Meeting Abstract

P1.9  Tuesday, Jan. 4  Oases in the desert: leaf microclimates in two host plants of M. sexta WILSON, J.K.*; POTTER, K.A.; WOODS, H.A.; FöRSTER, T.D.; University of Montana; University of Montana; University of Montana; University of Montana keatonwilson@me.com

Unlike adult and larval insect forms, sessile eggs are at the mercy of the environment in which they are placed. For herbivorous insects that deposit their eggs directly on plant surfaces, the physical environment of the leaf structures many aspects of the insect-host interaction. Our research focuses on the sphingid hawkmoth Manduca sexta and its two main host plants in southwestern deserts (US): sacred datura (Datura wrightii, Solanaceae) and devil’s claw (Proboscidea parviflora, Martyniaceae). We examined whether host-plant leaves provide favorable conditions for eggs and neonate larvae, and we estimated several components of leaf heat budgets, the most important of which was transpiration rate. In July and August of 2010, we used short-wave infrared thermography to examine both single-leaf and whole-plant temperatures of both host plants under field conditions. This technique provides precise estimates of temperature and allows us to examine patterns of temperature at several spatial scales. In addition, we measured transpiration rates of both species. Collectively, leaves were both cooler than their surrounding environment, and had very high rates of transpiration, which likely accounted for their low temperatures. These two species demonstrate limited homeothermy, and in turn provide cool, moist microclimates for M. sexta eggs and neonate larvae.