Quarantine evaluation of the weevil, Eucryptorrhynchus brandti (Harold) (Coleoptera: Curculionidae), a potential biological control agent of the tree-of-heaven

Ailanthus altissima (Mill.) Swingle, tree-of-heaven, is a species native to China and North Vietnam. It was first introduced into the United States in the 1700’s and is now distributed and invasive throughout much of North America where it out-competes native vegetation. The invasiveness of tree-of-heaven is primarily attributed to the lack of natural enemies in North America, its aggressive invasion within newly disturbed areas, tolerance of extreme conditions, and allelopathic properties. Mechanical and chemical controls are current tactics used for suppression, but implementation is costly, and can be as much as 8,750 USD/ha. Biological control was initiated in 2004 as a potentially sustainable tactic for tree-of-heaven suppression. The weevil, Eucryptorrhynchus brandti (Harold), was identified in China and imported into quarantine testing as a possible biological control agent. Studies to characterize the general biology and development of the weevil have been evaluated. Eucryptorrhynchus brandti can be reared efficiently in quarantine. It has a life cycle similar to closely related weevil species, and preferentially feeds on tree-of-heaven. Rearing experiments were conducted to determine the most efficient method of mass production of E. brandti. Host specificity tests on 29 taxonomically, economically, and/or ecologically non-target plant species from 14 families that are related to tree-of-heaven indicate that Leitneria floridana Chapman might be affected. Development of larvae inoculated into this endangered tree species is a concern, requiring further evaluation of its potential non-target impact on this species.