Fig. 6.

Larval navigation. (A) Paradigm containing a 22-cm × 22-cm square agarose Petri plate. Odorant is placed on discs at the right; paraffin oil diluent alone is placed on discs to the left. The chamber is sealed by placing a clear glass plate over the arena. Third-instar larvae are placed along the central y axis parallel to the line of odor discs. Movement of larvae is recorded with a CCD camera. (B and C) Trajectories of WT (B) and Orco (C) larvae in response to ethyl acetate, neat. Gray bars along the y axis indicate starting positions of larvae (n = 84 tracks were analyzed for CS WT in six assays; n = 81 tracks in six assays for Orco). (D) navigational indices of indicated genotypes to ethyl acetate (ea) and paraffin oil. (E) Relative probabilities of orientations along the trajectories of WT (black) and Orco (green). Directions refer to those illustrated in A. The probability indicated for each angle θ is the sum of the probabilities for θ and −θ. (F) Trajectories of WT larvae to acetal (F) and 2,5-dimethylpyrazine (G), both neat (n = 111 tracks for acetal in eight assays; n = 110 tracks for 2,5-dimethylpyrazine in eight assays). (H) Navigational indices of WT to acetal and 2,5-dimethylpyrazine. (I) Relative probabilities of orientation. (J and K) Trajectories of WT and Or42a; odorant is 4-hexen-3-one, diluted 10⁻² in paraffin oil (n = 68 tracks in six assays for WT; n = 43 tracks in six assays for Or42a). (L) Navigational indices of indicated genotypes to 4-hexen-3-one. (M) Relative probabilities of orientation of WT and Or42a; odorant is 4-hexen-3-one.