Understanding interactions between dung beetles and gastrointestinal nematodes of livestock

27 November 2020
Simon Fowler, Manaaki Whenua - Landcare Research and Paul Weston, Charles Sturt University, Australia

The literature available on dung beetle ecosystem services and activities impacting gastro-intestinal nematodes has been reviewed and findings have been reported to DBEE project researchers. The summarized findings are presented in a simplified framework below. In a nutshell, dung beetles are usually expected to decrease infection rates of gastro-intestinal nematodes in stock. But the story is complicated because there are a few ways that dung beetle activity could benefit gastro-intestinal nematodes, and these in turn are affected by factors such as weather conditions and soil type. A simulation modelling approach is designed to encompass this complexity, identify important research gaps and ultimately allow the development of a farmer-friendly decision tool enabling better decisions on whether drench treatments are necessary.

Due to Covid-19 travel restrictions, a meeting to discuss the development of a modelling approach to predict the impact of dung beetles on nematode presence was held via Skype in March 2020. Ideas, approaches and information were shared and the planned modelling can now take place. The inability to hold an intensive brainstorming session in person has slowed the model development process; however, such sessions should resume in 2021.

The conceptual impact of dung beetles on the development and transmission of gastrointestinal nematodes of livestock via dung beetle activities affecting key nematode juvenile stages

Nematode juvenile stage

Dung disturbance

Dung burial/brood balls

Egg hatch

Aerobic conditions can greatly increase hatch rate

Aerobic conditions increase nematode egg hatch but processing into brood balls destroys most eggs

Nematode larval stages L1/L2

Greatly reduced survival of nematode larval stages L1/L2 if dung dries out

Burial could increase survival of L1/L2 by preventing drying out, but processing into brood balls likely to kill larvae

Nematode L3 larval stage

Resistant to drying out. Can migrate onto foliage in moist conditions

Migration from buried dung possible from <10cm depending on moisture and soil type (e.g. lower survival in sandy soils but able to migrate from deeper than in clay soils)