High-risk insects caught at New Zealand’s border

This section presents information on exotic mosquitoes and other insects caught at our border (international airports and seaports) by Aotearoa New Zealand’s mosquito surveillance programme.

It prevents exotic mosquitoes from establishing in New Zealand while highlighting which species are arriving at our border, where they are coming from, and how they are getting here. This knowledge helps maintain New Zealand's public health.

About high-risk insects

Insects are able to travel internationally through multiple pathways. Exotic mosquitoes are considered high-risk insects in New Zealand due to their ability to spread serious infectious diseases such as Dengue Fever and Malaria.

Common practices preventing the spread of insects include spraying aircraft with insecticides, and freight cargo being sealed until entering inspection zones. Surveillance takes place at New Zealand’s international ports. 

When an interception is made the species and likely origin is recorded. Any interception where the origin is unknown is considered potentially international. Species are classified as:

• Non-mosquito’s: Any insect that is not a mosquito, such as crane flies.
• Exotic mosquito’s already in New Zealand: An international mosquito species that is established in New Zealand such as C. quinquefasciatus or A. notoscriptus.
• Unidentifiable exotic (Unknown): The specimen has been lost or damaged beyond recognition.
• New exotic species: Mosquitos that are not established in New Zealand

While new exotic species are a direct threat to New Zealand's health, the other categories can assist in identifying routes that high-risk insects could use to cross our borders. A list of high and low-risk mosquito species can be found on the NZBioSecure website.

Interceptions of insects of potential overseas origin remained high since 2014

Before 2014 there was an average of ten interceptions of high-risk insects of international origin each year. This increased in 2014 and has averaged 21 interceptions per year through to 2021. The cause of this increase is unknown.

Over the past five years, 2017–2021, there were 107 interceptions which included 215 new exotic mosquitoes and 454 other species such as established mosquitoes or other insects. Some notable events that have occurred between 2017 and 2021 include:

• 2017: Nine separate interceptions of Aedes aegypti during advanced surveillance of Auckland international airport.
• 2018: 154 Aedes vexans and one Aedes aegypti found dead in a shipping container from Tonga.
• 2019: Four Aedes vexans found dead on a flight from Fiji.
• 2020: 12 Culex pipiens, one Aedes albopictus and 11 other insects found dead during inspection of wind turbines from Italy.
• 2021: One Aedes aegypti caught alive by traps surrounding Auckland international airport. 

Seaports have more interceptions but are not necessarily higher risk

Of the 107 interceptions made in 2017–2021, two-thirds were imported by sea. However, the number of live specimens was similar at both seaports and airports (21 and 17 interceptions respectively). Given live specimens present a higher risk to New Zealand, both seaports and airports should be considered high-risk.

Interceptions frequently originate from the Asia-Pacific region

Since 2001, the majority of interceptions have originated from either the Pacific (108 interceptions) or Asia (96 interceptions). Among individual nations, Australia was the origin of the majority of interceptions (69 interceptions) (Figure 1)

Figure 1: Border interceptions by country and mode of transport, 2001–2021.

References

1. New Zealand BioSecure Entomology Laboratory. 2022. Mosquito interceptions dataset. Southern Monitoring Services Limited. (Accessed 2022 by personal correspondence)

2. New Zealand BioSecure Entomology Laboratory. 2022. Exotic Mosquitoes. Southern Monitoring Services Limited. (accessed February 2021). Available at: www.smsl.co.nz

3. Statistics New Zealand (Statistics NZ). 2022a. Infoshare. Overseas Cargo Statistics: Total imports by New Zealand port. (Annual-Jun). URL: www.stats.govt.nz (accessed February 2022).

4. Statistics New Zealand (Statistics NZ). 2022b. Infoshare. International Travel and Migration: Total passanger movements by NZ port and selected overseas ports. (Annual-Jun). URL: www.stats.govt.nz (accessed February 2022).