Identification and molecular phylogenetics of the cryptic species of the Gonipterus scutellatus complex (Coleoptera: Curculionidae: Gonipterini)

Abstract

The Eucalyptus Weevil, generally referred to as Gonipterus scutellatus Gyllenhal, 1833 is a significant pest of Eucalyptus species in Africa, America, Europe and New Zealand. It has recently become a pest of Eucalyptus globulus plantations in Western Australia, despite the presence there of the mymarid egg‐parasitoid Anaphes nitens (Girault). Recent taxonomic study has indicated G. scutellatus to comprise a complex of cryptic species, obscuring the identity of the various pest populations of the weevil in the world. We examined (1) whether the apparent cryptic species identifiable on genital differences have a genetic basis; (2) the distribution of these species; and (3) the origin of the population in Western Australia. We studied specimens from across the distribution range of Eucalyptus Weevil in Australia and obtained sequences of three genes from them: cytochrome oxidase I mtDNA, elongation‐factor 1‐α nuclear DNA and 18s rDNA. The cladogram of COI haplotypes resolved 10 well supported clades fully corresponding with genital‐morphologically distinct species, eight of them constituting a monophyletic G. scutellatus complex. Only four of these species proved to be described, as G. balteatusLea, 1897G. platensis (Marelli, 1926), G. pulverulentusLea, 1897 and G. scutellatus Gyllenhal, 1833. The pest species in the world were found to be G. platensis (New Zealand, America, western Europe), G. pulverulentus (eastern South America) and an undescribed species (Africa, France, Italy). The population of G. platensis in Western Australia showed little genetic variation and is indicated to be a recent introduction from Tasmania. The discrimination of the cryptic species of the G. scutellatus complex enables improvements in the management of the pest species in terms of biological control and plantation practices. Our study highlights the critical importance of proper taxonomic studies underpinning biocontrol programs.

Increasing numbers and intercontinental spread of invasive insects on eucalypts

“…Gonipterus scutellatus was thought to have spread globally (except Asia), but it was later discovered that the species had been misidentified and that 'G. scutellatus' represents a complex of at least three species (Mapondera et al 2012). These include G. platensis found in New Zealand, South and North America and western Europe, G. pulverulentus in South America, and an undescribed species (Gonipterus sp.…”

“…plicatuloides detected in South Africa in 2014 (Samantha Bush, unpublished). In addition, Nahrung and Swain (2015) listed the Gonipterus scutellatus complex and not the three Gonipterus species as described by Mapondera et al (2012). These changes have been included in Table 1, which lists a total of 42 pest introductions.…”

A review of the introduced forest pests in Brazil

“…This is the case of G. pulverulentus, which had been previously misidentified in eastern South America as Gonipterus gibberus Gyllenhal, 1833. In New Zealand, America, and Western Europe, it was found that the reported pest species was actually G. platensis, instead of G. scutellatus (Mapondera et al, 2012); both species were dispersed with the host plant (eucalyptus).…”

“…to eucalyptus plantations was first noticed when a large number of this species was found in E. globulus plantations in Australia (Mapondera et al, 2012). The introduction of E. globulus from the Tasmanian region in many parts of the world may have been responsible for the entry of the pest in South America (Mapondera et al, 2012).…”

“…The genus contains about 20 described species, most of them occurring in Australia (Mapondera et al, 2012). It should be noted that, outside of their native range, adults and larvae feeding on leaves cause severe damages to eucalyptus.…”