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Fas‐associated death domain protein (FADD) is an apoptotic adapter molecule that recruits caspases and facilitates the formation of death‐inducing signaling complexes in mammals. In lower animals, FADD forms a complex with immune deficiency and death‐related ced‐3/Nedd2‐like caspase to elicit antimicrobial responses. In this study, we characterized the FADD sequence of Tenebrio molitor (TmFADD) using molecular informatics to understand its role in immune surveillance of the host against microorganisms. The 618 bp open reading frame of TmFADD encodes a polypeptide of 204 amino acids. The protein includes two promiscuous domains, the death‐effector domain and the death domain, found at the N‐ and C‐termini, respectively. TmFADD is clustered with the coleopteran FADD sequences in the phylogenetic tree. Homology‐based structural analysis showed an α‐helical model with a QMEAN score of 0.58. The expression of TmFADD mRNA was conspicuous in the larval and early pupal stages. TmFADD mRNA was distributed in the immune tissues of the larva and was found predominately in the gut of the adult. Infection of the host with Candida albicans, Escherichia coli or Staphylococcus aureus increased the expression of TmFADD mRNA, suggesting that these microorganisms trigger the innate immunity of the host. The silencing of TmFADD transcripts resulted in an increased susceptibility of T. molitor larvae to infection with E. coli, but not to infection with C. albicans or S. aureus. Hence, these results indicate that FADD plays a role in the defense of T. molitor and could open avenues for understanding insect immunity. [ABSTRACT FROM AUTHOR]

Edible insects such as the mealworm (Tenebrio molitor) are emerging as an alternative animal protein resource to meet the needs of a growing global population. However, despite the successful mass production of edible insects, research into practical compound feed for edible insect is still insufficient. In this study, mealworms were fed wheat bran, layer chicken feed mash, chicken pellets and cattle pellets for 1 to 36 days, after which their body length was measured. In the groups fed with chicken feed mash, chicken pellets or cattle pellets, the mean body lengths were 2.88, 2.92 and 2.95 cm, respectively, similar to the 2.95 cm of the control T. molitor fed with wheat bran. Individual weight measurements yielded similar results: control, 7.87 g; chicken feed mash, 7.43 g; chicken pellets, 7.60 g; and cattle pellets, 7.63 g. Analysis of livestock feed intake showed that the intake was 290.4 g in control insects, 137.7 g in insects fed chicken feed mash, 220.2 g in insects fed chicken pellets and 230.3 g in insects fed cattle pellets. In the excretion analysis, the excretion of the control insects (161.60 g) was larger than that of the insects fed with chicken feed mash (93.37 g), chicken pellets (93.40 g) or cattle pellets (133.87 g). An analysis of the nutritional content of T. molitor based on nine major nutrients showed no significant differences between the control and the test groups. These results can be used to improve the price competitiveness and quality of T. molitor for commercial development. [ABSTRACT FROM AUTHOR]

Selective herbicides are used to control undesirable vegetation or weeds in fields without harming crops. Herbicide use for weed management can directly impact the densities of insect pests in agricultural communities as a result of insect mortality during and immediately after application. In insects, the glutathione S‐transferase (GST) enzyme is involved in both the detoxification process and the defense of cellular membranes against oxidative damage. In this study, two TmGSTs (TmGST‐iso1 and TmGST‐iso2) were identified and characterized to elucidate the GST family in Tenebrio molitor. Among the developmental stages of T. molitor, eggs had the highest expression levels of TmGST‐iso1. TmGST‐iso2 expression was highest in the pre‐pupal stage. TmGST‐iso1 expression was high in the guts of early and late larvae, whereas TmGST‐iso2 expression was not observed in early larvae. Adults, both male and female, had the highest levels of TmGST‐iso1 mRNA expression in the gut and reproductive organs, and the highest levels of TmGST‐iso2 expression in the reproductive organs. Quantitative polymerase chain reaction was used to investigate the impact of treatment with butachlor on the mRNA expression of TmGST‐iso1 and TmGST‐iso2 in larvae. TmGST‐iso1 expression increased in the butachlor‐treated group after 3 and 24 h, whereas TmGST‐iso2 expression peaked at 24 h after treatment. This study provides vital information about the detoxifying activities of T. molitor. [ABSTRACT FROM AUTHOR]

In insects, the production of antimicrobial peptides is considered to be the solo arm of the innate immune response. The Toll and immune deficiency pathways are two major signaling pathways that lead to the production of antimicrobial peptides as final effectors. The dynamic functions of Toll/Toll‐like receptors have been thoroughly reviewed in mammals and Drosophila. During the last decade, we have attempted to clarify the immunological roles of different Toll receptor variants and their ligands in Tenebrio molitor. Accordingly, we showed that TmToll‐8, −9, and −10 mRNA transcripts are induced following systemic injections of Gram‐negative, Gram‐positive, and fungal infections. Our data revealed harmonic expression patterns of TmToll‐8, −9, and −10 throughout the developmental stages of healthy individuals and in response to infections in the examined tissues (Malpighian tubules, gut, fat bodies, and hemolymph), illustrating similar evolutionary conversions of different Toll receptor variants in T. molitor. Taken together, our findings highlight the immunological actions of TmToll‐8, −9, and −10 in response to pathogenic insults in T. molitor. [ABSTRACT FROM AUTHOR]

Agricultural intensification has led to significant increases in production, but the overuse of pesticides and associated hazards pose threats to biodiversity and ecological functions. Catalase (CAT), a key antioxidant enzyme, plays a crucial role in alleviating oxidative stress by directly interacting with toxins. In this study, we identified three CAT isoforms in Tenebrio molitor (TmCAT‐iso1, TmCAT‐iso2 and TmCAT‐iso3). These CATs possess a CAT domain, tetramer interface sites and a heme‐binding pocket. We examined the expression of Tm catalases across all developmental stages and in specific tissues using quantitative real time polymerase chain reaction (qRT‐PCR) experiments. Our findings demonstrate that TmCAT‐iso1 and TmCAT‐iso3 exhibit peak expression in young and late larval stages, respectively, whereas TmCAT‐iso2 shows peak expression during the egg and pre‐pupal stages. Tissue distribution analysis revealed the high expression of TmCAT‐iso1 and TmCAT‐iso2 in larval hemocytes, whereas TmCAT‐iso3 is predominantly expressed in larval Malpighian tubules. Furthermore, injection with chlorantraniliprole significantly elevated mRNA expression levels of TmCAT‐iso1, TmCAT‐iso2, and TmCAT‐iso3 in larval groups, compared with control groups. Our study highlights the distinct developmental stages and tissues where TmCATs are expressed. We also elucidated the effects of pesticide application on the expression of each TmCAT, revealing the physiological characteristics of CATs in response to these pesticides, which are dose‐ and time‐dependent in T. molitor. [ABSTRACT FROM AUTHOR]

Mealworms beetles, Tenebrio molitor, are the limelight next-generation food for humans due to their high nutrient contents. Since Tenebrio molitor is used as feed for pets and livestock in addition to their ability to decompose polystyrene and plastic waste, it is recognized as an insect with an industrial core value. Therefore, it is important to study the immune mechanism related to the development and infection of mealworms for mass breeding purposes. The immune deficiency (Imd) signaling is one of the main pathways with pivotal roles in the production of antimicrobial peptides (AMPs). Transforming growth factor-β activated kinase (TAK1) is one of the Imd pathway components, forms a complex with TAK1 binding protein 2 (TAB2) to ultimately help activate the transcription factor Relish and eventually induce host to produce AMPs. Relatively, little has been revealed about TAK1 in insect models, especially in the T. molitor. Therefore, this study was conducted to elucidate the function of TmTak1 in T. molitor. Our results showed that the highest and lowest mRNA expression of TmTak1 were found in egg and young larvae respectively. The tissue-specific expression patterns were reported in the gut of T. molitor larvae and the fat bodies of adults. Systemic microbial challenge illustrated TmTak1 high expression following the fungal infection in all dissected tissues except for the whole body. However, silencing TmTak1 experiments showed that the survivability of T. molitor larvae affected significantly following Escherichia coli infection. Accordingly, AMP induction after TmTak1 knock down was mainly reported in the integument and the fat bodies. [ABSTRACT FROM AUTHOR]

Although Toll-like receptors have been widely identified and functionally characterized in mammalian models and Drosophila, the immunological function of these receptors in other insects remains unclear. Here, we explored the relevant innate immune response of Tenebrio molitor (T. molitor) Toll-3 against Gram-negative bacteria, Gram-positive bacteria, and fungal infections. Our findings indicated that TmToll-3 expression was mainly induced by Candida albicans infections in the fat bodies, gut, Malpighian tubules, and hemolymph of young T. molitor larvae. Surprisingly, Escherichia coli systemic infection caused mortality after TmToll-3 knockdown via RNA interference (RNAi) injection, which was not observed in the control group. Further analyses indicated that in the absence of TmToll-3, the final effector of the Toll signaling pathway, antimicrobial peptide (AMP) genes and relevant transcription factors were significantly downregulated after E. coli challenge. Our results indicated that the expression of almost all AMP genes was suppressed in silenced individuals, whereas the expression of relevant genes was positively regulated after fungal injection. Therefore, this study revealed the immunological involvement of TmToll-3 in T. molitor in response to systematic infections. [ABSTRACT FROM AUTHOR]

The antimicrobial roles of Toll-like receptors have been mainly identified in mammalian models and Drosophila. However, its immunological function in other insects has yet to be fully clarified. Here, we determined the innate immune response involvement of TmToll-2 encountering Gram-negative, Gram-positive, and fungal infection. Our data revealed that TmToll-2 expression could be induced by Escherichia coli, Staphylococcus aureus, and Candida albicans infections in the fat bodies, gut, Malpighian tubules, and hemolymph of Tenebrio molitor young larvae. However, TmToll-2 silencing via RNAi technology revealed that sole E. coli systemic infection caused mortality in the double-strand RNA TmToll-2-injected group compared with that in the control group. Further investigation indicated that in the absence of TmToll-2, the final effector of Toll signaling pathway, antimicrobial peptide (AMP) genes and relevant transcription factors were significantly downregulated, mainly E. coli post-insult. We showed that the expression of all AMP genes was suppressed in the main immune organ of insects, namely, fat bodies, in silenced individuals, while the relevant expressions were not affected after fungal infection. Thus, our research revealed the immunological roles of TmToll-2 in different organs of T. molitor in response to pathogenic insults. [ABSTRACT FROM AUTHOR]

The inhibitor of nuclear factor-kappa B (NF-κB) kinase (IKK) is the core regulator of the NF-κB pathway against pathogenic invasion in vertebrates or invertebrates. IKKβ, -ε and -γ have pivotal roles in the Toll and immune deficiency (IMD) pathways. In this study, a homolog of IKKε (Tm IKKε) was identified from Tenebrio molitor RNA sequence database and functionally characterized for its role in regulating immune signaling pathways in insects. The TmIKKε gene is characterized by two exons and one intron comprising an open reading frame (ORF) of 2,196 bp that putatively encodes a polypeptide of 731 amino acid residues. Tm IKKε contains a serine/threonine protein kinases catalytic domain. Phylogenetic analysis established the close homology of Tm IKKε to Tribolium castaneum IKKε (Tc IKKε) and its proximity with other IKK-related kinases. The expression of TmIKKε mRNA was elevated in the gut, integument, and hemocytes of the last-instar larva and the fat body, Malpighian tubules, and testis of 5-day-old adults. TmIKKε expression was significantly induced by Escherichia coli , Staphylococcus aureus , and Candida albicans challenge in whole larvae and tissues, such as hemocytes, gut, and fat body. The knockdown of the TmIKKε messenger RNA (mRNA) expression significantly reduced the survival of the larvae against microbial challenges. Further, we investigated the induction patterns of 14 T. molitor antimicrobial peptides (AMPs) genes in TmIKKε gene-silencing model after microbial challenges. While in hemocytes, the transcriptional regulation of most AMPs was negatively regulated in the gut and fat body tissue of T. molitor , AMPs, such as TmTenecin 1 , TmTenecin 4 , TmDefensin , TmColeoptericin A , TmColeoptericin B , TmAttacin 1a , and TmAttacin 2 , were positively regulated in TmIKKε -silenced individuals after microbial challenge. Collectively, the results implicate TmIKKε as an important factor in antimicrobial innate immune responses in T. molitor. [ABSTRACT FROM AUTHOR]

The dimeric cytokine ligand Spätzle (Spz) is responsible for Toll pathway activation and antimicrobial peptide (AMP) production upon pathogen challenge in Tenebrio molitor. Here, we indicated that Tm Spz5 has a functional role in response to bacterial infections. We showed that the highest expression of TmSpz5 is induced by Candida albicans. However, TmSpz5 knockdown reduced larval survival against Escherichia coli and Staphylococcus aureus. To evaluate the molecular mechanism underlying the observed survival differences, the role of TmSpz5 in AMP production was examined by RNA interference and microbial injection. T. molitor AMPs that are active against Gram-negative and -positive bacteria, including Tm tenecins, Tm attacins, Tm coleoptericins, Tm taumatin-like-proteins, and Tm cecropin-2, were significantly downregulated by TmSpz-5 RNAi in the Malpighian tubules (MTs) following a challenge with E. coli and S. aureus. However, upon infection with C. albicans the mRNA levels of most AMPs in the ds TmSpz5 -injected group were similar to those in the control groups. Likewise, the expression of the transcription factors NF-κB, TmDorX2 , and TmRelish were noticeably suppressed in the MTs of TmSpz5 -silenced larvae. Moreover, E. coli -infected TmSpz5 knockdown larvae showed decreased antimicrobial activity in the MTs and hindgut compared with the control group. These results demonstrate that Tm Spz5 has a defined role in T. molitor innate immunity by regulating AMP expression in MTs in response to E. coli. [ABSTRACT FROM AUTHOR]

Antimicrobial peptides (AMPs) are considered to be candidate effectors for eliciting humoral immune responses against infectious pathogens in the host. Cecropins are α‐helical peptides of 30–40 amino acids, which are known to permeabilize bacterial membranes, and play authoritative roles in the innate immune system of insects. In the present study, we identified the full‐length open reading frame (ORF) encoding the Tenebrio molitor cecropin‐2 (TmCec2) gene using the Tribolium castaneum cecropin‐2 (TcCec2) gene to query a T. molitor Rnaseq database. Phylogenetic analysis revealed close identity of TmCec2 with TcCec2. TmCec2 was ubiquitously expressed in the insect during all developmental stages, with the highest expression observed in the adult. Tissue‐specific TmCec2 expression was highest in larval hemocytes and in the adult integument and hemocytes. Microbial challenge experiments revealed that TmCec2 was highly induced in response to gram‐positive and gram‐negative bacteria, and fungi. These data provide credible evidence for a putative role of TmCec2 in insect innate immunity against a plethora of pathogens. [ABSTRACT FROM AUTHOR]

Defensins are a major family of antimicrobial peptides that serve as the innate immune defense of both vertebrates and invertebrates. Due to their antimicrobial, chemotactic, and regulatory activities, Defensins have been exploited for their therapeutic potential. Insect Defensins are cysteine‐rich and contain an N‐terminal loop, α‐helix, and antiparallel β‐sheet, forming a "cysteine‐stabilized alpha beta (CSαβ)" or "loop–helix‐sheet" structure. In this study, we identified the full‐length open reading frame (ORF) sequences of Defensin (TmDef) and Defensin‐like (TmDef‐like) genes from the mealworm beetle Tenebrio molitor using in silico methods. TmDef and TmDef‐like genes encode the peptides of 72 and 71 amino acid residues, respectively. TmDefensin is comprised of a Defensin domain and the TmDefensin‐like is comprised of a signal peptide of 21 amino acid residues. Phylogenetic analysis revealed close similarities of TmDefensin with the Defensin of Acalolepta luxuriosa of the longhorn beetle family. The expression of TmDef mRNA was found to be greater than that of TmDef‐like mRNA and was mostly expressed in the pupal and adult stages. Tissue distribution showed high expression of TmDef‐like mRNA in larval hemocytes, gut, integument, and fat body, while in adults, the expression was high in gut and hemocytes. Following bacterial and fungal stimulation in vivo, TmDef was upregulated at 24 h post‐infection in whole body, fat body, and hemocytes of the larvae. Even TmDef‐like mRNA was upregulated in the gut and hemocytes at 12 and 9 h post‐infection respectively. These results suggest that TmDef and TmDef‐like genes play important roles in protecting T. molitor from microbial contact. [ABSTRACT FROM AUTHOR]

Antimicrobial peptides (AMPs) are effector candidates that elicit humoral immunity in invertebrates. AMPs facilitate bacterial clearance by either physically disrupting the microbial membranes or the intracellular targets. In the Coleopteran pest, Tenebrio molitor, transcriptional regulation of AMPs has been studied in the context of innate immune signaling cascades and antimicrobial immunity. Here, we report the transcriptional response of three AMP genes, Coleoptericin A, B, and C (TmCole A, B and C) in T. molitor in response to bacterial (Escherichia coli, Staphylococcus aureus), and fungal (Candida albicans) challenges. These genes were expressed essentially in the gut and hemocytes followed by the integument tissue of the T. molitor larva. Further, these genes were highly expressed in the late‐larval, pupal, and early adult stages. Furthermore, while all of these transcripts were highly upregulated in the fat body and Malpighian tubules after bacterial challenge, TmCole B and TmCole C were induced in the gut after E. coli challenge. Fungal stimulation was not required for the upregulation of the transcription of Coleoptericin genes in T. molitor. [ABSTRACT FROM AUTHOR]

Toll and IMD pathways regulate antimicrobial innate immune responses in insect model systems. The transcriptional activation of antimicrobial peptides (AMPs) confers humoral immunity in the host against invaded pathogens. The IKK kinase complex (IKKα, IKKβ, and the regulatory subunit IKKγ/NEMO) centrally regulates the NF-κB response to various stimuli. It triggers an appropriate antimicrobial immune response in the host. In this study, a Tm IKKβ (or Tm Ird5) homolog was screened from the RNA-seq database of the coleopteran beetle, Tenebrio molitor. A single exon characterizes the Tm IKKβ gene, and the open reading frame (ORF) comprises of 2112 bp that putatively encodes a polypeptide of 703 amino acid residues. Tm IKKβ contains a serine/threonine kinase domain and is phylogenetically close to Tribolium castaneum IKKβ homolog (Tc IKKβ). TmIKKβ transcripts were highly expressed in the early pupal (P1) and adult (A5) stages. Among the tissues, TmIKKβ showed higher expression in the integument of the last instar larvae and the fat body and hemocytes of 5-day-old adults. TmIKKβ mRNA was upregulated post- E. coli challenge to the host. Moreover, RNAi-based TmIKKβ mRNA silencing increased host larvae' susceptibility against E. coli, S. aureus and C. albicans. TmIKKβ RNAi in the fat body led to a downregulation in mRNA expression of ten out of fourteen AMP genes, including TmTenecin1, -2, and -4 ; TmDefensin, and -like ; TmColeoptericinA, and -B ; and TmAttacin1a, - 1b, and -2 , suggesting the requirement of the gene in antimicrobial innate immune responses. Further, a decrease in the mRNA expression of NF-κB factors such as TmRelish, TmDorsal1 , and TmDorsal2 in the fat body of T. molitor larvae was observed post-microorganisms challenge. Thus, Tm IKKβ regulates antimicrobial innate immune responses in T. molitor. • We have newly identified IκB kinase β gene from the Tenebrio molitor , named TmIKKβ and domain analysis indicated that it contains one Serine/Threonine protein kinase catalytic domain, suggesting that TmIKKβ may regulate cell signaling by phosphorylation. • The temporal and spatial expression patterns of TmIKKβ transcripts and its induction patterns in responses to microbial challenges indicated that the TmIKKβ may have important roles in development as well as immune responses against microbial challenges. • We have investigated the effects of TmIKKβ RNAi on larval survivability, and expression patterns of antimicrobial peptide (AMP) genes and transcription factors for Toll and Imd pathways to understand the critical function of TmIKKβ in antimicrobial immune responses. [ABSTRACT FROM AUTHOR]

The cystine knot protein Spätzle is a Toll receptor ligand that modulates the intracellular signaling cascade involved in the nuclear factor kappa B (NF-κB)-mediated regulation of antimicrobial peptide (AMP)-encoding genes. Spätzle-mediated activation of the Toll pathway is critical for the innate immune responses of insects against Gram-positive bacteria and fungi. In this study, the open reading frame (ORF) sequence of Spätzle-like from T. molitor (TmSpz-like) identified from the RNA sequencing dataset was cloned and sequenced. The 885-bp TmSpz-like ORF encoded a polypeptide of 294 amino acid residues. TmSpz-like comprised a cystine knot domain with six conserved cysteine residues that formed three disulfide bonds. Additionally, TmSpz-like exhibited the highest amino acid sequence similarity with T. castaneum Spätzle (TcSpz). In the phylogenetic tree, TmSpz-like and TcSpz were located within a single cluster. The expression of TmSpz-like was upregulated in the Malpighian tubules and gut tissues of T. molitor. Additionally, the expression of TmSpz-like in the whole body and gut of the larvae was upregulated at 24 h post-E. coli infection. The results of RNA interference experiments revealed that TmSpz-like is critical for the viability of E. coli-infected T. molitor larvae. Eleven AMP-encoding genes were downregulated in the E. coli-infected TmSpz-like knockdown larvae, which suggested that TmSpz-like positively regulated these genes. Additionally, the NF-κB-encoding genes (TmDorX1, TmDorX2, and TmRelish) were downregulated in the E. coli-infected TmSpz-like knockdown larvae. Thus, TmSpz-like plays a critical role in the regulation of AMP production in T. molitor in response to E. coli infection. [ABSTRACT FROM AUTHOR]

IKKγ/NEMO is the regulatory subunit of the IκB kinase (IKK) complex, which regulates the NF-κB signaling pathway. Within the IKK complex, IKKγ/NEMO is the non-catalytic subunit, whereas IKKα and IKKβ are the structurally related catalytic subunits. In this study, TmIKKγ was screened from the Tenebrio molitor RNA-Seq database and functionally characterized using RNAi screening for its role in regulating T. molitor antimicrobial peptide (AMP) genes after microbial challenges. The TmIKKγ transcript is 1521 bp that putatively encodes a polypeptide of 506 amino acid residues. TmIKKγ contains a NF-κB essential modulator (NEMO) and a leucine zipper domain of coiled coil region 2 (LZCC2). A phylogenetic analysis confirmed its homology to the red flour beetle, Tribolium castaneum IKKγ (TcIKKγ). The expression of TmIKKγ mRNA showed that it might function in diverse tissues of the insect, with a higher expression in the hemocytes and the fat body of the late-instar larvae. TmIKKγ mRNA expression was induced by Escherichia coli, Staphylococcus aureus, and Candida albicans challenges in the whole larvae and in tissues such as the hemocytes, gut and fat body. The knockdown of TmIKKγ mRNA significantly reduced the survival of the larvae after microbial challenges. Furthermore, we investigated the tissue-specific induction patterns of fourteen T. molitor AMP genes in TmIKKγ mRNA-silenced individuals after microbial challenges. In general, the mRNA expression of TmTenecin1, -2, and -4; TmDefensin1 and -2; TmColeoptericin1 and 2; and TmAttacin1a, 1b, and 2 were found to be downregulated in the hemocytes, gut, and fat body tissues in the TmIKKγ-silenced individuals after microbial challenges. Under similar conditions, TmRelish (NF-κB transcription factor) mRNA was also found to be downregulated. Thus, TmIKKγ is an important factor in the antimicrobial innate immune response of T. molitor. [ABSTRACT FROM AUTHOR]

Vertebrates rely on the most sophisticated adaptive immunity to defend themselves against various pathogens. This includes immunologic memory cells, which mount a stronger and more effective immune response against an antigen after its first encounter. Unlike vertebrates, invertebrates' defense completely depends on the innate immunity mechanisms including humoral and cell-mediated immunity. Furthermore, the invertebrate equivalent of the memory cells was discovered only recently. Since the discovery of transgenerational immune priming (TGIP) in crustaceans, numerous findings have proven the IP in invertebrate classes such as insects. TGIP can be induced through maternal priming pathways such as transcriptional regulation of antimicrobial peptides, and also paternal IP including the induction of proPO system activity. We appraise the diversity and specificity of IP agents to provide sustained immunologic memory in insects, particularly T. molitor in the review. An understanding of IP (more so TGIP) response in T. molitor will deepen our knowledge of invertebrate immunity, and boost the mass-rearing industry by reducing pathogen infection rates. • Unlike mammals, solo arm of defense mechanism in invertebrates is innate immunity, particularly, antimicrobial peptide production. • The ability of being immunized against a preexisting elicitor, was a matter of uncertainty until a wile ago. • This phenomenon known as "immune priming", can be transferred to progenies by both parents. • The diversity and specificity of immune priming in insects more precisely, Tenebrio molitor has been investigated in numbers of studies. • Understanding of immune priming in insects can provide us with novel strategies and applications at the field during T. molitor mass rearing. [ABSTRACT FROM AUTHOR]