Determining the importance of propagule pressure and wind dispersal of invading crapemyrtle bark scale populations

Crapemyrtle bark scale, Acanthococcus lagerstroemiae Kuwana (Hemiptera: Eriococcidae; CMBS) is a non-native pest that has become widespread in the urban landscape of the southeastern U.S. following its initial detection in north Texas in 2004. This sap-feeding insect decreases the aesthetic value of the commonly planted crapemyrtle (Lagerstroemia spp.) by facilitating the colonization and growth of sooty mold and reducing plant vigor. Limited research exists on the population dynamics of CMBS, and the factors governing its establishment and spread in the urban environment are incompletely understood. Studies were undertaken to determine the minimum number of individual scales required for CMBS to establish and evaluate the role of wind in CMBS dispersal. After artificially infesting crapemyrtle saplings with up to four individual scales, scale densities on individual plants- including those infested with one scale- reached upwards of 1,000 scales within three months. Although scale movement between saplings appeared non-existent, investigations using a laboratory wind tunnel indicated that ecologically-relevant wind speeds of ~4 m/s can dislodge and disperse scales over short distances. Management implications of the ability of CMBS to (i) establish following introduction of a single ovisac and (ii) disperse via wind currents will be discussed.