Agricultural and Forest Entomology (2014), 16, 45–53 DOI: 10.1111/afe.12032 Biology of the Eucalyptus leaf beetle Paropsisterna selmani (Chrysomelidae: Paropsini): a new pest of Eucalyptus species (Myrtaceae) in Ireland Philip D. Fanning and Jan-Robert Baars BioControl Research Unit, School of Biology and Environmental Science, Science Centre West, Dublin 4, Ireland Abstract 1 The biology of the Eucalyptus leaf beetle Paropsisterna selmani (de Little) (Chrysomelidae: Paropsini) was assessed in the field and under laboratory conditions. The invasive species, most probably from Tasmania, severely defoliates the new flush foliage of several Eucalyptus species in Ireland. 2 The adult beetles and larvae both fed on the foliage and caused typical broom-top damage to trees. Adult beetles over-wintered in the soil and emerged in April and laid egg batches of approximately seven eggs on the leaves. Teneral adults were most noticeable in late June and July. 3 In bioassays, the life cycle took approximately 26 days to complete at 20 ◦ C, and survival rates were approximately 67% when fed on E. parvula . Teneral adults took 13.3 days to initiate egg-laying. Leaf consumption was highest in female larvae, and adult beetles consumed a leaf area of approximately 102 mm 2 /day. 4 A mean daily egg-laying rate of 11.4 eggs/female was recorded over a period of 130 days. This egg-laying rate is comparable to other leaf beetles attaining pest status in other Eucalyptus -growing regions. 5 The biology of Pt. selmani suggests that this will be a significant pest of Eucalyptus species grown for cut-foliage and forestry in Ireland. It also poses a potential threat to eucalypt-growing regions in the U.K. and mainland Europe. Keywords Biology, defoliator, Eucalyptus , Europe, forestry, impact, invasive species, life cycle, Paropsisterna . Introduction A relatively small fraction of the phytophagous species occurring on Eucalyptus in Australia has been accidentally introduced to the Eucalyptus -growing areas in the world. Nonetheless, these species, largely made up of insects, prove to be a serious threat to forestry and ornamental foliage production in Europe (Cadahia, 1986; Cavalcaselle, 1986; Cordero Rivera et al., 1999; Valente et al., 2004; Hodkinson, 2007; Valente & Hodkinson, 2009; Laudonia & Sasso, 2012). As in other parts of the world, reports on new introductions into Europe have increased over the last two decades. Despite the biosecurity and border control measures adopted by countries, the colonization of new Australian insects on eucalypts is expected to continue (Withers, 2001; Wingfield et al., 2008; Paine et al., 2011). Although isolated from the European mainland, new species are still being introduced into Ireland and the U.K. One Correspondence: Philip D. Fanning and Jan-Robert Baars. Tel.: +353(0)17162346; fax: +353(0)17161153; e-mail: philipfanning@ hotmail.com; janrobert.baars@ucd.ie of the recent introductions is a leaf defoliator Paropsisterna selmani (de Little) (Chrysomelidae: Paropsini), which was first discovered on Eucalyptus cut-foliage plantations in the south west of Ireland in 2007 and referred to then as Paropsisterna nr. gloriosa (Horgan, 2011). The beetle has persisted as a leaf defoliating pest subsequent to its discovery and is the first paropsine leaf beetle to become established in Europe. A related species, Paropsisterna bimaculata (Olivier), had been intercepted on tree ferns imported into the U.K. from Australia but was subsequently eradicated (Eyre, 2005). Eucalyptus leaf beetles are herbivores native to Australia, although they are major pests of commercially grown eucalypts (Ohmart & Edwards, 1991; Elliott et al., 1993; Ramsden & Elek, 1998; Nahrung, 2006). In the native range, these leaf beetles are usually rare and only become problematic where eucalypts are grown outside the natural ranges (Strauss, 2001; Nahrung, 2006) and in extensive monocultures. Several species have emerged as pests, such as Paropsisterna (formerly Chrysophtharta ) agricola (Chapuis) and Paropsis atomaria (Olivier) in south-eastern Australia (de Little & Griffith, 1989; Nahrung et al., 2008), as well as Pt. bimaculata and  2013 The Royal Entomological Society