Surveillance for weevils and cobweb spiders at high risk sites around Christchurch, New Zealand

Most arthropod traps available for biosecurity surveillance are either generic and incur problems with large bycatches, or are targeted at one or a few species and have limited application. Traps designed to be of intermediate specificity were tested at three high risk sites in Christchurch. Traps with and without attractants targeting weevils (Curculionidae), and two trap types targeting cobweb spiders (Theridiidae) were evaluated. The weevil traps captured nine weevil species from six genera, including the first detection of Sitona lepidus in the South Island. Significantly more weevils were captured in the traps with attractants. The spider traps captured spiders in the families Theridiidae, Linyphiidae and Agelenidae, including the first detection of Nesticodes rufipes (Theridiidae) in the South Island. For all traps, bycatches were small and readily processed, and included a cricket, Gryllodes sigillatus, that is not established in New Zealand. Traps of intermediate specificity have potential for operational use in high risk site surveillance.