P1: IZO Journal of Chemical Ecology [joec] PP1178-joec-485197 March 10, 2004 22:8 Style file version June 28th, 2002 FOR PROOFREADING ONLY Journal of Chemical Ecology, Vol. 30, No. 5, May 2004 (  C 2004) GENETIC ANALYSIS OF BENZOQUINONE PRODUCTION IN Tribolium confusum ANN YEZERSKI, 1,∗ TIMOTHY P. GILMOR, 2 and LORI STEVENS 3 1 Biology Department, King’s College 133 N. River St., Wilkes-Barre, Pennsylvania 18711, USA 2 Johnson & Johnson, Pharmaceutical Research and Development L.L.C., Route 202, Raritan, New Jersey 08869, USA 3 Biology Department,University of Vermont Marsh Life Science Building, Burlington, Vermont 05405, USA (Received March 11, 2003; accepted January 14, 2004) Abstract—Many species of tenebrionid beetles produce and secrete benzo- quinones from specialized prothoracic and postabdominal glands. Tribolium confusum produces two compounds methyl-1,4-benzoquinone (MBQ) and ethyl- 1,4-benzoquinone (EBQ). These compounds are hypothesized to function as external defense compounds, killing microbes and deterring predators, and their ability to evolve by natural selection depends on both selection and the genetic vs. environmental contribution to phenotypic variation. We crossed a strain of T. confusum that produces high quantities of benzoquinones, b-Pakistan, with a low-producing strain, b-+, and measured both the internal and external quanti- ties of MBQ and EBQ for the two extreme strains and their F 1 progeny. Internal amounts show a clear pattern of inheritance, with at least 50% of the phenotypic variation attributed to genotype. Additive and dominance coefficients for inter- nal amounts indicate that the trait is additive with no significant dominance. In contrast, external quantities show little pattern of inheritance. The role of genet- ics and environment in determining quantities of secretory defensive compounds is important to elucidating the ecology and evolutionary potential of chemical defenses. Key Words—Defense compounds, genetic vs. environmental components, Tri- bolium, benzoquinones, evolutionary adaptation. INTRODUCTION Many organisms produce constitutive defense chemicals. The evolution of con- stitutive defensive compounds is likely to be affected by the costs and benefits ∗ To whom correspondence should be addressed. E-mail: amyezers@kings.edu 1029 0098-0331/04/0500-1029/0 C  2004 Plenum Publishing Corporation