Earleaf acacia (Acacia auriculiformis A.Cunn. ex Benth) is a fast-growing, evergreen tree from Australia that was introduced into the United States as an ornamental plant, but it has become a serious plant invader in Florida, USA. Spread of this invasive tree has accelerated in recent years and current control efforts do not meet conservation or land management needs. Our objective was to review and summarize available information to determine if pursuing classical biological control for earleaf acacia is warranted. Feasibility studies such as this identify pitfalls and conflicts before a project begins, increasing the likelihood that biological control efforts will be successful. This review compiles a list of non-target species based on their geographic overlap with the weed invasion and their relatedness to A. auriculiformis. Feasibility is also determined based on other criteria including conflicts of interest and availability of potential biological control agents. We also present a report from our initial explorations for natural enemies in the native range of Australia. Eighty-nine arthropod and one pathogen species have been identified feeding on earleaf acacia in the native range. Several of the arthropods found have the potential to be host specific and impactful. Few potential conflicts of interests were identified. These findings paired with the high-risk assessment for invasion and lack of sustainable and effective control methods, supports our conclusion that earleaf acacia is a promising target for classical biological control.

Melaleuca quinquenervia (hereafter melaleuca) was until recently one of the worst ecological invaders in Florida. Introduced for horticulture and levee stabilisation during the early twentieth century, melaleuca spread to cover vast areas of the largest freshwater wetlands ecosystem in North America, The Everglades. From 1997 until 2008, four insects and an associated nematode were approved and released for control of melaleuca, three of which are known to have established. Biological control is frequently a slow and incremental process, but with the integration of complimentary control methods (e.g. chemical and mechanical removal), melaleuca infestations are a fraction of their former range. These few persistent infestations are facilitated by conditions that prevent one species, Oxyops vitiosa, the melaleuca snout weevil, from completing its life cycle, which prompted the testing of and application to release Lophodiplosis indentata (Diptera: Cecidomyiidae). This leaf gall forming midge feeds within pea-shaped growths distributed throughout the canopy. No-choice host range tests suggest that L. indentata will occasionally oviposit on unsuitable host plants, but gall induction and formation is only accomplished on M. quinquenervia. A petition for the release of L. indentata was recommended by TAG in May 2020. [word count: 181]

The U.S. Department of Agriculture–Agricultural Research Service (USDA-ARS) has been a leader in weed science research covering topics ranging from the development and use of integrated weed management (IWM) tactics to basic mechanistic studies, including biotic resistance of desirable plant communities and herbicide resistance. ARS weed scientists have worked in agricultural and natural ecosystems, including agronomic and horticultural crops, pastures, forests, wild lands, aquatic habitats, wetlands, and riparian areas. Through strong partnerships with academia, state agencies, private industry, and numerous federal programs, ARS weed scientists have made contributions to discoveries in the newest fields of robotics and genetics, as well as the traditional and fundamental subjects of weed–crop competition and physiology and integration of weed control tactics and practices. Weed science at ARS is often overshadowed by other research topics; thus, few are aware of the long history of ARS weed science and its important contributions. This review is the result of a symposium held at the Weed Science Society of America’s 62nd Annual Meeting in 2022 that included 10 separate presentations in a virtual Weed Science Webinar Series. The overarching themes of management tactics (IWM, biological control, and automation), basic mechanisms (competition, invasive plant genetics, and herbicide resistance), and ecosystem impacts (invasive plant spread, climate change, conservation, and restoration) represent core ARS weed science research that is dynamic and efficacious and has been a significant component of the agency’s national and international efforts. This review highlights current studies and future directions that exemplify the science and collaborative relationships both within and outside ARS. Given the constraints of weeds and invasive plants on all aspects of food, feed, and fiber systems, there is an acknowledged need to face new challenges, including agriculture and natural resources sustainability, economic resilience and reliability, and societal health and well-being.

Mosquito pesticides effectively control vectors of human disease but have numerous unintended consequences. These may include adversely affecting non-target species such as weed biological control agents. Acute toxicity of two mosquito pesticides, naled and permethrin, was studied on three biological control agents released against invasive weeds in south Florida. These were the biological control agent Oxyops vitiosa of melaleuca, Melaleuca quinquenervia, the agent Neomusotima conspurcatalis for Old World climbing fern, Lygodium microphyllum, and the agent Lilioceris cheni for air potato Dioscorea bulbifera. We calculated LD₅₀ values for both pesticides on early and late instars for each herbivore species. The air potato herbivore, L. cheni was the most sensitive species tested and all three species were more sensitive to the pesticide permethrin than naled. These results indicate that even low concentrations of these products can have a detrimental effect on these weed biological control agents. The unintended consequences of mosquito adulticide applications should be considered when evaluating biological control agent impacts.

Dioscorea bulbifera has invaded, smothered, and disrupted ecological functions of native plant communities in Florida. Vines senesce in late fall, then overwinter as tubers and aerial bulbils which sprout in spring and repeat the growth cycle. A foliage-feeding beetle Lilioceris cheni, introduced from Asia as a biocontrol agent has established throughout D. bulbifera's range in Florida. Synchronies among the growth phenology of the weed, life stages of biocontrol agents and weather conditions, are considered essential for the successful suppression of an introduced weed. We conducted a common garden study that encompassed pre-biocontrol release attributes of D. bulbifera followed by a 5-yr post-L. cheni release impacts study on its natural infestations in four sites. We gathered monthly data on D. bulbifera and L. cheni and assessed possible synchronies between their life stages and with local weather variables. Air and soil temperatures and total rainfall showed positive correlation with timing of D. bulbifera vine emergence/senescence, vine coverage, adult beetle emergence from diapause, and their life stages (egg clutches, larvae, and adults). Vine sprouting and beetle emergence in two southern sites began in February and April, and in the remaining two northern sites in March and May, respectively. Vine sprouting and beetle emergence was initiated at 15 and 20°C, respectively. All sites achieved maximum vine coverage in July. Bulbil development, oviposition by overwintering adults, and vine damage by adult and larval feeding began in June. These sequences of events indicated phenological synchrony of the beetle and air potato life stages in Florida.