The impacts of light and light types on nocturnal carrion beetles (Silphidae) including ABB

Rachel M. Anschutz

William J. Allgeier

Daniel G. Snethen

W. Wyatt Hoback

American Burying Beetle History

• Once distributed over 35 U.S. states and three Canadian provinces.

• During the 20th century its range shrank to less than 10% of this distribution.

• The remaining populations are at the peripheries of the former range.

American Burying Beetle History

Artificial Light Impacts

• Artificial light disturbs nocturnal insects’ essential activities which include: migration, dispersal, foraging, mating, and reproduction.

• Light types have different impacts– Usually ultraviolet light is most attractive

while sodium vapor is least attractive.

Hypotheses

• ABB will be most attracted to light that contains high levels of ultraviolet wave lengths.

• Light will impact ABB behavior in responding to carrion resources.

Laboratory Study

• 27 ABB were used once.

• 19 liter buckets connected with P.V.C. pipe.

• 5 types of light used:– Mercury Vapor– Incandescent– Fluorescent – Sodium Vapor– Blacklight

• Controlled for intensity

Laboratory Study

• Conducted between 20:30 and 05:09.• 300 seconds to acclimate.• 600 seconds to choose.• Given two trials.

Laboratory Results

0

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9

Mer

cury

Vap

or

Black

Lig

ht

No Cho

ice

No Lig

ht

Inca

ndes

cent

Fluo

resc

ent

Sodiu

m V

apor

Nu

mb

er o

f A

BB

• A chi-square goodness of fit test indicated that attraction to these light sources is significantly different (Chi-square=13.18, df=6, c.v.=12.59, p<0.05).

Field Study

• Three separate trapping arrays were established

> than 1 km apart from each other.

60 meters

Field Study

• Mercury vapor, ultraviolet, and halogen were alternated between array sites.• 24 nights of sampling.• Generators started 30 minutes before sunset and ran all night.• Traps checked before starting generator and in the morning prior to 0800.

Field Results

• 112 nocturnal beetles were trapped over 24 trap nights. – 32 ABB.

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Light andBait

Light noBait

Bait Only

Trap condition

Perc

ent o

f tot

al c

olle

cted

Nicrophorus americanus

Nicrophorus pustulatus

Nicrophorus orbicollis

Necrodes surinamensis

Field Results

• These results indicate that ABB foraging

behavior may be disrupted by the presence of lights in the environment.

Field Results

• ABB collected most frequently of nocturnally active beetles in lighted traps.– UV was the most

attractive.0

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Num

ber o

f AB

B

• A trend is evident that indicates ABB to be more affected by light than other species of carrion beetles.

Significance

• MV lights have potential to significantly impact ABB.

• Possibly explains why ABB has declined compared to other nocturnally active carrion beetle.

• Reduction of light and alternative lighting types should be used in areas near the known range of ABB.

Acknowledgements

• U.S. Fish and Wildlife Service.

• Nebraska Game and Parks Commission.

Questions?