Host Range of Laricobius osakensis (Coleoptera: Derodontidae), a New Biological Control Agent of Hemlock Woolly Adelgid (Hemiptera: Adelgidae)

Hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae), is an invasive pest of eastern hemlock (Tsuga canadensis (L.) Carriere) and Carolina hemlock (T. caroliniana Englem.) in eastern United States. Host-range tests for Laricobius osakensis Montgomery and Shiyake (Coleoptera: Derodontidae), imported from Japan, were conducted under quarantine in Blacksburg, VA, to determine the suitability of this predator as a biological control agent of A. tsugae. Host-range testing for L. osakensis, involved no-choice and paired choice feeding, oviposition, and development tests with A. tsugae, three other adelgids, and three nonadelgid species. L. osakensis fed and laid more eggs on A. tsugae over all the other host species. The difference was greater in paired-choice tests. L. osakensis completed development only on A. tsugae. The overall results of the host range study indicate that L. osakensis is a specific predator of A. tsugae, supporting its potential as a biological control agent, and is not a threat to nontarget species populations.