Biology of immature stages and host range characteristics of Sudauleutes bosqi (Coleoptera: Curculionidae), a candidate biological control agent of exotic Ludwigia spp. in the USA

Authors: DASILVA, AMY - US Department Of Agriculture (USDA); Reddy, Angelica; Pratt, Paul; Hansel Friedman, Marielle; Grewell, Brenda; HARMS, NATHAN - Us Army Engineer Research And Dvelopment Center; CIBILS-STEWART, XIMENA - Instituto Nacional De Investigaciones Forestales Y Agropecuarias (INIFAP); CABRERA WALSH, GUILLERMO - Fuedei; FALTLHAUSER, ANA - Fuedei; Chamorro, Maria

Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/26/2022
Publication Date: 10/3/2022
Citation: DaSilva, A., Reddy, A.M., Pratt, P.D., Hansel Friedman, M.S., Grewell, B.J., Harms, N.E., Cibils-Stewart, X., Cabrera Walsh, G., Faltlhauser, A., Chamorro, M.L. 2022. Biology of immature stages and host range characteristics of Sudauleutes bosqi (Coleoptera: Curculionidae), a candidate biological control agent of exotic Ludwigia spp. in the USA. Florida Entomologist. 105(3):243-249. https://doi.org/10.1653/024.105.0310.
DOI: https://doi.org/10.1653/024.105.0310

Interpretive Summary: Exotic water primroses (Ludwigia spp.) are aggressive plant invaders in aquatic ecosystems worldwide. Management of exotic Ludwigia spp. is limited to physical and chemical control methods. Biological control, the use of insects to control exotic plants, is an alternative approach for the management of exotic Ludwigia spp. However, little is known regarding the natural enemies of these plants in their native range in South America. In this study, we investigated the biology and host range of a natural enemy, the beetle Sudauleutes bosqi, to determine its suitability as a biocontrol agent of exotic Ludwigia spp. in the USA. The beetle matures from egg to adult in approximately 18 days at 25°C, and female and adult males are the same size at approximately 2.5 ml long. Development and oviposition tests were conducted using four exotic Ludwigia species and seven USA native plant species. Sudauleutes bosqi showed little discrimination between the plant species tested: larvae fed and completed development, and females laid eggs on most plant species regardless of origin. These results indicate that the beetle is not sufficiently host-specific for further consideration as a biological control agent of exotic Ludwigia spp. in the USA and further testing is not warranted.

Technical Abstract: South American invasive plants in the genus Ludwigia (Onagraceae) degrade many riparian and aquatic ecosystems worldwide. Biological control may aid in the management of these exotic weeds, but data on the host specificity of Ludwigia natural enemies is limited. The biology and host range of Sudauleutes bosqi Hustache (Coleoptera: Curculionidae), an herbivore of Ludwigia spp. in South America, was studied to determine its suitability as a biocontrol agent for 3 exotic Ludwigia spp. (targets) in the USA. Weevils maintained at 25 °C (± 1 °C) and 14:10 h L:D photoperiod developed through 7 life stages, with a generation time from egg to adult of 17.6 (± 1.2) d when reared on the target weed Ludwigia hexapetala. There was no difference in mean body length between females (2.6 ± 0.1 mm) and males (2.5 ± 0.1 mm). No-choice and multiple-choice host range tests were conducted using 4 exotic Ludwigia spp. and 7 USA native plant species. Sudauleutes bosqi larvae completed development on the 3 target weeds and 4 native plant species, and oviposition occurred on all but one of the plant species that supported larval development. In multiple-choice tests, S. bosqi oviposited on 9 of 11 plant species tested. Results indicate that host selection and development of S. bosqi is not limited to target weeds but also includes valued non-target species. Therefore, S. bosqi is not sufficiently host-specific for further consideration as a biological control agent of exotic Ludwigia spp. in the USA and additional testing is not warranted.