10 - Non-zoonotic disease (bats)

Question 1

Bats make up what % of all mammalian species? Order?

Answer 1

20%
Chiroptera

Question 2

Smallest bat? Largest bat?

Answer 2

Smallest = kitti’s hog-nosed bat (bumblebee bat; 2g)

Largest = giant golden crowed flying fox (5’6” wingspan, fruit bat)

Question 3

Suborders of chiroptera

Answer 3

• megachiroptera (flying foxes): fruit eating
• microchiroptera: echolocating

Question 4

What do most bats eat?

Answer 4

70% are insectivores
Most of rest are fruit eaters

Question 5

How many bat species in Canada

Answer 5

19-21

Question 6

How many species of bats in US/Canada? What are the endangered spp? How many rely on hibernation?

Answer 6

45 species

Gray bat, big-eared bat, indiana bat, etc endangered

25% rely on hibernation

Question 7

Bat lifespan and birth rate

Answer 7

> 20 year lifespan

Slow birth rate (=population recovery very slow)

Question 8

Bat that pollinates agave plan

Answer 8

Mexican long-tongued bat

Nectar eater
Get tequila from distillation of juices from agave

Question 9

Association between long-nosed bats and agave

Answer 9

Bat-plant association is so strong, the disappearance of one would threaten the survival of the other

Question 10

Indirect effects of bats on one health

Answer 10

• pest control (echolocators)
• pollination

Question 11

What is durian

Answer 11

One of the most important fruits of SE asia
Export value: 254 million USD

Pollinated primarily by bats

Question 12

How do bats affect corn crops?

Answer 12

Important for predation of insects

Structures are inserted into corn fields and a net is put over corn plots in the evening and taken down during the day
Found that bat prey (insects) had a large impact on corn (more larva, damaged kernels)

Question 13

How many insects are consumed by a colony of big brown bats in a year? How many by a little brown bat in a night?

Answer 13

1.5 million insects a year

4-8 g of insects each night

Question 14

Value of bats per acre? To the US agriculture industry per year?

Answer 14

$12-$173/acre value in pest suppression

~22.9 billion/year value to US ag industry

Includes reduced cost of pesticide applications that are not needed

Question 15

What is white-nosed syndrome? Caused by…

Answer 15

Emerging infectious disease
Affects hibernating cave-dwelling bats throughout NA

Caused by fungus (Pseudogymnoascus destructans)

Question 16

Where did WNS emerge in NA?

Answer 16

New York state in 2006

Winter of 2006-07: ~10,000 bats dead and dying in four caves

Question 17

Slides 25, 26

Answer 17

Spread in NA

Question 18

Mortality with WNS? Spread in NA?

Answer 18

> 6 million bats in NA dead (likely higher)

Spread to 43 US states and 10 provinces

Question 19

Different ways bats are affected by WNS

Answer 19

• 12 bat species get skin lesions (white fungus on muzzle and/or wings)
• 9 species DNA (pathogen identified by DNA tests, mortality less likely to be discovered)

Question 20

Three species that have declined >90% bc of WNS

Answer 20

Northern long-eared bat
Little brown bat (Myotis lucifigus)
Tricolored bat

Question 21

Signs of WNS

Answer 21

• white fungus on bats body
• flying outside during day in very cold temperatures (animals are starving; fungus uses up energy reserves)
• bats clustered near the entrance of hibernacula
• dead or dying bats on the ground, on buildings, trees during winter months

Question 22

P. destructans infection? Temperature growth range? Bat body temp?

Answer 22

Fungal infectious of skin (bat wing) (not systemic)

Growth range: 4-20C
Optimal growth 12-16C

Active bats: 37-40C body temp
Hibernating bats: 1-16C (in optimal range)

Question 23

Why is WNS only found in hibernating bats (not migrating)

Answer 23

Hibernating bats body temps drop into optimal growth range (12-16C) for P. destructans

Question 24

How does bat hibernation work in infected vs uninfected bats?

Answer 24

Torpor (decreased physical activity / decreased physiological activity)

Uninfected bats: bouts of torpor last from days-> weeks (brief <3h arousals)

Infected bats: increased arousal episodes, increased fat depletion

Question 25

Why was P. destructans being the cause of WNS initially controversial?

Answer 25

- fungal infections in mammals typically a response to immune dysfunction - P destructans present in bat pops in EU with no evident bat mortality

Question 26

How did they prove WNS was caused by P destructans?

Answer 26

Exposure of healthy little brown bats to pure cultures of P destructans causes WNS Live P destructans was subsequently cultured from diseased bats Koch's postulates = P destructans is primary pathogen

Question 27

2 hypotheses of EU vs NA WNS

Answer 27

1. WNS historically present in Europe - european bats adapted to the disease - accidentally transported to NA (tourist cave) 2. P. destructans variant in NA?

Question 28

P destructans global origin? How

Answer 28

Western EU EU and NA strains both cause disease when experimentally inoculated in North American bat (same pathogen)

Question 29

Slides 45, 47

Answer 29

Look

Question 30

Colony numbers of the little brown bat are declining, however...

Answer 30

- 12 banded bats with WNS survived over multiple years - 14/20 recaptured bats had healed wing damage

Question 31

What is happening in persisting bat populations?

Answer 31

- over winter mortality declining (~80% -> ~50%) - 2x increase in torpor bout length (increase in body fat)

Question 32

Treatments for WNS

Answer 32

- vaccine in development - antifungal experiments

Question 33

How can temperature affect P. destructans growth

Answer 33

- grows more slowly at temperatures lower than optimal range (colder hibernacula: 3-6C) - low humidity associated w reduced growth

Question 34

How can we cool bat hibernacula

Answer 34

One-time engineering of entrances (sealing main entrance, side entrances used by bats) - cools on average 2.1C - populations increased over time - cool warm sties that were not being used by bats

Question 35

How do wind turbines affect bats? Fatalities?

Answer 35

Tree-dwelling, migratory bat species are susceptible to wind turbines 600,000-900,000 annual bat fatalities

Question 36

Wind turbine collision is linked to...

Answer 36

blade movement

Question 37

How are hoary bats at risk bc of wind turbines

Answer 37

- 2.5 million of them in Canada - estimated 2.3% mortality annually for next 15 years - migratory (US and Canada wind turbines) - 11.5% decline in 15 years

Question 38

Direct means of bat deaths by wind turbines

Answer 38

- collision with blades - barotrauma (drop in air pressure at the turbines, bats become disoriented)

Question 39

Conclusion on barotrauma from a recent paper...

Answer 39

Barotrauma not the cause of bat fatalities Pressure changes that occur in proximity to moving blades affect is low

Question 40

Five hypotheses of why bats are attracted to wind turbines

Answer 40

- attracted to the noise - increased prey availability - wind turbines as roost sites - rendezvous point to mating aggregations - olfaction Slide 66**

Question 41

Most likely hypothesis on why bats are attracted to turbines

Answer 41

Wind turbines as potential roost sites (migratory bats attracted to tall structures)

Question 42

How can we mitigate bat mortality

Answer 42

- most fatalities occur in low-wind conditions (less activity in high) - raising "cut in" speed (wind speed at which turbines produce electricity/ blade movement occurs) - mortality reductions of >44%

Question 43

Bat fatality reduction when turbines not operating with mean wind speeds of...

Answer 43

reduced 82 to 85% if not operating with mean wind speeds of less than 6 m/sec