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Biocontrol introduction

Target pest: Alternanthera philoxeroides (Caryophyllales: Amaranthaceae), alligator weed

Agent introduced: Disonycha argentinensis (Coleoptera: Chrysomelidae), alligator weed beetle



Import source:

Brazil (via Australia?)

Import notes:

Cameron et al. (1989) - one shipment of D. argentinensis, consisting of approximately 250 adults and some eggs, was received from CSIRO in October 1981. These insects came from a laboratory colony in its ninth (adults) and tenth (eggs) generation, which was set up in 1979 using insects imported from Marium, Sergipe, in southern Brazil.



Release details:

Cameron et al. (1989) - between February 1982 and February 1984, a total of 18,700 adults released at 17 sites in Northland and Auckland. In 1982 at Kaipara (Northland) and 1983 at Woodhill (Auckland) some beetles were released into cages to monitor establishment.


Cameron et al. (1989) - failed to establish. In the caged releases, larvae, prepupae were found, so reproduction was occurring, but in all cages population levels dropped quickly. However, survival inside cages was superior to that outside the cages; the slightly higher temperature and humidity inside the cages may indicate that D. argentinensis requires warmer or more humid conditions than occur in Northland and Auckland. Post-release visits to release sites yielded no D. argentinensis and no damage that could be definitely attributed to them was observed.

Impacts on non-targets:

Cameron et al. (1989) - host range testing in Australia using 37 species of plants and in New Zealand against a further three species confirmed the host specificity of D. argentinensis.


Cameron PJ, Hill RL, Bain J, Thomas WP (1989). A Review of Biological Control of Invertebrate Pests and Weeds in New Zealand 1874-1987. Technical Communication No 10. CAB International Institute of Biological Control. DSIR Entomology Division. 424p.

Landcare Research (2007a). New Zealand Arthropod Collection (NZAC) Biological Control Voucher Collection. Landcare Research website [Updated 2020] https://www.landcareresearch.co.nz/tools-and-resources/collections/new-zealand-arthropod-collection-nzac/databases-and-holdings/new-t2-landing-page/