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Trade‐offs in host use by Manduca sexta : plant characters vs natural enemies
Author(s) -
Mira Alex,
Bernays Elizabeth A.
Publication year - 2002
Publication title -
oikos
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.672
H-Index - 179
eISSN - 1600-0706
pISSN - 0030-1299
DOI - 10.1034/j.1600-0706.2002.970309.x
Subject(s) - biology , predation , parasitism , host (biology) , herbivore , larva , competition (biology) , ecology , manduca sexta , zoology
There are two principal native host plants for the sphingid moth Manduca sexta L. in south eastern Arizona: Datura wrightii (Solanaceae), and the more recently reported, nonsolanaceous host, Proboscidea parviflora (Martyniaceae). A comparative study on causes and rates of mortality was conducted, since this provided a “natural experiment” for examining potential trade‐offs in host use. The field data identified a dramatic trade‐off between plant quality and predation. D. wrightii appears to provide a high quality food source in growth experiments, and eggs laid on its leaves hatch at high rates. The eggs and larvae, however, underwent extremely high levels of predation and parasitism in the field, and fewer than 0.5% reached the final larval stage. Eggs laid on P. parviflora , on the other hand, suffered low levels of predation and virtually no parasitism, but many eggs did not hatch due to developmental abnormalities induced by the plant, while a large proportion of larvae died after a few days of feeding. Overall, 3% of the eggs reached the final stage on this plant. The maintenance of the two host plants cannot be explained by single factors, but rather by the outcome of multiple factors on the insect fitness, including plant quality, suitability for egg development, predation risk, plant availability and competition with other herbivores. Our data emphasize the importance of predation in shaping host‐plant ranges and support the idea of host‐specific predation rates and “enemy‐free” space.