Un nuovo insetto invasivo e nocivo è arrivato in Svizzera e sta prendendo di mira le piante ornamentali ticinesi, ma potrebbe presto minacciare anche i boschi. È la takahashia japonica, una cocciniglia di pochi millimetri, innocua per l'essere umano, ma nociva, appunto, per alcune piante ornamentali, come i gelsi. È stata individuata per la prima volta nella Confederazione, a Brissago. Trattamento biologico e monitoraggio le prime misure decise.
La takahashia japonica è di origine asiatica, descritta per la prima volta su alberi di gelso in Giappone e diffusa anche in Cina, Corea del Sud e India. In Europa è stata segnalata per la prima volta in un parco comunale nel 2017 a Cerro Maggiore (provincia di Milano), si legge sul sito dela Regione Lombardia. È presente anche in altri comuni in provincia di Milano, Varese e Monza Brianza.
Dalle prime osservazioni condotte in Lombardia, l’insetto compie una sola generazione all’anno. In primavera, verso fine aprile inizio maggio, le femmine producono i caratteristici ovisacchi. A fine maggio le neanidi escono dalle uova e migrano verso le foglie. Si alimentano della linfa rimanendovi fino a ottobre, quando ritornano sui rami per svernare, continuando a nutrirsi della linfa.
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