Potential effects of climate change on biological control systems: case studies from New Zealand

Biological control systems are integral to New Zealand’s success as a nation reliant on exporting quality agricultural, forestry and horticultural products. The likely impacts of climate change projections to 2090 on one weed and four invertebrate management systems in differing production sectors were investigated, and it was concluded that most natural enemies will track the changing distributions of their hosts. The key climate change challenges identified were: disparities in natural enemy capability to change distribution, lack of frosts leading to emergence of new pests and additional pest generations, non-target impacts from range and temperature changes, increased disruptions caused by extreme weather events, disruption of host-natural enemy synchrony, and insufficient genetic diversity to allow evolutionary adaptation. Five classical biological control systems based on the introduced species Longitarsus jacobaeae, Cotesia kazak, Aphelinus mali, Microctonus aethiopoides and Microctonus hyperodae are discussed in more detail.