Drought impacts African black beetle feeding on perennial ryegrass





interactions between plants, herbivorous insects and fungal Epichloë endophytes. However, water availability fluctuates, a phenomenon intensified by climate change, challenging the success of New
Zealand’s pastoral industry. The impacts of climatic changes, such as intensifying drought, on pastoral insect pests have received little attention. In a no-choice bioassay, African black beetle (ABB) were fed semi-synthetic diets containing freeze-dried foliage material from drought-exposed and well-watered perennial ryegrass containing endophyte strains AR37 or NZCT, or with material free of endophyte (Nil). Diet consumption, beetle weight change, fungal alkaloid concentrations, phytohormones, and NRI (nitrogen reflectance index) concentrations were measured and compared. Except for AR37, ABB consumed more diets containing drought-exposed rather than well-watered material, with a 61% increase in Nil and a 50% increase in diets containing NZCT, though these effects were not accompanied by corresponding ABB weight changes. Here, we discuss the implications of these results on ABB damage in New Zealand pastures in the context of increasing drought and illustrate how spatial patterns of ABB damage could change over the next 75 years. Areas that do not currently have high populations of ABB such as Manawatū-Whanganui, Wairarapa and Marlborough will become increasingly vulnerable to damage. 


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Author Biographies

Craig B. Phillips, AgResearch Ltd.

Senior Scientist, Weeds Pests and Biosecurity, Resilient Agriculture

Rainer W. Hofmann, Lincoln University

Professor, Faculty of Agriculture and Life Sciences

Olivier J. Ball

Lecturer, NorthTec-Te Pūkenga

Dongwen Luo, AgResearch Ltd.

Senior Scientist, Statistics, Digital Agriculture

Alison J. Popay, AgResearch Ltd.

Senior Scientist, Plant Invertebrate Interactions, Ethical Agriculture




How to Cite

Hewitt, K. G., Phillips, C. B., Hofmann, R. W., Ball, O. J., Luo, D., & Popay, A. J. (2023). Drought impacts African black beetle feeding on perennial ryegrass. Journal of New Zealand Grasslands, 85, 239–251. https://doi.org/10.33584/jnzg.2023.85.3664



Vol 85 (2023)