Host Specificity and Preliminary Impact of Lepidapion argentatum (Coleoptera, Brentidae), a Biocontrol Candidate for French Broom (Genista monspessulana, Fabaceae)

French broom (Genista monspessulana) (Fabaceae) is a perennial species native to the Mediterranean basin. Introduced in the 19th century as an ornamental plant, it is currently invasive in California and Australia. The current research is focused on biocontrol with the use of the phytophagous weevil Lepidapion argentatum (Brentidae). Its capacity to develop both in the stem galls and pods of French broom makes it a promising candidate. The impact on the reproduction of French broom was studied in Southern France and revealed that it could effectively reduce the number of viable seeds by 18.8%, but also increased the number of aborted seeds by 10% within the attacked pods. To evaluate the specificity of L. argentatum, choice and no-choice tests were performed in 2012 and 2015 on a total of 36 non-target closely related species. Results revealed the presence of galls and larvae in the stems of seven species, including two endemic Californian lupines; i.e., Lupinus arboreus blue and Lupinus chamissonis. In the future, new tests will be conducted to determine if L. argentatum is able to complete its entire development lifecycle on the non-target species where galls have previously been observed.

Physicochemical Analysis and Essential Oils Extraction of the Gorse (Ulex europaeus) and French Broom (Genista monspessulana), Two Highly Invasive Species in the Colombian Andes

Gorse (Ulex europaeus) and French broom (Genista monspessulana) are two highly invasive species that have become a threat to tropical countries, especially in Andean ecosystems. This research focused on providing a physicochemical characterization and essential oils extraction of both species to better understand their potential valorization and guide further environmental management efforts. For this purpose, the following analyses were conducted for both species: higher heat value (HHV), elemental analysis, proximate analysis, thermogravimetric analysis to obtain constituent natural polymers (hemicellulose, cellulose, and lignin), and extraction of essential oils and other interest chemical compounds through supercritical fluids. Ecological closeness was found between the two species mostly regarding HHV, fixed carbon, and volatile matter, which calls for similar potential uses. Both species were also found to be suitable for combustion processes, gasification, extraction of chemical compounds, and use of lignocellulosic content; however, only U. europaeus appeared suitable for activated carbon obtention. Therefore, this work provided relevant data that can be used as preliminary basis to establish strong scientifically-based management and control strategies for these two invasive species. We recommend focusing primarily on thermal processes such as pyrolysis, gasification, or combustion, and also essential oils extractions of acetic acid, dodecanoic acid, anagyrine, amylene hydrate, caulophylline, and maltol in the future.

Fuel characteristics of the invasive shrub Teline monspessulana (L.) K. Koch

Some broom species have the ability to modify elements of the fire regime in invaded areas. One such species, Teline monspessulana (Syn. Genista monspessulana; French Broom), has expanded notoriously in south-central Chile’s Mediterranean climate. The biota of this area may be particularly vulnerable to effects of invasive species on the fire regime, as it is less adapted to wildfires. The properties of the fuel accumulated in T. monspessulana populations of different ages are characterised in this paper. For this, models were constructed to estimate fuel accumulation in T. monspessulana populations, and tests for flammability of foliage were also performed. The results show that the rapid growth of this invasive shrub ensures a significant accumulation of fuel (close to 90 ton ha–1) in periods shorter than a decade, which may influence the severity of wildfires. Further, the fuel has a significant accumulation of fine material and high flammability, both of which may facilitate the ignition of fires. The large volume and high flammability of the fuel accumulated in T. monspessulana populations can thus play an important role in changing the fire regime in areas where it has invaded.