Meeting Abstract

34.3  Wednesday, Jan. 5  Costs and benefits of pupal chamber construction by the hawkmoth Manduca sexta (Lepidoptera: Sphingidae) SPRAGUE, J. C.*; WOODS, H. A.; The University of Montana; The University of Montana jonathan1.sprague@umontana.edu

Functional organismal traits have costs and benefits: e.g. hearts, kidneys, and appendages do things for an organism, but there are energetic, resource, and/or time costs associated with building and maintaining them. While this is well understood for somatic traits, many organisms have “extended traits” such as burrows, nests, or dams that are every bit as important as internal organs, and carry similar costs and benefits. In this study, we explore the costs, benefits and fitness consequences of underground pupal chambers made by larvae of the tobacco hawkmoth (Manduca sexta). These chambers can affect M. sexta during four discrete timeframes: 1) during chamber construction, 2) during ecdysis from larval to pupal cuticle, 3) through metamorphosis, and finally 4) during adult emergence. We found that 1) the cost of chamber construction varies significantly with soil moisture, 2) that chamber space underground is vitally important for larval-pupal ecdysis, 3) that pupae lose more mass during metamorphosis without chamber space, and 4) that chamber space is important to adult emergence in wet soils but not dry soils. These results are broadly important, and strongly suggest that underground pupal chambers, while costly to make, provide benefits that affect the ecology, physiology and fitness of M. sexta.