Field evaluation of augmentative biological control as a management tool against an invading scale insect, Acanthococcus lagerstroemiae (Kuwana) (Hemiptera: Eriococcidae)

Urban plantings are often faced with herbivorous pest outbreaks and thus require extensive management regimes to protect plant health. Scale insects are common landscape pests that are frequently controlled with various insecticides. However, off-target effects and subsequent restrictions of certain pesticides have created uncertainty in management options for some scale insects. Acanthococcus lagerstroemiae (Kuwana) (Hemiptera: Eriococcidae) is a non-native scale that is most easily controlled with neonicotinoids, in part because cultural methods and resident natural enemies have provided insufficient control in many contexts. Therefore, the use of augmentative biological control (ABC) may be a potential management option against A. lagerstroemiae in the urban landscape. Here, we investigated the use of Rhyzobius lophanthae (Blaisdell) (Coleoptera: Coccinellidae) and Chrysoperla rufilabris Burmeister (Neuroptera: Chrysopidae) individually and in combination for use against A. lagerstroemiae in a two-year field study. We determined that R. lophanthae can reduce A. lagerstroemiae population growth when released as a single species and when netting is used to confine beetles to the plant. Chrysoperla rufilabris did not impact A. lagerstroemiae population growth regardless of density released. However, we identified several landscape factors that significantly increased A. lagerstroemiae population growth (e.g., ant attendance). Results presented here guide ABC application procedures relating to the timing, methodology, density, and frequency of releases that may be needed to successfully control A. lagerstroemiae. Further work investigating how R. lophanthae can be incorporated into an IPM program is needed to optimize A. lagerstroemiae management plans.