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Fertility Control for Grey Squirrels : what do the next 5 years look like?
Giovanna Massei National Wildlife Management Centre APHA
RSST, UK Squirrel Accord and Royal Forestry Society Sand Hutton, 19 October 2017
Conflitti uomo-fauna selvatica
Road traffic accidents
Impact on native species
Disease transmission
Livestock predation
Damage to crops, forestry, property
Human-wildlife conflicts are increasing
Methods to mitigate human-wildlife conflicts
poisoning shooting trapping
Lethal methods
fertility control
exclusion
behaviour modification
diversionary feeding
Non-lethal methods
translocation
Novel immuno-contraceptives
GonaCon
Gonadotrophin Releasing Hormone vaccine
“single-dose” injectable vaccines from our US partners
Vaccines inducing antibodies against proteins or hormones essential for reproduction
75-100% animals infertile for 2-8 years
Credible practical applications
BUT animals must be captured
we need an oral contraceptive
Fertility control applications via injectable vaccine
Wild boar: 1 dose GonaCon stopped reproduction in 92% sows for 5-8 years
Feral goats: 1 dose GonaCon reduced fertility by 83-92% for > 4 years
California ground squirrels: 1 dose GonaCon reduced the % of lactating females by 91% (year 1) and 96% (year 2)
Developing and delivering oral contraceptives to
control populations of grey squirrels
The project
5 years 1 M £ 4 research groups: UK x2 France USA
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ar 1
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ar 2
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The project
Test novel contraceptive formulations (lab rats) Design systems to monitor feeding patterns by squirrels (lab + field) Start breeding colony of squirrels
Test contraceptive doses, frequency, bait type (lab rats) Optimise bait uptake by squirrels (field)
Test effectiveness of contraceptive in squirrels (lab) Optimise bait uptake by squirrels in different contexts (urban,rural) Liaise with regulatory authorities to assemble registration package Refine model on integrated methods to reduce squirrel numbers
Pilot trials with contraceptives on squirrel populations Initiate trials for registration package
The APHA team
Project leader
1 statistician
Field studies coordinator
Lab studies coordinator
2 lab technicians 2 modellers
4 field ecologists 2 lab ecologists
Biology, behaviour, population dynamics Oral immuno-contraceptive vaccine targeting GnRH
60% rats fed the contraceptive did not breed
(control rats: 10-30%)
Rats fed the contraceptive in a bait showed reduced response to the
vaccine: fewer rats responded and had lower antibodies to the vaccine
Novel formulation needed for oral vaccine to increase immune response
APHA and collaborators developed
novel GnRH-based oral vaccine
Novel formulation to deliver an oral immuno-contraceptive
Spores and pollen grains
Pollen/spores are natural and renewable
Commercially available
Genetic material removed to obtain sporopollenin exine
capsules (SpECs)
SpECs withstand stomach conditions
Proven effective delivery of drugs such as fats, oils, vitamins, enzymes, hormones, ibuprofen
SpECs for an oral contraceptive vaccine
Proven vaccine delivery in SpECs fed to mice
increased antibodies in mice
antibody response lasted for up to 7 months
SpECs move into mouse gut wall, thus offering :
a possible mechanism for oral vaccination
potential to maintain this response for at least a few months
Proposed work
Identify SpECs species
Trials with laboratory rats to test SpEC-encapsulated oral vaccine
Captive trial repeated on grey squirrels
Field pilot trials to confirm efficacy, % of the population treated
Large-scale trials to monitor effects at population level
Developing an oral contraceptive
Biology, behaviour, population dynamics
For contraceptives that are not target specific
Specificity through delivery
Grey squirrel specific hopper
Target species delivery
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Grey squirrel-specific hopper to deliver baits containing oral contraceptives
Target species delivery
Rhodamine B in whiskers of grey squirrels
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1. Model the effort required to reduce grey squirrel population size via culling, contraception or culling + contraception 2. Identify data to collect to improve the ability of the model to predict the impact of population control on squirrels’ number
Defra study January-March 2017: aims
Defra study January-March 2017: results
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Defra study January-March 2017: results
Culling with different levels of effort
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Defra study January-March 2017: results
Fertility control with different levels of efficacy
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Defra study January-March 2017: results
Culling in Year 1, followed by fertility control with different levels of efficacy
Proven GnRH-based contraception
Candidate oral contraceptive available
Delivery method available
Done
In progre
ss To d
o
Current and future work
Model impact of fertility control on population dynamics
Confirm effectiveness of contraceptives
Test bait uptake by % of grey squirrels
Manage public expectations
Captive and field trials Registration of drugs
Funding Public support Stakeholder engagement
Over-abundant wildlife
Non-native invasive species, incl. feral animals
To complement culling to control populations or
their economic / environmental impact
Where culling is illegal, unfeasible, undesirable
Oral contraceptives scalable to new species and contexts
Scalable applications for oral contraceptives
Oral contraceptives will be an important tool to manage wildlife
Raising public awareness on feasibility, cost, safety, sustainability of different methods will be key to successful management
In summary
