss; Hydrocarbon; Coleoptera; Arthropoda; Insecta; Interspecific comparison; Cicindelidae; Cuticle; Lipids; Water balance; Invertebrata
• ISSN: 0022-1910; 1879-1611
• DOI: 10.1016/0022-1910(87)90050-3

Water loss rates in dry air at 30°C and cuticular lipid/hydrocarbon composition were determined for three species (eight populations) of tiger beetles ( Cicindela oregona, C. tranquebarica and C. obsoleta). The highest water loss rates were found in C. oregona (0.049 to 0.052 mg cm −2h −1 mmHg −1), a species active in spring and fall along water courses in Arizona, while the lowest rates were exhibited by C. obsoleta (0.022 to 0.028 mg cm −2h −1 mmHg −1), a summer-active species that inhabits dry grasslands. Water loss rates for C. tranquebarica were closer to those of C. obsoleta even though C. tranquebarica often coexists with C. oregona. Hydrocarbons were an important constituent of the cuticular lipids of all three species; smaller quantities of wax and cholesterol esters, triacylglycerols, free fatty acids, alcohols, and cholesterol were also detected. C. obsoleta contained the greatest amount of hydrocarbon per surface area. All of its hydrocarbon molecules were saturated, with branched components accounting for about 60% of the total fraction. Saturated (primarily n-alkanes) and unsaturated ( n-alkenes) molecules were present in both C. oregona, which contained the lowest hydrocarbon surface density, and C. tranquebarica. The hydrocarbon composition of the three species is discussed in terms of its contribution to the epicuticular waterproofing barrier and its potential use as a chemotaxonomic tool.