Initial response by a native beetle, chrysochus auratus (Coleoptera: Chrysomelidae), to a novel introduced host-plant, vincetoxicum rossicum (Gentianales: Apocynaceae)
deJonge RB, RS Bourchier, and SM Smith. 2017. Initial Response by a Native Beetle, Chrysochus auratus (Coleoptera: Chrysomelidae), to a Novel Introduced Host-Plant, Vincetoxicum rossicum (Gentianales: Apocynaceae). Environmental Entomology, 46(3), 2017, 617–625
Plain language summary
When a new plant like dog strangling vine is introduced and invades North America, insects that are already in Canada can sometimes use the introduced plant as a new food source or host to complete their life cycle. This study examines the response of the native dogbane beetle to the new invasive plant, dog-strangling vine. The dogbane beetles normally fed on a plant, dogbane which is very closely related to dog-strangling vine and thus we expected that the beetles might be able to use the new plant. Experiments in the laboratory and field measured the amount of feeding, how long the insects lived, if they laid eggs and if the amount of time that beetles had been exposed to dog strangling vine affected the beetles ability to use it. The result showed that beetles were able to feed on the new plant and could survive for up to 10 days on the plant as adults. Adult beetles would lay eggs on the dog strangling vine and larvae could start to grow on the roots of the plant but they could not complete their life cycle on the plant. Insects that had not had previous exposure to dog-strangling vine were more likely to feed on it than those that had encountered the plants. The work indicates the new plant, dog strangling vine may be having a negative effect on populations of the dogbane beetles because when beetles lay eggs on dog strangling vine rather than then dogbane, those eggs cannot survive.
© The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. Native insects can form novel associations with introduced invasive plants and use them as a food source. The recent introduction into eastern North America of a nonnative European vine, Vincetoxicum rossicum (Kleopow) Barbar., allows us to examine the initial response of a native chrysomelid beetle, Chrysochus auratus F., that feeds on native plants in the same family as V. rossicum (Apocynaceae). We tested C. auratus on V. rossicum and closely related or co-occurring native plants (Apocynum spp., Asclepias spp., and Solidago canadensis L.) using all life stages of the beetle in lab, garden, and field experiments. Experiments measured feeding (presence or absence and amount), survival, oviposition, and whether previous exposure to V. rossicum in the lab or field affected adult beetle feeding. Beetles fed significantly less on V. rossicum than on native Apocynum hosts. Adult beetles engaged in exploratory feeding on leaves of V. rossicum and survived up to 10 d. Females oviposited on V. rossicum, eggs hatched, and larvae fed initially on the roots; however, no larvae survived beyond second instar. Beetles collected from Apocynum cannabinum L. field sites intermixed with V. rossicum were less likely to feed on this novel nonnative host than those collected from colonies further from and less likely to be exposed to V. rossicum (<5km). Our experimental work indicates that V. rossicum may act as an oviposition sink for C. auratus and that this native beetle has not adapted to survive on this recently introduced novel host plant.