Updating new invasions: The Australian tortoise beetle Trachymela sloanei (Blackburn, 1897) (Coleoptera: Chrysomelidae) in the Iberian Peninsula

Abstract

Trachymela sloanei (Blackburn, 1897) is a non‐indigenous beetle of the Iberian Peninsula herbivorous of several species of Eucalyptus trees. Since its first detection in Europe in 2014, little information is available about the populations of this beetle in this distribution range. Therefore, a complete chorological update of the Australian tortoise beetle in the Iberian Peninsula is carried out. The ecology, phenology and potential distribution are discussed. Certain features of its morphology are fully illustrated to increase knowledge of this species. Finally, other remarks of interest that could be useful for the future management perspectives of this plague of Eucalyptus in the European continent are commented on briefly.

The expansion of the Australian tortoise beetle Trachymela sloanei (Chrysomelidae: Chrysomelinae, Chrysomelini, Paropsina) in Spain: Using human‐made shelters for an early detection strategy

“…(c) Negative (red circles) and positive (yellow symbols, triangles: trees monitored the whole study period, circles: trees monitored during June–July) records of T. sloanei on Eucalyptus trees in Campo de Tabernas (Almería), whose location is marked by a rectangle in (1b). Green circles are positive records reported in Pérez‐Gómez et al (2022). See Methods section for further details.…”

“…However, the species was not found behind nest boxes placed elsewhere (other tree species, cliffs or farmhouses) (but see Pérez-Gómez et al, 2022), nor pupae were ever observed behind or in the nest boxes. We found a similar probability of detection of the species behind trees and bark, although future studies with a larger sample size would be desirable.…”

“…In 2014, it was first recorded in Europe (Southwestern Spain) (Sánchez et al, 2015), and it has recently been established in China (Zhang et al, 2020), South America (Villablanca & Villablanca‐Miranda, 2022), Greece (Gastouniotis et al, 2023) and the Canary Islands (Cordero‐Rivera & Santolamazza‐Carbone, 2023). Recently, the species has widely spread throughout the southern part of the Iberian Peninsula, reaching central Spain as well as Portugal (Pérez‐Gómez et al, 2022). This 6–8 mm long beetle feeds mostly on a wide variety of Symphyomyrtus Eucalyptus species (Garrison, 1998; Steven & Mulvey, 1977), although it prefers the red gum (Garrison, 1998) and may cause extensive tree damage (i.e., defoliation) on Eucalyptus plantations (Steven & Mulvey, 1977).…”

“…During 2015-2019, most records came from neighbouring provinces(Pérez-Gómez et al, 2022). Since then, there has been a remarkable expansion both to the north (Cáceres and Madrid), east (Almería), northeast (Córdoba) and northwest (Santarem, Portugal)(Pérez-Gómez et al, 2022). The expansion may have been a consequence of natural dispersal movements and/or may be associated with human activity.…”

“…Moreover, our results suggest a rapid population growth in a recently colonised area in a very short time. The first records in Almería were taken in October 2020 and in our study area(Pérez-Gómez et al, 2022). Precisely, in that area, we hadF I G U R E 3 Percent occurrence of imagoes and larvae of Trachymela sloanei and of mating pairs observed behind nest boxes from mid-June 2021 (first sampling date: 14 June) to the end of November 2021 (weekly data).…”