Dung Beetles a no brainer

ANDREW RITCHIE

The introduction of dung beetles is a no brainer according to Dr Shaun Forgie who is responsible for the importation of dung beetles into New Zealand.

Forgie says beetles have been around since the time of the dinosaurs however the 15 native species in New Zealand are largely confined to the forest floor.

The imported beetles specifically feed on bovine and ovine manure. The beetles are attracted by the smell of dung and can dispose of a cow pat within 48 hours. One of the major advantages is the eradication of repugnant herbage and the loss of grazing area caused by the proliferation of dung patches. The beetle buries its larvae in sausages of manure 45 to 60 cms underground where they then lay their eggs.

The burrowing action aerates the soil and improves soil structure, fertiliser and drainage, enabling pasture plant roots to penetrate deeper into the soil. Forgie claims a 76% reduction in parasites on herbage due to the action of the Beetles. His organisation has conducted field trials to measure the runoff reduction. On a slope of 11% it was found there was an 81% reduction in pollution runoff after a 150mm rain event.

In the Waikato riparian planting and fencing has been carried out for 30 years and there has been no improvement in water quality. In Pukekohe district it is estimated that the fencing of all waterways will cost 20 billion dollars, obviously unaffordable. In comparison the cost of a beetle programme is $10 to $40 per hectare. In addition, a severe flood event is likely to carry much of the fencing away. The introduction of beetles would mean less land loss due to riparian planting.

Dr.Forgie estimates that buffer zones could be reduced by 2metres. Despite the obvious advantages of the beetle programme Forgie’s programme has met resistance from DairyNZ that suggest environmentally unfriendly polystyrene floats planted with herbage, for waterways.

These are likely to disappear in a flood and have to be dug out of the riverbed in a drought, not to mention their limited lifespan. Opposition by a small group to the importation of beetles was found to be funded by drench supplier Pfizer, says Forgie. In Western Australia, famous for the Aussie wave, it has been estimated that the reduction in the fly population has made a saving of 1 billion dollars in the local economy with the introduction of the dung beetle.

Again, politicians and decision makers have failed to listen to scientific voices. Dung beetles a no brainer.