Ecology and management of Mindarus kinseyi Voegtlin (Aphidoidea: Mindaridae) on white-fir seedlings at a California forest nursery

Abstract

In recent years, an aphid identified as balsam twig aphid, M. abietinus, was observed on seedlings of Abies concolor at a nursery near Placerville, California. Investigations revealed that the aphid had a life cycle that differed from that reported for M. abietinus. The aphid was recently described as M. kinseyi Voegtlin. Ecological studies of M. kinseyi revealed that initial infestation of first-year seedlings was coincident with the discrete flight period of alate viviparae. Mean aphid density peaked at >25 per seedling (>100 per infested seedling), and up to 21% of the first-year seedlings were infested. Initial infestation of second-year seedlings was due to either overwintering eggs, a late viviparae, or both. Survival of marked seedlings from emergence to harvest was very high (97.3%). However, cull-rate at harvest was independent of previous aphid infestation. Mean height, stem diameter, and dry weight of marked seedlings at harvest were not significantly reduced by aphid infestation. A management program for M. kinseyi was developed and evaluated at the nursery. The primary aphid-suppression tactics (soap spray, lacewing larvae) that were effective in a nursery setting could also be employed against M. kinseyi at Christmas-tree farms. -from Authors