Ambrosia artemisiifolia control in agricultural areas: effect of grassland seeding and herbivory by the exotic leaf beetle Ophraella communa

Abstract

Ambrosia artemisiifolia (common ragweed) is an invasive species native to North America and was accidentally introduced to Europe in the 19 th century. Widespread in disturbed habitats, it is a major weed in spring-sown crops and it causes serious allergic rhinitis and asthma due to its allergenic pollen. The aim of this research was to analyse the effects of both competitive vegetation and herbivory by Ophraella communa to control A. artemisiifolia in an agricultural area of north-western Italy. 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 in terms of plant height and inflorescence size. Defoliation of A. artemisiifolia by O. communa at the end of the growing season was conspicuous but most of the plants still produced flowers and seeds. However, significant O. communa attack was recorded for reproductive structures. As for non-target species, O. communa was mainly recorded on Asteraceae, with low density and low degree of damage. Reduction of inflorescence size due to competitive vegetation and damage to male flowers by O. communa may diminish the amount of available pollen. The results of this study may be useful for the implementation of management measures to control A. artemisiifolia in agricultural areas using mixtures of native species.

Rapid growth and defence evolution following multiple introductions

“…Up to 50 polyphagous insect species have been associated with A. artemisiifolia in Europe, yet most cause little damage (Essl et al, 2015;Gerber et al, 2011). Ophraella communa has been sighted in Southern Switzerland and Northern Italy since 2013 (Müller-Schärer et al, 2014), where it greatly affects A. artemisiifolia seedling survival and growth (Cardarelli et al, 2018). In Australia, generalists Zygogramma bicolorata (leaf-feeding) and Epiblema strenuana (stem-boring) are widespread and seemingly exert some control (Palmer & McFadyen, 2012).…”

Seeding and Overseeding Native Hayseed Support Plant and Soil Arthropod Communities in Agriculture Areas

“…A previous study performed in the same area ascertained the effectiveness of hayseed seeding or overseeding in controlling noxious alien species like A. artemisiifolia. Indeed, a lower number of plants and reduced inflorescences contribute to diminish the soil seed bank of this species and its pollen production [18,46].…”

“…Creating or recovering temporary and permanent grassland habitats in rotation to crops or surrounding fields by using native hayseed mixtures is considered a cost-effective environmentalfriendly practice. It concomitantly enhances ecosystem resilience, increases soil quality and crop yield, favors pollinators, and contrasts segetal weeds and invasive alien species [7,[18][19][20]. Indeed, herbaceous fields or strips may act as refugee for plants and wildlife from detrimental agronomic practices, by acting as a reservoir of native flora and soil biodiversity [21,22], and hosting natural enemies of crop pests [23].…”

“…In the past, farmers collected hay (including seed and plant residuals) from the floor of barns and sowed it on fields to establish new meadows and pastures, or to improve existing ones [25]. Recently, this management method has been successfully applied to control invasive species as a result of its mulching effect and to increase levels of competition [18,26].…”

“…In agricultural areas, an increase in species richness can be accomplished by using seeding or overseeding methods. While in the seeding method fields are subject to harrowing and ploughing, the overseeding foresees only harrowing [18]. Therefore, different levels of environmental conditions are assumed to be obtained from the two methods also in comparison with agriculture areas cultivated with main crops (e.g., cereals).…”