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The use of insect-based protein sources in aquaculture is gaining increasing attention with Hermetia illucens (black soldier fly, BSF) larvae meal representing a promising substitute to fishmeal (FM). This study evaluated the effect of partial dietary inclusion of BSF meal (BSF0, BSF2.5, BSF5, BSF10%) on the volatilome of rainbow trout (Oncorhynchus mykiss) fillets, before and after cooking, using gas chromatography–mass spectrometry (GC–MS) and a metal oxide sensor-(MOX)-based device. Fish were fed diets with increasing BSF inclusion, and both raw and cooked fillets were analyzed to assess changes in volatile organic compounds (VOCs). GC–MS enabled the identification and semi-quantitative analysis of VOC classes, while MOX sensor responses were processed using Linear Discriminant Analysis (LDA) to assess discrimination among dietary treatments. Results showed that BSF inclusion influenced the volatile profile, with clearer separation at higher inclusion levels (BSF5–BSF10%), especially in cooked fillets. Thermal processing enhanced these differences. GC–MS analysis revealed a reduction in aldehydes and ketones and an increase in carboxylic acids with higher BSF inclusion. Key compounds such as hexanal and heptanal decreased, indicating changes in lipid-derived volatile pathways. Overall, the integration of GC–MS and MOX sensors proved effective in detecting diet-induced changes, supporting their application as effective and reliable tools for quality assessment in aquaculture products, with potential implications for sensory quality that should be further confirmed through dedicated sensory studies.

This study focused on the effects of including a mixture of Hermetia illucens (HI) and Tenebrio molitor (TM) meals on feed colour, growth performance, carcass yield, somatic indexes, nutrient digestibility, intestinal microbiota, histomorphometry, and fillet quality of rainbow trout (Oncorhynchus mykiss). Seven diets were formulated: one control diet (CTRL) containing 15% fishmeal, two diets where the fishmeal was replaced with 100% HI (HI100) or TM (TM100) meal, and four diets containing increasing levels of a mix (1:1) of HI and TM meals, replacing 25% (MIX25), 50% (MIX50), 75% (MIX75) and 100% (MIX100) of the fishmeal. A total of 378 fish (average weight: 126 ± 1.71 g (g)) were randomly distributed in 21 experimental tanks (3 replicates/treatment and 18 fish/replicate) and fed for 84 days. A digestibility trial was also conducted to assess the apparent nutrient digestibility coefficients of the diets. Diet significantly affected pellet colour (L*, a*, b*; p < 0.001), with CTRL and MIX25 being the lightest and HI100 and MIX75 the darkest. Fillet colour, pH24h, and drip loss were significantly affected by diet (p < 0.001). The pH24h parameter, reflecting stress and freshness, was lowest in MIX25 and highest in MIX75, suggesting a synergistic effect and potential impact on shelf life. No significant differences were found in growth performance, carcass yield, somatic indexes, fillet chemical composition, intestinal microbiota, and the histopathology of internal organs among the experimental diets (p > 0.05), nor in nutrient digestibility. This study confirms that HI and TM meals, alone or combined, are viable alternatives in low-fishmeal diets for rainbow trout.

The black soldier fly is considered the most promising insect species for mass production; however, information on the effects of handling, which is unavoidable during experimental trials and rearing practices, is still limited. To address this gap, three different manipulation intensities were tested on 100 6-day-old larvae per replica (6 replicates/treatments) fed on Gainesville diet: (1) hard-handled (HH), larvae underwent continuous manipulation until the end of larval stage, (2) soft-handled (SH), larvae were manipulated after the appearance of the first prepupa, (3) no-handled (NH), larvae remained untouched. Every 4 days from the beginning to the end of the larval stage, the manipulations lasted 30 min and occurred under laboratory conditions (20°C). During the sampling operations, at least 30 larvae were randomly extracted, washed, dried, and weight-mimicked. At the end of larval stage, all the boxes remained untouched until the adult fly stage, and the emergency rate and sex ratio were evaluated on dead flies. Data were statistically analyzed using IBM SPSS V20.0.0 software and the considered significance level was  < 0.05. The larval stage lasted 8.2 days for both HH and SH (  > 0.05). Despite the HH larvae being the most manipulated, no difference was also observed in final weight (HH, 160 mg; SH, 150 mg;  > 0.05) and survival rate (HH, 96.2%; SH, 94.5%;  > 0.05). The manipulation did not influence the bioconversion capacity of the larvae (bioconversion efficiency corrected for the residue: HH, 14.3%; SH, 12.91%; reduction rate: HH, 58.4%; SH, 55.9%; waste reduction index: HH, 7.28%/day; SH, 7.25%/day;  > 0.05). Finally, the development time from larva to fly (about 20.7;  > 0.05), the emergency rate (NH: 92.8%; SH: 89.5%; HH: 82.7%) and sex ratio (~1.2% to male flies) were not affected by the handling (  > 0.05). In conclusion, the handling procedures used in the current study did not influence the life history traits of the black soldier fly. However, further studies are needed to evaluate if different experimental protocols on various scales, the colony strain or other handling procedures may suggest a different scenario or confirm the results.

This study evaluated the effects of dietary Hermetia illucens (HI) meal on growth performance, nutrient digestibility, general health status and gut health of post-weaning piglets reared under commercial conditions. A total of 336, 28–days-old mixed-sex weaned piglets were randomly allotted to 4 dietary treatments (control [C] and 3, 6 and 9% HI meal inclusion [HI3, HI6 and HI9], with 4 replicate boxes/treatment, 21 animals/box and 3 feeding phases) and slaughtered after 63 days of trial (4 animals/box, 16 piglets/diet). In the whole trial, the average daily gain and feed conversion ratio showed a linear response to dietary HI meal inclusion (p < 0.05). The nutrient digestibility also displayed a linear and/or quadratic response to dietary HI meal inclusion during phases I and II, while the opposite trend was highlighted during phase III (p < 0.05). Increased blood antioxidant response was also identified for HI6- and HI9-fed animals (p < 0.01). Dietary HI meal inclusion did not influence gut histomorphology or organ histopathological findings, as well as caecal microbiota alpha and beta diversity. However, selected amplicon sequence variants were associated with specific dietary treatments (p < 0.05), such as Dorea, Faecalitalea, Bacteroides, Anaerostipes and Oscillospiraceae (HI3), Phascolarctobacterium, Rhodospirillales and Odoribacter (HI9), Lachnospiraceae, Oscillospiraceae, Anaerovoracaceae, Faecalibacterium, Lachnospira, Alistipes, Lachnoclostridium and Acinetobacter (HI3 and HI6), and Enterobacter, Roseburia, Ruminococcaceae, Lachnospiraceae and Bifidobacterium (HI-based diets). In conclusion, including up to 9% of HI meal enhanced growth performance and antioxidant response, and partially improved nutrient digestibility and caecal microbiota of the weaned piglets, without impairing their gut morphology and overall health status.