Ambrosia artemisiifolia control in agricultural areas in North-west Italy
Ambrosia artemisiifolia (Asteraceae: EPPO List of Invasive Alien Plants) is a North American native plant which was accidentally introduced into the EPPO region in the 19th century. It is a major problem in spring-grown crops and causes allergic rhinitis and asthma in sufferers due to its pollen. The current study aimed to assess the effects of competitive vegetation and herbivory by Ophraella communa (Chrysomelidae) to control A. artemisiifolia in an agricultural area in North-west Italy. O. communa is utilised as a biological control agent against A. artemisiifolia in China and the beetle was detected in Europe in 2013 where it was accidentally introduced. In 2014, three sites invaded by A. artemisiifolia were selected to include (1) a short-rotation clover field (2) an oat field and (3) a short rotation meadow. Each site contained three square plots of 100 m2. At each site the following treatments were carried out: (a) control not seeded: the plot was ploughed no deeper than 15 cm and vegetation was left to naturally colonise the area, (b) hayseed: the plot was harrowed and ploughed no deeper than 15 cm and then seeded with hayseed at a density of about 20 g/m2, (c) the plot was only superficially harrowed and over-seeded with hayseed at a density of about 20 g/m2. This was repeated in 2015. Vegetation parameters (percentage cover, species abundance, height of A. artemisiifolia and other vegetation) were measured in three 2m x 2m quadrats randomly selected within each plot. The presence of O. communa, and the damage caused by the beetle on A. artemisiifolia was evaluated in September 2015 by recording life stage abundance and percent damage on 25 plants. Non-target damage was also recorded from June to September 2015. Hayseed mixtures, both over-seeded over the resident plant community or after ploughing, when seeded before the winter season, were able to suppress the establishment of A. artemisiifolia as well as to reduce its growth. Defoliation of A. artemisiifolia by O. communa at the end of the growing season was evident but most plants still produced flowers and seeds. For non-target species, O. communa was mainly recorded on Asteraceae, with low density and low degree of damage.
Sources
Cardareli E, Musacchio A, Montagnani C, Bogliani G, Citterio S, Gentili R. (2018) Ambrosia artemisiifolia control in agricultural areas: effect of grassland seeding and herbivory by the exotic leaf beetle Ophraella communa. NeoBiota 38, 1-22.