Pesticide Stress Research Articles

Comparative analysis of transcriptomic responses to sub-lethal levels of six environmentally relevant pesticides in Saccharomyces cerevisiae.

Accidental spills and misuse of pesticides may lead to current and/or legacy environmental contamination and may pose concerns regarding possible risks towards non-target microbes and higher eukaryotes in ecosystems. The present study was aimed at comparing transcriptomic responses to effects of sub-lethal levels of six environmentally relevant pesticide active substances in the Saccharomyces cerevisiae eukaryotic model. The insecticide carbofuran, the fungicide pyrimethanil and the herbicides alachlor, S-metolachlor, diuron and methyl(4-chloro-2-methylphenoxy)acetate were studied. Some are currently used agricultural pesticides, while others are under restricted utilization or banned in Europe and/or North America albeit being used in other geographical locations. In the present work transcriptional profiles representing genome-wide responses in a standardized yeast population upon 2 h of exposure to concentrations of each compound exerting equivalent toxic effects, i.e., inhibition of growth by 20% relative to the untreated control cells, were examined. Hierarchical clustering and Venn analyses of the datasets of differentially expressed genes pointed out transcriptional patterns distinguishable between the six active substances. Functional enrichment analyses allowed predicting mechanisms of pesticide toxicity and response to pesticide stress in the yeast model. In general, variations in transcript numbers of selected genes assessed by Real-Time quantitative reverse transcription polymerase chain reaction confirmed microarray data and correlated well with growth inhibitory effects. A possible biological relevance of mechanistic predictions arising from these comparative transcriptomic analyses is discussed in the context of better understanding potential modes of action and adverse side-effects of pesticides.

Exposure to chlorpyrifos induces morphometric, biochemical and lipidomic alterations in green beans (Phaseolus vulgaris)

Chlorpyrifos (CPF) is a worldwide used pesticide that raises concerns from the environmental and human health perspectives. The presence of pesticides such as CPF in edible vegetables has been already reported, but little is known about the effects induced by this pesticide stress on the morphology, oxidative response and lipid composition of treated plants. In this work, green bean plants (Phaseolus vulgaris) were exposed to increasing concentrations of CPF and the different plant parts (roots, stem bases, stem, leaves, pods and beans) were subjected to different analyses. First, morphometric parameters and the oxidative response caused by CPF were explored. In a second phase of the study, an untargeted lipidomic analysis of the different tissue extracts was performed and MALDI-TOF mass spectrometry images of pods and beans were recorded and analysed to illustrate the spatial distribution of the changes observed. As a result of CPF treatment, plants showed a significant decrease in their height, leaf length, and pod number. The biochemical analysis showed lipid peroxidation and the activation of antioxidant mechanisms in roots, stem and leaves. Regarding the lipidomic results, changes in lipid levels were observed, mainly in leaves, pods and seeds. The main changes observed were a reduction of photosynthetic pigments and lipids in leaves and a decrease of triacylglycerols levels in pods and seeds. This last point was confirmed by the analysis of mass spectrometry images of the pods. These observations suggest that CPF would affect the yield of green bean crops as well as the nutritional value of pods and beans. This work represents a step forward in the knowledge of the effects of CPF, one of the most used pesticides worldwide, in plants.

Interactions between immunotoxicants and parasite stress: Implications for host health

Many organisms face a wide variety of biotic and abiotic stressors which reduce individual survival, interacting to further reduce fitness. Here we studied the effects of two such interacting stressors: immunotoxicant exposure and parasite infection. We model the dynamics of a within-host infection and the associated immune response of an individual. We consider both the indirect sub-lethal effects on immunosuppression and the direct effects on health and mortality of individuals exposed to toxicants. We demonstrate that sub-lethal exposure to toxicants can promote infection through the suppression of the immune system. This happens through the depletion of the immune response which causes rapid proliferation in parasite load. We predict that the within-host parasite density is maximised by an intermediate toxicant exposure, rather than continuing to increase with toxicant exposure. In addition, high toxicant exposure can alter cellular regulation and cause the breakdown of normal healthy tissue, from which we infer higher mortality risk of the host. We classify this breakdown into three phases of increasing toxicant stress, and demonstrate the range of conditions under which toxicant exposure causes failure at the within-host level. These phases are determined by the relationship between the immunity status, overall cellular health and the level of toxicant exposure. We discuss the implications of our model in the context of individual bee health. Our model provides an assessment of how pesticide stress and infection interact to cause the breakdown of the within-host dynamics of individual bees.

Author's response: Pesticides and heat stress in the global epidemic of chronic kidney disease of non-traditional origin

Author's response: Pesticides and heat stress in the global epidemic of chronic kidney disease of non-traditional origin

Respuesta: Pesticidas y estrés térmico en la epidemia global de enfermedad renal crónica de causas no tradicionales

Respuesta: Pesticidas y estrés térmico en la epidemia global de enfermedad renal crónica de causas no tradicionales

Tolerance strategies in cyanobacterium Fischerella sp. under pesticide stress and possible role of a carbohydrate-binding protein in the metabolism of methyl parathion (MP)

The tolerance strategy of cyanobacterium Fischerella sp. under methyl parathion (MP) stress was investigated through proteomics analysis using 2-DE technique coupled with MALDI- TOF MS/MS. Proteomic study of the cyanobacterium treated with or without MP for two and eight days exhibited differential expressions of proteins related to photosynthesis, energy and protein metabolism, redox homeostasis, signal transduction and cellular defence. Inhibitory effect of MP on the growth of the test organism was more pronounced after the 2nd day of treatment and the majority of the proteins, except those involved in the protein metabolism (DnaK, Ef-Tu and proteases), were downregulated. However, the growth of the cyanobacterium was significantly less affected after the 8th day of MP treatment and a number of proteins, viz., antioxidative enzymes, signalling protein, chaperones, were induced. Transcript analyses of the genes of few upregulated and downregulated proteins, i.e., phycocyanin α subunit (cpcA), ribulose bisphosphate carboxylase (rbcl), F0F1 ATP synthase subunit α, F0F1 ATP synthase subunit β, SOD (sod), NifH (nif H), DnaK (dnaK) and Peptidase S8 showed similar results after the 8th day of MP treatment. Furthermore, some hypothetical proteins were also found to be upregulated in the cyanobacterium under MP stress. Functional prediction of four of these hypothetical proteins using bioinformatic tools revealed their roles in signalling and carbohydrate metabolism. Interestingly, one hypothetical protein was homologous to lectin and found to possess a binding pocket for MP. Therefore, this lectin-type protein of the cyanobacterium might have a crucial role in the removal and degradation of MP.

Identification and characterization of heat shock proteins in a parasitic wasp Chouioia cuneae (Hymenoptera: Eulophidae)

AbstractHeat shock proteins (HSPs) are known to be induced in response to various stress factors. Although HSPs have been studied in a number of insects, not much is known about HSPs in the natural enemies of insects, especially parasitoids. In this study, we identified and characterized five full‐length HSP genes (Cchsp40, Cchsp60, Cchsp70, Cchsp83, and Cchsp90) from an endoparasitic chalcid wasp, Chouioia cunea, which parasitizes the fall webworm, Hyphantria cunea pupae, a worldwide pest. The expression of Cchsps in response to temperature, pesticide stresses and UV radiation were also investigated by quantitative real‐time polymerase chain reaction (RT‐qPCR). The results showed that all five Cchsps were induced in response to hot and cold temperatures. Four pesticides induced the abundant expression of Cchsp70, Cchsp83 and Cchsp90 while ultraviolet radiation up‐regulated Cchsp40, Cchsp70, Cchsp83 and Cchsp90. These results indicate the different transcriptional profiles of the five different Cchsps in response to various abiotic stresses. The findings of this study provide insights into the response of C. cunea to abiotic stresses and insight into the use of this parasitoid in biological control strategies.

Revealing Pesticide Residues Under High Pesticide Stress in Taiwan's Agricultural Environment Probed by Fresh Honey Bee (Hymenoptera: Apidae) Pollen.

Significant pesticide residues are among the most serious problems for sustainable agriculture. In the beekeeping environment, pesticides not only impact a honey bee's survival, but they also contaminate bee products. Taiwan's agricultural environment has suffered from pesticide stress that was higher than that found in Europe and America. This study deciphered problems of pesticide residues in fresh honey bee pollen samples collected from 14 monitoring apiaries in Taiwan, which reflected significant contaminations within the honey bee population. In total, 155 pollen samples were screened for 232 pesticides, and 56 pesticides were detected. Among the residues, fluvalinate and chlorpyrifos showed the highest concentrations, followed by carbendazim, carbaryl, chlorfenapyr, imidacloprid, ethion, and flufenoxuron. The average frequency of pesticide residues detected in pollen samples was ca. 74.8%. The amounts and types of pesticides were higher in winter and in southwestern Taiwan. Moreover, five of these pollen samples were contaminated with 11-15 pesticides, with average levels between 1,560 and 6,390 μg/kg. Compared with the literature, this study emphasized that pollen gathered by honey bee was highly contaminated with more pesticides in Taiwan than in the America, France, and Spain. The ubiquity of pesticides in the pollen samples was likely due to the field applications of common pesticides. Recently, the Taiwanese government began to improve the pesticide policy. According to the resurvey data in 2016, there were reductions in several pesticide contamination parameters in pollen samples from west to southwest Taiwan. A long-term investigation of pollen pesticide residues should be conducted to inspect pesticides usage in Taiwan's agriculture.

Alterations in liver marker enzymes and recovery ability of cyprinids as indicators of aquatic pollution.

Information on the detection of pesticides in fresh water Lakes of Kashmir (Dal and Mansbal) through GC-MS technique is scarce, and also the recovery in biochemical parameters (AST, ALT and ALP) of fish after transferring them to clean media has not been reported yet. The water samples were collected from three sites and analyzed for their pesticide profile by dispersive liquid-liquid micro extraction (DLLME) followed by GC-MS. Influence of pesticides on liver marker enzymes of Cyprinus carpio and Carassius carassius was also investigated. The results obtained showed the presence of three main pesticides viz. chlorpyrifros, dimethoate and dichlorvos in waters of Dal Lake whereas no pesticide was detected in waters of Mansbal. The higher values for AST, ALT and ALP activities and decrease in protein content were obtained in the samples from the Dal Lake compared with those from Mansbal Lake (p<0.05). These data when compared with the values found in C. carpio and C. carassius from both the Dal Lake and Mansbal Lake kept under laboratory conditions after 15, 30, 45 and 60days of maintenance in clean media found that during depuration, all the enzyme activities came down significantly (p<0.05) indicating the compensatory response by the fish against the pesticide stress. Therefore, these parameters could be used as indicators of pesticide pollution in aquatic organisms and were recommended for environmental monitoring for investigating the mechanism involved in the recovery pattern.

The influence of the population dynamics of spider mites on Annona spp. under the pesticides stress

Four species of spider mites were investigated on Annona spp. (sugar apple and atemoya) in the 1980s: Eutetranychus orientalis, Oligonychus coffeae, O. mangiferus, and Tetranychus neocaledonicus. Results showed that populations of these spider mites changed in the last decade, with T. kanzawai becoming the dominant species since 1999. By investigating the species component of spider mites during 2009-2013, O. coffeae remained as the dominant species in the winter, T. piercei was found only one time at Beinan Township, but O. mangiferus and T. neocaledonicus were not discovered. However, the two-spotted spider mite, T. urticae, might be a substitute for T. kanzawai at Banjiu village of Beinan Township, and individuals of the former retained highly acaricide resistance potential than the latter. The evolution of species of spider mites might be caused by the pesticides used for controlling mealybugs and diseases. Thus, we suggest that the tactics of pest control on sugar apple and atemoya should be adjusted in order to slow down pesticide stress on spider mites.

Different response–effect trait relationships underlie contrasting responses to two chemical stressors

Summary Trait‐based approaches evaluate ecosystem functioning under environmental change by relating traits predicting changes in species densities (response traits) to traits driving ecosystem functioning (effect traits). Stressors can, however, affect ecosystem functioning not only by altering species densities but also by directly changing species effect traits. We first identified the response traits predicting the cell density of 18 marine benthic diatom strains along gradients of two chemical stressors (a pesticide and a metal, atrazine and copper). We then tested if response traits could predict stressor‐induced changes in ecosystem functioning, i.e. changes in the effect traits driving the diatoms’ potential contribution to primary production, sediment stabilization and energy content in intertidal systems. Finally, we examined if changes in density and changes in ecosystem functioning were correlated, to assess whether species capable of growing under stressful conditions could maintain their contribution to ecosystem functioning. The relationship between response traits and stressor‐induced changes in density and ecosystem functioning was different depending on stressor type: a set of intercorrelated morphological traits predicted changes in both density and ecosystem functioning under metal stress, with large cells being more stress resistant. Changes in density and changes in ecosystem functioning were positively related: diatoms whose density was least affected by the metal were also able to sustain functioning under metal exposure. In contrast, the capacity for mixotrophic growth predicted changes in density, but not changes in ecosystem functioning under pesticide stress. Pesticide effects on density and on ecosystem functioning were negatively related for energy content and sediment stabilization, indicating a limited capacity of pesticide‐tolerant diatoms to maintain their contribution to ecosystem functioning. Synthesis. Ecosystem functioning under stress can depend on whether the response traits driving changes in species densities also predict direct stress effects on the species’ contribution to functioning. Based on our results, we expect a disproportionate loss of functioning when traits driving species densities do not allow to maintain ecosystem functioning under stress.

Impacts of Dietary Phytochemicals in the Presence and Absence of Pesticides on Longevity of Honey Bees (Apis mellifera).

Because certain flavonols and phenolic acids are found in pollen and nectar of most angiosperms, they are routinely ingested by Apis mellifera, the western honey bee. The flavonol quercetin and the phenolic acid p-coumaric acid are known to upregulate detoxification enzymes in adult bees; their presence or absence in the diet may thus affect the toxicity of ingested pesticides. We conducted a series of longevity assays with one-day-old adult workers to test if dietary phytochemicals enhance longevity and pesticide tolerance. One-day-old bees were maintained on sugar syrup with or without casein (a phytochemical-free protein source) in the presence or absence of quercetin and p-coumaric acid as well as in the presence or absence of two pyrethroid insecticides, bifenthrin and β-cyfluthrin. Dietary quercetin (hazard ratio, HR = 0.82), p-coumaric acid (HR = 0.91) and casein (HR = 0.74) were associated with extended lifespan and the two pyrethroid insecticides, 4 ppm bifenthrin (HR = 9.17) and 0.5 ppm β-cyfluthrin (HR = 1.34), reduced lifespan. Dietary quercetin enhanced tolerance of both pyrethroids; p-coumaric acid had a similar effect trend, although of reduced magnitude. Casein in the diet appears to eliminate the life-prolonging effect of p-coumaric acid in the absence of quercetin. Collectively, these assays demonstrate that dietary phytochemicals influence honey bee longevity and pesticide stress; substituting sugar syrups for honey or yeast/soy flour patties may thus have hitherto unrecognized impacts on adult bee health.

Pesticide stress on plants negatively affects parasitoid fitness through a bypass of their phytophage hosts.

Pesticides taken up by plants from the soil or interstitial (pore) water can cascade to higher trophic levels, which are expected to be more affected due to cumulative bottom-up effects. Knowledge about the impact of indirect exposure to pesticides on non-target terrestrial trophic chains, however, is still lacking. Therefore, we examined the direct and indirect effects of three concentrations of the herbicide 2,6-dichlorobenzonitrile (DCBN) and an insecticide with a similar molecular structure (1,4-dichlorobenzene, DCB) on the fitness traits of a tritrophic system: the wheat plant Triticum aestivum, the aphid Sitobion avenae and its specialist parasitoid Aphidius rhopalosiphi. To mimic exposure via interstitial water the toxicants were added to the growth medium of the plant. Passive dosing between the medium and a silicon layer was used to achieve constant exposure of the poorly soluble pesticides. Wheat plants exposed to both pesticides grew smaller and had reduced biomasses. Negative effects on the reproductive rate, biomass and the number of aphids were only observable at the highest concentration of DCBN. Overall parasitism rate decreased when exposed to both pesticides and parasitoid attack rates decreased at lower concentrations of DCBN and at the highest DCB concentration. The parasitoid sex ratio was extremely male-biased in the presence of DCBN. Our results demonstrate that pesticides can alter the performance of higher trophic levels by sublethal effects, through a bypass of the second trophic level. In addition, the novel test system used was suitable for detecting such carryover effects on non-target organisms.

Ureide Content of Guar under Influence of Hexaconazole and Triazophos

The important part of regular human diet is vegetable, which supply minerals and nutrients for maintenance of health. India is first rank producer of guar comprise 83% of total world production but these are affected by diseases like leaf spots, leaf blotch and insect pest such as serpentine leaf miners, hairy caterpillars and jassids. The major biotic constraint in vegetable production is pest problem. Application of pesticides has now become a common practice in modern agriculture. Chemicalization of agriculture rescues the crop from pest and diseases but when applied in excessive dose affects on plant health and metabolism. The various stresses alter the plant metabolism including pesticidal stress. The ureide content is reported in this study under pesticidal stress of Hexaconazole and Triazophos in leguminous vegetables guar (Cyamopsis tetragonoloba (L.) Taub.) after seed treatment and foliar sprays to ensure the nitrogen fixation and metabolism. Changes in the correlation between nitrogen fixation and ureide levels accelerate disturbance in the nitrogen metabolism and nitrogen products in plant. The concentrations of both pesticides for this experiment were 0.05, 0.1, 0.15, 0.2 and 0.3%. The seeds were soaked in these concentrations of pesticides for 12 h. After 12 h seed soaking period, the treated seeds were thoroughly washed with distilled water and sown in earthen pot containing garden soil and manure. The first foliar spray of Hexaconazole and Triazophos were applied with respective concentrations on 10th day while second foliar spray was on 25th day of plant growth. Analysis of ureide was carried out on the 15th and 30th day of growth that is 5 days after each spray. The uriede content in guar was remarkable increased after seed treatment followed by first foliar spray of 0.10, 0.15 and 0.20% hexaconazole however decreased it with dose concentrations of second foliar spray. The ureide content was decreased after both the foliar sprays of Triazophos.

Impact of Profenofos and Carbosulfan on Dehydrogenase activity of Freshwater fish, Labeo rohita (Hamilton)

Experiments were intended to study effects of profenofos and carbosulfan on the activities of dehydrogenase of freshwater fish, Labeo rohita. Healthy freshwater fish, Labeo rohita (Hamilton) were collected from the Nandivelugu fishfarm, India. Profenofos and carbosulfan pesticides were purchased from local pesticide store in Guntur, India, based on the preliminary lethal toxicity tests (96 hr LC50 i.e. 100 μg l-1; 1.2 mg l-1 and 1/10th 96 hr LC50 i.e.10 μg l-1; 0.12mg l-1 and) were selected as lethal and sublethal concentrations. After the acclimation, fish were exposed to lethal and sublethal concentrations in groups of 10 fish in 15 L of the test water in test chambers for 1 and 8 days. Fluctuations in succinate dehydrogenase (SDH), lactate dehydrogenase (LDH) and malate dehydrogenase (MDH) were observed in different tissues of the experimental animal. The activity of LDH was highly elevated following profenofos and carbosulfan exposure indicating increased anaerobic respiration to meet the energy demands where aerobic oxidation is lowered. Rapid depletion of SDH activity in all tissues of fish, L. rohita treated with sublethal and lethal concentrations of profenofos and carbosulfan. When compared to their respective controls. The general reduction in SDH activity due to pesticidal stress was associated with the inhibition of mitochondrial respiratory mechanism of dearrangement on ultra-structure, architectural integrity and permeability of mitochondria. Decreased MDH activity levels due to the inhibition exerted by oxaloacetate; maybe decrease in the activity of TCA cycle dehydrogenase is consistent with the disintegration of mitochondria of CO2 formation from acetate. Both profenofos and carbosulfan intoxication exerted a profound influence on the dehydrogenase enzymes of fish L. rohita but comparatively profenofos treated fish tissues showed more deterioration when compared to carbosulfan treated fish.

Organophosphorus pesticides stress deranged kinetic values of a few midgut carbohydrases of naiad of Trithemis aurora (burm.) (Odonata: Libellulidae)

The 40 Hrs. treatment of last instar naiad of Trithemis aurora (Burm.) in Chlorphyriphos and Quinalphos pesticides concentrations (LC50 = 5.12 ×10-7 ppm and 7.6 × 10-8 ppm) has shown significant variations in the enzyme kinetic parameters and arrested the enzymatic activity in the midgut tissue of last instar naiad of T. aurora causing deleterious effect on various carbohydrases at standard temp. and pH value. The midgut amylase ( μ and β amylase) showed the change in the velocity of enzymatic reaction under LC50 conc. of chlorpyriphos. The data of initial velocity and substrate concentration were processed to achieve their reciprocal values. These values were plotted and a characteristic Lineweaver Burke straight line was observed from the graph and values of maximum reaction velocity (Vmax) and Michaelis Menten constants (km) were assessed. The present organophosphorus pesticide showed an inhibitory impact on midgut amylase reaction velocity. The double reciprocal plot of initial velocity and substrate concentration after exposing the enzyme under LC50 conc. of chlorphyriphos resulted in varied Vmax and Km. values. These carbohydrase on treatment with LC50 conc. of chlorphyriphos showed an inhibitory change in the reaction velocity. The 1/V and 1/S values were plotted to achieve a characteristic Lineweaver – Burke pattern of Vmax and km values obtained as 5.0 × 10-2 [M] and 2.0 under LC50 chlorphyriphos stress for α amylase. The km and Vmax values were obtained from 0.625 × 10-3 [M] to 1.25 × 10-2 [M] for various other midgut carbohydrases with Vmax value obtained from 0.28 to 5.0 under chlorpyriphos stress. The Quinalphos inhibited the enzymatic efficiencies of various carbohydrases severely and changed Km and Vmax values were found under the pesticidal stress and found as potent uncompetitive inhibitor for enzymes as values compared to the controlled enzymatic reactions by deranging the kinetic values. The Km values determined as on 1/V and 1/S basis found deranged from 1.66 × 10-3 [M] to 10 × 10-2 [M]. The Vmax values were found in a range of 0.41 to 3.3 under LC50 Quinalphos stress for midgut hydrolases. The analysis of enzymec kinetic values revealed the great inhibitory and deranged activities of various carbohydrases under both the pesticide constrain. The present toxicants were found to change the enzymatic velocity negatively. The LC50 concentrations of these toxicants were sufficient to inhibit the activity of present hydrolases as α and β amylase, α glucosidase, α galactosidase, β galactosidase, β frictosidase and α trehalase obtaining a meaningful Lineweaver – Burke line of plotted reciprocals of data of reaction velocity and substrate concentration.

Transcription of four Rhopalosiphum padi (L.) heat shock protein genes and their responses to heat stress and insecticide exposure

The bird cherry-oat aphid, Rhopalosiphum padi (L.), a worldwide destructive pest, is more heat tolerant than other wheat aphids, and it has developed resistance to different insecticides. Heat shock proteins (HSPs) play an important role in coping with environmental stresses. To investigate Hsp transcriptional responses to heat and insecticide stress, four full-length Hsp genes from R. padi (RpHsp60, RpHsc70, RpHsp70-1, and RpHsp70-2) were cloned. Four RpHsps were expressed during all R. padi developmental stages, but at varying levels. The mRNA levels of RpHsps were increased under thermal stress and reached maximal induction at a lower temperature (36°C) in the alate morph than in the apterous morph (37°C or 38°C). RpHsp expressions under heat stress suggest that RpHsp70-1 and RpHsp70-2 are inducible in both apterous and alate morphs, RpHsc70 is only heat-inducible in apterous morph, and RpHsp60 exhibits poor sensitivity to heat stress. The pretreatment at 37°C significantly increase both the survival rate and the RpHsps expression level of R. padi at subsequent lethal temperature. Under exposure to two sublethal concentrations (LC10 and LC30) of beta-cypermethrin, both RpHsp70-1 and RpHsp70-2 expressions were induced and reached a maximum 24h after exposure. In contrast, expression of RpHsp60 was not induced by either sublethal concentration of beta-cypermethrin. Moreover, the responses of RpHsp70-1 and RpHsp70-2 to heat shock were more sensitive than those to beta-cypermethrin. These results suggest that induction of RpHsp expression is related to thermal tolerance, and that RpHsp70-1 and RpHsp70-2 are the primary genes involved in the response to both heat and pesticide stress.

Pre-sowing Seed Treatment with 24-Epibrassinolide Ameliorates Pesticide Stress in Brassica juncea L. through the Modulation of Stress Markers.

The present experiment was designed to assess the effects of seed soaking with 24-epibrassinolide (EBR) on the physiology of Brassica juncea L. seedlings grown under imidacloprid (IMI) toxicity. Application of EBR increased the length of seedlings, dry weight, and pigment contents, polyphenols, total phenols, and organic acids under IMI toxicity. The expression of genes coding key enzymes of pigment, phenols, polyphenols, and organic acid biosynthetic pathways was also studied including CHLASE (chlorophyllase), PSY (phytoene synthase), CHS (chalcone synthase) and PAL (phenylalanine ammonialyase), CS (citrate synthase), SUCLG1 (succinyl Co-A ligase,), SDH (succinate dehydrogenase), FH (fumarate hydratase), MS (malate synthase). Multiple linear regression (MLR) analysis revealed that IMI application regressed negatively on seedling length, dry weight and total chlorophyll content. However, EBR seed treatment regressed positively on all the parameters studied. Moreover, interaction between IMI and EBR showed positive regression for growth parameters, content of pigments, total polyphenol, total phenol and malate, and expression of PSY and PAL. Negative interactions were noticed for the contents of fumarate, succinate and citrate, and expression of CHS and all genes studied related to organic acid metabolism. In conclusion, EBR enhanced the growth and contents of all studied metabolites by regulating the gene expression of B. juncea seedlings under IMI stress.

Combined neonicotinoid pesticide and parasite stress alter honeybee queens' physiology and survival.

Honeybee colony survival strongly relies on the queen to overcome worker losses exposed to combined stressors like pesticides and parasites. Queen’s capacity to withstand these stressors is however very little known. The effects of the common neonicotinoid pesticide imidacloprid in a chronic and sublethal exposure together with the wide distributed parasite Nosema ceranae have therefore been investigated on queen’s physiology and survivorship in laboratory and field conditions. Early physiological changes were observed on queens, particularly the increase of enzyme activities (catalase [CAT] and glutathione-S-transferase [GST] in the heads) related to protective responses to xenobiotics and oxidative stress against pesticide and parasite alone or combined. Stressors also alter the activity of two other enzymes (carboxylesterase alpha [CaE α] and carboxylesterase para [CaE p] in the midguts) involved in metabolic and detoxification functions. Furthermore, single and combined effects of pesticide and parasite decrease survivorship of queens introduced into mating hives for three months. Because colony demographic regulation relies on queen’s fertility, the compromise of its physiology and life can seriously menace colony survival under pressure of combined stressors.

Book Review: Legumes under Environmental Stress: Yield, Improvement and Adaptations

Book Review: Legumes under Environmental Stress: Yield, Improvement and Adaptations