Geminisem 500 microscope

Scanning electron microscopy (SEM) measurements were executed by using Gemini SEM 500 microscope (Carl Zeiss, Munich, Germany). The Raman spectroscopy were obtained by laser Raman spectrometer with excitation at 632 nm. The PL spectrum was performed using Edinburgh FLS9 (LongRun, Xi’an, China) with excitation at 325 nm. Moreover, the UV-Vis-NIR visible spectrum was measured by PE Lambda950 (Cernet, Beijing, China) at a wavelength of 697.5 nm and experiments were set up by photocatalysis system CEL-SPH2N (AuLight, Beijing, China). The surface resistance was obtained by an Agilent B1505A power device analyzer (Agilent Technologies, Santa Clara, CA, USA).

Flies were placed in 70% ethanol and sonicated for 5 minutes to remove surface wax from the cuticle. Heads were carefully excised, dehydrated in 100% ethanol, dried in a critical-point drier (CPD7501, Quorum), mounted on aluminum stubs with argent glue, and oriented so that the external side of the funiculus was exposed. Three specimens per species were coated with platinum (7 nm thickness; EM ACE600, Leica, Germany) and examined with a GeminiSEM 500 microscope (Zeiss, Germany). Olfactory sensilla on the surface of the external side of the funiculus were counted, localized, and assigned to the four main morphological classes (trichoid, basiconic, clavate, and coeloconic sensilla). The number of coeloconic sensilla is probably underestimated since some of these small sensilla may have been hidden. To generate sensilla density maps, antenna length (from the arista to the tip) and width were normalized. Sensilla density maps were computed with convolving spatial positions of sensilla with a 2D-Gaussian Kernel of standard deviation equal to 2% of funiculus length and 5% of funiculus width. The sensilla dominance index was defined as (D_b + D_c − D_t)/(D_b + D_c + D_t) with D_b, D_c, and D_t being the average density of basiconic, clavate, and trichoid sensilla, respectively, along the proximo-distal axis.