PARENT SESSION
Wednesday, August 9, 8:00-11:30 am
COS 50 - Effects of herbivory I
L-2, Lobby Level, Cook Convention Center
Presiders: C Ivey
Influence of above and below ground herbivory on pollination and plant reproduction in Cucurbita moschata.
Hladun, Kristen*,1, Adler, Lynn2, 1 University of Massachusetts, Amherst, Amherst, MA2 University of Massachusetts, Amherst, Amherst, MA
ABSTRACT- In the natural world, plants have to defend themselves in a complex environment, experiencing antagonism from several different sources and on several different tissues. Investigations into the effects of herbivory on plant fitness have typically focused on either aboveground or belowground herbivory separately. This study examines the effects of both above- and below-ground herbivory on floral traits, pollinator visitation, and plant reproduction. The major herbivore on the crop plant Cucurbita moschata (butternut squash) is Acalymma vittatum, the striped cucumber beetle. Above and belowground herbivory can happen simultaneously in this system when the second generation of root-feeding larvae overlaps with the first generation of foliage-feeding adult beetles. I conducted an above- and below-ground herbivory experiment at South Deerfield Research Farm (Deerfield, MA) during summer 2005. I applied aboveground herbivory treatments using adult cucumber beetles to inflict several rounds of 50% leaf area removal. I applied belowground herbivory treatments using 100 cucumber beetle eggs per plant to cause root damage by cucumber beetle larvae. Aboveground herbivory reduced both fruit and seed yield, but also decreased subsequent herbivore damage to female flowers. If aboveground herbivory can induce defenses to protect high risk organs like female flowers, then the deleterious effects on reproduction may not be as severe. Belowground herbivory increased fruit weights, possibly due to a compensation effect caused by low levels of root damage. An enhanced pollination treatment was also used to determine if plants were pollen limited. Fruits from plants receiving enhanced pollination were heavier than naturally pollinated fruits, indicating pollen limitation in this cucurbit. These results suggest that interactions between herbivores and plants go beyond what can be seen on the surface − above ground herbivory can negatively affect reproduction, but low levels of root damage may be beneficial.
Key words: herbivory, crops, Cucurbita moschata