Biological Control Potential of a Japanese Plant Bug Stethoconus japonicus (Heteroptera: Miridae), an Adventive Predator of the Azalea Lace Bug (Heteroptera: Tingidae)

Abstract

Stethoconus japonicus Schumacher, a Japanese plant bug, is the first host-specific lace bug predator established in the Western Hemisphere. In studies with immigrant and native species of lace bugs, S. japonicus showed the highest biological control potential for species of Stephanitis lace bugs. The developmental rate of immature stages at 26.1°C was similar to that of its preferred host, the azalea lace bug, Stephanitis pyrioides (Scott). At 26.1°C, females generally lived 20-30 d and laid an average of 236 eggs. Instars developed at the same rate on fifth instars of two of three Stephanitis and one Corythucha lace bug species and, when reared on S. pyrioides , males consumed 17.0 nymphs and females consumed 18.7 nymphs. Females consumed 5.5 adult female S. pyrioides daily, and males consumed 2.4. Female S. japonicus are host adaptable and regularly consumed hawthorn lace bugs, Corythucha cydoniae (Fitch), either at a low or high rate when offered an equal number of female lace bugs. Eggs deposited in the midrib of young leaves hatch during the current season and, as the host matures through the season, eggs are deposited at the base of leaf petioles and leaf scars on the stem, and hatch the following spring. That overwintered eggs in the azalea stem hatch asynchronously to the overwintered eggs of the host may indicate that voltinism is regulated by host plant water potential. Laboratory development of temporally synchronized eggs is lengthy. A protocol for quantifying and standardizing predation potential of nymphs is evaluated.