Table 1.
Historical accounts.
Fig 1.
Ethnohistorically reported use of animal fats as insect repellents.
Shown are regions within in the Gulf of Mexico that have historically documented use of specific animal fats as repellents. This image was generated using Adobe Illustrator 25.4.1 https://www.adobe.com/products/illustrator.html. The base map was generated by QGIS 3.34.3-Prizren https://qgis.org/en/site/ using raster and physical data from Natural Earth https://www.naturalearthdata.com/downloads/. Note: This map does not represent or intend to represent official or legal boundaries of Indigenous nations.
Fig 2.
Rancidity scores for animal fats used in this study.
1Rancidity scores determined by human olfaction to rank fats on a scale from 1 to 5, with 5 being the most pungent smell. The asterisks denote significant differences between the different samples of each animal fat. (p ≤ 0.05*; p ≤ 0.001***; ns = not significant).
Table 2.
Components of animal fats.
Fig 3.
Setups of the assays used in this study.
a. Arm-in-cage experimental setup. b. Dimensions of the treatment area and visualization of how CPT (complete protection time) was measured for the arm-in-cage experiment. c. Y-tube olfactometer experimental setup. d. Margin measurements of the experimental parameters for the tick skin-crawling assay. e. Tick skin-crawling assay experimental setup.
Fig 4.
GC/MS odorant composition of fats used in this study.
Shown are percentage concentrations for each identified compound, with 0% meaning the compound was not detected. The labels above columns two through nine indicate the different fat types; B1—Bear Fat #1, B2—Bear Fat #2, S1—Shark Oil #1, S2—Shark Oil #2, C1—Cod Oil #1, C2—Cod Oil #2, A1—Alligator Oil #1, A2—Alligator Oil #2.
Table 3.
Composition profiles of animal fats analyzed via GC/MS.
Fig 5.
Results of tick and mosquito repellency and odor categorization of animal fats.
Shown are the odor categorization of each sample (a-d), and the three behavioral assays conducted (e-g). a-d. Radar odorant charts. Odorant categories of each putatively identified compound were weighted based on the summed peak area. Presented in the charts are the relative abundance changes within each odorant category within each fat source and its sensorially more rancid version. Major gridlines represent a 5% change in the summed relative peak abundances of all components contributing to the odorant category in charts A & B and a 10% change in charts C & D. e. Tick-crawling assay results. The complete protection time from I. scapularis tick crossings for each of the different samples tested. The x-axis displays the complete protection time (CPT) in minutes from tick crossing and the y-axis represents the different treatments tested. A Kruskal-Wallis test was conducted to determine the difference between treatments. The resulting significant difference between groups are represented by asterisks (*: p ≤ 0.05 and ***: p ≤ 0.001). f. Arm-in-cage assay experimental results. The complete protection time from A. aegypti mosquito bites was measured for each sample. The x-axis displays the complete protection time (CPT) in minutes and the y-axis represents the different treatments tested. A one-way ANOVA test was used to analyze significance between treatments. Significant differences between groups is indicated with asterisks (*: p ≤ 0.05, ***: p ≤ 0.001 and ****: p ≤ 0.0001). g. Y-tube olfactometer assay results. The average percent attraction of A. aegypti mosquitos to volunteers anointed with different animal fats was measured for each sample. Lower values of % attraction identify a reduction in attraction. The x-axis represents each sample tested, and the y-axis represents percent attraction of mosquitoes to a host treated with a sample or untreated as a control. A one-way ANOVA test was performed to determine the statistical significance of different experimental groups. Significant differences are indicated by asterisks (*: p ≤ 0.05 and ** p ≤ 0.01).
Fig 6.
Correlation analysis for rancidity score and contact and spatial mosquito repellency.
Shown are the correlation analyses for rancidity score and mosquito repellency. Each point represents a treatment. The Pearson correlation coefficient is represented by “r”. a. Correlation analysis for rancidity score and CPT. “AIC” represents Arm-in-cage. The average rancidity score is on the x-axis, and the average complete protection time (CPT) in minutes is on the y-axis. b. Correlation analysis for rancidity score and percent attraction. “YT” represents Y-tube. The average rancidity score is on the x-axis, and the average percent attraction is on the y-axis.