General Esterase Research Articles

Potential of insect growth regulators for the control of Musca domestica (Diptera: Muscidae) with respect to their biochemical and histological effects

BackgroundHousefly causes a variety of health problems to humans and animals. Therefore, it is crucial to find out effective methods for the control of housefly larvae to avoid health problems associated with the presence this disease vector insect. Efficacy of insect growth regulators (IGRs), chlorfluazuron, lufenuron, methoxyfenozide and pyriproxyfen, against larvae of Musca domestica (Diptera: Muscidae), was assessed. The IGRs were mixed with food media at concentrations of 2.5, 5.0, 10.0, 25.0, 50.0, 75.0 and 100.0 mg/kg (ppm).ResultsThe highest larvicidal activity was obtained by chlorfluazuron and pyriproxyfen with LC50 values of 6.79 and 7.10 ppm, respectively, 72 h post-treatment. Also, 25.0 ppm of chlorfluazuron and 75.0 ppm of methoxyfenozide as well as lufenuron were shown to fully suppress adult emergence and survival percentages (0.0%). Moreover, the activity of three digestive enzymes suppressed in the treated larvae with pyriproxyfen and chlorfluazuron: amylase (enzyme ratio (ER) = 0.71 and 0.78), lipase (ER = 0.54 and 0.63) and proteases (ER = 0.62 and 0.66), respectively. Also, methoxyfenozide and pyriproxyfen inhibited acetylcholinesterase (AChE) and general-esterase (GE) activity with ER (0.28 and 0.59) and (0.61 and 0.72), respectively. The histological examination of M. domestica larvae treated with IGRs showed changes in midgut; for example, the epithelial cells were broken, deformed and loss their columnar structure. Also, the peritrophic membrane disappeared completely.ConclusionsThe findings of the current study indicate that the tested IGRs have a potential to be applied in IPM programs of M. domestica.

Decoding defenses: Biochemical insights into insecticide resistance in tea mosquito bug, Helopeltis theivora Waterhouse (Hemiptera: Miridae) from tea plantations of Eastern India

Helopeltis theivora is one of the major tea pests in India and the strategies of management largely depend on application of different insecticides. Resistance in ten field populations of H. theivora collected from different tea growing regions of Eastern India to three insecticides was evaluated by leaf dip method in the laboratory. The results showed varied levels of susceptibility in nine populations to thiamethoxam and deltamethrin with a resistance coefficient (RC) ranging from 2.04 to 30.95 and 1.56–59.81-fold, respectively. Upper Assam and Central Dooars populations showed high resistance to thiamethoxam and deltamethrin. A high resistance to deltamethrin was also recorded in the Eastern Dooars (RC = 52.74) and Western Dooars (RC = 53.07) populations. There was no resistance to quinalphos in any of the populations (RC = 0.11–0.60). The Darjeeling population was relatively susceptible to the insecticides. Biochemical enzyme assays suggested that glutathione S-transferases (GST), general esterase (GE) and cytochrome P450 (CYP) activities were high in most of the field populations as compared to the susceptible population. However, the expression of CYP was statistically at par between the Cachar, Tripura, Darjeeling and susceptible population. GST and GE activity displayed a strong significant correlation with LC50 values of thiamethoxam and deltamethrin while a moderate to strong linear relationship was recorded between CYP and the LC50s of thiamethoxam and deltamethrin, respectively. A weak positive correlation was established between LC50 of quinalphos and the enzymes. Synergistic assays reveal that the addition of synergists’ piperonyl butoxide and diethyl maleate with thiamethoxam and deltamethrin enhanced the toxicity of these insecticides. The results of this study will contribute to the insecticide resistance management and integrated management of H. theivora.

Biochemical features of tomato under the influence of gibberellin and its impact on life table and physiology of Tuta absoluta (Merick) (Gelechiidae, Lepidoptera) reared on tomato

The Tomato leaf miner Tuta absoluta is an important agricultural pest and exerts a considerable influence on tomato production across the world. In the present research tomato plants were sprayed with a gibberellin solution at a concentration of 50 µM. The gibberellin treatment resulted in a prolonged duration of T. absoluta preadult stage (33.67 days) compared to control group (27.38 days). The fecundity rate in treated females (82.33 eggs/female) was lowered compared to the controls (96.92 eggs/female). The intrinsic rate of increase (r) (0.080 day−1) was also reduced in treatments compared with the control (0.110 day−1). The finite rate of increase (λ) in treatment (1.084 day−1) decreased compared to the controls (1.116 day−1). The antioxidant system enzymes of T. absoluta, including catalase, peroxidase, and superoxide dismutase (SOD) were increased in treated insects. The gibberellin also increased the activity of detoxifying enzymes including Glutathione s-transferase with two substrates (DCNB and CDNB) and cytochrome P450 compared to the control group. While general esterase did not show significant differences in treatment and control. The secondary metabolites in treated plants including total sugar, total phenol content, anthocyanin, flavonoid and tannin showed an increasing trend. The results clearly show the negative impact of gibberellin on life table and physiology of the tomato leaf miner and can be considered favorable in integrated pest management programs of this pest.

The Rise of Remimazolam: A Review of Pharmacology, Clinical Efficacy, and Safety Profiles.

Anesthesiologists often use benzodiazepines (BZDs) due to their remarkable amnestic and anxiolytic capabilities. Because of this, they are perfect for use during the perioperative phase, when patients' anxiety levels are already high. Remimazolam has replaced certain commonly used intravenous (IV) anesthetics due to its excellent safety profile, rapid onset of action, and short half-life. The four classes of BZDs, 2-keto-benzodiazepines, 3-hydroxy-benzodiazepines, triazolobenzodiazepines, and 7-nitro-benzodiazepines based on chemical structure, provide various levels of drowsiness, forgetfulness, and anxiolysis. Based on their elimination half-life, short-acting BZDs typically have a half-life ranging from one to 12 hours, e.g., oxazepam; intermediate-acting BZDs have an average elimination half-life of 12 to 40 hours, e.g., alprazolam; and long-acting BZDs have an average elimination half-life of more than 40 hours, e.g., diazepam. The chloride ion channel is conformationally shifted by the benzodiazepine molecule resulting in central nervous system (CNS) inhibition and hyperpolarization. Each type of benzodiazepine has a favored use. For example, diazepam is used to treat anxiety. Midazolam is used for its anxiolytic and anterograde amnestic effects during the perioperative phase. Anxiety and epilepsy are two conditions that lorazepam effectively treats. There are now phase II and III clinical studies investigating remimazolam. It is not sensitive to alterations in its surroundings and has a brief half-life so that it may be removed rapidly, even after extensive infusion. Being a soft drug means the body easily breaks it down via metabolism, which explains many features. Remimazolam is hydrolyzed into methanol and its carboxylic acid metabolite CNS 7054 by esterase metabolism. Therefore, remimazolam has a shorter onset time and faster recovery than other BZDs. Remimazolam is metabolized independently of any particular organ. Patients with hepatic and renal problems will not see any changes in metabolism or excretion since the drug's ester moiety makes it a substrate for general tissue esterase enzymes. Like its predecessor, midazolam, it has a high potential for addiction. Some side effects that could occur during infusion include headaches and drowsiness. In clinical trials, hypotension, respiratory depression, and bradycardia were noted in participants. BZDs are helpful when used in conjunction with anesthesia. Remimazolam stands out, thanks to its unique pharmacokinetics, pharmacodynamics, safety profile, and potential medical applications. Its desirable properties make it a potential surgical premedication and sedative in the critical care unit. Anesthesiologists and other doctors could have access to more consistent and safer medication. However, additionalcomprehensive clinical trials are necessary to understand remimazolam's advantages and disadvantages.

Efficiency of Artemisia annua L. essential oil and its chitosan/tripolyphosphate or zeolite encapsulated form in controlling Sitophilus oryzae L.

The rice weevil, Sitophilus oryzae L., is one of the most widespread and destructive stored-product pests and resistant to a wide range of chemical insecticides. In this research, Artemisia annua L. essential oil (EO) and its encapsulated form by chitosan/TPP (tripolyphosphate) and zeolite were tested against S. oryzae adults. The order of toxicity was chitosan/TPP (LC30: 30.83, LC50: 39.52, and LC90: 72.50 μL/L air) > pure EO (LC30: 35.75, LC50: 46.25, and LC90: 86.76 μL/L air) > EO loaded in the zeolite (LC30: 43.35, LC50: 55.07, and LC90: 98.80 μL/L air). These encapsulated samples were characterized by dynamic light scattering (DLS) and field emission scanning electron microscope (FE-SEM) which revealed the size and morphology of the droplets measuring 255.2 to 272 nm and 245 to 271.8 nm for EO loaded in chitosan and zeolite respectively. The encapsulation efficiency and loading percentages of A. annua EO in chitosan/TPP and zeolite were 40.16% and 6.01%, and 88% and 85%, respectively. Fumigant persistence was increased from 6 days for pure EO then, 20 and 22 days for encapsulated oil in zeolite and chitosan/TPP, respectively. Our results showed that A. annua EO contains (±)-camphor (29.29%), 1,8-cineole (12.56%), β-caryophyllene (10.29%), α-pinene (8.68%), and artemisia ketone (8.48%) as its major composition. The activity level of glutathione S-transferase increased while general esterase and acetylcholinesterase activity were significantly inhibited in the treated group compared with the control. Antioxidant enzymes, including catalase, peroxidase, and superoxide dismutase were activated in treated adults compared to controls. The current results suggest that encapsulation of A. annua EO by chitosan/TPP and zeolite in addition to safety and environmentally friendly approach could increase its sustainability and therefore enhancing the efficiency in controlling S. oryzae in storage.

Potential key genes involved in metabolic resistance to malathion in the southern house mosquito, Culex quinquefasciatus, and functional validation of CYP325BC1 and CYP9M12 as candidate genes using RNA interference

BackgroundMetabolic detoxification is one of the major mechanisms contributing to the development of resistance in mosquitoes, including the southern house mosquito, Culex quinquefasciatus. The three major detoxification supergene families, cytochrome P450s, glutathione S-transferases and general esterases, have been demonstrated to play an important role in metabolic resistance. In this study, we performed differential gene expression analysis based on high-throughput transcriptome sequencing on samples from four experimental groups to give insight into key genes involved in metabolic resistance to malathion in Cx. quinquefasciatus. We conducted a whole transcriptome analysis of field captured wild Cx. quinquefasciatus from Harris County (WI), Texas and a malathion susceptible laboratory-maintained Sebring colony (CO) to investigate metabolic insecticide resistance. Field captured mosquitoes were also phenotypically classified into the malathion resistant and malathion susceptible groups following a mortality response measure conducted using a Centers for Disease Control and Prevention (CDC) bottle assay. The live (MR) and dead (MS) specimens from the bottle assay, along with an unselected WI sample and a CO sample were processed for total RNA extraction and subjected to whole-transcriptome sequencing.ResultsWe demonstrated that the genes coding for detoxification enzymes, particularly cytochrome P450s, were highly up-regulated in the MR group compared to the MS group with similar up-regulation observed in the WI group compared to the CO group. A total of 1,438 genes were differentially expressed in comparison between MR and MS group, including 614 up-regulated genes and 824 down-regulated genes. Additionally, 1,871 genes were differentially expressed in comparison between WI and CO group, including 1,083 up-regulated genes and 788 down-regulated genes. Further analysis on differentially expressed genes from three major detoxification supergene families in both comparisons resulted in 16 detoxification genes as candidates potentially associated with metabolic resistance to malathion. Knockdown of CYP325BC1 and CYP9M12 using RNA interference on the laboratory-maintained Sebring strain significantly increased the mortality of Cx. quinquefasciatus after exposure to malathion.ConclusionWe generated substantial transcriptomic evidence on metabolic detoxification of malathion in Cx. quinquefasciatus. We also validated the functional roles of two candidate P450 genes identified through DGE analysis. Our results are the first to demonstrate that knockdown of CYP325BC1 and CYP9M12 both significantly increased malathion susceptibility in Cx. quinquefasciatus, indicating involvement of these two genes in metabolic resistance to malathion.

Effect of insecticides on locomotory behaviour and enzyme activity of Spodoptera litura (Fabricius) populations from Punjab

Aim: The variations in locomotory behaviour and enzyme activity, i.e., acetylcholinesterase and general esterases of Spodoptera litura Fabricius larval populations collected from different regions of Punjab, i.e., Amritsar, Kapurthala and Ludhiana were investigated in the laboratory prior exposure to different insecticides. Methodology: The test larvae were exposed to sublethal doses of different insecticides via surface and food treatment. For locomotory behaviour, they were allowed to move on treated surface and their movements were recorded with an automated video tracking system, Ethovision while on other hand food treatment was opted for observing the influence on enzyme activity. Results: The pronounced variations were observed in the locomotor behaviour of S. litura upon surface exposure of different insecticides. The larva travelled more distance with higher speed and larger turn angle on insecticide-treated surfaces than the untreated ones, while on comparison of different larval populations, the Amritsar population larvae travelled less distance with low speed and maximum turnings. The decrease in acetylcholinesterase and general esterase activity was recorded in treated larvae than untreated ones. The influence of emamectin benzoate was recorded more on locomotion and enzyme activity of S. litura as compared to the remaining insecticides and the Amritsar population was least affected. Interpretation: The sublethal doses of insecticides influenced the overall behavioural physiology of S. litura and this biological parameter could be useful in designing the management strategies for S. litura. Key words: Acetylcholinesterase, Esterases, Insecticides, Locomotory behaviour, S. litura

Resistance status and activity of detoxifying enzymes in Oligonychus coffeae (Nietner)(Acari:Tetranychidae) on tea

Regular monitoring of acaricide resistance in economically important plant feeding mites is important for effective management. Oligonychus coffeae is one of the most important mite pests of tea and acaricides are frequently used to manage this pest, yet control failures sometimes occur at recommended doses. Hence, bioassay experiments were conducted to confirm whether such control failures were caused by resistance development in populations collected from major tea growing areas of Sub-Himalayan West Bengal, India. The adult females of O. coffeae were bio-assayed with commonly used six acaricides viz., dicofol, ethion, fenpropathrin, fenpyroximate, fenazaquin and propargite. Moreover, we estimated the activity of general esterase (GE), glutathione S-transferase (GST) and cytochrome P450 monooxygenase in the field collected samples as well as laboratory reared susceptible population. Based on the LC50 values, the resistance ratio of the field collected populations compared to the laboratory reared susceptible population varied from 3.29 to 5.85-fold,4.13–11.21-fold,12.07–28.28-fold,1.19–1.67-fold,1.12–1.77-fold, 2.73–5.34-fold for dicofol, ethion, fenpropathrin, fenpyroximate, fenazaquin and propargite, respectively. General esterase, GST and MFO activities of the tested populations were in the ranges of 5.69–16.54 mOD/min/mg protein, 91.51–319.91 μM/min/mg protein and 0.040–0.071 mOD/min/mg protein, respectively. The highest enzyme activity was detected in the Naxalbari population which was one of the most resistant populations to all the tested acaricides. The findings will be useful to the tea industry for selection of most effective chemical for successful management of this pest. Use of fenpropathrin and ethion should be discontinued for tea pest management and use of other chemicals having different mode of actions may be continued with rotation.

Membrane Permeant Analogs for Independent Cellular Introduction of the Terpene Precursors Isopentenyl- and Dimethylallyl-Pyrophosphate.

Isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP) are the central five-carbon precursors to all terpenes. Despite their significance, exogenous, independent delivery of IPP and DMAPP to cells is impossible as the negatively charged pyrophosphate makes these molecules membrane impermeant. Herein, we demonstrate a facile method to circumvent this challenge through esterification of the β-phosphate with two self-immolative esters (SIEs) that neutralize the negatively charged pyrophosphate to yield membrane-permeant analogs of IPP and DMAPP. Following cellular incorporation, general esterase activity initiates cleavage of the SIEs, resulting in traceless release of IPP and DMAPP for metabolic utilization. Addition of the synthesized IPP and DMAPP precursor analogs rescued cell growth of glioblastoma (U-87MG) cancer cells concurrently treated with the HMG-CoA reductase inhibitor pitavastatin, which otherwise abrogates cell growth via blocking production of IPP and DMAPP. This work demonstrates a new application of a prodrug strategy to incorporate a metabolic intermediate and promises to enable future interrogation of the distinct biological roles of IPP and DMAPP.

Acute toxicity of atrazine, alachlor, and chlorpyrifos mixtures to honey bees

The acute toxicity of chlorpyrifos and chlorpyrifos-oxon (organophosphorothioate insecticides) was examined alone and in combination with atrazine (triazine herbicide) and alachlor (chloroacetanilide herbicide) to honey bees (Apis mellifera). Atrazine and alachlor were observed to not be acutely toxic to bees at doses up to 10 and 4 μg per bee, respectively. However, atrazine significantly increased chlorpyrifos toxicity by 3-fold while reducing chlorpyrifos-oxon toxicity by 1.8-fold. These changes in toxicity are correlated with significant 1.3- and 1.2-fold inhibition of acetylcholinesterase (AChE) activity in bees exposed to chlorpyrifos and chlorpyrifos-oxon, respectively. Atrazine significantly increased cytochrome P450, general esterase, and glutathione S-transferase (GST) activities by 1.5-, 1.2-, and 1.2- fold respectively, in bees compared to untreated individuals. Alachlor increased chlorpyrifos toxicity by 2.5-fold but did not affect the toxicity of chlorpyrifos-oxon. Exposure to alachlor and chlorpyrifos did not affect AChE compared to chlorpyrifos alone. However, exposure to chlorpyrifos-oxon and alachlor significantly increased acetylcholinesterase (AChE) activity by 1.4-fold. GST activity, but not P450 or general esterases, was significantly increased in bees exposed to alachlor. These data provide evidence that triazine and chloroacetanilide herbicide exposure alters detoxification enzyme activity and, in turn, alters the sensitivity of bees to organophosphorothioate insecticides. Importantly, these data can be used to guide future studies aiming to test safety profiles for pollinators and expand regulatory framework required for pesticide registration.

Synergism of deltamethrin with a mixture of short chain fatty acids for toxicity against pyrethroid-resistant and susceptible strains of Tribolium castaneum (Coleoptera: Tenebrionidae)

Deltamethrin is one of the most effective pyrethroid compounds used in stored product protection to control a wide range of pests. However, the development of resistance to deltamethrin in many pest species has been reported and useful research to overcome this problem is required. The present study investigated the possible synergistic effect of a commercial formulation of a mixture of the short chain fatty acids, octanoic, nonanoic and decanoic acid, in a formulation called “C8910” on the lethal activity of deltamethrin against susceptible (Lab-S) and relatively pyrethroid-resistant (Pyr-R) strains of T. castaneum. The possible mechanisms of synergism were studied by investigating the inhibitory effect of C8910 on the activity of detoxification enzymes including cytochrome P450s, esterases, and glutathione S-transferases (GST). In addition, the possible role of C8910 in enhancement of cuticular penetration of deltamethrin through insect cuticle was studied using GC analysis. The results showed that C8910 enhanced the toxicity of deltamethrin at mixing ratios of 1:5 and 1:10 against the Lab-S strain after 24 and 48 h of exposure, and synergistic factors (SF) ranged between 5.69 and 13.59. C8910 also showed greater synergism on the deltamethrin toxicity against the resistant strain than the susceptible one after 24 and 48 h of treatment at 1:5 and 1:10 ratios with SF values ranging from 22.82 and 47.16. C8910 showed strong inhibition of cytochrome P450 of rat microsomal fraction with IC50 value of 6.24 mM. Meanwhile, C8910 inhibited the activity of general esterases in Lab-S and Pyr-R strains with IC50 values of 26.22 and 51.73 mM, respectively. However, weak inhibition of GST activity was observed with inhibition of 52.0 and 22.6% at concentration of 100 mM of C8910 for Lab-S and Pyr-R, respectively. In addition, the results showed no significant difference between the unpenetrated amounts of deltamethrin when insects were treated with deltamethrin alone or with deltamethrin+C8910 (1:20) through the insect cuticle. Results suggested that the synergism between C8910 and deltamethrin could be related to the ability of C8910 to inhibit the detoxification enzymes such as cytochrome P450 and esterases. Therefore, C8910 could be a promising synergist to enhance deltamethrin toxicity and to be a possible natural alternative for conventional synergists such as piperonyl butoxide.

Effects of the extract and the essential oil of Allium sativum on tea mealy bug, Pseudococcus viburni Sigornet (Hemiptera: Pseudococcidae)

The effects of methanolic extract (ME) and essential oil (EO) of garlic were studied on the third-instar nymphs of Pseudococcus viburni Signoret to elucidate whether garlic essential oil and extract may cause mortality on tea mealybug and physiological disorders. The nymphs exposed to ME showed the LC50 values of 0.33 and 0.12% after 24 and 48 h while those were 0.42 and 0.31% in case of EO. The ED50 values of ME and EO were calculated to be 0.31 and 0.22%, respectively. The LC50 concentrations of Garlic ME and EO significantly increased the activities of general esterase and glutathione S-transferase. Meanwhile, treating P. viburni nymphs by ME and EO significantly increased the activities of aspartate- and alanine aminotransferases as well as ɤ-glutamyl transferase compared to control. The lower activity of lactate dehydrogenase was recorded in the nymphs treated by ME and EO compared to control but the significant increase of acid- and alkaline phosphatase activities was found in the nymphs treated by ME and EO, respectively. Finally, garlic ME and EO significantly decreased the content of protein and glycogen as storage macromolecules compared to control. Our results demonstrated garlic metabolites imposed significant mortality on the nymphs of P. viburni and prominently caused discrepancies in the physiological processes.

Carbohydrate esterase family 16 contains fungal hemicellulose acetyl esterases (HAEs) with varying specificity

Acetyl esterases are an important component of the enzymatic machinery fungi use to degrade plant biomass and are classified in several Carbohydrate Esterase families of the CAZy classification system. Carbohydrate Esterase family 16 (CE16) is one of the more recently discovered CAZy families, but only a small number of its enzyme members have been characterized so far, revealing activity on xylan-derived oligosaccharides, as well as activity related to galactoglucomannan. The number of CE16 genes differs significantly in the genomes of filamentous fungi. In this study, four CE16 members were identified in the genome of Aspergillus niger NRRL3 and it was shown that they belong to three of the four phylogenetic Clades of CE16. Significant differences in expression profiles of the genes and substrate specificity of the enzymes were revealed, demonstrating the diversity within this family of enzymes. Detailed characterization of one of these four A. niger enzymes (HaeA) demonstrated activity on oligosaccharides obtained from acetylated glucuronoxylan, galactoglucomannan and xyloglucan, thus establishing this enzyme as a general hemicellulose acetyl esterase. Their broad substrate specificity makes these enzymes highly interesting for biotechnological applications in which deacetylation of polysaccharides is required.

Lethal and sublethal effects of fenazaquin and acequinocyl on demographic and some biochemical parameters of Panonychus citri (McGregor) (Acari: Tetranychidae)

ABSTRACT A major pest of citrus orchards in northern regions of Iran is Panonychus citri which is mainly controlled by using chemical acaricides. Knowledge of the lethal and sublethal effects of pesticides on pests is necessary for successful performance of each control programme. In this study, the toxicities of fenazaquin and acequinocyl as well as the effects of the sublethal concentration LC20 and LC30 on demographic and some biochemical traits of P. citri offspring were studied. The results showed that the toxicity of acequinocyl was 2.18 times higher than that of fenazaquin. The developmental time of females was influenced and prolonged by sublethal concentrations of both acaricides. Sublethal concentration effects of both acaricides considerably decreased the total fecundity. A significant reduction was observed in the net reproduction rate (R0 ), and intrinsic rate of natural increase (r) of the mites exposed to LC20 and LC30 concentrations of both acaricides compared to control. Both acaricides showed a negative impact on the content of lipid, carbohydrate, and glycogen. The LC20 concentration of fenazaquin resulted in an increase in general esterase activity, and both acaricides inhibited glutathione S-transferase (GST) activities. Our findings show that the sublethal doses of both acaricides had adverse effects on the biological and physiological characters of P. citri.

Toxicity and sublethal effects of plant essential oils on life history and detoxification enzymes activity of two-spotted spider mite (Acari: Tetranychidae)

We studied the lethal and sublethal effects of essential oils (EOs) of Allium sativum L. and Vitex pseudo-negundo (Hausskn) on Tetranychus urticae Koch. Based on LC50 concentrations, A. sativum (19.2 µL/L air) was more toxic than V. pseudo-negundo (51.9 µL/L air). To assess the sublethal effects, adult mites were exposed to the LC10 and LC30 of each EO. Exposure to LC30 of A. sativum and V. pseudo-negundo negatively affected the development, survival, fecundity, and fertility of T. urticae F1 generation, as well as general esterase and MFO enzymes activity. These concentrations affected the detoxification enzyme activity of treated mites.

Mortality and physiological impacts of the tea saponin against Ephestia kuehniella Zeller (Lepidoptera: Pyralidae)

The toxicity of a tea saponin (TS) was investigated on mortality, digestive system, detoxifying and antioxidant enzymes of Ephestia kuehniella Zeller. The larvae were fed on a diet containing different concentrations of TS (5, 10, 20, 40, and 80 mg/mL) to determine the lethal dose and the lethal exposure time. The LC50 of TS was calculated as 28 mg/mL while the LT5 value was found to be 4.14 days following the bioassay experiment. The activities of all enzymes except for lipase decreased in the TS-fed larvae, while the activities of general esterase and glutathione S-transferases as the detoxification enzymes significantly increased contradictory. Moreover, the larvae fed on TS demonstrated the higher activities of antioxidant enzymes including superoxide dismutase, peroxidase, and catalase in addition to the content of malondialdehyde. These findings indicated the significant toxic effects of TS on inhibition of digestive activities and induction of antioxidant enzymes which developed our knowledge on physiological disruptions due to TS treatment.

Evaluation of a Lecithin Supplementation on Growth Performance, Meat Quality, Lipid Metabolism, and Cecum Microbiota of Broilers.

Simple SummaryLecithin can not only provide energy to animals but also serves as an emulsifier and has the potential to enhance the utilization of dietary fat by animals. Thus, there is a need to elucidate the underlying mechanism of the positive effect in broilers. The present feeding trial aims to evaluate the effect of lecithin on broilers’ performance, meat quality, lipid metabolism, and cecum microbiota. The obtained results revealed significant improvements in broiler meat quality resulting from the lipid metabolism and microbiota that were affected by lecithin treatment. Consequently, it could be used in broilers’ diets for the aim of meat quality improvement.The present study was conducted to evaluate the effects of lecithin on the performance, meat quality, lipid metabolism, and cecum microbiota of broilers. One hundred and ninety-two one-day-old AA broilers with similar body weights (38 ± 1.0 g) were randomly assigned to two groups with six replicates of sixteen birds each and were supplemented with 0 and 1 g/kg of lecithin for forty-two days. Performance and clinical observations were measured and recorded throughout the study. Relative organ weight, meat quality, lipid-related biochemical parameters and enzyme activities were also measured. Compared with broilers in the control group, broilers in the lecithin treatment group showed a significant increase in L* value and tenderness (p < 0.05). Meanwhile, the abdominal adipose index of broilers was markedly decreased in lecithin treatment after 42 days (p < 0.05). In the lipid metabolism, broilers in the lecithin treatment group showed a significant increase in hepatic lipase and general esterase values at 21 days compared with the control group (p < 0.05). Lower Firmicutes and higher Bacteroidetes levels in phylum levels were observed in the lecithin treatment group after 21 and 42 days. The distribution of lactobacillus, clostridia, and rikenella in genus levels were higher in the lecithin treatment group after 21 and 42 days. No statistically significant changes were observed in performance, relative organ weight, or other serum parameters (p > 0.05). These results indicate that supplementation with lecithin significantly influence the lipid metabolism in broilers at 21 and 42 days, which resulted in the positive effect on the meat color, tenderness, and abdominal adipose in broilers.

Synergistic Efficacy of Plant Essential Oils with Cypermethrin and Chlorpyrifos Against Spodoptera littoralis, Field Populations in Egypt

Background: The essential oils of the plant synergize the synthetic chemical pesticide activity against pests. Controlling pests mainly with synthetic chemical pesticides causes the resistance to build up in these pests like S. littoralis. Methods: This study was conducted to evaluate the synergistic effect of garlic and thymol oils with cypermethrin and chlorpyrifos on field populations of S. littoralis. Also, the impact of the mixtures on activities of three enzymes: Glutathione S-transferase (GST), general esterase (ά-β-EST) and mixed function oxidase (MFO) of S. littoralis using dipping technique. Results: Bioassay shows elevated LC50 for each of cypermethrin and chlorpyrifos alone. Whereas, the toxicity of cypermethrin and chlorpyrifos were synergized 2.81- to 9-fold; 2.74- to 8.35-fold by garlic oil respectively, but far less synergism occurred with thymol oil. The analysis showed the GST, ά-β-EST and MFO were notably inhibited by garlic and thymol oils synergism with cypermethrin and chlorpyrifos in S. littoralis. Conclusions: The results concluded that inhibition of the enzymes could be the result of the synergist of the essential oils when it mixed with synthetic insecticides to control S. littoralis in the field.

Detrimental effects of pyriproxyfen on the detoxification and abilities of Belostoma anurum to prey upon Aedes aegypti larvae

Despite being effective in controlling mosquito larvae and a few other target organisms, the application of insecticides into aquatic systems may cause unintended alterations to the physiology or behavioral responses of several aquatic non-target organisms, which can ultimately lead to their death. Here, we firstly evaluated whether the susceptibility of the giant water bug, Belostoma anurum (Hemiptera: Belostomatidae), a predator of mosquito larvae, to pyriproxyfen would be similar to that of its potential prey, larvae of Aedes aegypti (Diptera: Culicidae). Secondly, we recorded the nominal concentrations of pyriproxyfen in water and evaluated whether sublethal exposures would lead to physiological or behavioral alterations on the B. anurum nymphs. We characterized the activities of three major families of detoxification enzymes (i.e., cytochrome P450 monooxygenases, glutathione-S-transferase, and general esterases) and further evaluated the abilities of pyriproxyfen sublethally-exposed B. anurum to prey upon A. aegypti larvae at different prey densities. Our findings revealed that nominal pyriproxyfen concentration significantly decreased (approximately 50%) over the first 24 h. Furthermore, when applied at the concentration of 10 μg a.i./L, pyriproxyfen was approximately four times more toxic to A. aegypti larvae (LT50 = 48 h) than to B. anurum nymphs (LT50 = 192 h). Interestingly, the pyriproxyfen sublethally-exposed (2.5 μg a.i./L) B. anurum nymphs exhibited reduced enzyme activities (cytochrome P450 monooxygenases) involved in detoxication processes and preyed significantly less on A. aegypti larvae when compared to unexposed predators. Collectively, our findings demonstrate that mortality-based pyriproxyfen risk assessments are not always protective of aquatic non-target organisms.

The contribution of detoxification pathways to pyrethroid resistance in Hyalella azteca

Chronic exposure to pyrethroid insecticides can result in strong selective pressures on non-target species in aquatic systems and drive the evolution of resistance and population-level changes. Characterizing the underlying mechanisms of resistance is essential to better understanding the potential consequences of contaminant-driven microevolution. The current study found that multiple mechanisms enhance the overall tolerance of Hyalella azteca to the pyrethroid permethrin. In H. azteca containing mutations in the voltage-gated sodium channel (VGSC), both adaptation and acclimation played a role in mitigating the adverse effects of pyrethroid exposures. Pyrethroid resistance is primarily attributed to the heritable mutation at a single locus of the VGSC, resulting in reduced target-site sensitivity. However, additional pyrethroid tolerance was conferred through enhanced enzyme-mediated detoxification. Cytochrome P450 monooxygenases (CYP450) and general esterases (GE) significantly contributed to the detoxification of permethrin in H. azteca. Over time, VGSC mutated H. azteca retained most of their pyrethroid resistance, though there was some increased sensitivity from parent to offspring when reared in the absence of pyrethroid exposure. Permethrin median lethal concentrations (LC50s) declined from 1809 ng/L in parent (P0) individuals to 1123 ng/L in the first filial (F1) generation, and this reduction in tolerance was likely related to alterations in acclimation mechanisms, rather than changes to target-site sensitivity. Enzyme bioassays indicated decreased CYP450 and GE activity from P0 to F1, whereas the VGSC mutation was retained. The permethrin LC50s in resistant H. azteca were still two orders-of-magnitude higher than non-resistant populations indicating that the largest proportion of resistance was maintained through the inherited VGSC mutation. Thus, the noted variation in tolerance in H. azteca is likely associated with inducible traits controlling enzyme pathways. A better understanding of the mechanistic and genomic basis of acclimation is necessary to more accurately predict the ecological and evolutionary consequences of contaminant-driven change in H. azteca.