## 1 Introduction  
The invasive polyphagous pest _Drosophila suzukii_ (Matsumura) (Diptera: Drosophila), also known as spotted wing drosophila (SWD), spread from its native distribution in eastern and southeastern Asia [1] and emerged as a critical invasive insect pest of wild and domesticated berries and stone fruits in the Americas and Europe in the late 2000s [2]. Human activities facilitated SWD colonization, particularly the movement and export of infested fruits, climatic conditions similar to the pest native range [3], and the low effectiveness of natural enemies [4]. Insect feeding damages occur without an apparent external symptom until fruits are nearly fully mature. In most cases, the serrated ovipositor of female SWD allows it to lay eggs in ripening, and ripe intact soft-skinned fruits, particularly strawberries, raspberries, blueberries, and sweet cherries; in this regard, SWD has a wide range of hosts [5; 6]. Several authors have also indicated sweet cherry as a high-risk host for SWD because it bears fruit when few alternative host fruits are available [7; 8]. Once the fruit is infested, the internal larval feeding causes direct damage, making the fruit unmarketable and unsuitable for consumption and processing industries. In addition, oviposition exposes fruit to secondary infection by providing access to pathogens, including fungi, yeasts, and bacteria [9; 10]. Consequently, the infested fruits become soft and rot rapidly after harvest, resulting in reduced yields and significant economic losses [11; 12; 13]. The insect damages mainly occur inside the fruits without any visual symptoms during the larval stage. For this reason, it is difficult to detect and remove these fruits in packing houses and processing lines; the low-quality fruits enter the storage and cause damage to the surrounding healthy ones. Therefore, any method of early detection of the infestation is welcomed as it can improve productivity [14; 15]. Countries allocate considerable resources to limit the spread and control of transboundary pests, also adapting plant health services and activities and cooperating regionally and globally for prevention, early warning, and control. As zero-tolerance regulations make the shipment unmarketable for just a few infested cherries [13], the early identification of the infestation before the shipment is essential. However, most of the current monitoring methods rely on visual inspection; these traditional sorting techniques are laborious, time-consuming, subjective, and inadequate for detecting and removing cherry fruits with hidden internal damages [16]. Consequently, non-destructive detection methods for insect infestation of agricultural commodities have emerged, including spectroscopic methods [17; 18]. Commercial spectrometers usually have variable ranges: visible/shortwave near-infrared (Vis/SWNIR), near-infrared (NIR), or visible/near-infrared (Vis/NIR), using wavelengths between 350-1100 (Vis/SWNIR), 780-2500 nm (NIR), or 350-2500 nm (Vis/NIR), respectively. Spectroscopy is widely accepted as a non-destructive technique for qualitative and quantitative analyses in the agriculture industry, especially for the assessment of the quality of fruits [19; 20; 21; 22; 23; 24; 25]. This technology is environmentally friendly, safe, and cost-effective. In addition, as spectroscopic techniques normally require no sample preparation, they can be used for on/in-line inspection [26; 27] and have been investigated for non-destructive detection of internal insect infestation in fruits like sour cherries, wild blueberries, jujube, olive, and pomeranate [28]. [PERSON] et al. tested three NIR instruments to classify fruit fly larvae damage in wild blueberries, achieving an infestation detection rate between 58% and 82% [29]. [PERSON] et al. employed a genetic algorithm (GA) to select the most suitable spectral bands for detecting internal insect infestation in sour cherries [30]. [PERSON] et al.