Research published in Biological Invasions shows that Australian redback spiders are invading New Zealand and could become established in many urban areas around major ports.
The paper, The invasive Australian redback spider, Latrodectus hasseltii Thorell 1870 (Araneae: Theridiidae): current and potential distributions, and likely impacts, details recorded sightings of redback spiders in New Zealand, then used biological and climatic information to reveal where redbacks could establish. Warm, dry conditions in some eastern areas of New Zealand are suitable for redback spiders to become established, and they are likely to spread further as they are surviving in places with relatively high rainfall. Urban areas, for example, provide shelter from the rain. The spread of redbacks is likely to have arisen from the establishment of new invasions through New Zealand's ports.
There is genetic evidence that redbacks have interbred with the protected, endemic katipo and there is a danger that redbacks could competitively displace katipo or cause extinction by interbreeding. Redbacks are also a public health issue as they have the potential to become established in areas close to urban populations. Successful border control already produces regular interceptions of the redback as well the invasive brown widow and the western black widow. Both these species are related to the redback and have similar habitat and climate requirements.
I spoke to lead researcher Dr Cor Vink about this work and how they are developing new approaches and tools to ensure harmful organisms are kept out of New Zealand.
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Cor J. Vink, José G. B. Derraik, Craig B. Phillips, & Phil J. Sirvid (2010). The invasive Australian redback spider, Latrodectus hasseltii Thorell 1870 (Araneae: Theridiidae): current and potential distributions, and likely impacts. Biological Invasions