Conclusions

1
Investigating the residual toxicity of lavender
essential oils as acaricides against the poultry
red mite (Dermanyssus gallinae)
Callaghan, K. 1,2, George, D.R. 1, Guy, J.H. 1,
Sparagano, O.A.E. 1. 1 School of Agriculture,
Food Rural Development, 2 School of Medical
Sciences, Newcastle University, Newcastle upon
Tyne, NE1 7RU, UK (Olivier.sparagano_at_ncl.ac.uk)
Use of synthetic acaricides is hampered by issues
of pest resistance product withdrawals
Plant essential oils contain chemicals toxic to
pests, such as linalool from lavender
More research is therefore needed to assess the
potential of plant essential oils as acaricides
Lavender
Plant essential oils have been investigated as
control products for poultry red mite
Essential oils may be highly volatile. Any
acaricidal effect might therefore be short-lived
Results
Aim ? Lavender essential oils are toxic to
poultry red mite (Dermanyssus gallinae) may
thus offer an alternative to synthetic acaricides
for managing this pest. ? The aim of the current
work was to investigate the residual toxicity of
lavender essential oils to the poultry red mite
to allow further comment on the potential of
these products as acaricides. Methods ? 25
poultry red mite were placed in Petri dishes with
a filter paper impregnated with 0.21 mg/cm² of
essential oil from one of the selected six types
of lavender. ? These filter papers had been
placed in a fume cupboard for either 3 mins or 24
hrs after impregnation. Eight replicates were
done for each treatment. ? Mites were left in
dishes at 22C for 24 hours, after which they
were checked for mortality. ? Mortality was
corrected (to account for control mortality)
differences in percentage mortality between
treatments was assessed for each lavender type
(see Figure 1).
Figure 1. Mean percentage mortality rate of
Dermanyssus gallinae, when exposed to filter
papers 3 mins 24 hrs after being impregnated
with six different lavender essential oils. Stars
represent significant differences in mite
mortality between different treatments using the
same oil, where P lt 0.001. Means 95
confidence limits have been back-transformed from
arcsin square root transformed data used in
ANOVA. Lavender 1 Lavandula angustifolia,
origin Australia. Lavenders 2 and 3 Lavandula
angustifolia, origin France (different regions).
Lavender 4 Lavandula angustifolia, origin
Croatia. Lavender 5 Lavandula officinalis,
origin France. Lavender 6 Lavandula dentata,
origin France.
24 hr
Conclusions ? When exposed to filter papers 3
mins after they had been impregnated with
lavender essential oil, 66 - 90 poultry red
mite mortality occurred within 24 hrs. This
suggests that lavender essential oils may hold
promise as acaricides for managing this pest. ?
If impregnated filter papers were left for 24 hrs
prior to use, mortality rates fell to 11 or
less, suggesting that if used as acaricides, the
residual toxicity of these products is likely to
be short-lived
Poultry red mite, Dermanyssus gallinae
Acknowledgements This work was partially
funded by Defra (UK) via Newcastle Universitys
MITEeHEN Project
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