Meeting Abstract

P3.4  Friday, Jan. 6  Environmental Humidity Effects on M. Sexta Foraging Behavior PIERCE, C.T.*; CONTRERAS , H.L.; DAVIDOWITZ, G; Univ. of Arizona

Manduca sexta is a common model system used in biological studies. Although a lot is known about this insect’s behavior and underlying physiology, there are still many behavioral and physiological factors that remain unresolved. Datura wrightii is the main host plant for M. sexta. However, this moth also feeds from Agave palmeri flowers which provide a more dilute nectar compared to Datura wrightii. It is unclear when these insects choose to feed from a particular type of nectar. In this study, we hypothesized that M. sexta feed from a dilute nectar when environmental humidity is low in order to diminish the effects of dehydration. In order to determine if preference for a particular nectar is driven by differences in environmental humidities, we examined M. sexta at 20, 40, 60, and 80% RH and provided nectar varying in sucrose concentration (0 [water], 12 and 24%). Individual moths were placed in separate cages the first day after emergence. Daily consumption of nectar and changes in weight were recorded until each moth died. Our results show a threshold in the response to changes in RH for M. sexta. We saw that at low RH (20, 40%) a higher percentage of moths fed from nectar, regardless of sucrose concentration. These moths consumed more nectar overall than moths placed in higher RH (60 and 80%). There was no real difference in the preference for nectar containing sucrose in relation to changes in RH. However, moths drank more water when placed at lower RH than when placed at higher RH.