Meeting Abstract

6.4  Tuesday, Jan. 4  The importance of nectar sugar content in Manduca sexta flight performance and cost CONTRERAS, Heidy L.*; DAVIDOWITZ, Goggy ; University of Arizona; University of Arizona hcontrer@email.arizona.edu

Since migrating insects, such as many hawkmoths, utilize carbohydrates as fuel in the initial 30 minutes of flight, nectar sugar concentration may be an important factor determining hawkmoth flight performance. When presented with dilute nectar, starved insects imbibe an increased volume of nectar compared to insects that are presented with a more concentrated substrate. In their natural habitat in southern Arizona, Manduca sexta (Sphingidae) nectar from two very distinct plants: Datura wrightii (Solanaceae) and Agave palmerii (Agavaceae). These two native plants differ significantly in the concentration and volume of nectar that they provide. D. wrightii provides a small volume of concentrated nectar (22%) while A. palmerii provides large volumes of dilute nectar (12%) . In this study we aimed to determine the effects these different sugar concentrations may have on hawkmoth flight performance. We measured flight duration, speed and distance of M. sexta after these were fed nectar of one of four different sucrose concentrations (5%, 15%, 25%, 35%). Metabolic rates of moths fed one of the four different nectars were also measured during flight. Dilute sugar solutions (like those of A. palmerii) may add to the cost of flying as there is an increase in the volume of nectar that is consumed, and therefore an increase in the load that the moth may be carrying during flight. As a result of increased load, flight duration, speed and distance may decrease causing an overall decrease in flight performance. Therefore, we predict that insects fed dilute solutions will show decreased flight performance and increased cost of flying, while moths fed concentrated nectar solutions will show increased flight performance and decreased costs of flying.