New Zealand’s pastoral ecosystems: challenges, solutions, and the protective role of Epichloë endophytes

Abstract

New Zealand’s pastoral ecosystems heavily rely on introduced grass species like perennial ryegrass (Lolium perenne) and fescues (Festuca spp.), which can form mutualistic relationships with Epichloë endophytes. These endophytes protect grasses from insect herbivory by producing alkaloids that deter insect pests. However, while they benefit the plant, these alkaloids can also negatively affect grazing livestock. Unlike many other temperate grassland systems, New Zealand’s pastures have low plant diversity, with most sown species originating from Europe. This lack of diversity, combined with a historically limited suite of natural enemies, has contributed to a unique pasture insect pest burden. Pests such as Argentine stem weevil (Listronotus bonariensis), black beetle (Heteronychus arator), and root aphid (Aploneura lentisci) cause significant economic losses, threatening pasture persistence and productivity. To mitigate these challenges, many of New Zealand’s dominant pasture grasses are artificially associated with selected Epichloë endophytes that provide insect protection against key insect pests while minimising impacts on grazing livestock. These endophytes produce alkaloids that act as feeding deterrents and/or reduce the fitness of herbivorous insects, providing a natural bio-protection mechanism. This review explores the unique ecological characteristics of New Zealand’s pasture systems, including the impact of invasive and native insect pests and the role of Epichloë endophytes in pasture protection. Emerging challenges include climate change-driven shifts in pest populations and the need for sustainable pasture management strategies. Integrating ecological principles with advanced endophyte technologies can improve pasture resilience while minimising environmental trade-offs.