PARENT SESSION
Poster Session 34: Herbivory
Thursday, August 11, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Nectar amino acids attract antagonists.
Lentz, Amanda*,1, Adler, Lynn2, 1 Virginia Polytechnic Institute and State University, Blacksburg, VA2 University of Massachusetts, Amherst, MA
ABSTRACT- Floral traits are thought to evolve largely in response to positive selection by pollinators. However, depending on the life stage, some pollinator species can exert conflicting selection pressures on a single plant trait. For example, moths can be antagonists as larvae since they are herbivorous, but mutualists as adults since they provide pollinator services. In this case, the selective advantage of floral traits will depend on how the trait affects both mutualist and antagonist insect behaviors. Larvae of Manduca sexta L. are specialist herbivores of tobacco (Nicotiana tabacum L.) and provide pollinator services as adults. Adult moths are protein limited, especially females since they can continue to mature eggs as adults. We examined how the feeding behavior and oviposition preferences of adult M. sexta are affected by the enhancement of floral nectar with the essential amino acid arginine, and how changes in pollinator behavior can affect the fitness of tobacco. We manipulated tobacco nectar by adding artificial floral nectar with or without arginine. We found that females allocated more eggs to plants with amino acid enhanced nectar, suggesting that floral nectar may serve as an indicator of host plant suitability for developing larvae. Male and female hawkmoth floral visitation did not vary among treatments and plant fitness was not affected by nectar manipulation. However, if we had allowed eggs to mature into larvae, nectar amino acids may have had a negative impact on plant fitness, since a single hornworm can defoliate an entire tobacco plant. Results suggest that floral nectar may provide information about the nutritional status of the plant and that females use this information when assessing plant suitability during oviposition. Further, herbivores may act as a selective agent on nectar traits. Thus, nectar amino acids may not always be beneficial to plants, and in some cases, can have a negative impact on plant fitness.
Key words: antagonists, hawkmoths, nectar, amino acids