Climate change impacts on pest ecology and risks to pasture resilience

Mansfield, Sarah; Ferguson, C. M.; Gerard, P.J.; Hodges, David; Kean, John M.; Phillips, C.B.; Hardwick, S.; Zydenbos, S. M.

doi:10.33584/rps.17.2021.3477

Cited by 9 publications

(12 citation statements)

References 62 publications

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“…The impact of the Lolium ‐ Epichloë complex is well demonstrated by the time trend data for ryegrass persistence‐related variables in the two Waikato trials in Table 6. It is well‐known that populations of insect pests of perennial ryegrass are greater in the northern regions of New Zealand (below latitude c. 38.5 o S) than in the rest of the country, related to differences in climate and soil factors (Mansfield et al, 2021). The Lolium ‐ Epichloë complex is essential for protecting ryegrass plants from several insect pests, particularly African black beetle ( Heteronychus arator ) and Argentine stem weevil ( Listronotus bonariensisi ).…”

Section: Discussionmentioning

confidence: 99%

The contribution of perennial ryegrass (Lolium perenne L.) breeding to whole pasture productivity under dairy cattle grazing in New Zealand. 1. Variation in yield, nutritive value and persistence‐related traits

Chapman

Wims

Ludemann³

et al. 2022

Grass and Forage Science

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Perennial ryegrass (PRG, Lolium perenne L.) breeding effort in New Zealand (NZ) has increased since c. 1990, resulting in greater functional trait diversity (e.g. heading date, ploidy, and associated Epichloë endophyte strain) in commercial products. This study quantified the variation, associations and interactions in dry matter (DM) yield, nutritive value and persistence‐related traits among commercial cultivar‐endophyte combinations released between 1973 and 2012, as a basis for assessing gains in value being delivered to the pasture‐based livestock industries. Twenty‐four or 28 combinations were compared over 3 years in two trials in each of two regions: Waikato in northern NZ (dryland), and Canterbury in central eastern South Island (irrigated). Cultivar‐endophyte combinations were sown in mixtures with white clover, and pastures were intensively grazed 8–11 times per year by dairy cows. Principal Component Analysis identified 4 distinct clusters for the DM yield variables and for metabolisable energy (ME) content in each of the four trials. A broadly‐adapted group of three late‐season flowering, AR37‐infected diploids with NZ and Spanish breeding backgrounds dominated the highest‐yielding clusters. Tetraploids dominated the high ME content clusters. Interactions with region were observed throughout the data set: the strongest of these was driven by endophyte strain effects in Waikato. High‐yielding cultivar‐endophyte combinations in these trials were also generally high‐yielding in the standard cultivar merit testing system operated in New Zealand, as interpreted via the DairyNZ Forage Value Index. However, alignment was poorer for medium‐ and lower‐yielding cultivar‐endophyte combinations. Several implications for forage evaluation methods and end‐user industries are identified.

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Section: Discussionmentioning

confidence: 99%

The contribution of perennial ryegrass (Lolium perenne L.) breeding to whole pasture productivity under dairy cattle grazing in New Zealand. 1. Variation in yield, nutritive value and persistence‐related traits

Chapman

Wims

Ludemann³

et al. 2022

Grass and Forage Science

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“…Climate change and extreme weather events, such as drought, are major drivers of pest populations as well as crop production (Skendžić et al 2021). Despite the importance of the pastoral industry to New Zealand's economic well-being, few studies have investigated and predicted the impacts of climate change on pasture insects in New Zealand's farm systems (Dynes et al 2010;Mans eld et al 2021). The wide distribution of root aphids in New Zealand and the increasing severity and frequency of droughts makes root aphids an increasingly important group of herbivorous insects.…”

Section: Pastoral Farming In a Changing Environmentmentioning

confidence: 99%

Root aphid (Aploneura lentisci) population size on perennial ryegrass is determined by drought and endophyte strain

Hewitt

Hofmann

Ball³

et al. 2023

Preprint

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Climate change is anticipated to lead to an increase in the occurrence and intensity of drought and fluctuations in insect cycles that will challenge modern pasture systems. Feeding by root aphids such as Aploneura lentisci Pass. can be a significant challenge to pastures. These below-ground living aphids are commonly found in New Zealand and Australia, feeding year-round on the roots of graminaceous plants such as perennial ryegrass (Lolium perenne L.). Some strains of the fungal endophyte Epichloë festucae var. lolii in perennial ryegrass can provide protection against root aphids and greater resilience under drought, contributing to higher persistency and growth than endophyte-free plants. However, the interaction between insect pressure and drought is not understood. This study examined the effect of drought on root aphid populations and plant performance in perennial ryegrass plants relative to endophyte status (+/-) and endophyte strain (AR37, NZCT) in a glasshouse experiment. Plants were cloned across the drought and well-watered treatments and half of the plants were inoculated with root aphids while half of the plants were treated with insecticide. Aphid populations were significantly higher in drought-stressed than in well-watered plants in both endophyte-infected and endophyte-free treatments. This resulted in reduced above and below ground plant growth. Our results suggest that root aphids are likely able to exploit the higher availability of amino acids in the plant sap of drought-exposed plants. This study provides evidence that climate change-mediated impacts of root aphids could reduce production in perennial ryegrass-dominant pastures. However, field trials would be necessary to determine whether this effect is seen in situ, where numerous additional factors will be operating at the same time.

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“…This conclusion holds across all livestock sectors in New Zealand, as explicated by Stevens et al (2021). 'Resilience' in the context of pastures includes mitigating the effects of: increased climate variability and the underlying drying and warming trends predicted by climate change models (e.g., Keller et al 2021); higher pest, weed and disease burdens, also related to changes in climate (e.g., Mansfield et al 2021); and lower inputs of fertiliser, herbicides and other synthetic products that are subject to changes in regulation and/ or customer demands.…”

Section: Resiliencementioning

confidence: 99%

“…Climate change projections indicate that temperate pasture species will experience increased abiotic growth stresses across much of the North Island (Keller et al 2021), while damaging levels of several key insect pests will be exceeded more often (Mansfield et al 2021). Recent trends toward hotter, drier summers/ autumns in Waikato have been highlighted by Glassey et al (2021), including the observation that six out of the last 10 years in Waikato have brought significant summer/autumn droughts.…”

Section: Job Security: Pasture Persistence Adaptation and Resiliencementioning

confidence: 99%

Organising Committee Chair's address: Resilient pastures

Chapman

2022

NZGA R&P Series

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High value animal products from New Zealand’s pasture-based livestock systems have consistently earned $25-$30B in export earnings per year for the country over the past 5 years (Ministry for Primary Industries 2021). Total earnings from dairy and meat of $30.5B in 2020 equate to 35% of New Zealand’s total goods and services export earnings of $86.4B. The importance of this revenue to the national economy has been shown in stark relief recently with the Covid-19 pandemic substantially reducing the earnings generated by other key export sectors such as tourism and international education. While our pasture-based livestock industries have ridden the coronavirus wave well compared with other sectors of the economy, they are facing change at a scale and pace not seen since the far-reaching reforms to the economic settings for agriculture introduced by the Lange Government in the early 1980s. Locally, the ramping-up of government environmental policies beginning c. 2011 has resulted in stringent regulations controlling the amounts of nitrogen (N), phosphorus (P) and sediment that can be discharged into freshwater from farm systems. The most recent iteration in this policy sequence includes new National Environmental Standards for Freshwater, and the new National Policy Statement for Freshwater Management (NPS-FW), which came into force in September 2020. These policies reverse the trends of the past two decades when agricultural productivity grew substantially in the virtual absence of regulation to control the environmental externalities of systems intensification. While the initial impacts on land use and farming practices have been localised (e.g., in the lake districts of Rotorua and Taupo), disruption to the farm systems that have emerged over the past two decades, especially intensive dairy systems, will be widespread in the future. For example, Doole et al. (2021) estimated that the new standards introduced in 2020 will require about 40% of New Zealand’s 11400 dairy farms to reduce nitrate leaching by an average of around 42% relative to requirements in previous iterations of the NPS-FW. The most significant global force driving change in New Zealand agriculture is climate change, via New Zealand’s commitment to the Paris Agreement to reduce carbon (C) emissions to net zero by 2050, C-neutral strategies being implemented by some of our largest customers (e.g., Nestle 2020), and the physical impacts of climate change on conditions for plant growth (e.g., Keller et al. 2021). Of direct and significant relevance to the livestock industries are the methane emission reduction targets proposed by government, of between 27% and 47% below 2017 levels by 2050. Meanwhile our international competitors have been steadily closing the gap in costs of production with New Zealand, and now have other fields on which to out-compete us (e.g., in C footprint) unless we can keep pace.

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Climate change impacts on pest ecology and risks to pasture resilience

Cited by 9 publications

References 62 publications

The contribution of perennial ryegrass (Lolium perenne L.) breeding to whole pasture productivity under dairy cattle grazing in New Zealand. 1. Variation in yield, nutritive value and persistence‐related traits

The contribution of perennial ryegrass (Lolium perenne L.) breeding to whole pasture productivity under dairy cattle grazing in New Zealand. 1. Variation in yield, nutritive value and persistence‐related traits

Root aphid (Aploneura lentisci) population size on perennial ryegrass is determined by drought and endophyte strain

Organising Committee Chair's address: Resilient pastures

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