Pests of Australian dairy pastures: distribution, seasonality and potential impacts on pasture production

Abstract

The dairy industry provides an important contribution to the Australian economy, but its productivity relies on grass pastures that suffer significant damage from invertebrate pests. Managing these pests remains a challenge as information on their abundance and impact is only available for a handful of taxa in a few Australian dairy regions. In this study, we undertook an extensive survey of above-and below-ground pest communities across seven dairy regions in south-eastern Australia by repeatedly sampling 57 paddocks in 2017 and 2018. We then applied energetic models to estimate the amount of metabolisable energy produced by pastures that are potentially consumed by pests. Our survey indicates that dairy farmers encounter a similar composition of above-ground pests in most sampled regions, with a few pests, especially Sminthurus viridis (lucerne flea) and Rhopalosiphum padi (bird cherry-oat aphid), dominating pest communities. Below-ground pests were more variable between regions and are more likely to require region-specific control strategies. Our energetic modelling suggests that pests consume a threefold greater percentage of metabolisable energy produced by pastures during autumn than spring. S. viridis and R. padi were among the most economically important pests across all regions and seasons, while other pests, including several species of scarabs and the small pointed snail, Prietocella barbara, were predicted to be particularly damaging in specific regions. Together, our field survey and energetic modelling provide baseline information to assist dairy farmers manage invertebrate pests and help guide future research in the Australian dairy industry.

Fungicides have transgenerational effects on Rhopalosiphum padi but not their endosymbionts

“…Farmers worldwide invest vast amounts of time and resources to protect crop plants from the bird cherry‐oat aphid, Rhopalosiphum padi , Linnaeus (Hemiptera: Aphididae) 1,2 . Rhopalosiphum padi attacks several plant families but causes the greatest economic damage to grains crops and grass‐based pastures through direct feeding and transmitting plant viruses such as the barley yellow dwarf virus 3–5 . In Australian cereals crop, R. padi and other cereal aphids are estimated to reduce yield by 6% via their direct feeding and up to 30% due to the viruses they transmit 4 .…”

“…1,2 Rhopalosiphum padi attacks several plant families but causes the greatest economic damage to grains crops and grass-based pastures through direct feeding and transmitting plant viruses such as the barley yellow dwarf virus. [3][4][5] In Australian cereals crop, R. padi and other cereal aphids are estimated to reduce yield by 6% via their direct feeding and up to 30% due to the viruses they transmit. 4 While farmers currently have effective control strategies for R. padi, these strategies are over-reliant on insecticide treatments.…”

How plant traits respond to and affect vertebrate and invertebrate herbivores—Are measurements comparable across herbivore types?

“…This trend likely reflects funding and societal priorities to support global red meat production (Lemaire et al, 2005). Invertebrates, and other native mammalian herbivores, however, can also have huge impacts on grassland productivity and consequential livestock production (Risch et al, 2013; Saunders, 2018; Umina et al, 2021). Improving our understanding on how these herbivores impact plant defence syndromes may benefit the pastoral industry, while also providing a better overall understanding of how herbivores affect grassland plant communities.…”

How plant traits respond to and affect vertebrate and invertebrate herbivores---are measurements comparable across herbivore types?

“…This trend likely reflects funding and societal priorities to support global red meat production (Lemaire et al, 2005). Invertebrates, and other native mammalian herbivores, however, can also have huge impacts on grassland productivity and consequential livestock production (Risch et al, 2013;Saunders, 2018;Umina et al, 2021). Improving our understanding on how these herbivores impact plant defence syndromes may benefit the pastoral industry, while also providing a better overall understanding of how herbivores affect grassland plant communities.…”