On the conditional nature of neotropical caterpillar defenses against their natural enemies
2002
Gentry, Grant L. | Dyer, Lee A.
Lepidopteran larvae possess multiple defenses against a diverse group of predators and parasitoids. Many studies of larval defenses have determined whether a defense works against a particular enemy, but the question of which types of defenses are most effective against which types of enemy has not been examined closely. We assessed the efficacy of different caterpillar defenses against parasitoid wasps, flies, and nematodes, and compared the results to earlier work with predatory invertebrates. Third to fifth instar caterpillars from 266 species and 30 families were collected in a lowland wet forest in Costa Rica during wet and dry seasons from 1996 through 1999, scored for various behavioral and morphological defenses, and then reared in the laboratory. Defense categories were used as predictor variables in logit models with parasitism as the response variable. Whether or not a particular caterpillar defense was effective depended on the taxon of parasitoid that attacked. Caterpillars attacked by flies benefited from a solitary, exophytic feeding habit; wasps were most deterred by biting, dropping, and regurgitating; and larvae attacked by nematodes benefited from both a solitary habit and behavioral defenses. Mortality caused by parasitoids was high for caterpillars that are normally protected from predators. In particular, chemically defended herbivores that are undesirable meals for predators are safe hosts for parasitoids.
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