Managing the risk of the stink bug
With the volume of international trade and travel greater than ever before there is constant risk to New Zealand from the movement of goods and people that could potentially harbour pests of plants.
Trade into New Zealand of vehicles, machinery and equipment, and containerised goods, are two such import pathways that pose a significant risk to our country due to association of the unwanted pest brown marmorated stink bug (BMSB) (Halyomorpha halys).
Since 2014 the Ministry for Primary Industries has had import requirements in place to manage the risk of BMSB and other unwanted pests on these and sea container pathways. However, the risk situation in exporting countries is changing as a result of the rapid spread of BMSB to new areas where there are minimal control tools. This has meant increasing instances of infestation. As can be expected this additional pathway pressure has resulted in a significant increase in border interceptions of BMSB from the United States of America (USA) and Italy, in the last three years.
To ensure protection of the horticulture industry, Horticulture New Zealand, along with several product groups, have been closely monitoring this risk situation. Concerns have primarily focused on the occurrence of live BMSB interceptions at the border that indicate treatment applications in exporting countries may not have been effectively applied. One may argue that because BMSB is being intercepted at the border then the biosecurity system is working. Well, in a way yes, however it’s in New Zealand’s best interests to protect our unique environment and resources by keeping risk offshore.
In the current BMSB risk season, which runs from September to April annually, we have seen the highest rate of interceptions recorded to date, including significant numbers (aggregations) of BMSB which cluster together to overwinter in imported goods. However, the threat that is posed to New Zealand crops and amenity plants is several months after the risk season, when BMSB experience warmer temperatures and become active again, leaving their hiding places to feed and then mate. The increased pressure - interception frequency, aggregations, multiple entry pathways - we have seen this risk season has generated significant concern to Hort NZ and product groups who worked with MPI to evaluate the risk. They then consider if immediate changes need to be made to strengthen import requirements from high risk countries.
MPI responded to industry and acknowledged the current measures were not adequately managing the risk of BMSB on the import pathways, particularly from Italy where most of the interceptions were coming from. This resulted in a temporary change to the Italian sea container cargo import pathway to require mandatory treatment either offshore, or onshore in New Zealand, within 48 hours of arrival.
Although the change in requirements has strengthened the measures on the Italian sea container pathway, these are only temporary and there is still risk presented by exports from other countries where BMSB is present. Therefore, Hort NZ will continue to lobby for ongoing review of the appropriateness of measures to be applied on BMSB risk pathways in an effort to keep risk offshore. This preventative approach is essential, rather than being reactive to risk on our doorstep.
Leanne Stewart is biosecurity manager for Hort NZ