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. Author manuscript; available in PMC: 2020 Apr 9.
Published in final edited form as: Curr Biol. 2019 Dec 12;30(1):127–134.e5. doi: 10.1016/j.cub.2019.11.002

Figure 1. Geosmin Mediates Egg Laying Selection in Aedes aegypti.

Figure 1.

(A) Geosmin has, to the human nose, the distinct smell of wet soil and is produced by a wide range of micro-organisms, both terrestrial and aquatic. Photo: M. Stensmyr

(B) Plastic trays lined with filter paper used in oviposition experiments. On top, water with geosmin added is shown; on the bottom, water only control is shown. In the inset, close-up of a cluster of Aedes eggs in the geosmin-containing tray is shown.

(C) Oviposition indices (OI) of wild-type (WT) (20 mosquitoes per trial; n = 6) and Orco5 mosquitoes (20 mosquitoes per trial; n = 6 trials) from a binary-choice test between water and water spiked with geosmin. Total number of eggs is as follows: WT 4,036, Orco5 582; WT geosmin 593 ± 143 eggs, control 191 ± 58; Orco5 geosmin 167 ± 37, control 124 ± 23 (mean ± SEM). The edges of the boxes are the first and third quartiles, thick lines mark the medians, and whiskers represent data range. Preference was tested with one-sample Wilcoxon test, theoretical mean 0. Star denotes significantly different from 0; p < 0.05.

(D) Feeding indices (FIs) from a CAFE assay of WT (n = 10) and Orco5 mosquitoes (n = 10) given a choice to feed from two capillaries with sucrose water (10%), one of which in addition containing geosmin (10−1, 10−3, or 10−5). Boxplots and statistics as per (C) are shown.

(E) Probing index (PI) from WT mosquitoes (20 mosquitoes per trial; n = 5) in a constrained contact assay over 6 min, provided with a choice to approach and probe two hands (from the same individual), one of which scented with geosmin (10−1, 10−3, or 10−5). Shaded line indicates SEM. Statistics as per (C) are shown.

(F) Schematic of the larval behavioral assay. Dashed lines denote the two zones in which time spent was measured.

(G) Sample tracks of WT larvae with antennae (above) and with antennae removed (below).

(H) Response indices of WT larvae with antennae (n = 44), without antennae (n = 33), and Orco5 mutants (n = 30) toward geosmin (10−5). Boxplots and statistics as per (C) are shown.