High-risk pests 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 New Zealand’s mosquito surveillance programme.

It highlights which exotic mosquitoes are arriving at our border, where they are coming from, and how they are getting here.

Suspected mosquito interceptions of overseas origin, 2001 – 2020

Mosquitoes of overseas origin include new exotic mosquito species entering New Zealand and exotic species established in New Zealand re-entering New Zealand from overseas.

Between 2011 and 2020, there were 128 interceptions of overseas origin. This compares to 73 interceptions the decade earlier (Figure 1).

Figure 1: Number of mosquito interceptions of overseas origin, 2001 – 2020

Fig 1

*Note: An interception may include several insects which fall into different categories. Therefore, the sum of all categories is higher than the total number of interceptions.

Source: [1]

Mosquitos of overseas origin include new exotic mosquito species entering New Zealand and exotic species established in New Zealand re-entering New Zealand from overseas.

In 2020, there were 14 interceptions containing mosquitoes of overseas origin, compared to an average of 13 interceptions per annum between 2011 and 2020. Of the 14 interceptions in 2020, five contained mosquitoes whose species is already established in New Zealand. Nine interceptions contained new exotic mosquitos.

About 70% of all interceptions of overseas origin took place in the Auckland region between 2011 and 2020. Christchurch was the next most frequent location (14%) and then Wellington (9%)[1].

43 types of exotic mosquito species were intercepted, 2011–2020

Forty-three types of exotic mosquitoes were caught at the New Zealand border between 2011 and 2020. Twenty were high-risk species, that is, on New Zealand’s list of exotic mosquitoes of public health concern [1, 2].

These included:

  • 20 interceptions of Aedes aegypti, a severe-risk species for many diseases eg, Chikungunya, Zika, dengue and yellow fevers.

  • 7 interceptions of Aedes vexans, capable of carrying West Nile virus.

Table 1 summarises all suspected mosquitoes of overseas origin caught at the New Zealand border, 2011–20 (See Table 1). 

Interceptions of overseas origin were most frequently from countries in the Pacific region

Of all interceptions of overseas origin between 2011 and 2020, 34.3% originated from the Pacific region. Australia was the most common source country for interceptions (41), followed by Ecuador (14), USA and China (11 each) (Table 1) [1]. 

Table 2: Number of mosquito and non-mosquito interceptions of overseas origin, by region and country,
2011–2021

Region of Origin Country of origin (Number of interceptions Percentage of Total Interceptions Travel  mode

 

Pacific

Australia (41), Fiji (9), Tonga (4), Samoa (3), New Caledonia (1), Vanuatu (1)
Total: 59

34.3

Sea: 71%

Air: 27%

Unknown: 2%

Asia

China (11), India (9), Japan (6), Malaysia (5), Singapore (5), Philippines (3), Hong Kong (2), Korea (2), Taiwan (2), Thailand (2), Bangladesh (1), Cambodia (1), Indonesia (1)
Total: 50

29.1

Sea: 72%

Air: 24%

Unknown: 4%

Americas

Ecuador (14), USA (11), Chile (2), Colombia (2), Argentina (1), Mexico (1), Panama (1)
Total: 32

18.6

Sea: 81%

Air: 19%

Europe

Germany (3), Italy (2), UK (2), Belgium (1), Netherlands (1)

Total: 9

5.2

Sea: 100%

Africa

 South Africa (1)
Total: 1

0.6

 Sea: 100%

Unknown

Total: 21

12.2

Sea: 29%

Air: 67%

Unknown: 4%

Source: [1]

High-risk pests most often travel by sea and in ‘other cargo’

Between 2011 and 2020, 69.8% of mosquito and non-mosquito interceptions were suspected to have travelled by sea [1]. In 2020, over 99% of imported goods to New Zealand were transported by sea [3].

Between 2011 and 2020, 36.7% of interceptions of suspected mosquitoes of overseas origin were transported alongside other cargo (eg, household goods, shipping containers—contents not specified). Fruit (eg, bananas, grapes) made up 19.5% of discovery locations at the New Zealand border, followed by 12.5% for other produce (eg, flowers, wood, oats, corn) (Figure 2).  Compared to the previous decade, the percentage of mosquito interceptions of foreign origin found alongside other cargo decreased, and the percentage of interceptions found alongside fruit increased.

Figure 2:Mosquito interceptions of overseas origin, by location of discovery at the New Zealand border, 2011–2020 (%)

Fig 2

Source: [1]

References

1. New Zealand BioSecure Entomology Laboratory. Mosquito interceptions dataset. Southern Monitoring Services Limited. (Accessed 2021 by personal correspondence)

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

3. Statistics New Zealand (Statistics NZ). Infoshare. Overseas cargo statistics: Total imports by New Zealand port
(Annual-Jun). URL: www.stats.govt.nz (accessed February 2021).

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