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THE SOUTHWESTERN NATURALIST 49(2):189196 JUNE 2004 SIZE-MEDIATED PERFORMANCE OF A GENERALIST HERBIVORE
 

Summary: THE SOUTHWESTERN NATURALIST 49(2):189196 JUNE 2004
SIZE-MEDIATED PERFORMANCE OF A GENERALIST HERBIVORE
FEEDING ON MIXED DIETS
LYNN S. ADLER*
Department of Biology, Virginia Tech, 2119 Derring Hall, Blacksburg, VA 24061
*Correspondent: lsadler@vt.edu
ABSTRACT Mixed diets can allow generalist insect herbivores to obtain nutritionally balanced
resources or dilute toxins from specific foods, but also present the generalist with greater chal-
lenges in decision-making and require a greater ability to detoxify a wide range of plant defensive
compounds. Young and small generalist larvae can have different nutritional requirements, ability
to detoxify compounds, and mobility compared to older and larger larvae. In this field study, I
asked how larval size affected performance of the woolly bear (Platyprepia virginalis), a generalist
herbivore, on a uniform diet of bush lupine (Lupinus arboreus) compared to a mixed diet including
bush lupine. Large larvae had greater survival on the mixed diet treatment compared to the
lupine-only diet, but survival of small larvae did not vary with diet. Larval size also influenced
growth on each diet, but this effect varied with year. In 1997, large larvae had higher growth on
a lupine-only diet compared to a mixed diet, whereas small larvae had equivalent growth on both
diets. In 1998, larvae of each size did not differ in their response to diet treatments. In the field,
large larvae apparently eat a more diverse diet than small larvae, which contrasts with the growth
result for 1997. This suggests that factors other than growth, such as parasitism or predation,

  

Source: Adler, Lynn - Department of Plant, Soil and Insect Sciences, University of Massachusetts at Amherst

 

Collections: Environmental Sciences and Ecology