AbstractStable flies are important hematophagous ectoparasites due to their broad range of mammalian hosts and world-wide distribution. As a result of their interrupted feeding behaviour, stable fly biting can result in a suite of direct and indirect adverse effects for their hosts. When densities are high, stable fly control is important particularly in dairy and beef cattle systems, on economic and welfare grounds. However, recently, the negative environmental and health consequences associated with exposure to conventional synthetic insecticides have become evident as well as the increasing development of resistance. Consequently, there is a need for an environmentally sustainable and effective alternative mechanism for stable fly control to be identified. The work set out in this thesis aimed to evaluate the efficacy of essential oils as insecticides and repellents for stable flies.
A semi-quantitative literature analysis of essential oils against biting flies suggested that lavender and tea tree oils were likely to be effective and hence these oils were chosen for investigation against stable flies. Using laboratory bioassays using laboratory bioassays in the stable fly, Stomoxys calcitrans, 5% (v/v) lavender and tea tree essential oils with ethanol excipient, caused 100% mortality for 4 and 6 h after exposure, respectively. In repellency bioassays, 5% (v/v) lavender and tea tree oils were able to deter 83.3% and 90% of stable flies from crossing an impregnated filter paper funnel for 1 h, respectively. The repellency of these essential oils was greater than that of a commercial repellent (20% DEET) which repelled 63.3% of flies for 1 h. The effectiveness of these oils in vitro, suggests that future work should focus on examining their potential in vivo. If effective in the field, these oils pose as viable alternatives to conventional synthetic treatments used in high value animal husbandry, particularly if issues associated with their cost and limited residual activity can be overcome.
|Date of Award||26 Nov 2020|
|Supervisor||Richard L Wall (Supervisor) & Andy M Bailey (Supervisor)|