Age-Specific Host Utilization in the Eastern Tent Caterpillar (Lepidoptera: Lasiocampidae)

Larval growth and survival of the eastern tent caterpillar, Malacosoma americana F., was assessed on its preferred host, black cherry (Prunus serotina Ehrhart), black locust (Robinia pseudoacacia L.), hackberry (Celtis occidentalis L.), white oak (Quercus alba L.), and white pine (Pinus strobus L.), and on the herbaceous biennial poison hemlock (Conium maculatum L.). Larvae grew largest and had the greatest pupation and survival rates when fed black cherry and white oak. They did not grow well on black locust or white pine, but survival rates were relatively high, suggesting that both plant species could potentially serve to sustain tent caterpillar populations. Growth and survival was so low on hackberry and poison hemlock that they pose little chance of sustaining outbreaking caterpillar populations.

Does Early-Season Defoliation of Crabapple (Malus sp.) by Eastern Tent Caterpillar (Lepidoptera: Lasiocampidae) Induce Resistance to Japanese Beetles (Coleoptera: Scarabaeidae)?

We tested the hypothesis that early-season defoliation of flowering crabapple, Malus sp., by eastern tent caterpillars, Malacosoma americanum F., induces localized or systemic resistance to Japanese beetles, Popillia japonica Newman, feeding on the same trees in late June. ‘Candymint Sargent’ crabapple trees were inoculated with M. americanum egg masses, resulting in extensive defoliation during March and April. Second flush leaves of defoliated trees were smaller and thinner than those of control trees. In laboratory feeding assays with non-damaged foliage, beetles generally preferred fully expanded leaves over partially expanded ones, regardless of whether or not the source tree had been defoliated. Detached first flush leaves with caterpillar damage were fed upon less than comparable non-damaged leaves, suggesting that early-season wounding causes some within-leaf reduction in palatability to P. japonica. Other assays with detached first- and second-flush leaves, however, indicated absence of induced, systemic resistance. Previously-defoliated and control trees sustained comparable damage from natural beetle populations in the field. Our results suggest that defoliation of Malus sp. by tent caterpillars in early spring is unlikely to reduce feeding damage by Japanese beetles later in the same growing season.