Evaluation of Reduced Risk Insecticides for Armored Scales (Hemiptera: Diaspididae) Infesting Ornamental Plants1
ABSTRACT Armored scale insects (Hemiptera: Diaspididae) are economically important pests of ornamental trees and shrubs in nurseries and landscapes. The cycad aulacaspis scale, Aulacaspis yasumatsui Takagi, and the tea scale, Fiorinia theae Green, are economically important armored scale pests of cycads, Cycas spp. and camellia, Camellia spp. respectively, in the southeastern United States. Our objective was to evaluate fungal, botanical, and chemical insecticides that were applied as foliar sprays or drenches when the motile crawler stages were active. In tests with A. yasumatsui over two years, products based on a mineral oil (SuffOil X(r) azadirachtin (Molt X(r) an entomopathogenic fungus (BotaniGard(r) ES) and an azadirachtin/fungus combination applied three times, significantly reduced the number of scales on cycads, Cycas revoluta Thunb. over 3 4 months, but were less effective overall compared with the insecticidal standard dinotefuran (Safari(r) In tests with F. theae, spinetoram sulfoxaflor (GF 2860) cyantraniliprole (Mainspring(r) pyriproxifen (Distance(r) buprofezin (Talus(r) horticultural oil (SuffOil X) and dinotefuran (Safari) applied between one and three times, significantly reduced scale numbers (adults and large nymphs) on established foliage (older leaves) of Japanese camellia, Camellia japonica L. compared with controls within five months. The apparent slow activity (decline) in numbers of armored scales on old foliage was influenced by the difficulty of differentiating between live and dead insects that remained attached to leaf surfaces for some time after death. Monitoring infestations spreading to new foliage later in the season is a more reliable method to estimate the efficacy of insecticides against this group of pests.