Development of free-living stages of equine strongyles in faeces on pasture in a tropical environment.

The research article focuses on the study of the development and growth of free-living stages of equine strongyles, a type of worm, in horse faeces left on pastures in a tropical environment. The influence of seasonal variations and dung beetle activity on the development and yield of these worms were also evaluated.

Research Methodology

• The research was conducted over a period of two years in a coastal area of tropical north Queensland.
• The faeces of a horse with a mixed natural infection were deposited on pasture plots.
• The research involved two sets of faecal masses; one was exposed to natural dung beetles while the other was protected from them.
• Every month, faecal samples were taken after 7 days of their deposition for larval recovery and count.

Research Findings

• The free-living stages of the worm started developing in the faeces deposited on the pasture throughout the year, regardless of the season.
• The development was quick with the infective stages reached within a week of faecal deposition in all months.
• The yield of infective larvae was affected by both the season and activity of dung beetles.
• The highest yields were obtained in winter (June to August) from faecal masses exposed to, as well as protected from beetles. The lowest yields were recorded in spring (September to November).
• The harsh conditions involving high temperatures in spring and summer led to lower larval yields. Specifically, the dry conditions in spring made it the most unfavorable period for the development of these worms.
• During the cooler autumn and winter months, the temperatures were not low enough to halt or slow down the worm development rate, allowing for the development of a large number of infective larvae.
• Dung beetle activity, observed all year round, usually dispersed exposed faeces within 24 hours of deposition. This led to lower yields of infective larvae as compared to the protected faeces.
• Even with lower yields, the number of larvae was still large enough to question the effectiveness of dung beetles as biological control agents against equine strongylosis in dry tropical climates.

Research Implications

• This research contributes valuable insights to the field of parasitology and equine health management, especially in tropical climates.
• The findings challenge the widely held belief about dung beetles’ effectiveness as a natural control against equine strongyle infestations, calling for more research into other potential control methods.