The information contained in the samples of these recordings will provide complementary information and precise quantification of size on the difficult task of discerning morphologically similar insects whose wingbeat spectrum may overlap significantly in the frequency domain. The sensor aims to extract complementary information from the microstructural and melanization features of the wing and coloration of the main body of the species. In this work, we elaborate on this finding and the new accomplishments are that we expand to a multispectral sensor configuration that integrates recordings from multiple orientations. In Reference, we have demonstrated that a backscattered light signal originating from an insect is better that the extinction light provided by the same wingbeat event in terms of signal to noise ratio (SNR) and number of harmonics standing out of the noise floor. In such cases, we rely on the wingbeat of the incoming insect and the analysis of its frequency content to classify sex and/or species identity. There are other cases, however, where there are no widely accepted pheromones that attract both sexes (entomologists are especially interested in female counts) therefore, a general food bait is used (i.e., in the case of some fruit flies or sent in the cases of mosquitoes). For these applications, we recommend a simple optical counter based on the extinction light. We present all the necessary details to reproduce the device and we analyze many insects of interest like the bee Apis mellifera, the wasp Polistes gallicus, and some insects whose wingbeating characteristics are pending in the current literature, like Drosophila suzukii and Zaprionus, another member of the drosophilidae family.Ĭases (a) and (c) are simple in the sense that they count insects that pass through specific constrictions and quantify their size based on the measured optical intensity variation between an emitter and a receiver. In this work, we present a different kind of wingbeat sensor and its associated recorder that aims to extract a deeper representational signal of the wingbeat event and color characterization of the main body of the insect, namely: a) we record the backscattered light that is richer in harmonics than the extinction light, b) we use three different spectral bands, i.e., a multispectral approach that aims to grasp the melanization and microstructural and color features of the wing and body of the insects, and c) we average at the receiver’s level the backscattered signal from many LEDs that illuminate the wingbeating insect from multiple orientations and thus offer a smoother and more complete signal than one based on a single snapshot. In this type of recording devices, the emitter uses light and is placed opposite to the receiver, which is usually a single (or multiple) photodiode. Most reported optical recorders of the wingbeat of insects are based on the so-called extinction light, which is the variation of light in the receiver due to the cast shadow of the insect’s wings and main body.
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