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Title:Factors contributing to variation in cuticular hydrocarbon profiles of two species of longhorned beetles (Coleoptera: Cerambycidae)
Author(s):Silliman, Christina
Advisor(s):Hanks, Lawrence M.
Department / Program:Entomology
Degree Granting Institution:University of Illinois at Urbana-Champaign
cuticular hydrocarbons
environmental variation
body size
Abstract:In many insects, females have certain hydrocarbons in their cuticular hydrocarbon profile that serve as contact pheromones. These sex-specific mate recognition signals are present in much smaller quantities, or even absent in males. Although hydrocarbon profiles are to some degree heritable, the relative abundance of specific hydrocarbons can be altered by a variety of environmental factors, such as nutrition, temperature, and relative humidity. I investigated factors influencing the composition of cuticular hydrocarbons of two species of longhorned beetles that are native to eastern North America, Neoclytus acuminatus (F.) and Xylotrechus colonus F. The cuticular wax layer of N. acuminatus comprises at least 20 hydrocarbons ranging from C24 to C29, three of which serve as the contact pheromone of females. The wax layer of X. colonus contains at least 17 hydrocarbons that range from C25 to C31, and the contact pheromone is again a blend of three components. Body size of adult beetles was significantly associated with the relative amounts of some, but not all, contact pheromone components and non-pheromone hydrocarbons. With respect to contact pheromones, this relationship could provide a means by which males assess the size of females, and allow for mating preference based on body size. The relative abundance of hydrocarbons, including contact pheromones of X. colonus, varied significantly during the seasonal flight period. The causes of this variation are not known, but could reflect seasonal differences in host quality or other external factors. Cuticular hydrocarbons of adult N. acuminatus also varied significantly in relative abundance spatially, both across small geographical distances in east-central Illinois (not more than ~55 km), and more distantly between populations in Illinois and Pennsylvania. Hydrocarbon profiles of beetles, as assessed by solid-phase microextraction (SPME) did not change when they were killed and frozen, an important consideration for the methods used during the study. Profiles varied across body regions of individual beetles, suggesting that sampling only one portion of the body by SPME may not yield a profile that is truly characteristic of the species, especially with regard to contact pheromones. In summary, this study provides evidence that hydrocarbon profiles of insects are dynamic, varying spatially and temporally, and may be influenced by environmental factors.
Issue Date:2014-05-30
Rights Information:Copyright 2014 Christina Silliman
Date Available in IDEALS:2014-05-30
Date Deposited:2014-05

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