Is the Invasive Species Listronotus bonariensis (Kuschel) (Coleoptera: Curculionidae) (Argentine Stem Weevil) a Threat to New Zealand Natural Grassland Ecosystems?

Abstract

Listronotus bonariensis (Argentine stem weevil) is a stem-boring weevil that has become a major pasture pest in New Zealand, and cool climate turf grass in Australia. This species is also frequently found in native tussock grassland in New Zealand. Laboratory and field trials were established to determine the risk posed to both seedlings and established plants of three native grass species compared to what happens with a common host of this species, hybrid ryegrass (L. perenne X L. multiflorum). Adult weevil feeding damage scores were higher on Poa colensoi and Festuca novae-zelandiae than Chionochloa rigida. Oviposition was lower on P. colensoi than hybrid ryegrass, and no eggs were laid on F. novae-zelandiae. In field trials using the same four species established as spaced plants L. bonariensis laid more eggs per tiller in ryegrass in a low altitude pasture site than in ryegrass in a higher altitude site. No eggs were found on the three native grass species at the tussock sites, and only low numbers were found on other grasses at the low altitude pasture site. Despite this, numbers of adult weevils were extracted from the plants in the field trials. These may have comprised survivors of the original weevils added to the plants, together with new generation weevils that had emerged during the experiment. Irrespective, higher numbers were recovered from the tussock site plants than from those from the pasture site. It was concluded that L. bonariensis is likely to have little overall impact, but a greater impact on native grass seedling survival than on established plants.

Diversity and impacts of key grassland and forage arthropod pests in China and New Zealand: An overview of IPM and biosecurity opportunities

“…Similarly, the impact of exotic insects within these systems seems low, although Argentine stem weevil (Listronotus bonariensis) Kuschel (Coleoptera: Curculionidae) (ASW) is widespread (Murray et al 2003) and has been shown to feed on seedling blue tussock (Poa colensoi Hook.f. ), F. novae-zelandiae and narrow-leaved snow tussock (Chionochloa rigida (Raoul) Zotov) and, potentially, could impact on seedling survival (Barratt et al 2016). Indigenous insects have been shown to feed on exotic plants in areas where native vegetation is largely intact; for example, the native weevils Chalepistes spp.…”

Pest categorisation of Listronotus bonariensis

“…Barratt et al. () reported L. bonariensis as a potential risk to endangered native grass species in New Zealand.…”

“…in wheat in southern Brazil and Argentina, where yields were lowered (Gassen, 1984;Anon, 1996). Barratt et al (2016) reported L. bonariensis as a potential risk to endangered native grass species in New Zealand.…”

Feeding Performance of Argentine Stem Weevil Is Reduced by Peramine from Perennial Ryegrass Infected with Endophyte Fungus

“…Adult weevils feed on the leaves, leaving characteristic 'window-like' feeding scars on the adaxial leaf surface. Eggs are laid in the pseudostem; the larvae bore into the stem and tunnel through the center of tillers, causing substantial damage that can lead to plant mortality [6,7]. In Chile, the first recorded incidence of L. bonariensis was reported by Norambuena and Gerding [8] on wheat and barley in the southern region of the country, with a detection of 27.9% and 7.1% attacked axes, respectively.…”