Vol. 59, 2020
Vertebrate Scavengers Control Abundance of Diarrheal-causing Bacteria in Tropical Plantations
Norman T-L Lim1,2,3,*, Douglas A Kelt2, Kelvin KP Lim3, and Henry Bernard4
Institute of Education, Nanyang Technological University. 1 Nanyang
Walk, Singapore 637616, Singapore. *Correspondence: E-mail:
email@example.com (Lim). Tel: +65-67903882. Fax: +65-68969414.
Fish, & Conservation Biology, University of California, Davis. One
Shields Avenue. Davis, CA 95616, USA. E-mail: firstname.lastname@example.org
Kong Chian Natural History Museum, National University of Singapore. 2
Conservatory Drive, Singapore 117377, Singapore. E-mail:
4Institute for Tropical Biology and Conservation,
Universiti Malaysia Sabah. 88400 Jalan UMS, Kota Kinabalu, Sabah,
Malaysia. E-mail: email@example.com
Received 18 May 2020 / Accepted 26 September 2020
Communicated by Benny K.K. Chan
is a common phenomenon, particularly amongst carnivorous vertebrates.
By consuming carrion, vertebrate scavengers reduce resource
availability for both pathogenic bacteria and their insect vectors. We
investigated the ability of wild vertebrate scavengers to control
agents of human diarrheal diseases (specifically Salmonella spp. and Shiga toxin-producing Escherichia coli
[STEC]) at oil palm plantations in Sabah (East Malaysia), and the
existence of spillover effect whereby additional vertebrate scavengers
from adjacent forest patches resulted in greater disease control at
plantation sections near these forest edges. Experimental carcasses
were removed by common scavengers (Varanus salvator, Canis lupus familiaris, and Viverra tangalunga)
at different time points, and this determined the length of time that
carcass persisted in the environment. The amount of pathogenic bacteria
on the surfaces of filth flies collected above the experimental
carcasses was positively correlated to the duration of carcass
persistence, and reduction in pathogenic bacterial abundances was
largely due to carcass consumption by these vertebrate scavengers.
Instead of a predicted positive spillover effect (greater scavenger
activity near forest edges, hence reduced pathogen abundance), we
detected a weak inverse spillover effect where STEC counts were
marginally higher at plantation sections near to forest patches, and we
suspect that human hunting along the forest-plantation boundaries could
be a potential reason. We propose that making oil palm plantations
scavenger-friendly could yield significant human health benefits for
the millions of workers employed in this rapidly-expanding industry,
without drastic changes in current management practices.
Key words: Carcass removal, Filth flies, Salmonella, Shiga toxin-producing E. coli, Spillover effect.
Lim NTL, Kelt DA, Lim KKP, Bernard H. 2020. Vertebrate scavengers
control abundance of diarrheal-causing bacteria in tropical
plantations. Zool Stud 59:0uu. doi:-.