|CHAWNER, M. - University Of Michigan|
|WILLIAMS, D. - Texas Christian University|
Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/24/2014
Publication Date: 3/21/2014
Publication URL: http://dx.doi.org/10.1016/j.biocontrol.2014.02.017
Citation: Wheeler, G.S., Chawner, M., Williams, D.A. Predicting the host range of Nystalea ebalea: secondary plant chemistry and host selection by a surrogate biological control agent of Schinus terebinthifolia. Biological Control. 73:39-49. 2014.
Interpretive Summary: A caterpillar species, Nystalea ebalea was studied as a prospective biological control agent of the invasive weed, Brazilian peppertree. The host range of this insect was examined on several related and valued plants from Florida. Additionally, the chemistry of these plants that might influence plant selection and utilization by this insect was analyzed that included nitrogen, terpenoids, and urushiols. We found that this insect had low survival and general larval performance when fed plants that contained urushiol, the plant compound that causes skin irritation in sensitive humans. However, the terpenoids analyzed seemed to have only minor influence on host range of this insect. Other potential biological control agents may also be sensitive to these compounds and this may limit their host range.
Technical Abstract: The safety of weed biological control depends upon the selection and utilization of the target weed by the agent while causing minimal harm to non-target species. Selection of weed species by biological control agents is determined by the presence of behavioral cues, generally host secondary plant compounds that elicit oviposition and feeding responses. Non-target species that possess the same behavioral cues as found in the target weed may be at risk of damage by classical biological control agents. Here we conducted host range tests and examined secondary plant compounds of several test plant species. We studied the specialist herbivore Nystalea ebalea (Lepidoptera: Notodontidae) a Neotropical species, present in Florida as a surrogate biological control agent of the weed, Brazilian peppertree Schinus terebinthifolia, invasive in Florida and Hawaii. We found that the larvae had the greatest survival when fed the target weed, the Neotropical species Spondias purpurea, the Florida native species Rhus copallinum, and the ornamental Pistacia chinensis. Reduced survival and general larval performance were found on the native species Metopium toxiferum and Toxicodendron radicans. Both the volatiles and the allergen urushiols were chemically characterized for all species but urushiol diversity and concentration best predicted host range of this herbivore species. These results provide insight into host selection and utilization by one oligophagous Schinus herbivore. Other potential biological control agents may also be sensitive to plants that contain urushiols and if so, they may pose minimal risk to these native species.