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by Cindy Edward and Ary Hoffmann
June 2007
RIRDC Publication No 07/090 RIRDC Project No UM-71A
Who is the report targeted
at?
This report represents a
user friendly strategy targeted at recreational horse owners, stud managers,
riding instruction establishments, equestrian clubs and environmental groups
such as Landcare. Data from this report shows a need for further research
on equine parasitology and pasture pest management.
Background
The dependence on insecticides
to control pests in agriculture became very prevalent after the Second
World War as new effective chemicals were developed. The ability to “clean
up” pest problems in agriculture with chemicals such as DDT (Dichlorodiphenyltrichloroethane)
was thought to be the answer to numerous pest problems. The development
of resistance to chemicals, contamination of the environment and food products,
and recognition of secondary pests has required a reduction in pesticide
use and development of sustainable methods of pest control. The use of
natural enemies is a main control component of alternative strategies.
A prime goal of an Integrated Pest Management (IPM) program is to maximize
the impact of these enemy organisms (van Emden 1982).
Aims/Objectives
This study aims to develop
an alternative strategy to current equine parasite management that will
aid and maintain environmentally sustainable horse farms. The lifecycle
of horse parasites involves a ground dwelling stage that is vulnerable
to native and exotic predators.
The intention is to develop a biological control program that identifies native ground dwelling predators that can break the lifecycle of horse parasites. Predator lifecycles will be studied in relation to the effects of various horse wormers. Exotic dung beetles will also be established on horse farms to help aerate and fertilise pastures, increase water absorbency and reduce fecal run-off into farm and community water supplies.
The biological control program will:
Methods used
The data presented in this
report was obtained from ten horse farms which had different worming programs,
ranging from drenching continually to drenching annually. The data was
collected for two years from August 2004 – July 2006. The data collected
from each trial site included studies of invertebrates from pitfall traps
and invertebrates from dung.
Exotic dung beetles were commercially purchased and released at six sites. The winter active dung beetle Bubus bison was released in July 2004 at six sites and the summer active dung beetle Onthophagus binodis was released at the same six sites in November 2004. These beetles were not present before the releases. Although these beetles take years to establish it was evident that certain horse management practices would influence the establishment of the beetles such as continual use of ivermectin and encouraging bird activity in dung.
Fecal egg counts were taken by collecting fresh dung from the trial paddocks. Fecal egg counts were done monthly using the McMaster Technique (Bowman et al. 2003). Paddock management was recorded fortnightly for the number of horses, new horses, drenching time and chemical used per trial site. Management records showed that horse owners are rotating chemical brands and not actives when drenching.
Results/Key findings
There was no influence of
chemicals used for drenching horses on ground dwelling invertebrates. Direct
search of dung indicated that birds scattering the dung had a detrimental
effect on the establishment of dung beetles. However, birds scattering
dung caused the dung to desiccate, destroying the moist habitat that parasites
require, leading to a reduction of parasite burden and quicker breakdown
of the dung. Other invertebrates that live in dung had a composting effect,
enabling faster breakdown of horse dung. Invertebrates in the dung were
affected by drenching chemicals although bird activity was a significant
variable. Seasonal gaps in beetle activity were evident enabling drenching
chemicals to be used with a reduced risk of dung beetle mortality.
Exotic dung beetles were commercially purchased and released. Although beetles take years to establish it was evident that certain horse management practices were likely to negatively influence the establishment of the beetles such as continual use of ivermectin and encouraging bird activity in dung. Establishment of dung beetles, especially winter active beetles, should be encouraged on the horse farm.
Fecal egg counts were taken by collecting fresh dung from the trial paddocks. Resistance in worms to ivermectin was found for the first time in horses. Resistance should be a major concern for the horse owner.
Paddock management was recorded fortnightly in terms of the number of horses in a paddock, new horses introduced to a paddock, drenching time and chemical usage.
Management records showed that horse owners are rotating chemical brands but not active constituents when drenching. This is a major concern for the development of resistance in worms especially with respect to resistance to ivermectin. Cultural practices such as harrowing, removal of dung and paddock rotation should prove to be a valuable component of horse parasite management.
Implications for relevant
stakeholders
This project has highlighted
limitations of current parasite control strategies in the horse industry.
Parasitology should be a priority for further research as new technology
and environmental direction is sought. Stud managers, recreational riders
and other workers on horse farms would benefit from new technology as suggested
in the recommendations.
Workshops, media articles, talks and collaboration with community and Landcare groups represent channels to provide the industry with relevant information. There is a need for inexpensive fecal egg counts and commercial dung beetle supplies to ensure adoption of sustainable control strategies.
We have developed an IPM strategy that has the potential to:
The guidelines developed
here should lead to more environmentally friendly and ecologically sustainable
horse farms.
Recommendations
The following recommendations
were made:
Rotating pastures for
horses is a valuable component of parasite management.
