Male pheromone composition depends on larval but not adult diet in Heliconius melpomene

Abstract

1. Condition-dependent traits can act as honest signals of mate quality, with fitter individuals able to display preferred phenotypes. Nutrition is known to be an important determinant of individual condition, with diet known to affect many secondary sexual traits. 2. In Heliconius butterflies, male chemical signalling plays an important role in female mate choice. Potential male sex pheromone components have been previously identified, but it is unclear what information they convey to the female. 3. Here, we test the effect of diet on androconial and genital compound production in male Heliconius melpomene rosina. To manipulate larval diet, we rear larvae on three different Passiflora host plants: P. menispermifolia, the preferred host plant, P. vitifolia, and P. platyloba. To manipulate adult diet, we rear adult butterflies with and without access to pollen, a key component of their diet. 4. We find no evidence that adult pollen consumption affects compound production in the first ten days after eclosion. We also find strong overlap in the chemical profiles of individuals reared on different larval host plants. The most abundant compounds produced by the butterflies do not differ between host plant groups. However, some compounds found in small amounts differ both qualitatively and quantitatively. We predict some of these compounds to be of plant origin and the others synthesized by the butterfly. Further electrophysiological and behavioural experiments will be needed to determine the biological significance of these differences.KD was supported by a Natural Research Council Doctoral Training Partnership and a Smithsonian Tropical Research Institute Short Term Fellowship. KJRPB and CDJ were supported by a European Research Council grant number 339873 SpeciationGenetics. WOM was supported by the Smithsonian Tropical Research Institute and NSF grant DEB 1257689. SS thanks the Deutsche Forschungsgemeinschaft (DFG) for support through grant Schu984/12-1