Tenebrio Molitor Research Articles

Molecular Detection and Phylogenetic Analysis of the alkB Gene in Klebsiella oxytoca Strains Isolated from the Gut of Tenebrio molitor.

The challenge in polystyrene disposal has caused researchers to look for urgent innovative and ecofriendly solutions for plastic degradation. Some insects have been reported to use polystyrene as their sole carbon source, and this has been linked to the presence of microbes in their guts that aid in plastic digestion. Thus, this study focuses on the molecular detection and phylogenetic analysis of the alkane-1-monooxygenase (alkB) gene in Klebsiella oxytoca strains isolated from the gut of Tenebrio molitor. The alkB gene encodes for alkane-1-monooxygenase, an enzyme involved in the oxidation of inactivated alkanes. This gene can be used as a marker to assess bacteria's ability to biodegrade polystyrene. Three bacterial strains were isolated from the guts of T. molitor mealworms and were confirmed using polymerase chain reaction (PCR) of the 16S ribosomal RNA gene. The primers used in the amplification of the 16S ribosomal RNA region were designed using NCBI, a bioinformatics tool. To detect the presence of the alkB gene in the isolated bacterial strains, a set of primers used in the amplification of this gene was manually designed from the conserved regions of the alkB nucleotide sequences of eleven bacterial species from GenBank. TCOFFE online tool was used to align the alkB sequences of the bacteria, while Jalview and ConSurf were used to view the alignment. The amplified alkB gene was then sequenced using the Sanger sequencing technique, blasted on NCBI to look for similar sequences, and a phylogenetic tree was constructed. Based on the 16S ribosomal RNA gene sequences, the isolated bacterial strains were confirmed to be Klebsiella oxytoca NBRC 102593, Klebsiella oxytoca JCM 1665, and Klebsiella oxytoca ATCC 13182. The alkB gene sequence identical to fourteen alkB gene sequences derived from Actinobacteria whole genome was detected in Klebsiella oxytoca for the first time to the best of our knowledge. The novel nucleotide sequence was published in the NCBI database under accession number OP959069. This gene sequence was found to be for the enzyme alkane-1-monooxygenase and may be one of the enzymes responsible for polystyrene degradation by the putative Klebsiella oxytoca ATCC 13182 in T. molitor.

Mealworm (Tenebrio molitor) rearing and growth optimization as a sustainable food source using various larval diets under laboratory conditions

AbstractA new approach to supplying foods and feeds that are high in protein has emerged in the form of insect farming. Insect‐farmed food may also serve as part of a sustainable diet for humans. The mealworm Tenebrio molitor L. (Coleoptera: Tenebrionidae) is the most widely consumed insect worldwide. In this study, 10 larval diets were tested in the laboratory to determine their suitability for mass‐feeding mealworms at 28 °C and 60–65% r.h., in a completely randomized design. Various larval diets had a significant impact on the biological features of T. molitor. The larvae, pupae, and adults were greater on diets containing wheat bran alone and wheat bran in combination with maize and porridge. Larval mortality was significantly higher (60.7%) on a diet with porridge alone, compared to a control diet, followed by diets with porridge in combination with barley (55.6%) or maize (50.6%). Sex ratio was also affected by the tested larval diets. Female hatch (65%) was higher than male hatch (35%) on diet containing wheat bran alone as compared to all other diets. The findings contribute to optimizing mealworm rearing practices for sustainable food production and promote the potential use of mealworms as a viable protein source – especially livestock diets based on mealworm reared on wheat bran show promise.

Innovative Applications of Tenebrio molitor Larvae in the Production of Sustainable Meat Sausages: Quality and Safety Aspects.

With the world's population continuing to grow, ensuring sustainable protein sources for everyone is becoming increasingly challenging. Despite meat being considered unsustainable, people find it challenging to abstain from consuming it. However, one solution to this dilemma could be the incorporation of mealworms into conventional meat products, i.e., sausages. The incorporation of mealworms into sausage formulations appears to shift the fatty acid profile towards higher levels of monounsaturated fats and polyunsaturated fatty acids (PUFAs), particularly omega-3s, potentially enhancing the nutritional value and offering health benefits. Therefore, our study aimed to improve the nutritional value and safety parameters of traditional sausages by enriching them with the flour of mealworm larvae. For this purpose, the larvae were reared on a sustainable substrate with brewery by-products, brewer's yeast, and carrots. They were used frozen and freeze-dried in sausage recipes, replacing pork in different proportions. The analysis of the product's chemical safety parameters (biogenic amines, nitrates and nitrites, volatile fatty acids (FA), and peroxide) and nutritional value (including collagen, cholesterol, amino acids, FA, and hydroxyproline) was carried out in an accredited laboratory. The results of our study have demonstrated that the incorporation of mealworms into sausages, particularly through freeze-drying, increased fat content and enhanced the profile of FA, including omega-3s while reducing protein and cholesterol levels, and altering collagen content, suggesting improved nutritional value and potential health benefits without compromising the safety of the product. Therefore, we are highlighting that the addition of mealworms influences the quality of amino acids positively and maintains biogenic amine levels within safe limits, alongside a negligible impact on nitrates and nitrites and a reduction in peroxide values. These findings indicate an overall improvement in sausage quality and safety without compromising safety.

In silico identification and expression analysis of superoxide dismutases in Tenebrio molitor.

Insects encounter various environmental stresses, in response to which they generate reactive oxygen species (ROS). Superoxide dismutase (SOD) is an antioxidant metalloenzyme that scavenges superoxide radicals to prevent oxidative damage. To investigate expressions of SODs under oxidative stress in Tenebrio molitor. Here, we investigated the transcriptional expression of SODs by pesticide and heavy metals in Tenebrio moltior. First, we searched an RNA-Seq database for T. molitor SOD (TmSOD) genes and identified two SOD isoforms (TmSOD1-iso1 and iso2). We examined their activities under developmental stage, tissue-specific, and various types (pesticide and heavy metal) of oxidative stress by using qPCR. Our results revealed two novel forms of TmSODs. These TmSODs had a copper/zinc superoxide dismutase domain, active site, Cu2+ binding site, Zn2+ binding site, E-class dimer interface, and P-class dimer interface. TmSODs (TmSOD1-iso1 and iso2) were expressed in diverse developmental phases and tissues. Pesticides and heavy metals caused an upregulation of these TmSODs. Our findings suggest that the two TmSODs have different functions in T. molitor, providing insights into the detoxification ability of T. molitor.

Defatted Tenebrio molitor meal time-dependently altered sensory quality and nutritional value of turbot Scophthalmus maximus during growing-out phase

The yellow mealworm Tenebrio molitor (TM) is promising feed ingredient for aquafeed. However, consumers might reject insect-fed fish unless they know their quality. Nevertheless, reports on how TM influences fish quality were rare and yielded conflicting results; furthermore, there are no evaluations on quality of turbot Scophthalmus maximus fed TM. Therefore, turbot with an initial body weight of 150 g were fed six experimental feeds containing increasing levels of defatted TM to replace fishmeal for 85 days. The substitution levels were 0% (control), 15% (TM15), 22 30% (TM30), 45% (TM45), 60% (TM60), and 75% (TM75). The result showed TM replacing up to 45% of fishmeal did not negatively impact growth performance or fillet yield. Dietary TM optimized the health value of muscle fatty acids regarding thrombogenicity index, atherogenicity index, and hypocholesterolemic to hypercholesterolemic fatty acids ratio but linearly decreased the muscle contents of hydroxyproline, collagen, and n-3 PUFA. However, turbot fed TM15 maintained the contents of these nutrients compared with those fed the control diet. The naked eye cannot perceive skin color changes induced by TM; but the odor, flavor, and texture of cooked fillets changed by TM at both sampling times could be distinguished by sensory evaluation. Furthermore, texture analyzer reported that the hardness of raw fillets significantly decreased by the end of the experiment but not on the 56th day. Correlation analysis revealed that the fillet was softened due to the muscle water content increase and muscle ultrastructure (lengths of H band, bright band, dark band, sarcomere) alternation. In conclusion, there were time-dependent effects of TM on turbot growth performance and fillet texture. Substitution of fishmeal with TM at 15% or less level did not influence the nutritional quality, but TM at any dose softened the fillet, which could be attributed to its influence on moisture content and myofibrillar structure.

Valorization of local agricultural by-products as nutritional substrates for Tenebrio molitor larvae: A sustainable approach to alternative protein production

In pursuit of sustainable protein sources, the agricultural sector and emerging edible insect industry intersect in the valorization of agricultural by-products. Establishing a mutually beneficial relationship involves utilizing agricultural by-products as feeding substrates for insect farming, potentially enhancing the sustainability of both sectors. In the present study, by-products from beer, rice, oat, maize, sunflower, and lucerne, as well as mill residues and spent mushroom substrate from the regions of Thessaly and Central Macedonia (Greece) were investigated as nutritional sources for the larvae of the yellow mealworm (Tenebrio molitor). Results show that the suitability of the tested by-products for rearing T. molitor larvae varies greatly, with larvae surviving better in some by-products than in others. The highest survival rate and the highest weight of larvae were recorded for larvae reared on rice bran, spent grains, and oat by-products. Similarly, high feed conversion and growth rate were observed when the larvae were fed with rice bran and spent grains. Thus, this research promotes cost-effective and sustainable T. molitor rearing, aligning with circular economy principles.

Optimizing polystyrene degradation, microbial community and metabolite analysis of intestinal flora of yellow mealworms, Tenebrio molitor

This study explored a direct feeding of expanded polystyrene as the sole diet for breeding Tenebrio molitor larvae. Temperature and relative humidity were manipulated to evaluate polystyrene biodegradation efficiency, survival rate, and formation of micro-polystyrene residue. Efficient conditions were at temperature of 25 °C with a humidity of 65 ± 5 %. Comparative metabolomic and metabolic-metabolic network analyses was performed for visualizing detailed pathway. Possibility of forming 4 (p)-hydroxyphenylacetic acid from phenylacetic acid with further conversion to 4-methylphenol, 4-hydroxybenzaldehyde, and 4-hydroxybenzoate could be seen as a side chain route for further biodegrading process. Key species identified in the gut of T. molitor larvae included Citrobacter sp., Serratia marcescens, Klebsiella aerogenes, and Klebsiella oxytoca. Pseudomonas aeruginosa was detected only under an anaerobic condition whereas Acinetobacter sp. was present only under an aerobic condition. These results demonstrate the potential to decrease micro-polystyrene by optimizing breeding conditions and biodegradation process of polystyrene.

Effects of high doses of zearalenone on some antioxidant enzymes and locomotion of Tenebrio molitor larvae (Coleoptera: Tenebrionidae).

The mealworm Tenebrio molitor L. (Coleoptera: Tenebrionidae) feeds on wheat bran and is considered both a pest and an edible insect. Its larvae contain proteins and essential amino acids, fats, and minerals, making them suitable for animal and human consumption. Zearalenone (ZEA) is the mycotoxin most commonly associated with Fusarium spp. It is found in cereals and cereal products, so their consumption is a major risk for mycotoxin contamination. One of the most important effects of ZEA is the induction of oxidative stress, which leads to physiological and behavioral changes. This study deals with the effects of high doses of ZEA (10 and 20mg/kg) on survival, molting, growth, weight gain, activity of antioxidant enzymes superoxide dismutase (SOD) and glutathione S-transferase (GST), and locomotion of mealworm larvae. Both doses of ZEA were found to (i) have no effect on survival, (ii) increase molting frequency, SOD, and GST activity, and (iii) decrease body weight and locomotion, with more pronounced changes at 20mg/kg. These results indicated the susceptibility of T. molitor larvae to high doses of ZEA in feed.

Impact of urban diets on the nutritional physiology of mealworms

Mealworms ( Tenebrio Molitor), the larval stage of yellow mealworm beetles, are a popular feeder insect for birds, amphibians, reptiles, fish, and even human populations throughout the world. As such, the goal of this work was to understand how the diet of mealworms impacts their nutritional quality as variations in quality can impact the animals (and humans) that consume them. We hypothesized that the nutritional quality of mealworms would be altered by dietary intake with urban substrates resulting in reduced nutritional quality. We divided 500 mealworms among each of the following diets designed to model substrates available in urban vs rural, more natural areas: 100% wheat germ (control); 100% Styrofoam; mixture of soil, grasses, and leaves from urban lawns; mixture of soil, grasses and leaves from rural lawns; mixture of wheat germ + carrots; natural organic fertilizer; or natural organic fertilizer with turf builder. The mealworms were maintained at room temperature and the diets were replaced weekly to prevent spoilage and to remove mealworm wastes. Once a week for three weeks, mealworms were sampled and frozen. Data were analyzed by two-way ANOVA with time and substrate as factors. After 3 weeks, mealworms housed in wheat germ + carrots weighed significantly more than all other groups (p<0.05), whereas those housed in styrofoam or urban lawn substrates weighed significantly less at week 3 as compared to week 1 (p<0.01). The urban lawn substrate resulted in greater molting and the highest number of pupae, but also the greatest mortality among the substrates. Moreover, mealworms provided urban lawn weighed less at week 3 as compared to week 1 (p=0.006). Mealworms maintained on wheat germ had significantly greater total protein content (p<0.05) and the greatest increase in protein content from week 0 to week 3 as compared to any other diet (p<0.05). Glucose content, on the other hand, was significantly lower in all groups at week 3 compared to week 0 (p<0.05). Similar trends were seen in total soluble sugars as mealworms housed in styrofoam, urban lawn, rural lawn, natural fertilizer, and fertilizer with turf builder had lower levels of total soluble sugars at week 3 compared to baseline (p<0.03) whereas those fed wheat germ, with or without carrots, had the highest content (vs WG: p≤0.03; vs WGCAR p<0.05). Interestingly, mealworms housed in wheat germ had higher oxidized lipoproteins compared to all other groups (p<0.05) whereas those fed natural fertilizer or wheat germ and carrots had the lowest level of oxidative stress compared to baseline (p<0.05). Together, these variations support our hypothesis that the nutritional quality of mealworms is altered by dietary intake. In general, urban substrates reduced the nutritional content (body mass, protein, and sugar content) of mealworms, which may negatively impact the health and behavior of predators that rely on such prey for food. This study was funded in part by a Jumpstart Grant awarded to RL by the Graduate and Professional Student Association, Arizona State University. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Peningkatan Ekonomi Paska-Pandemi Melalui Pengembangan Ulat Hongkong pada Kelompok Masyarakat Pembudidaya Ikan Air Tawar “Sumber Duren” Kabupaten Malang

Senggreng Village is one of the areas in Sumber Pucung District, Malang Regency, promising to be developed in agriculture, animal husbandry, fisheries, and agro-tourism. Abundant water resources mainly support the fisheries and agriculture potency due to its position near the Sutami Dam. One of the community groups in Senggreng Village, "Sumber Duren", is "engaged in developing a small amusement park that integrates culinary, fishing park and freshwater fish farming business, managed through a cage system. Regardless of its considerable potency, fish farming has not been carried out intensively, especially due to the high prices of commercial fish feed. Therefore, this community service team proposed a solution by initiating mealworm (Tenebrio molitor) cultivation as a cheap, high-protein, and sustainable source of fish feed to increase crop yields. Experienced mealworm practitioners also provided intensive mealworm cultivation education, training, and profitable business planning. Through this program, the community group "Sumber Duren" has been" successful in cultivating mealworms starting from the seedling phase to becoming broodstock and laying eggs. Based on the questionnaire data collection, most community group members stated that this community service activity helped provide new knowledge interested in cultivating alternative feeds, and 80% of respondents expected the activity to continue in the following years.

Biodegradation of polystyrene nanoplastics by Achromobacter xylosoxidans M9 offers a mealworm gut-derived solution for plastic pollution

Nanoplastics pose significant environmental problems due to their high mobility and increased toxicity. These particles can cause infertility and inflammation in aquatic organisms, disrupt microbial signaling and act as pollutants carrier. Despite extensive studies on their harmful impact on living organisms, the microbial degradation of nanoplastics is still under research. This study investigated the degradation of nanoplastics by isolating bacteria from the gut microbiome of Tenebrio molitor larvae fed various plastic diets. Five bacterial strains capable of degrading polystyrene were identified, with Achromobacter xylosoxidans M9 showing significant nanoplastic degradation abilities. Within 6 days, this strain reduced nanoplastic particle size by 92.3%, as confirmed by SEM and TEM analyses, and altered the chemical composition of the nanoplastics, indicating a potential for enhanced bioremediation strategies. The strain also caused a 7% weight loss in polystyrene film over 30 days, demonstrating its efficiency in degrading nanoplastics faster than polystyrene film. These findings might enhance plastic bioremediation strategies.Graphical abstract

Antifungal activity of Caryocar brasiliense camb. Alone or along with antifungal agents against multidrug-resistant Candida auris

Ethnopharmacological relevanceCandida auris poses a severe global health threat, with many strains resistant to antifungal treatments, complicating therapy. Exploring natural compounds alongside conventional drugs offers promising therapeutic avenues. The antifungal potential of the ethanolic extract from Caryocar brasiliense (Cb-EE), a plant native to the Brazilian cerrado and renowned for its medicinal properties, was investigated against C. auris. Aim of the studyThe study examined the chemical composition, antifungal activity, mechanisms of action, and in vivo effects of Cb-EE. Materials and methodsLeaves of C. brasiliense were processed to extract ethanolic extract, which was evaluated for phenolic compounds, flavonoids, and tannins. The antifungal capacity was determined through broth microdilution and checkerboard methods, assessing interaction with conventional antifungals. ResultsCb-EE demonstrated fungistatic activity against various Candida species and Cryptococcus neoformans. Synergy with fluconazole and additive effects with other drugs were observed. Cb-EE inhibited C. auris growth, with the combination of fluconazole extending inhibition. Mechanistic studies revealed interference with fungal membranes, confirmed by sorbitol protection assays, cellular permeability tests, and scanning electron microscopy (SEM). Hemocompatibility and in vivo toxicity tests on Tenebrio molitor showed safety. ConclusionCb-EE, alone or in combination with fluconazole, effectively treated C. auris infections in vitro and in vivo, suggesting its prospective role as an antifungal agent against this emerging pathogen.

Responses of physiological, microbiome and lipid metabolism to lignocellulose wastes in gut of yellow mealworm (Tenebrio molitor)

There is limited research on physiological and degradation mechanisms of yellow mealworm, a novel organic waste converter, in processing lignocellulosic wastes. This study has selected two types of lignocellulosic wastes, distillers’ grains (DG) and maize straw (MS), to feed yellow mealworms. This study investigated the effects of lignocellulosic wastes on the growth, antioxidant system, microbiome, and lipidome of yellow mealworms. The relative growth of lignocellulosic waste group was not significantly different from wheat bran. The antioxidant level was elevated in DG. MS was significantly enriched in cellulose-degrading bacteria in the gut and was accompanied by disturbances in lipid metabolism. The correlation coefficients were used to construct a network connecting diet, microbiota, and lipids. The correlation analysis indicated that two sphingolipids, hexylglyceramide and dihydroglyceramide, were strongly and positively linked with the dominating species. This study provides comprehensive information on physiological and mechanism of mealworms in process of treating lignocellulosic waste.

Dietary Tenebrio molitor larvae meal effects on cellular stress responses, antioxidant statusand intermediate metabolism of Oncorhynchus mykiss.

In the context of evaluating the impact of environmentally friendly and sustainably produced alternative protein sources in fish feed, the present study's aim was to examine the overall physiological stress response in one of the main fish species of European freshwater aquaculture, Oncorhynchus mykiss (rainbow trout), following the partial substitution of fish meal (FM) with a Tenebrio molitor (TM) (yellow mealworm) full-fat meal. In total, 222 rainbow trout individuals (115.2 ± 14.2 g) were allocated randomly into six tanks, three per dietary treatment, and were fed a formulated diet containing 60% yellow mealworm (TM60) compared to a control diet without insect meal (TM0). Both diets contained equal amounts of crude protein, dry matter and, lipid content, while the FM in TM60 was 100 g kg-1 corresponding to the one seventh of the TM0. Heat shock response (HSR), MAPK signalling, cell death pathways (apoptosis and autophagy), antioxidant defence mechanisms, and intermediate metabolism were evaluated. In general, HSR and MAPK signalling were activated in response to the inclusion of T. molitor. Moreover, triggering of apoptotic and autophagic processes and the onset of antioxidant defence mechanisms underlined the existence of physiological stress. Despite the apparent dietary-induced stress, rainbow trout in the present study exhibited no mortality and no significant effects regarding growth performance parameters. Specifically, TM60 dietary inclusion resulted in no changes in final body weight, weight gain, and specific growth rate. However, feed intakedepicted a statistically significant decrease in TM60 fish compared to TM0 individuals. Nevertheless, nutrient stress should be considered a limiting factor regarding the utilization of T. molitor in O. mykiss diet due to the associated risks for health and welfare.

Apirhabdus apintestini gen. nov., sp. nov., a member of a novel genus of the family Enterobacteriaceae, isolated from the gut of the western honey bee Apis mellifera.

A Gram-negative, motile, rod-shaped bacterial strain, CA-0114T, was isolated from the midgut of a western honey bee, Apis mellifera. The isolate exhibited ≤96.43 % 16S rRNA gene sequence identity (1540 bp) to members of the families Enterobacteriaceae and Erwiniaceae. Phylogenetic trees based on genome blast distance phylogeny and concatenated protein sequences encoded by conserved genes atpD, fusA, gyrB, infB, leuS, pyrG and rpoB separated the isolate from other genera forming a distinct lineage in the Enterobacteriaceae. In both trees, the closest relatives were Tenebrionicola larvae YMB-R21T and Tenebrionibacter intestinalis BIT-L3T, which were isolated previously from Tenebrio molitor L., a plastic-eating mealworm. Digital DNA-DNA hybridization, orthologous average nucleotide identity and average amino acid identity values between strain CA-0114T and the closest related members within the Enterobacteriaceae were ≤23.1, 75.45 and 76.04 %, respectively. The complete genome of strain CA-0114T was 4 451669 bp with a G+C content of 52.12 mol%. Notably, the apparent inability of strain CA-0114T to ferment d-glucose, inositol and l-rhamnose in the API 20E system is unique among closely related members of the Enterobacteriaceae. Based on the results obtained through genotypic and phenotypic analysis, we propose that strain CA-0114T represents a novel species and genus within the family Enterobacteriaceae, for which we propose the name Apirhabdus apintestini gen. nov., sp. nov. (type strain CA-0114T=ATCC TSD-396T=DSM 116385T).

Eugenia uniflora (pitanga) juice as a new alternative vehicle for Limosilactobacillus fermentum ATCC 23271: evaluation of antioxidant and anti-infective effects.

Probiotic-containing foods are among the most appreciated functional foods; however, probiotic-based dairy products cannot be consumed by people who are lactose intolerant, allergic to milk, or vegetarian or vegan individuals. Thus, new non-dairy matrices have been tested for probiotics delivery. This study evaluated the growth and viability of Limosilactobacillus fermentum ATCC 23271 and Lacticaseibacillus rhamnosus ATCC 9595 in Pitanga juice (Eugenia uniflora L.). The effects of the fermentation on the antioxidant and anti-infective properties of the juice were also analyzed. The E. uniflora juice allowed lactobacilli growth without supplementation, reaching rates around 8.4 Log CFU/mL and producing organic acids (pH values < 4) after 72h of fermentation. The strain remained viable after 35 days of refrigerated storage. Fermentation by these bacteria increases the antioxidant capacity of the juice. The central composite rotational design was employed to evaluate the effects of bacterial inoculum and pulp concentration on growth and organic acids production by L. fermentum ATCC 23271. The strain was viable and produced organic acids in all tested combinations. L. fermentum-fermented juice and its cell-free supernatant significantly increased the survival of Tenebrio molitor larvae infected by enteroaggregative Escherichia coli 042. The results obtained in this study provide more insights into the potential of Pitanga juice to develop a functional non-dairy probiotic beverage with antioxidant and anti-infective properties.

Use of irradiation against stored product insect species that infest edible insect rearing

Hermetia illucens (Linnaeus, 1758) and Tenebrio molitor (Linnaeus, 1758) larvae are considered the most important edible insects almost of the world. Infestation of these insect meals with stored-product pests may pose a significant threat to their production process or storage. This study investigated the efficacy of phytosanitary irradiation in protecting H. illucens and T. molitor meals from the three major stored-product pests, Necrobia rufipes (De Geer, 1775), Tribolium castaneum (Hrebst, 1797) and Oryzaephlius surinamensis (Linnaeus, 1758). The obtained data revealed that the longevity periods of N. rufipes, T. castaneum and O. surinamensis were higher (16.8, 30.7 and 19.7 day), respectively when fed on T. molitor compared to BSF diet (7.4, 18.6, and 18.35 days, respectively). Results indicated that O. surinamensis was highly susceptible to irradiation followed by N. rufipes and T. castaneum in response to different doses when reared on both H. illucens and T. molitor meals. The data demonstrated that exposure of the three tested insect pests reared on the both diets to gamma radiation has reduced their population growth and next offspring. The present findings provide a new set of valuable insights towards a comprehensive pest management approach that can be utilized to optimize the farming facility and maximize the utilization of H. illucens and T. molitor products.

Sourcing chitin from exoskeleton of Tenebrio molitor fed with polystyrene or plastic kitchen wrap

In this work we have characterized and compared chitin sourced from exoskeleton of Tenebrio molitor larvae fed with polystyrene or plastic kitchen wrap combined with bran in the ratio 1: 1 with chitin sourced from larvae exoskeleton fed only with bran. Analysis of the frass by ATR-FTIR showed very similar spectra and confirmed degradation of the plastic feed components, while ATR-FTIR analysis of the exoskeleton verified the absence of any plastic residue. Deproteinization followed by demineralization produced 6.78–5.29 % chitin, showing that plastic (polystyrene or plastic kitchen wrap) in the larvae diet resulted in heavier insect exoskeleton, but yielded slightly less chitin, with the lowest value obtained for plastic kitchen wrap in the insect diet. The deacetylation degree of 98.17–98.61 % was determined from measured ATR-FTIR spectra. XRD analysis confirmed the presence of α-chitin with a crystallinity index of 66.5–62 % and crystallite size 4–5 nm. Thermogravimetric analysis showed similar degradation curves for all chitin samples, with two degradation steps. These results show that chitin sourced from exoskeleton of T. molitor larvae fed with plastic (polystyrene or plastic kitchen wrap) and contributing to significant biodegradation of major polluting materials can be a feasible and alternative source of chitin, further promoting a bio-circular economy.

Validation of Diets with Tomato Pomace in Complete Cycle Breeding of Tenebrio molitor (L.) (Coleoptera: Tenebrionidae).

By-product-based diets have the potential to improve the environmental and economic sustainability of Tenebrio molitor (Linnaeus, 1758) production. However, evaluations of the efficacy of new diets are generally focused on larval performance, while the effect on adults is poorly understood. This aim of this study was to evaluate diets enriched with tomato pomace over a complete breeding cycle. The results showed that when used as an oviposition substrate, all the tested diets, including tomato pomace (T), outperformed the control bran-yeast diet (WY, 95:5 ratio), possibly due to the presence of cholesterol and linoleic acid. The adults fed with the bran-tomato pomace-brewer's spent grain diet (WTB, 50:27:23 ratio), the bran-tomato pomace-yeast diet (WTY, 50:41:9 ratio), and the bran-tomato pomace diet (WT, 50:50 ratio) produced significantly more larvae than those fed with the WY diet. The WTB diet (despite being yeast-free) performed similarly to the WY control diet during the subsequent larval growth phase, making it suitable for the entire production cycle. In conclusion, the results show that tomato pomace can be used a valid by-product in the formulation of efficient diets for the breeding of T. molitor and also provide an alternative to expensive yeast.

Long-term suitability of an alternative host for rearing the sugarcane stalk borer parasitoid Tetrastichus howardi.

The continuous utilisation of an alternative host may influence parasitoid performance across successive generations due to conditioning in natal hosts. Tetrastichus howardi (Olliff) has successfully been reared using Tenebrio molitor L. pupae as a feasible alternative host. However, the extended rearing of T. howardi on this alternative host may impact the biological features of the parasitoids. Parasitoids were reared using T. molitor pupae for 30 consecutive generations. Quality criteria were assessed during the generations F5, F15, and F30, offering pupae of the target pest, Diatraea saccharalis (Fabr.), and compared with the F0 generation (parasitoids reared in D. saccharalis pupae). Criteria included assessments of parasitism performance, host selection, and wing form variation in the parasitoid wasps. Additionally, we examined the fecundity of T. howardi females that emerged from both hosts, considering their age, egg loading before and after one oviposition, as well as parasitism of sugarcane stalk borer pupae. Rearing T. howardi using pupae of T. molitor did not affect its biological traits or preference for the target pest for 30 generations. After parasitism, the parasitoid left the host pupa inside the stalk, and one oviposition was enough to kill D. saccharalis pupae and obtain viable parasitoid progeny. Female sexual maturation and egg loading occurred 72 and 96 h after parasitoid emergence. Egg-loading recovery after parasitism did not happen within 24 h. T. howardi can be reared for up to 30 generations using alternative hosts without compromising its parasitism performance or egg loading.