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Research update

Assessing the biosafety of the Samurai wasp as a biocontrol agent for the brown marmorated stink bug (BMSB)

20 Sep 2019

The brown marmorated stink bug (BMSB), Halyomorpha halys, is an invasive temperate/subtropical pest of many horticultural crops, and is considered to be one of the world's worst insect biosecurity threats. Native to parts of Asia, the stink bug has successfully invaded other parts of the world, including the USA and Europe, and poses a major economic threat to New Zealand. 

Despite numerous interceptions at the border, BMSB is not yet established in New Zealand, however, in anticipation of its likely arrival, a pre-emptive classical biocontrol programme using the egg parasitoid Trissolcus japonicas (commonly known as Samurai wasp) has been initiated. Samurai wasp is considered one of the most effective biocontrol agents of BMSB, parasitising up to 70% of eggs. 

Knowledge of the potential impacts on non-target species could allow the biocontrol agent to be part of an effective biosecurity response against BMSB. 

This laboratory study proactively investigated the host range of the Samurai wasp in New Zealand, and found that a number of species of stink bugs present in New Zealand (exotic and native) are within the physiological host range of the Samurai wasp, although not all appeared to be equally susceptible to parasitism. 

The EPA recently approved (August 2018) the conditional release of the Samurai wasp should a BMSB incursion occur in New Zealand. This EPA approval is a huge milestone for pre-emptive classical biocontrol in NZ, and probably a world first.

The EPA noted that the risk of alternative stink bug host parasitism by T. japonicus was likely to be mitigated by a lack in overlap in locations where populations of endemic pentatomids live and where the BCA is expected to be released. Endemic stink bugs are likely to be protected from exposure by the climatic and altitudinal range they inhabit and the creation of refuges in large habitats. 

This work was funded by New Zealand’s Ministry of Science and Innovation, the Better Border Biosecurity (B3) research collaboration and The New Zealand Institute for Plant & Food Research Limited Strategic Science Investment Fund. 

Journal Reference

Charles J, Avila G, Hoelmer K, Hunt S, Gardner-Gee R, MacDonald F, Davis V  2019 Experimental assessment of the biosafety of Trissolcus japonicus in New Zealand, prior to the anticipated arrival of the invasive pest Halyomorpha halys. BioControl 64: 367–379.


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