Delivering and developing oral contraceptives for grey squirrels

Delivering and developing oral contraceptives for grey squirrels G. Massei, J. Lane, S. Beatham, R. Pinkham, K. Rickell, M. Gomm National Wildlife Management Centre APHA Royal Forestry Society meeting, National Memorial Arboretum 30 October 2018

Human-wildlife conflicts are increasing q Damage to crops, forestry, property q Disease transmission q Impact on native species q Road traffic accidents q Livestock predation

Grey vs. red squirrel 3

Impact of grey squirrels v Conservation of native species v Impact on forestry through bark stripping (£ 10 million per year) v affects tree growth and timber value v may cause death of tree, hence costs of restocking v increases the susceptibility of trees to various pathogens 36 species of UK trees are damaged by grey squirrels: beech, sycamore, oak, ash, maple, sweet chestnut, etc. Reduce grey squirrel number to decrease impact on forestry Control for 12 yrs in a beech woodland decrease % of squirrel damage from 50% to 8% of trees 4

Public attitudes Acceptability of grey squirrel control (n=3758) Planting trees Contraception Kill traps Shooting Live capture (+ kill) Biol. control (pine marten) Warfarin poisoning 0% 20% 40% 60% 80% 100% Blue + Red: very acceptable or acceptable

Novel immuno-contraceptives q Vaccines inducing antibodies against proteins or hormones essential for reproduction “single-dose” injectable vaccines from our US partners Gona. Con Gonadotrophin Releasing Hormone vaccine 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 contraceptives Wild boar: 1 dose Gona. Con stopped reproduction in 92% sows for 5 -8 years Feral goats: 1 dose Gona. Con reduced fertility by 83 -92% for > 4 years California ground squirrels: 1 dose Gona. Con reduced the reproduction by 91% (year 1) and 96% (year 2)

Oral immuno-contraceptive vaccine targeting Gn. RH Biology, behaviour, population dynamics APHA & collaborators developed a novel Gn. RH-based oral vaccine v 60% rats fed the contraceptive did not breed (control rats: 10 -30%) v Contraceptive fed in a bait : reduced response to the vaccine Novel formulation to increase effect of oral vaccine

Novel formulation to deliver an oral contraceptives Spores and pollen grains ü Pollen/spores: natural, renewable, commercially available ü Genetic material removed to obtain sporopollenin exine capsules (SPECs) üProven effective delivery of drugs such as fats, oils, vitamins, enzymes, hormones, ibuprofen

Sp. ECs 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 üa possible mechanism for oral vaccination

Developing and delivering oral contraceptives to control populations of grey squirrels Year 1 Identify SPECs species Lab trials with rats to test SPEC-encapsulated oral vaccine Field pilot trials with squirrels to confirm efficacy Year 5 Large-scale trials to monitor effects at population level Initiate trials for registration package Year 3+ 4 Lab trials with grey squirrels Optimise bait uptake by squirrels Year 2 Monitor bait uptake by squirrels (lab + field) 11

The project team Project leader Field studies coordinator 4 field ecologists 1 statistician Lab studies coordinator 2 lab ecologists 2 modellers 2 lab technicians Two teams in USA and France

Year 1 results: testing oral vaccine in model species Tested SPECs of sunflower and club moss fed to rats 60% (n=12 of 20) had antibodies to oral vaccine but not sufficient to cause infertility 100% rats (n= 19) had antibodies to the injected vaccine with 95% sufficient to cause infertility More work in Year 2 on formulation of oral vaccine

Year 1 results: delivering contraceptives to grey squirrels Developed grey squirrel-specific hopper to: ü deliver baits that will contain oral contraceptives ü monitor patterns of bait uptake by individual squirrels Tested Rhodamine B (RB) to: ü monitor bait uptake in the population Pilot trial 51 grey squirrels trapped in 2 woods, PIT-tagged, released 48 bait hoppers with PIT-tag readers deployed

Year 1 results: delivering contraceptives to grey squirrels Bait hoppers Established how often squirrels visit hoppers > 93% PIT-tagged squirrels entered >1 hopper at least once in 4 days Rhodamine B After 4 days of RB-treated baits > 56% squirrels had RB bands in hairs

Year 1 results integrated with Defra study Model the effort required to eradicate grey squirrels via culling, contraception or culling + contraception

Year 1 results integrated with Defra study Culling with different levels of effort

Year 1 results integrated with Defra study Culling in Year 1, followed by fertility control with different levels of efficacy

Highlights of Year 1 ü ü A method, based on SPECs, to encapsulate an oral vaccine Induced an immune response to an oral contraceptive vaccine A food hopper to monitor bait uptake patterns by individuals A bait marker (RB) to quantify the % of grey squirrels feeding on baits that will contain oral contraceptives ü Established captive colony of grey squirrels to test contraceptives

Scalable applications for oral contraceptives Oral contraceptives scalable to new species and contexts Non-native invasive species, incl. feral animals Over-abundant wildlife Where culling is illegal, unfeasible, undesirable To complement culling to control populations or their economic / environmental impact

Non-lethal control : when? When lethal control is: § illegal § unacceptable § unfeasible § unsustainable § environmentally hazardous § ineffective BUT also complementary to lethal control

What next… Integrated Pest Management Fertility control We have had spring traps for many years but we did not solve the problem • Sustained control over long period • Less staff intensive • More publicly acceptable

With thanks to… …the squirrel team! Questions? giovanna. massei@apha. gsi. gov. uk