The late flowering of invasive species contributes to the increase of Artemisia allergenic pollen in autumn: an analysis of 25 years of aerobiological data (1995–2019) in Trentino-Alto Adige (Northern Italy)

Abstract

Artemisia pollen is an important aeroallergen in late summer, especially in central and eastern Europe where distinct anemophilous Artemisia spp. produce high amounts of pollen grains. The study aims at: (i) analyzing the temporal pattern of and changes in the Artemisia spp. pollen season; (ii) identifying the Artemisia species responsible for the local airborne pollen load. Daily pollen concentration of Artemisia spp. was analyzed at two sites (BZ and SM) in Trentino-Alto Adige, North Italy, from 1995 to 2019. The analysis of airborne Artemisia pollen concentrations evidences the presence of a bimodal curve, with two peaks, in August and September, respectively. The magnitude of peak concentrations varies across the studied time span for both sites: the maximum concentration at the September peak increases significantly for both the BZ (p < 0.05) and SM (p < 0.001) site. The first peak in the pollen calendar is attributable to native Artemisia species, with A. vulgaris as the most abundant; the second peak is mostly represented by the invasive species A. annua and A. verlotiorum (in constant proportion along the years), which are causing a considerable increase in pollen concentration in the late pollen season in recent years.. The spread of these species can affect human health, increasing the length and severity of allergenic pollen exposure in autumn, as well as plant biodiversity in both natural and cultivated areas, with negative impacts on, e.g., Natura 2000 protected sites and crops.

Grassland allergenicity increases with urbanisation and plant invasions

“…Allergenic Artemisia invaders from warmer regions have been documented in other European cities (e.g. Cristofori et al 2020 ), suggesting that this genus may be of general concern in these regions, in particular as climate change will accentuate urban warming and favour warm-loving late bloomers (Li et al 2020 ).…”

“…But our study highlights the need to consider not only invasive neophytes but also the well-established resident allergenic flora of natives and archaeophytes in cities. For instance, Artemisia species pose a high allergy risk and are increasingly abundant in many European cities (Bogawski et al 2016 ; Cristofori et al 2020 ), but, being already widespread in the urban flora, are not candidates for removal actions.…”

Imported allergens in Italy: an emerging issue

“…This occurrence also seems to be due to the increased spread of two specific invasive allochthonous types, Artemisia annua and Artemisia verlotiorum , which may threaten the biodiversity of native plants. Allergic symptoms occur in September; the increased concentration of such pollen can exacerbate allergic symptoms in affected individuals [ 22 ]. Cannabis is another example of an imported allergen that also assumes relevance in the pediatric setting, given its frequent use in adolescents [ 23 – 24 ].…”

Research Advances on Health Effects of Edible Artemisia Species and Some Sesquiterpene Lactones Constituents

“…Pollen from the various Artemisia species is one of the most frequent and serious pollinosis causes in many parts of the world [ 114 , 115 , 116 , 117 , 118 ]. It has been verified as an allergen by nasal challenge and bronchial provocation tests, and these allergens have been shown to occur not only in its pollen but also in its leaves and stems.…”

“…The first peak was attributed to A. vulgaris (early flowering species) and the second one—to late flowering species (A. campestris , A. annua , A. verlotiorum , etc.) [ 115 , 124 ]. The authors supposed that the spread of these species could affect human health, increasing the length and severity of allergenic pollen exposure in autumn.…”