|GOLEC, JULIAN - University Of Delaware|
|HOUGH-GOLDSTEIN, JUDITH - University Of Delaware|
Submitted to: Journal of Pest Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/13/2019
Publication Date: 4/30/2019
Citation: Golec, J., Duan, J.J., Rim, K.A., Aparicio, E.M., Hough-Goldstein, J. 2019. Laboratory adaptation of a native North American parasitoid to a novel, invasive insect pest. Ecology and Evolution. 92:1179–1186. https://doi.org/10.1007/s10340-019-01101-z.
Interpretive Summary: Understanding the ability of native natural enemies (predators and parasitoids) to adapt to exotic insect pests is important for the development of new biological control strategies for protection of agricultural crops and/or forests. The parasitic wasp Ontsira mellipes is a native North American parasitic wasp that successfully attacks the exotic Asian longhorned beetle (ALB, Anoplophora glabripennis), which poses a serious threat to numerous urban and forest hardwood trees in the United States. This parasitic wasp is being considered for mass-rearing and field releases against ALB in the U.S. To determine the adaptive potential of this native natural enemy to ALB, scientists from USDA ARS and University of Delaware measured critical life history parameters (such as brood sizes, sex ratio and ovipositor length) over various generations of parasitoids (F1-2, F24-29, F41-44, and F68-74) that had been reared on ALB. The study showed that continuously rearing this natural enemy on ALB enhanced parasitism rates and improved the wasp’s fecundity. This research indicates that the native wasp can adapt to ALB and suggests that it may be useful for biological control of ALB in North America.
Technical Abstract: Researchers have documented the ability of native parasitic Hymenoptera to attack exotic pest species, yet few have investigated the potential of native parasitoids to adapt to novel host species for biocontrol purposes. Adaptation of parasitoids to novel hosts may be particularly important in new-association biocontrol programs, especially if parasitoid behavior and physiology can be affected in such a way as to enhance their virulence on a novel host. To determine the adaptive potential of a native parasitoid (Ontsira mellipes) to a novel invasive host (Anoplophora glabripennis), we measured the ovipositor length, host attack rate (parasitism), progeny size, and proportion of female progeny of various parasitoid generations (F1-2, F24-29, F41-44, and F68-74) that had been reared on A. glabripennis. Additionally, the specificity of O. mellipes was explored using no-choice assays with a potential native cerambycid host (Neoclytus acuminatus ssp. acuminatus). When larvae of A. glabripennis and N. acuminatus ssp. acuminatus were exposed to adult parasitoids, 70.4% of A. glabripennis and 0% of N. acuminatus ssp. acuminatus larvae were attacked, suggesting that the latter species is not the native host of O. mellipes. Anoplophora attack rates (parasitism) increased from 46.9% to 65.7% between F1-2 and F68-74 generation parasitoids, indicating a marginally significant increase in the number of newly-associated host larvae attacked by later generation parasitoids (F68-74). F68-74 generation parasitoids produced significantly more progeny on average (8.8 ± 0.8) than did F1-2 generation parasitoids (4.1 ± 0.8). Parasitoid generation had no effect on the proportion of female progeny or ovipositor length. These findings suggest that continuously rearing O. mellipes on a novel target species enhanced host attack rates (parasitism) and improved fecundity of parasitoids, providing evidence for the adaptive capacity of O. mellipes to a novel invasive host. However, shifts away from familiar to novel hosts by parasitoids may reduce fitness in the new host. This research indicates that some parasitoids can adapt to novel hosts and suggests that it may be advantageous to rear new-associations agents on their target prior to performing experimental assays or releasing them in the field.