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Classical biological control can provide an ecologically sound, cost‐effective, and sustainable management solution to protect diverse habitats. These natural and managed ecosystems are being invaded and transformed by invasive species. Chinese tallowtree, Triadica sebifera (L.) Small (Euphorbiaceae), is one of the most damaging invasive weeds in the southeastern USA, impacting wetlands, forests, and natural areas. A defoliating moth, Gadirtha fusca Pogue (Lepidoptera: Nolidae), was discovered feeding on Chinese tallowtree leaves in the weed's native range and has been tested for its suitability as a biological control agent. Natural history studies of G. fusca indicated that the neonates have five instars and require 15.4 days to reach pupation. Complete development from egg hatch to adult emergence required 25.8 days. No differences were found between males and females in terms of life history and nutritional indices measured. Testing of the host range of G. fusca larvae was conducted with no‐choice, dual‐choice, and multigeneration tests and the results indicated that this species has a very narrow host range. No‐choice experiments indicated that most larvae died in <3 days when fed each of the 78 non‐target taxa; a similar duration as larvae fed only water. Although 81.6% of the neonates fed Chinese tallowtree survived to adult, the only survivors in no‐choice tests were those fed the four non‐target taxa, Euphorbia hypericifolia L., Euphorbia hyssopifolia L., Euphorbia milii Des Moul., or Gymnanthes lucida Sw. where 14.3% or less of the larvae fed and completed development. The results of dual‐choice tests indicated that very little of each of these non‐target taxa was eaten when given a choice with Chinese tallowtree. Furthermore, when neonates were reared for multiple generations on each non‐target taxon, no more than two generations were completed when fed the non‐target G. lucida, whereas the larvae were unable to complete more than one generation when fed the remaining non‐targets. These tests indicate that although a small amount of feeding may occur in no‐choice conditions on four species of non‐targets, the larvae will not be able to maintain a population for more than two generations on any species except the target weed Chinese tallowtree. This species may play an important role and contribute to the integrated control of this invasive weed. This research examined the quarantine host range of Gadirtha fusca (Lepidoptera: Nolidae), a potential biological control agent of Chinese tallowtree (Euphorbiaceae). Results indicate that this species has narrow specificity and will be a safe control agent of this invasive weed. [ABSTRACT FROM AUTHOR]

Chinese tallowtree, Triadica sebifera (L.) Small ( Euphorbiaceae), is one of the worst invasive weeds of the southeastern USA impacting coastal wetlands, forests, and natural areas. Traditional mechanical and chemical controls have been unable to limit the spread, and this invasive species continues to expand its range. A proposed biological control candidate, the flea beetle Bikasha collaris ( Baly) ( Coleoptera: Chrysomelidae), shows high specificity for the target weed Chinese tallowtree. Results from a series of no-choice and choice feeding tests of B. collaris adults and larvae indicated that this flea beetle was highly specific to Chinese tallowtree. The larvae of B. collaris feed by tunneling in the roots, whereas the adults feed on the leaves of Chinese tallowtree. A total of 77 plant taxa, primarily from members of the tallow plant family Euphorbiaceae, were tested in numerous test designs. Larval no-choice tests indicated that larvae completed development only on two of the non-target taxa. Of 80 B. collaris larvae fed roots of Hippomane mancinella L. and 50 larvae fed roots of Ricinus communis L., two and three larvae completed development, respectively. The emerging adults of these five larvae died within 3 days without reproducing. Larval choice tests also indicated little use of these non-target taxa. Adult no-choice tests indicated little leaf damage by B. collaris on the non-targets except for Ditrysinia fruticosa ( Bartram) Govaerts & Frodin and Gymnanthes lucida Sw. When given a choice, however, B. collaris adults consumed much less of the non-targets D. fruticosa (7.4%) and G. lucida (6.1%) compared with the control leaves. Finally, no-choice oviposition tests indicated that no eggs were produced when adults were fed all non-target taxa, except those fed G. lucida. These B. collaris adults fed G. lucida leaves produced an average of 4.6 eggs compared with 115.0 eggs per female when fed Chinese tallowtree. The eggs produced from adults fed G. lucida were either inviable or the emerging larvae died within 1 day. These results indicate that the flea beetle B. collaris was unable to complete its life cycle on any of the non-target taxa tested. If approved for field release, B. collaris will be the first biological control agent deployed against Chinese tallowtree in the USA. This flea beetle may play an important role in suppressing Chinese tallowtree and contribute to the integrated control of this invasive weed. [ABSTRACT FROM AUTHOR]