Seasonal abundance of greedy scale (Homoptera: Diaspididae) and associated parasitoids on taraire (Beilschmiedia tarairi)

Greedy scale, Hemiberlesia rapax (Comstock), is an important quarantine pest of kiwifruit, Actinidia deliciosa (A. Chevalier.) C. F. Liang and A. R. Ferguson. Scale infest kiwifruit by aerial invasion of crawlers from adjacent host plants such as taraire, Beilschmiedia tarairi Bentham and Hooker. A study on the ecology of greedy scale on taraire measured scale abundance and parasitism by a complex of 3 parasitoids, Encarsia citrina (Craw), Signiphora merceti (Malenotti), and Signiphora flavella (Girault) over 3 seasons. Greedy scale was found to have 2 generations each year. Scale populations remained low (14-38 scale per 100 leaves) over 3 successive generations when parasitism rates remained steady (16-27 parasitoids per 100 scale). Scale populations increased 7-fold in the 4th winter generation when rates of parasitism dropped to low levels (4 parasitoids per 100 scale). Scale populations remained at high levels (303-356 scale per 100 leaves) over the next 2 generations causing massive invasion of scale into the adjacent kiwifruit orchard. This was despite the resurgence in the rates of parasitism (13-29 parasitoids per 100 scale)