The butterfly Cacyreus marshalli in northern Italy, and susceptibility of commercial cultivars of Pelargonium

Studies on the biology of geranium bronze butterfly (C. marshalli) were conducted in Milan (northern Italy) on Pelargonium spp. from April to the end of December, observing directly the presence of adult, larvae, eggs or damage. To test the susceptibility to the attack of the butterfly, 40 different ornamental geraniums were used: 10 cultivars of zonal pelargoniums (Pelargonium hortorum); 3 cultivars of ive-leafed pelargoniums (P. peltatum); 3 cultivars of regal pelargoniums (P. domesticum) and 16 species or cultivars of scented-leafed pelargoniums. The plants were exposed to the pest from the end of May to September. The plants were observed every week, and data on damage and their symptomatology were collected. Many overlapping generations of the pest occurred, with adults detected from the beginning of May to the middle of October. Damage was first observed on zonal and ivy-leafed pelargoniums in June; regal and scented-leafed pelargoniums were attacked later and less severely. Most of the plants tested were attacked. Only on some scented-leaf pelargoniums (Abrotanifolium, Concolor lace, Denticulatum, Fair ellen, Filicifolium, Odoratissimum, Purple unique, Prince of orange, Royal oak and Wayward angel) where no larvae or damage was found.