Effect of temperature on survival and cuticular composition of three different ant species

Abstract

Climatic factors, such as temperature variation, interfere with the survival of insects. To respond to these variations, insects have some specific characteristics. These include water content of the body, thickness of the lipid layer, as well as the qualitative and quantitative characteristics of cuticular chemical components. This study hypothesizes that different ant species respond to temperature changes in different ways and that such differences may be associated with cuticle hydrocarbons (CHCs) and fatty acids. As model ant species, Atta sexdens, Odontomachus bauri and Ectatomma brunneum were used for experimental analyses. Ants were submitted to a water bath for 5 h at different temperatures, and their CHCs and fatty acids were identified and quantified, followed by correlating these chemical compounds with temperature variations and the survival. Temperatures below 30 °C did not affect the survival of the three species. E. brunneum had a higher percentage of survival at temperatures above 30 °C. O. bauri was the most sensitive species with 100% mortality at 40 °C. Survival was found to be unrelated to any of the identified fatty acids. However, CHCs underwent significant quantitative and qualitative variation, as shown by an increased percentage of CHCs with longer chain length of linear alkanes at temperatures above 30 °C. These increase enables these ants to maintain the integrity of their cuticle and survive at temperatures above 30 °C. It can be concluded that the forager ants studied respond differently to temperature variation and that changes in the conformation of CHCs are in line with the ecological characteristics of the different studied species because, they vary in terms of diurnal/nocturnal foraging and types of environments foraged. Among the three species, E. brunneum foragers were found to be more active under adverse conditions and more tolerant to temperature variation with the correspondingly appropriate changes in CHCs composition.