Format

Send to

Choose Destination
Parasitology. 2012 Jun;139(7):847-63. doi: 10.1017/S0031182012000200. Epub 2012 Feb 16.

Pangloss revisited: a critique of the dilution effect and the biodiversity-buffers-disease paradigm.

Author information

1
Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK. sarah.randolph@zoo.ox.ac.uk

Abstract

The twin concepts of zooprophylaxis and the dilution effect originated with vector-borne diseases (malaria), were driven forward by studies on Lyme borreliosis and have now developed into the mantra "biodiversity protects against disease". The basic idea is that by diluting the assemblage of transmission-competent hosts with non-competent hosts, the probability of vectors feeding on transmission-competent hosts is reduced and so the abundance of infected vectors is lowered. The same principle has recently been applied to other infectious disease systems--tick-borne, insect-borne, indirectly transmitted via intermediate hosts, directly transmitted. It is claimed that the presence of extra species of various sorts, acting through a variety of distinct mechanisms, causes the prevalence of infectious agents to decrease. Examination of the theoretical and empirical evidence for this hypothesis reveals that it applies only in certain circumstances even amongst tick-borne diseases, and even less often if considering the correct metric--abundance rather than prevalence of infected vectors. Whether dilution or amplification occurs depends more on specific community composition than on biodiversity per se. We warn against raising a straw man, an untenable argument easily dismantled and dismissed. The intrinsic value of protecting biodiversity and ecosystem function outweighs this questionable utilitarian justification.

PMID:
22336330
DOI:
10.1017/S0031182012000200
[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Cambridge University Press
Loading ...
Support Center