Chagas disease vector control and Taylor's law

Abstract

BackgroundLarge spatial and temporal fluctuations in the population density of living organisms have profound consequences for biodiversity conservation, food production, pest control and disease control, especially vector-borne disease control. Chagas disease vector control based on insecticide spraying could benefit from improved concepts and methods to deal with spatial variations in vector population density.Methodology/Principal findingsWe show that Taylor's law (TL) of fluctuation scaling describes accurately the mean and variance over space of relative abundance, by habitat, of four insect vectors of Chagas disease (Triatoma infestans, Triatoma guasayana, Triatoma garciabesi and Triatoma sordida) in 33,908 searches of people's dwellings and associated habitats in 79 field surveys in four districts in the Argentine Chaco region, before and after insecticide spraying. As TL predicts, the logarithm of the sample variance of bug relative abundance closely approximates a linear function of the logarithm of the sample mean of abundance in different habitats. Slopes of TL indicate spatial aggregation or variation in habitat suitability. Predictions of new mathematical models of the effect of vector control measures on TL agree overall with field data before and after community-wide spraying of insecticide.Conclusions/SignificanceA spatial Taylor's law identifies key habitats with high average infestation and spatially highly variable infestation, providing a new instrument for the control and elimination of the vectors of a major human disease.

High levels of human infection with Trypanosoma cruzi associated with the domestic density of infected vectors and hosts in a rural area of northeastern Argentina

“…A detailed georeferenced database of triatomine occurrence over the follow-up was built. Domestic infestations remained below 5% during the follow-up [ 25 ], and infested domiciles exhibited very low bug abundances [ 28 ].…”

Improved detection of house infestations with triatomines using sticky traps: a paired-comparison trial in the Argentine Chaco

“…In the absence of a vaccine against the etiological agent of the disease, Trypanosoma cruzi, prevention of vectorborne transmission mainly relies on the detection of house infestations with triatomine bugs followed by residual insecticide spraying of domestic and peridomestic habitats [2][3][4][5]. The success of triatomine control efforts is threatened by the frequent occurrence of persistent peridomestic foci [6][7][8][9]; the emergence of resistance to pyrethroid insecticides [10], and/or house invasion of triatomines from sylvatic sources [11][12][13][14].…”

Yeast facilitates the multiplication of Drosophila bacterial symbionts but has no effect on the form or parameters of Taylor’s law

“…Many other variants of TL exist. TL holds in populations of various organisms [ 8 ] including bacteria [ 9 , 10 ] and can be of interest to address questions and resolve issues in conservation biology [ 11 ], epidemiology [ 12 , 13 ], human demography [ 14 , 15 ], fisheries [ 16 ], forestry [ 17 ], and crop protection [ 18 ]. Whether the relationship between population means and variances follows TL, and TL’s parameters when TL holds, can shed limited light on the demographic processes in the populations studied [ 8 , 19 ].…”