Induction Of Defenses Research Articles

Clonal Saplings of Trembling Aspen Do Not Coordinate Defense Induction.

Induction of plant chemical defenses in response to insect feeding may be localized to the site of damage or expressed systemically, mediated by signal transduction throughout the plant. Such systemic induction processes have been widely investigated in plants with single stems, but rarely in clonal plants comprised of multiple ramets with vascular connections. For a clonal tree species such as trembling aspen (Populus tremuloides Michx), integration of induced defense within clones could be adaptive, as clones are spatially extensive and susceptible to outbreak herbivores. We used pairs of aspen saplings with shared roots, replicated from three genotypes, to determine whether defense-induction signals are communicated within clones. One ramet in each pair was subjected to a damage treatment (feeding by Lymantria dispar, followed by mechanical damage), and subsequent changes in leaf defensive chemistry were measured in both ramets. Responses to damage varied by defense type: condensed tannins (CTs) increased in damaged ramets but not in connected undamaged ramets, whereas salicinoid phenolic glycosides (SPGs) were not induced in any ramets. Genotypes varied in their levels of CTs, but not in their levels of SPGs, and responded similarly to damage treatment. These results suggest that, even with both vascular and volatile information available, young aspen ramets do not induce defenses based on signals or metabolites from other ramets. Thus, unlike other clonal plant species, aspen do not appear to coordinate defense induction within clones. Lack of coordinated early induction in aspen may be related to the function of CTs in tolerance, rather than resistance.

Oligosaccharides successfully thwart hijacking of the salicylic acid pathway by Phytophthora infestans in potato leaves

Potato growing is severely threatened by the late blight agent Phytophthora infestans, which is usually controlled by massive amounts of fungicides. While variety resistance is often bypassed by the pathogen, the plant innate immunity opens the way to new biological plant protection tools, e.g. the COS‐OGA elicitor. This oligosaccharide composition mimics the interaction between plants and fungal pathogens as it combines chitosan oligomers (COS) with pectin‐derived oligogalacturonides (OGA). Two different COS‐OGA elicitors were evaluated against potato late blight: FytoSave, mainly efficient against powdery mildews, and FytoSol, a new composition still under development. In addition, a comparative study of plant defence induction was performed, focusing on the effect of repeated sprayings as well as on the stimulation of salicylic acid (SA), jasmonic acid and ethylene‐related pathways during the biotrophic and necrotrophic growth stages of the pathogen. The FytoSave elicitor strongly increased the SA content but failed to induce sufficient protection against late blight, while FytoSol maintained or even decreased the free SA content in the presence of P. infestans and was completely efficient. Surprisingly, the necrotrophic development of P. infestans occurred along with a strong leaf accumulation of free SA and SA‐related transcripts. This may represent an attempt by P. infestans to divert plant defences for its own benefit. Preventive sprayings with FytoSol but not FytoSave completely impeded this hijacking. FytoSol seemed to keep the SA pathway under control, thereby preventing its diversion by P. infestans.

Elucidating the mechanism of action of copper heptagluconate on the plant immune system against Pseudomonas syringae in tomato (Solanum lycopersicum L).

Phytopathogenic problems caused by the bacterial pathogen Pseudomonas syringae in tomato are becoming more serious due to the emergence of strains resistant to classical pesticides. This has led to research into new formulations with lower environmental problems. One of the most promising alternatives to the use of classical pesticides is the induction of natural plant defences. New formulations based on Cu complexed with heptagluconic acid induce plant innate defences and could be an alternative to classical treatments based on inorganic Cu against bacterial speck. To study the efficacy of this compound in tomato against P. syringae, we tested its systemic effect Applying the treatments via radicular. Treated plants showed less infection development and lower number of viable bacteria in leaves. We also observed better performance of parameters involved in plant resistance such as the antioxidant response and the accumulation of phenolic compounds. Results showed that soil drench applications can be highly effective for the prevention and control of bacterial speck in tomato plants, showing a reduction in symptoms of ∼ 50%. Moreover, application of Cu heptagluconate induced accumulation of the plant polyphenols caffeic and chlorogenic acids, and reduced the amount of reactive oxygen species in infected plants. © 2018 Society of Chemical Industry.

Wilt diseases of tomato (<em>Lycopersicum esculentum</em>) and chilli (<em>Capsium annum</em>) and their management strategies: Emphasis on the strategies employed in Sri Lanka: A review

Wilt is one of the major diseases causing economic losses in many crops. It is caused by infections of many bacterial (Ralstonia solanacearum), fungal (Fusarium spp., Vertcillium spp., Rhizoctonia spp., Sclerotium spp.), oomycete (Pythium spp., Phytophthora spp.) and viral (Tomato spotted wilt virus) pathogens. This review provides an overview on the control strategies used in other countries for the wilt disease in highly susceptible vegetable/fruit crops; tomato and chilli and make comparisons with Sri Lanka.Many studies have been performed on the prevalence, severity, pathogenicity and the control of these infections in both crops worldwide. Wilt in tomato is caused mainly by Ralstonia solanacearum and Fusarium oxysporum and in chilli mainly by Fusarium oxysporum. Tomato bacterial wilt is successfully managed through usage of resistant cultivars, grafting, biological control agents, inducing host systemic resistance and integrated management. Tomato and chilli wilt caused by Fusarium sp. have been successfully controlled mainly through the application of chemicals and biological approaches such as systemic defense induction and the use of microbial antagonists.In Sri Lanka, tomato wilt is reported as being the result of bacterial, fungal and viral infections which have been mainly controlled by the usage of resistant cultivars, physical measures and cultural practices. Chilli wilt in Sri Lanka has not been thoroughly studied yet. But application of fungicides has been an effective strategy for fungal wilts. Wilt threat of tomato and chilli in Sri Lanka has to be further studied for the proper management of these infections and for freeing tomato and chilli cultivations from the wilt disease.

Locally and systemically induced glucosinolates follow optimal defence allocation theory upon root herbivory

AbstractHerbivore‐induced defences in plants are considered a strategy to manage multiple interactions while saving resources. The optimal defence theory (ODT) is one of the most prominent theoretical frameworks to explain the defence allocation patterns within plants. It was recently shown that theODTgenerally applies to constitutive glucosinolate (GSL) allocation in shoot and root organs. Previous studies showed that both root and shoot herbivore feeding may alter defence allocation over plant organs. For shoots, the effect depends on where the herbivores feed. It is as yet unknown whether similar principles apply to root‐herbivore‐inducedGSLs.To analyse the effects of root localized herbivore feeding onGSLallocation, we conducted a pot experiment usingAnomala cupreagrubs and four Brassicaceae;Brassica rapa,B. nigra,B. oleraceaandSinapis alba. Individuals of these four plant species were grown in dedicated mesocosms. The grubs were confined either to the bottom soil, the middle section or the topsoil. Plants grown in the same set‐ups but without root herbivores served as controls. Glucosinolate levels of the leaf lamina, petiole and stem as well as of the taproot, lateral roots and fine roots were measured after 8 days of herbivory.Plant biomass reduction due to herbivory was the largest when herbivores were confined to the topsoil. In the threeBrassicaspecies, taprootGSLlevels increased upon herbivory independent of where the root herbivores were feeding. Glucosinolate levels in fine roots and shoots, on the other hand, hardly responded to root herbivory. IndoleGSLs, which are more effective to pathogens than to herbivores, were more strongly induced than aliphatic and aromaticGSLs, especially in the taproots.Sinapis albadid not show remarkable increments in anyGSLlevel upon herbivory.These results show that locally and systemically induced defences in roots are consistent with theODT: The taproot which is the most vulnerable and valuable to plant performance shows the highest increase in defence induction. The inducedGSLprofiles suggest that the response may not only target herbivores, but may also help to prevent secondary infection by microbial pathogens.Aplain language summaryis available for this article.

An Assessment of the Physiological Costs of Autogenous Defenses in Native and Introduced Lady Beetles.

Many lady beetles expel an autogenously produced alkaloid-rich 'reflex blood' as an antipredator defense. We conducted an experiment to determine whether there was a measurable fitness cost associated with the daily induction of this defensive behavior, and whether costs differed between native (Coccinella novemnotata Herbst (Coleoptera: Coccinellidae)) and invasive species (Coccinella septempunctata L. (Coleoptera: Coccinellidae) and Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae)). Newly mated females were provided a restricted or unrestricted amount of aphids and were bled for 10 d. We measured the mass of reflex blood produced and the total number and viability of eggs laid per day. The amount of reflex blood released per day increased for C. septempunctata at the restricted level and did not change for any other species-diet level combination. We did not detect a significant cost of reflex bleeding on the quantity or viability of eggs laid by any species, even at the restricted aphid level. Remarkably, bled individuals at the ad libitum level laid significantly more viable eggs compared to controls. All species laid significantly fewer total eggs (49-69% fewer) at the low versus high aphid level. These results demonstrate that while resource scarcity has a negative impact on fecundity, repeated use of the reflex bleeding defense system does not. These results support the findings of other reports and strongly suggest that adult lady beetles incur no measurable physiological costs related to the induction of the reflex-bleeding defense.

Acceleration or deceleration of litter decomposition by herbivory depends on nutrient availability through intraspecific differences in induced plant resistance traits

Abstract Herbivores often induce changes in plant defensive chemistry or nutrient content that may respectively inhibit or promote microbial decomposition of senesced litter. Often the directional impact of herbivores on decomposition is considered to be a property of a species or ecosystem. While rarely explored, plasticity in the induction of defensive strategies across environmental gradients may also result in divergent impacts of herbivores on decomposition (deceleration vs. acceleration). Here, we examined how soil nutrient conditions determine legacy effects of herbivory, using nine goldenrod genotypes grown across four levels of nutrient supply and with or without grasshopper herbivory. In this species, herbivory induces defensive traits in genotypes grown in high nutrient conditions but induces tolerance (compensatory growth) in low nutrient conditions. We combined senesced litter from each treatment with a common soil inoculum in microcosms and measured soil respiration and litter mass loss over 100 days as estimates of decomposition. Plant genotype, nutrient environment, and herbivory each altered decomposition. The legacy effect of herbivory overwhelmed the positive effect of high soil nutrient supply on decomposition. This significant herbivory × nutrient environment interaction meant that herbivore‐induced plants grown in high nutrient environments produced litter that was more resistant to microbial breakdown than litter from the same genotype not exposed to herbivores. But the opposite occurred at low nutrient levels where litter from herbivore‐induced plants was most readily decomposed. Furthermore, we mechanistically tie treatment‐induced changes in leaf traits to decomposition rates. Lastly, we demonstrate a significant correlation between herbivore growth rates on living tissue and decomposition efficiency by the microbial community of senesced tissue, suggesting that herbivores and microbes perceive the “quality” of the induced substrate similarly. Synthesis. Herbivore‐induced changes in leaf palatability and trait expression due to defense induction or compensatory growth can cascade through to either inhibit or promote the decomposability of leaf litter within a single species. Here, the key determinant of which occurs is the soil fertility environment of the goldenrod clone. These findings offer mechanistic understanding of how spatial heterogeneity in ecosystem process rates may be generated by spatial variation in herbivory and nutrient availability.

In silico identification of agriculturally important molecule(s) for defense induction against bacterial blight disease in Soybean (Glycine max)

In silico identification of agriculturally important molecule(s) for defense induction against bacterial blight disease in Soybean (Glycine max)

Exercise as a calorie restriction mimetic. Implications for the treatment of age associated frailty

The free radical theory of aging has provided a theoretical framework for an enormous amount of work leading to advances in our understanding of aging. A critical blow to the free radical theory of aging came from epidemiological studies showing that antioxidant supplementation did not lower the incidence of age-associated diseases. However, work from many laboratories supports the theory, for instance showing that overexpression of antioxidant enzymes results in increases not only in life-span but also in health-span. Improving healthy aging means delaying disability. Disability is often preceded by a state characterized by reduced capacity to respond to stressors, caused by a decline in functional reserves. This condition, frailty, might precede by several years the development of disability. We have recently found that a mouse model with overexpression of G6PD have lower levels of ROS-derived damage and this is accompanied by a protection from frailty. Two interventions with translational potential to improve healthy aging are caloric restriction and exercise training. Both of them share a common protective molecular mechanism, a reduction in oxidative damage through the induction of the antioxidant defense.

Spontaneous translocation of a human enterococcal gut pathobiont drives systemic autoimmunity

Abstract Host-microbiota interactions in the pathogenesis of autoimmunity remain poorly understood. Here, we show that a gut commensal, Enterococcus gallinarum, reaches lymphocytes beyond the gut barrier in the mesenteric lymph node, liver and spleen of lupus-prone (NZWxBXSB)F1 mice. Oral vancomycin treatment suppressed growth of E. gallinarum in tissues of these mice, prevented organ manifestations and mortality by lowering pathogenic autoantibodies, Th17 and Tfh cells. Hepatocyte-commensal cocultures revealed induction of the lupus signature cytokine IFN-α as well as the AhR pathway (AhR, Cyp1a1, Cyp1a2) that could be linked to Th17 induction in vivo. E. gallinarum monocolonization in germ-free C57BL/6 animals allowed for translocation to internal organs and induction of autoantibodies as well as increase of lamina propria plasmacytoid dendritic cells (pDCs) and systemic Th17 cells. Additionally, RNA-Seq of short-term ileum E. gallinarum-monocolonized mice demonstrated induction of molecules related to barrier function (occludin, claudins, Plvap, Axin2), the mucus layer (mucin, Fut2), antimicrobial defence (Reg3b, Defa2), and inflammation and pDC induction (AhR/Cyp1a1, Enpp3). Species-specific PCR of sterilely obtained liver tissue from autoimmune hepatitis and lupus patients revealed also E. gallinarum, suggesting similar processes in humans. Accordingly, human hepatocyte-commensal coculture demonstrated production of the same autoimmune-promoting factors as with murine hepatocytes. Collectively, these data indicate that a human pathobiont translocates spontaneously to promote autoimmunity in genetically predisposed hosts, broadening our understanding of autoimmune host-microbiota interactions.

Prior infections or defence priming: what determines the risk of trematode infections in amphipod hosts?

Inducible defences against parasites that are only activated when needed can mitigate the cost of immune or behavioural evasion of parasites. Priming of the immune system and activation of behavioural defences can follow exposure to cues associated with imminent infection risk. In contrast, prior infection can cause immune depression or leave the host with less energy to defend itself against further infections. We investigate the priming of anti-parasite defences and the effect of prior infections in the amphipod Paracalliope fluviatilis, the second intermediate host of the trematode Coitocaecum parvum. During experimental infections, amphipods that had been primed by exposure to chemical cues (from first intermediate snail hosts infected by C. parvum) of infection risk were not better at avoiding further infection than control amphipods. All amphipods showed the same swimming behaviour, whether or not they had been primed by chemical cues from infected snails, or whether or not they were in the presence of live infective stages. In contrast, regardless of whether or not they had been exposed to control water or chemical cues from infected snails, amphipods harbouring prior infections acquired in nature were significantly more likely to acquire new parasites under controlled conditions. These results suggest that the induction of defences via external cues associated with the threat of infection do not play a role in the amphipod's anti-parasite strategy. However, prior infections may pre-dispose a host to acquire further parasites, with consequences for the distribution of parasites among host individuals and the regulation of the host population.

Evaluating toxicity of copper(II) oxide nanoparticles (CuO-NPs) through waterborne exposure to tilapia (Oreochromis mossambicus) by tissue accumulation, oxidative stress, histopathology, and genotoxicity.

Metal oxide nanoparticles are widely used in industries, and peak level can be confirmed in their surroundings. In the present study, the sub-lethal effects of CuO-NPs from low to high concentration as 0.5 to 1.5mg/L were observed in tilapia (Oreochromis mossambicus). Accumulation of copper from CuO-NPs was increased with the increase in doses, and maximum accumulation was found in the gill than liver and muscles. The increased lipid peroxidation level was observed in the gill as compared to liver, and the similar results were obtained in catalase and glutathione while superoxide dismutase level was higher in the liver than gills. In histological alterations, gill edema, curved tips, fusion of gill lamellae, and thickening of primary and secondary gill lamellae were observed. Necrosis and apoptosis with condensed nuclear bodies and pyknotic nuclei were observed in the liver at the highest dose concentration. In a genotoxic study, the highest value of % tail DNA and olive tail movement was observed with increasing concentrations. Copper oxide nanoparticles has greater potential to accumulate in the soft tissues, which may cause respiratory distress such as oxidative stress, induction of antioxidant defense by raising glutathione, organ pathology, and genotoxicity.

Direct Effects of Physcion, Chrysophanol, Emodin, and Pachybasin on Germination and Appressorium Formation of the Barley ( Hordeum vulgare L.) Powdery Mildew Fungus Blumeria graminis f. sp. hordei (DC.) Speer.

Several anthraquinone derivatives are active components of fungicidal formulations particularly effective against powdery mildew fungi. The antimildew effect of compounds such as physcion and chrysophanol is largely attributed to host plant defense induction. However, so far a direct fungistatic/fungicidal effect of anthraquinone derivatives on powdery mildew fungi has not been unequivocally demonstrated. By applying a Formvar-based in vitro system we demonstrate a direct, dose-dependent effect of physcion, chrysophanol, emodin, and pachybasin on conidial germination and appressorium formation of Blumeria graminis f. sp. hordei (DC.) Speer, the causative agent of barley ( Hordeum vulgare L.) powdery mildew. Physcion was the most effective among the tested compounds. At higher doses, physcion mainly inhibited conidial germination. At lower rates, however, a distinct interference with appressorium formation became discernible. Physcion and others may act by modulating both the infection capacity of the powdery mildew pathogen and host plant defense. Our results suggest a specific arrangement of substituents at the anthraquinone backbone structure being crucial for the direct antimildew effect.

Cumulative effects of transgenerational induction on plant palatability to generalist and specialist herbivores

Abstract. Herbivore damage can induce anti-herbivore traits in plants. However, there is little data regarding how these induced traits affect a plant's palatability (an important factor in determining the likelihood and magnitude of herbivore damage) across multiple generations post-induction, or whether the effect of transgenerational induction differs between generalist and specialist herbivores. Here we used palatability as a measure of the effects of transgenerational defensive induction in wild radish plants. We conducted a greenhouse experiment to determine whether generalist (slugs) and specialist (caterpillars of the white cabbage butterfly) herbivores' preference for wild radish differed depending on the number of previous generations that experienced herbivory. We found lowered palatability in plants with two or three inductions in their past in the case of generalist slugs, while palatability to a specialist herbivore was not affected by transgenerational induction. We conclude that the history of herbivory experienced by a plant's ancestors over multiple generations may play an important role in its ability to defend itself against generalist herbivores, but not against the specialists with whom they have co-evolved. Our findings suggest that the effects that multiple past inductions may have on palatability down the family line can be expected to have ecological and evolutionary implications.

Correction: Distinct temporal roles for the promyelocytic leukaemia (PML) protein in the sequential regulation of intracellular host immunity to HSV-1 infection.

[This corrects the article DOI: 10.1371/journal.ppat.1006769.].

Emerging Mechanisms of Innate Immunity and Their Translational Potential in Inflammatory Bowel Disease.

Activation of the innate immune system through pattern-recognition receptor (PRR) signaling plays a pivotal role in the early induction of host defense following exposure to pathogens. Loss of intestinal innate immune regulation leading aberrant immune responses has been implicated in the pathogenesis of inflammatory bowel disease (IBD). The precise role of PRRs in gut inflammation is not well understood, but considering their role as bacterial sensors and their genetic association with IBD, they likely contribute to dysregulated immune responses to the commensal microbiota. The purpose of this review is to evaluate the emerging functions of PRRs including their functional cross-talk, how they respond to mitochondrial damage, induce mitophagy or autophagy, and influence adaptive immune responses by interacting with the antigen presentation machinery. The review also summarizes some of the recent attempts to harness these pathways for therapeutic approaches in intestinal inflammation.

Intraspecific differences in plant defense induction by fall armyworm strains.

The underlying adaptive mechanisms by which insect strains are associated with specific plants are largely unknown. In this study, we investigated the role of herbivore-induced defenses in the host plant association of fall armyworm (Spodoptera frugiperda) strains. We tested the expression of herbivore-induced defense-related genes and the activity of plant-defensive proteins in maize and Bermuda grass upon feeding by fall armyworm strains. The rice strain caterpillars induced greater accumulation of proteinase inhibitors in maize than the corn strain caterpillars. In Bermuda grass, feeding by the corn strain suppressed induction of trypsin inhibitor activity whereas the rice strain induced greater activity levels. Differences in elicitation of these plant defenses by the two strains seems to be due to differences in the activity levels of the salivary enzyme phospholipase C. The levels of plant defense responses were negatively correlated with caterpillar growth, indicating a fitness effect. Our results indicate that specific elicitors in the saliva of fall armyworm stains trigger differential levels of plant defense responses that affect caterpillar growth and thus may influence host plant associations in field conditions. The composition and secretion of plant defense elicitors may have a strong influence in the host plant association of insect herbivores.

Introns of the tobacco resistance gene N play important roles in elicitor-responsive upregulation and efficient induction of defense responses

The tobacco resistance gene N is known to be upregulated transcriptionally upon infection with Tobacco mosaic virus or the transient expression of the virus elicitor (termed p50), which is the helicase domain of the virus replicase, leading to cell death-associated defense responses. To investigate the roles of the encoded protein and introns of the N gene in its elicitor-triggered upregulation, we developed an Agrobacterium-mediated transient gene transfer system to express the N transgene controlled by the upstream region of the N gene itself in N-lacking tobacco. The transcript level of the N transgene with the introns was enhanced sharply when the p50 transgene was coexpressed. Introduction of a frameshift mutation in the intron-containing N transgene abolished its response to the elicitor, but an additional expression of the functional N protein supplied in trans complemented the upregulation of the mutant transgene. In contrast, an intron-less N transgene failed to be upregulated by the p50 coexpression, resulting in delayed and attenuated cell death and slow induction of defense-related gene expression. In addition, introduction of a frameshift mutation in the intron-less N transgene resulted in no response to the elicitor even with coexpression of the functional N protein. Our data provide the first evidence for important roles of introns of a resistance gene in elicitor-responsive gene regulation and efficient defense induction.

Distinct temporal roles for the promyelocytic leukaemia (PML) protein in the sequential regulation of intracellular host immunity to HSV-1 infection.

Detection of viral nucleic acids plays a critical role in the induction of intracellular host immune defences. However, the temporal recruitment of immune regulators to infecting viral genomes remains poorly defined due to the technical difficulties associated with low genome copy-number detection. Here we utilize 5-Ethynyl-2’-deoxyuridine (EdU) labelling of herpes simplex virus 1 (HSV-1) DNA in combination with click chemistry to examine the sequential recruitment of host immune regulators to infecting viral genomes under low multiplicity of infection conditions. Following viral genome entry into the nucleus, PML-nuclear bodies (PML-NBs) rapidly entrapped viral DNA (vDNA) leading to a block in viral replication in the absence of the viral PML-NB antagonist ICP0. This pre-existing intrinsic host defence to infection occurred independently of the vDNA pathogen sensor IFI16 (Interferon Gamma Inducible Protein 16) and the induction of interferon stimulated gene (ISG) expression, demonstrating that vDNA entry into the nucleus alone is not sufficient to induce a robust innate immune response. Saturation of this pre-existing intrinsic host defence during HSV-1 ICP0-null mutant infection led to the stable recruitment of PML and IFI16 into vDNA complexes associated with ICP4, and led to the induction of ISG expression. This induced innate immune response occurred in a PML-, IFI16-, and Janus-Associated Kinase (JAK)-dependent manner and was restricted by phosphonoacetic acid, demonstrating that vDNA polymerase activity is required for the robust induction of ISG expression during HSV-1 infection. Our data identifies dual roles for PML in the sequential regulation of intrinsic and innate immunity to HSV-1 infection that are dependent on viral genome delivery to the nucleus and the onset of vDNA replication, respectively. These intracellular host defences are counteracted by ICP0, which targets PML for degradation from the outset of nuclear infection to promote vDNA release from PML-NBs and the onset of HSV-1 lytic replication.

Research Article Sub-lethal doses of neonicotinoid and carbamate insecticides reduce the lifespan and alter the expression of immune health and detoxification related genes of honey bees (Apis mellifera)

Honey bees (Apis mellifera) are exposed to sublethal doses of insecticides, but little is known about insecticide effects on their survivorship associated to health-related gene expression. To test the effect of sublethal doses of clothianidin, imidacloprid and carbaryl on the lifespan and health of honey bees, workers were orally and topically exposed to LD5 doses of these insecticides. The survivorship of treated bees was monitored and the expression of three immune-related genes, hymenoptaecin (AmHym), basket (AmBask) and lysozyme (AmLyso2) was analyzed at 24 and 72 hours post treatment (hpt), as well as that of the antioxidant-related gene vitellogenin (AmVit2), the poly-U binding factor (AmPuf68), and the detoxification gene cytochrome P450 (AmCYP9Q3). The three insecticides significantly reduced the length of life of bees but the mode of application did not affect survivorship. AmHym, AmBask and AmVit2 expression was significantly down-regulated at 72 hpt in bees treated with clothianidin and imidacloprid, indicating immunosuppression. However, AmLyso2, AmCYP9Q3 and AmPuf68 were significantly up-regulated. The down-regulation of AmVit2 could have caused decreased resistance to oxidative stress. AmPuf68 expression could be associated with increased protection against xenobionts. AmCYP9Q3 was up-regulated at 24 and 72 hpt in oral exposures, but only until 72 hpt in topical exposures, indicating faster sensitivity towards detoxification mechanisms in oral treatments. This study demonstrated detrimental effects of sublethal doses of clothianidin, imidacloprid and carbaryl on honey bee survivorship, immunity and antioxidant mechanisms, and an induction of defense and detoxification responses that could be physiologically costly to the bees.