Corythucha Arcuata Research Articles

Plant water deficits and insect responses: the preference of Corythucha arcuata (Heteroptera: Tingidae) for the foliage of white oak, Quercus alba

ABSTRACT. The preference of Corythucha arcuata (Say) (Heteroptera: Tingidae) for the foliage of Quercus alba L. (Fagaceae) grown under water deficit was examined. Potted Q.alba saplings were grown under controlled levels of water deficit in a glasshouse. Adult C.arcuata were exposed to excised Q.alba foliage under controlled conditions in a growth chamber, and feeding preference assessed by recording the percentage of individuals feeding on leaves from each level of water deficit. Two experiments were performed. In the first, all foliage was supplemented with water (via the petiole) to alleviate physical changes in the leaves that accompany plant water deficits. In the second experiment, leaves were not supplemented with water. C.arcuata had no preference when presented water supplemented leaves, but preferred leaves that were fully hydrated when presented leaves that were not supplemented with water. These results suggest that plant water deficits are important in determining the feeding preference of C.arcuata because they lead to avoidance of drought grown foliage. This avoidance may be caused by an increase in the metabolic cost to the herbivore of maintaining water balance when ingesting drought grown foliage or to an increase in foliage toughness.

Biology and Nymphal Stages of Deraeocoris nebulosus (Hemiptera: Miridae), a Predator of Arthropod Pests on Ornamentals

Nymphal stages of the mirid Deraeocoris nebulosus (Uhler) are described and figured and results of field and laboratory studies on biology in Pennsylvania during 1973–74 are reported. This predator was associated with mites, aphids, scales, whiteflies, psyllids, and lace bugs on more than 50 species of ornamental trees and shrubs. D. nebulosus had 3 generations in an ornamental planting in central Pennsylvania and utilized a series of host plants and prey species during the season. Five weekly samples from 4 branches on each of 2 white oaks infested with oak lace bug, Corythucha arcuata (Say), showed that nebulosus can develop large populations in the second generation. In the laboratory, average duration of the 5 nymphal instars was 2.7, 3.2, 4.3, 4.6, and 5.0 days, respectively, with the nymphal period averaging 19.8 days. An average of 107.6 oak lace bug nymphs was consumed during nymphal development. Consumption of lace bug nymphs increased with increasing prey density, suggesting that nebulosus could be important in suppressing populations of lace bugs and other pests on ornamentals.