Hormetic effects of thiamethoxam on Schizaphis graminum: demographics and feeding behavior.

In agroecosystems, insects contend with chemical insecticides often encountered at sublethal concentrations. Insects' exposure to these mild stresses may induce hormetic effects, which has consequences for managing insect pests. In this study, we used an electrical penetration graph (EPG) technique to investigate the feeding behavior and an age-stage, two-sex life table approach to estimate the sublethal effects of thiamethoxam on greenbug, Schizaphis graminum. The LC5 and LC10 of thiamethoxam significantly decreased longevity and fecundity of directly exposed adult aphids (F0). However, the adult longevity, fecundity, and reproductive days (RPd)-indicating the number of days in which the females produce offspring - in the progeny generation (F1) exhibited significant increase when parental aphids (F0) were treated with LC5 of the active ingredient. Subsequently, key demographic parameters such as intrinsic rate of increase (r) and net reproductive rate (R0) significantly increased at LC5 treatment. EPG recordings showed that total durations of non-probing (Np), intercellular stylet pathway (C), and salivary secretion into the sieve element (E1) were significantly increased, while mean duration of probing (Pr) and total duration of phloem sap ingestion and concurrent salivation (E2) were decreased in F0 adults exposed to LC5 and LC10. Interestingly, in the F1 generation, total duration of Np was significantly decreased while total duration of E2 was increased in LC5 treatment. Taken together, our results showed that an LC5 of thiamethoxam induces intergenerational hormetic effects on the demographic parameters and feeding behavior of F1 individuals of S. graminum. These findings have important implications on chemical control against S. graminum and highlight the need for a deeper understanding of the ecological consequences of such exposures within pest management strategies across the agricultural landscapes.

Sublethal phosphine fumigation induces transgenerational hormesis in a factitious host, Corcyra cephalonica.

BACKGROUND: The rice moth, Corcyra cephalonica (Stainton) (Lepidoptera: Pyralidae) is a pest of stored grains and widely used as a factitious host during the mass rearing of several natural enemies of crop pests. Hormesis is well-documented in pest insects, to some extent in natural enemies of pests. RESULTS: We report transgenerational stimulatory effects of the widely used fumigant, phosphine. The study reports the consequences of sublethal, low lethal and median lethal concentrations (LC5 , LC25 and LC50 ) and untreated control for two sequential generations of the species (G1 to G2 ). In this study, we investigated the life-history traits, nutrient reserves (protein, lipid and carbohydrate) and larval gut microbiome (using 16 s rRNA V3-V4 metagenomics sequencing) of C. cephalonica. Stimulatory effects were observed for various biological traits of C. cephalonica, notably adult longevity, emergence and increased egg hatchability when exposed to LC5 of phosphine. The total protein, lipid and carbohydrate contents of C. cephalonica also were found to be significantly increased by LC5 in both generations. The microbial diversity of LC5 treated larval gut was higher and found to be different from the rest of the treatments. This is the first report showing hormesis to a fumigant insecticide. CONCLUSION: Our findings increase knowledge on the interaction between hormesis, nutrient reserves and gut bacteria in C. cephalonica exposed to insecticides. Overall, the present study establishes phosphine-induced hormesis at LC5 in the host C. cephalonica, which might help improve the quality of mass rearing of various natural enemies. © 2023 Society of Chemical Industry.

Studies on some neuropharmacological properties of Nevirapine in mice.

Nevirapine (NVP) is non-nucleoside reverse transcriptase inhibitor and an anti-retroviral drug (ARV) with the highest BBB penetrating ability. Its specific pharmacologic effects on central nervous system (CNS) are not well known. The objective of the study was to investigate some CNS effects of Nevirapine. Oral acute toxicity test (Lorke, 1983) was used to estimate the LD50. Exploratory or sedative effects were tested using open field test(OFT), Hole-board test (HBT), diazepam-induced sleeping time test, and ketamine-induced sleeping time test. Five groups of mice were used (5 mice /group). The negative control group received vehicle (distilled water) (10 mL /kg) while groups II, III, and IV received NVP- 15.625 mg/kg, 31.25 mg/kg, 62.5 mg/kg body weight respectively while group V received 0.25 mg/kg of diazepam intraperitoneal. Groups I to IV were treated orally. The oral LD50 was determined to be 2154. 07 mg/kg. NVP, in a dose dependent fashion, increased the number of line-crossing in the OFT. Also, NVP in a dose-dependent fashion, significantly reduced the duration of diazepam-induced sleeping time as well as delayed onset. NVP significantly potentiated ketamine-induced sleeping time duration. Nevirapine possess excitatory effects possibly through antagonism of GABA receptors. Nevirapine causes wakefulness (shortening of sleep) possibly via antagonism of GABAergic neurotransmission.

Survival, development and reproduction of Phenacoccus solenopsis (Hemiptera: Pseudococcidae) on kaolin-treated cotton / Sobrevivência, desenvolvimento e reprodução de Phenacoccus solenopsis (Hemiptera: Pseudococcidae) em algodão tratado com caulim

Abstract The mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) is a cotton pest widespread in several cotton growing regions of Brazil, particularly in the semi-arid region of southwestern Bahia. The impact of kaolin on survival, development and reproduction of P. solenopsis was evaluated in the laboratory. The experiment was developed in a completely randomized design with two treatments: immature or newly emerged adults of P. solenopsis sprayed with kaolin and fed with cotton leaf discs treated with kaolin suspension (with kaolin) (T1) and immature or newly emerged adults of P. solenopsis sprayed with distilled water and fed with cotton leaf discs treated with distilled water (without kaolin) (T2). The kaolin suspension shortens the life cycle, increases the reproductive potential and population growth of the cotton mealybug, P. solenopsis and, therefore, it should be used with caution on cotton plants in regions with a history of occurrence of this pest.

Resumo A cochonilha Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) é uma praga de algodão, amplamente, difundida em várias regiões produtoras do Brasil, particularmente, na região semiárida do sudoeste da Bahia. O impacto do caulim na sobrevivência, desenvolvimento e reprodução de P. solenopsis foi avaliado em laboratório. O delineamento experimental foi inteiramente casualizado com dois tratamentos: imaturos ou adultos recém-emergidos de P. solenopsis alimentados com discos foliares de algodão tratados com caulim (com caulim) e pulverizadas com este produto (T1) e imaturos ou adultos recém-emergidos de P. solenopsis alimentados com discos foliares de algodão tratados com água destilada (sem caulim) e pulverização dos insetos com água destilada (T2). A suspensão do caulim encurtou o ciclo de vida, aumentou o potencial reprodutivo e o crescimento populacional da cochonilha-do-algodoeiro, P. solenopsis e, portanto, deve ser utilizado com cautela em plantas de algodão em regiões com histórico de ocorrência desta praga.

Low-dose action of tryptanthrin and its derivatives against developing embryos of the sea urchin Strongylocentrotus intermedius.

Nine tryptanthrin derivatives, including tryptanthrin itself, were synthesized using different methods, including oxidation of the corresponding isatins to obtain 1-4, the reaction of tryptanthrin 1 with hydrazine and its derivatives to obtain 5-7, and aldol condensation of 1 with acetone and methylethylketone to obtain 8 and 9. The action of 1-9 in doses corresponding to the IC50 against developing embryos of the sea urchin Strongylocentrotus intermedius and in the sperm test allowed us to estimate to potency of all the compounds and to determine which were cytotoxic. In addition, these studies showed that compounds 3, 4, 8, and 9 had a stimulatory effect at lower doses. In particular, the tryptanthrin derivatives stimulated the larval stages of development in surviving embryos at concentrations lower than the IC50.

Strategies for improving the specificity of siRNAs for enhanced therapeutic potential.

INTRODUCTION: RNA interference has become a tool of choice in the development of drugs in various therapeutic areas of Post Transcriptional Gene Silencing (PTGS). The critical element in developing successful RNAi therapeutics lies in designing small interfering RNA (siRNA) using an efficient algorithm satisfying the designing criteria. Further, translation of siRNA from bench-side to bedside needs an efficient delivery system and/or chemical modification. Areas covered: This review emphasizes the importance of dicer, the criteria for efficient siRNA design, the currently available algorithms and strategies to overcome off-target effects, immune stimulatory effects and endosomal trap. Expert opinion: Specificity and stability are the primary concerns for siRNA therapeutics. The design criteria and algorithms should be chosen rationally to have a siRNA sequence that binds to the corresponding mRNA as it happens in the Watson and Crick base pairing. However, it must evade a few more hurdles (Endocytosis, Serum stability etc.) to be functional in the cytosol.

The effects of metallic engineered nanoparticles upon plant systems: An analytic examination of scientific evidence.

Recent evidence for the effects of metallic engineered nanoparticles (ENPs) on plants and plant systems was examined together with its implications for other constituents of the Society-Environment-Economy (SEE) system. In this study, we were particularly interested to determine whether or not metallic ENPs have both stimulatory and inhibitory effects upon plant performance. An emphasis was made to analyze the scientific evidence on investigations examining both types of effects in the same studies. Analysis of evidence demonstrated that metallic ENPs have both stimulatory and inhibitory effects mostly in well-controlled environments and soilless media. Nano zero-valent iron (nZVI) and Cu ENPs have potential for use as micronutrients for plant systems, keeping in mind the proper formulation at the right dose for each type of ENP. The concentration levels for the stimulatory effects of Cu ENPs are lower than for those for nZVI. Newer findings showed that extremely smaller concentrations of Au ENPs (smaller than those for nZVI and Cu ENPs) induce positive effects for plant growth, which is attributed to effects on secondary metabolites. Ag ENPs have demonstrated their usage as antimicrobial/pesticidal agents for plant protection; however, precautions should be taken to avoid higher concentrations not only for plant systems, but also, other constituents in the SEE. Further research is warranted to investigate the stimulatory and inhibitory effects of metallic ENPs in soil media in order to broaden the horizon of sustainable agriculture production in terms of higher and safer yields so as to meet the food requirements of human population.

Survival, development and reproduction of Phenacoccus solenopsis (Hemiptera: Pseudococcidae) on kaolin-treated cotton

Abstract The mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) is a cotton pest widespread in several cotton growing regions of Brazil, particularly in the semi-arid region of southwestern Bahia. The impact of kaolin on survival, development and reproduction of P. solenopsis was evaluated in the laboratory. The experiment was developed in a completely randomized design with two treatments: immature or newly emerged adults of P. solenopsis sprayed with kaolin and fed with cotton leaf discs treated with kaolin suspension (with kaolin) (T1) and immature or newly emerged adults of P. solenopsis sprayed with distilled water and fed with cotton leaf discs treated with distilled water (without kaolin) (T2). The kaolin suspension shortens the life cycle, increases the reproductive potential and population growth of the cotton mealybug, P. solenopsis and, therefore, it should be used with caution on cotton plants in regions with a history of occurrence of this pest.

Resumo A cochonilha Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) é uma praga de algodão, amplamente, difundida em várias regiões produtoras do Brasil, particularmente, na região semiárida do sudoeste da Bahia. O impacto do caulim na sobrevivência, desenvolvimento e reprodução de P. solenopsis foi avaliado em laboratório. O delineamento experimental foi inteiramente casualizado com dois tratamentos: imaturos ou adultos recém-emergidos de P. solenopsis alimentados com discos foliares de algodão tratados com caulim (com caulim) e pulverizadas com este produto (T1) e imaturos ou adultos recém-emergidos de P. solenopsis alimentados com discos foliares de algodão tratados com água destilada (sem caulim) e pulverização dos insetos com água destilada (T2). A suspensão do caulim encurtou o ciclo de vida, aumentou o potencial reprodutivo e o crescimento populacional da cochonilha-do-algodoeiro, P. solenopsis e, portanto, deve ser utilizado com cautela em plantas de algodão em regiões com histórico de ocorrência desta praga.

Low concentrations of dibromoacetic acid and N-nitrosodimethylamine induce several stimulatory effects in the invertebrate model Caenorhabditis elegans.

Dibromoacetic acid (DBAA) and N-nitrosodimethylamine (NDMA) have natural and anthropogenic sources and are ubiquitously distributed in the environment. They are classified as toxic and carcinogenetic and various studies have addressed their effects on vertebrates. Furthermore, there is no information about the whole-organism effects at low concentrations or about their impact on invertebrates. Therefore, these compounds were studied with the model invertebrate Caenorhabditis elegans (C. elegans) at relatively low concentrations. Biological tests (life span, reproduction, body size, thermal stress resistance) as well as biochemical (pro- and antioxidative capacity and lipid peroxidation) and biomolecular assays (transcription of stress genes) were performed. None of the applied concentrations showed a toxic potential. Instead, they extended life span and increased the body length. Both xenobiotics did not cause oxidative stress or DNA damages, or acted as endocrine disruptors. The stimulatory effects on C. elegans were most likely not a result of an induced protective stress response. Instead, an 'energy saving mode', indicated by the reduced transcription of many stress response genes, could have provided additional resources for longevity and growth. Although both substances are potentially toxic at higher doses, the present study underlines the importance of testing lower concentrations and their impact on invertebrates.

Characteristics of evodiamine-exerted stimulatory effects on rat jejunal contractility.

This study was designed to characterise the effects of evodiamine on intestinal contractility and reveal the correlated mechanisms. Evodiamine (2.5-80.0 µM) increased normal jejunal contractility and jejunal hypocontractility established under a variety of experimental conditions. Evodiamine-exerted stimulatory effects were blocked by the L-type Ca(2+) channel blocker nifedipine or abolished in the Ca(2+)-free assay condition. The stimulatory effects of evodiamine on jejunal contractility were partially blocked in the presence of neurotoxin tetrodotoxin or endogenous acetylcholine synthesis blocker hemicholinium-3 or muscarinic receptor antagonist atropine, respectively. Evodiamine-exerted stimulatory effects were blocked by c-kit receptor tyrosine kinase inhibitor imatinib. Evodiamine increased myosin phosphorylation in jejunal smooth muscle of constipation-prominent rats. These results showed that evodiamine-exerted stimulatory effects on jejunal segments are Ca(2+)-dependent, need the presence of interstitial cell of Cajal, requirement of cholinergic neuron and correlate with increased myosin phosphorylation, implicating the potential value of evodiamine in relieving hypo-motility disorders.

Stimulatory effects of Bordetella bronchiseptica antigen on bone marrow cells and immune memory responses / 대한수의학회지

Bone marrow is a hematological and immunological organ that provides multiple immune cells, including B lymphocytes, and thus plays a critical role in the efficacy of vaccine. We previously demonstrated that Bordetella (B.) bronchiseptica antigen has high immunogenicity in spleen cells, a peripheral immune organ. In this study, we investigated the immunogenicity of B. bronchiseptica antigen in bone marrow cells, a central immune organ. B. bronchiseptica antigen increased the cellular activity of bone marrow cells and significantly enhanced the production of nitric oxide, IL-6, and TNF-alpha. Bone marrow cells primed with B. bronchiseptica antigen in vivo were harvested and stimulated with the same antigen in vitro. The stimulation of B. bronchiseptica antigen significantly increased the cellular activity and proliferation rate of the primed cells. B. bronchiseptica antigen also greatly induced the production of antigen-specific antibody in the primed cells. Taken together, the present study demonstrated that B. bronchiseptica antigen can stimulate bone marrow cells, a central immune organ, and recall the immune response of the primed bone marrow cells.

An experimental study on the stimulatory effects of epidermal growth factor and transforming growth factor-alpha on the growth of squamous cancer cell lines