Why are possums pests in Australia

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In New Zealand, studies have been carried out with biodynamic tinctures to control pests against kusus (possums) - with no apparent success.

In the past century the fox kusu (Trichosurus vulpecula Kerr, also called Possum) introduced into New Zealand from Australia. These animals cause problems because, being herbivores, they damage agricultural crops and can transmit bovine disease. The repellent effect of five biodynamic tinctures was investigated with possums in enclosures, with the eating behavior, food intake and body weight being evaluated. The researchers also recorded the consumption of bait in treated and untreated feeding stations in the field. No effect of the tinctures on the behavior and no repellent effect was found in any of the experiments (for further experimental details see the publication mentioned below).

First try:
It was tested whether materials made from burned possum fur or burnt possum testicles had a repulsive or disruptive effect on a total of three male and three female wild possums. The animals were accustomed to captivity for two months and then kept in two mixed-sex groups of three animals each in two large free-range pens (20 x 60 m). Four weighed portions of fruit and vegetables were placed in each pen 10 m apart. Treatments: A and B, two tinctures supplied by Weleda Ltd. New Zealand; C, a tincture made by a local farmer; D, a tincture provided by the Biodynamic Association; E, a product made by the researchers themselves following detailed instructions from the Biodynamic Association. Sand, wood ash, tap water and water with 5% ethanol served as controls (placebo).

The materials tested were lubricated on and around the chuck. The treatments were randomly distributed to the feeding places during the study period of eight nights. The animals' reaction was observed discreetly and the amount of food not consumed was reweighed. In order to avoid the influence of the observer, the investigation was designed as a double-blind test.

Second try:
Using the same procedure, two tinctures (A and B) were compared with a common herbivore repellent.

Third try:
The biodynamic tincture C was tested on wild possums. 58 baits (feeding tubes filled with 1.2 kg of grain pellets) were laid out in the landscape at a distance of 50 m. The feed tubes were kept filled for three weeks. In half of the feeding places (randomized selection) the soil in a 2 m radius was 50-100 cm 3-6 hours before dusk-3 the tincture or sprayed with the same amount of tap water. The consumption of the bait was evaluated on two consecutive nights.

The daily food intake and the body weight of the possums in the enclosures showed no significant differences on average between the biodynamic and the control variants. No repellant effects or other abnormal behavior were observed from the tinctures. The mean bait intake of the wild possums was not significantly affected by the treatments.

Eason, C.T .; Hickling, G.J. (1992): Evaluation of a bio-dynamic technique for possum pest control. New Zealand Journal of Ecology 16, 141-144

Comment from biodynamic-research.net:

With such experiments, in which the various treatments were set up at a distance of 10 or 50 m, it is very difficult to decide whether the preparations were effective or not. When describing the method, Steiner said: “Its influence radiates far and wide”. However, nobody knows the radius in which this happens, i.e. how far away the control variant must be set up.