Predicting parasitoid accumulation of potential Brazilian peppertree biological control agents from assessments in the native and invaded ranges

Authors: Wheeler, Gregory; JONES, EMILY - Student Conservation Association; FUNG, JESSICA - Student Conservation Association; FERNANDEZ-TRIANA, JOSE - Canadian National Collection Of Insects & Ottawa Plant Laboratory, Entomology; VITORINO, MARCELO - Universidade Regional De Blumenau(FURB); MCKAY, FERNANDO - Fuedei

Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/25/2022
Publication Date: 7/8/2022
Citation: Wheeler, G.S., Jones, E., Fung, J., Fernandez-Triana, J., Vitorino, M., Mckay, F. 2022. Predicting parasitoid accumulation of potential Brazilian peppertree biological control agents from assessments in the native and invaded ranges. Biological Control. 173. https://doi.org/10.1016/j.biocontrol.2022.104981.
DOI: https://doi.org/10.1016/j.biocontrol.2022.104981

Interpretive Summary: Brazilian peppertree is one of the most invasive weeds of natural and agricultural areas of Florida, Hawaii, and Texas (USA). Biological control agents are being developed to control this invasive weed. The benefits of biological control may be reduced by parasites that exploit the new agent in the introduced range. During the initial releases, biological control agents may benefit from the lack of parasites as they are introduced to new habitats relatively free of natural enemies. However, some agents may be highly vulnerable to natural enemy attack and this may be predicted prior to release. This could assist in predicting attack rates and prioritization of proposed agents. We set out to predict the vulnerability of potential agents to attack by natural enemies by determining parasite impact on candidate biological agents in the native range of the target weed. Furthermore, assessments of the rate of attack of similar species in the invaded range where the agents are to be released may assist in predicting post release vulnerability. Potential agents and analogues were assigned to the feeding guilds: cryptic, leaf folders, thrashers, and sap feeders. Surveys of potential agents of the invasive weed Brazilian peppertree in their native range of South America indicated parasitism rates were generally less than 20% for cryptic feeders (17.6 (± 3.7%; n = 495), leaf folders (10.5 (± 6.3 %; n = 485), thrashers (12.1 (± 1.2%; n = 381), and sap feeders (2.5% (± 1.1%; n = 200). With exceptions, parasitism of the similar species of North America were similar to those from South America, with cryptic feeders (16.5 (± 5.2%; n = 285), and leaf folders (19.2 (± 7.9 %; n = 19), and sap feeders (0.2 (± 0.2%; n = 1247). Thrashers were not included in the analysis as a single parasite was found from few (n = 9) hosts recovered in North America. These results suggest that if species of these defoliating cryptic or leaf folder guilds are released for biological control in North America they will be parasitized at these same approximate levels. However, if sap feeders are released, these results predict very low parasitism would result. These pre-release assessments of parasitism may assist in the prioritization of potential biological control of weeds agent species.

Technical Abstract: The benefits of classical biological control may be reduced by natural enemies that exploit the new agent in the introduced range. During the initial releases, classical biological control agents may benefit from enemy-free-space as they are introduced to new habitats relatively free of natural enemies. Estimates of agent vulnerability to natural enemies prior to release could assist in predicting attack rates and prioritization of proposed agents. We set out to predict the vulnerability of potential agents to attack by natural enemies by determining parasitoid impact on candidate biological agents in the native range of the target weed. Furthermore, assessments of the rate of attack of ecological analogues in the invaded range where the agents are to be released may assist in predicting post release vulnerability. Potential agents and analogues were assigned to the feeding guilds: cryptic, leaf folders, thrashers, and sap feeders. Surveys of potential agents of the invasive weed Brazilian peppertree in their native range of South America indicated parasitism rates were generally less than 20% for cryptic feeders (17.6 (± 3.7%; n = 495), leaf folders (10.5 (± 6.3 %; n = 485), thrashers (12.1 (± 1.2%; n = 381), and sap feeders (2.5% (± 1.1%; n = 200). With exceptions, parasitism of the ecological analogues of North America were similar to those from South America, with cryptic feeders (16.5 (± 5.2%; n = 285), and leaf folders (19.2 (± 7.9 %; n = 19), and sap feeders (0.2 (± 0.2%; n = 1247). Thrashers were not included in the analysis as a single parasitoid was found from few (n = 9) hosts recovered in North America. These results suggest that if species of these defoliating cryptic or leaf folder guilds are released for biological control in North America they will be parasitized at these same approximate levels. However, if sap feeders are released, these results predict very low parasitism would result. These pre-release assessments of parasitism may assist in the prioritization of potential biological control of weeds agent species.