Flight activity of wood- and bark-boring insects at New Zealand ports

Main Article Content

Stephen M. Pawson
Jessica L. Kerr
Chanatda Somchit
Carl W. Wardhaugh

Keywords

Biosecurity, ecological risks, export logs, forest entomology, phytosanitary, quarantine, regulated pests, trade

Abstract

Background: Bark- and wood-boring forest insects spread via international trade. Surveys frequently target new arrivals to mitigate establishment. Alternatively, monitoring pest activity in exporting countries can inform arrival and establishment
risk.


Methods: We report >3 years data from daily sampling of bark- and wood-boring insects that are associated with recently felled Pinus radiata D.Don at five New Zealand ports.


Results: Average catch differed between ports and months with Arhopalus ferus (Mulsant), Hylurgus ligniperda F., and Hylastes ater (Paykull) comprising 99.6% of the total catch. Arhopalus ferus was absent during winter with Hylastes ater and Hylurgus ligniperda activity between June and August representing 3.5 and 3.7% of total catch, respectively. Maximum temperature and wind speed influenced flight activity of all three species but not universally across all ports. Flight activity transitioned to a nonlinear pattern above 20°C. Arhopalus ferus has a unimodal flight risk period between late-September and late-April. Hylastes ater was also unimodal except in Dunedin where it was bimodal like Hylurgus ligniperda was in all regions with spring and mid- to late-summer activity periods. Although Hylastes ater was observed during winter, the probability of a flight event during winter was between 0 and 0.02 per week. Hylurgus ligniperda flight probability was zero in Dunedin and low at all other ports from May  to August.


Conclusions: Modelling seasonal changes in flight probability can inform risk-based phytosanitary measures. We demonstrate the utility of maximum temperature and seasonality as a predictor of wood commodity infestation risk. Such predictors allow National Plant Protection Organisations to develop standards that protect the post-treatment phytosanitary security of individual consignments.

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