Comprehensive Transcriptome Analyses in Sea Louse Reveal Novel Delousing Drug Responses Through MicroRNA regulation.

The role of miRNAs in pharmacological responses through gene regulation related to drug metabolism and the detoxification system has recently been determined for terrestrial species. However, studies on marine ectoparasites have scarcely been conducted to investigate the molecular mechanisms of pesticide resistance. Herein, we explored the sea louse Caligus rogercresseyi miRNome responses exposed to delousing drugs and the interplaying with coding/non-coding RNAs. Drug sensitivity in sea lice was tested by in vitro bioassays for the pesticides azamethiphos, deltamethrin, and cypermethrin. Ectoparasites strains with contrasting susceptibility to these compounds were used. Small-RNA sequencing was conducted, identifying 2776 novel annotated miRNAs, where 163 mature miRNAs were differentially expressed in response to the drug testing. Notably, putative binding sites for miRNAs were found in the ADME genes associated with the drugs' absorption, distribution, metabolism, and excretion. Interactions between the miRNAs and long non-coding RNAs (lncRNAs) were also found, suggesting putative molecular gene regulation mechanisms. This study reports putative miRNAs correlated to the coding/non-coding RNAs modulation, revealing novel pharmacological mechanisms associated with drug resistance in sea lice species.

Lysophosphatidic acid receptors 2 and 3 regulate erythropoiesis at different hematopoietic stages.

Hematopoiesis, the complex developmental process that forms blood components and replenishes the blood system, involves multiple intracellular and extracellular mechanisms. We previously demonstrated that lysophosphatidic acid (LPA), a lipid growth factor, has opposing regulatory effects on erythrocyte differentiation through activation of LPA receptors 2 and 3; yet the mechanisms underlying this process remain unclear. In this study, LPA2 is observed that highly expressed in common myeloid progenitors (CMP) in murine myeloid cells, whereas the expression of LPA3 displaces in megakaryocyte-erythroid progenitors (MEP) of later stage of myeloid differentiation. Therefore, we hypothesized that the switching expression of LPA2 and LPA3 determine the hematic homeostasis of mammalian megakaryocytic-erythroid lineage. In vitro colony-forming unit assays of murine progenitors reveal that LPA2 agonist GRI reduces the erythroblast differentiation potential of CMP. In contrast, LPA3 agonist OMPT increases the production of erythrocytes from megakaryocyte-erythrocyte progenitor cells (MEP). In addition, treatment with GRI reduces the erythroid, CMP, and MEP populations in mice, indicating that LPA2 predominantly inhibits myeloid differentiation at an early stage. In contrast, activation of LPA3 increases the production of terminally differentiated erythroid cells through activation of erythropoietic transcriptional factor. We also demonstrate that the LPA3 signaling is essential for restoration of phenylhydrazine (PHZ)-induced acute hemolytic anemia in mice and correlates to erythropoiesis impairment of Hutchinson-Gilford progeria Symptom (HGPS) premature aging expressed K562 model. Our results reveal the distinct roles of LPA2 and LPA3 at different stages of hematopoiesis in vivo, providing potentiated therapeutic strategies of anemia treatment.

Effects of Sublethal Concentrations of Insecticides on the Fecundity of Sogatella furcifera (Hemiptera: Delphacidae) via the Regulation of Vitellogenin and Its Receptor.

White-backed planthopper (Sogatella furcifera, Hemiptera: Delphacidae) is an important migratory pest of rice. It causes severe economic losses by reducing crop production. Vg and VgR are important proteins that help in the successful reproduction of insects and have been studied in many insects. To understand the molecular mechanisms underlying the effects of insecticides on white-backed planthopper reproduction, we studied the expression profiles of SfVg, SfVg-like, and SfVgR in white-backed planthopper exposed to insecticides. SfVg and SfVgR silencing inhibited the ovarian development, number of eggs laid by, and hatching rate of white-backed planthopper. Thiamethoxam LC10 significantly inhibited SfVg-like and SfVgR expression. In contrast, triazophos LC25 significantly promoted SfVg, SfVg-like, and SfVgR expression and increased vitellogenin content in white-backed planthopper. These results demonstrate that insecticides can regulate the reproduction of white-backed planthopper by altering the expression of SfVg and SfVgR, thereby affecting the population density of white-backed planthopper. These findings build a foundation for improving our understanding of the molecular mechanisms underlying the effects of insecticides on the reproduction and resurgence of pests.

Trends in de-lousing of Norwegian farmed salmon from 2000-2019-Consumption of medicines, salmon louse resistance and non-medicinal control methods.

The salmon louse Lepeophtheirus salmonis has been a substantial obstacle in Norwegian farming of Atlantic salmon for decades. With a limited selection of available medicines and frequent delousing treatments, resistance has emerged among salmon lice. Surveillance of salmon louse sensitivity has been in place since 2013, and consumption of medicines has been recorded since the early 80's. The peak year for salmon lice treatments was 2015, when 5.7 times as many tonnes of salmonids were treated compared to harvested. In recent years, non-medicinal methods of delousing farmed fish have been introduced to the industry. By utilizing data on the annual consumption of medicines, annual frequency of medicinal and non-medicinal treatments, the aim of the current study was to describe the causative factors behind salmon lice sensitivity in the years 2000-2019, measured through toxicity tests-bioassays. The sensitivity data from 2000-2012 demonstrate the early emergence of resistance in salmon lice along the Norwegian coast. Reduced sensitivity towards azamethiphos, deltamethrin and emamectin benzoate was evident from 2009, 2009 and 2007, respectively. The annual variation in medicine consumption and frequency of medicinal treatments correlated well with the evolution in salmon louse sensitivity. The patterns are similar, with a relatively small response delay from the decline in the consumption of medicines in Norway (2016 and onward) to the decline in measured resistance among salmon louse (2017 and onward). 2017 was the first year in which non-medicinal treatments outnumbered medicinal delousing treatments as well as the peak year in numbers of cleanerfish deployed. This study highlights the significance of avoiding heavy reliance on a few substance groups to combat ectoparasites, this can be a potent catalyst for resistance evolution. Further, it demonstrates the importance of transparency in the global industry, which enables the industry to learn from poor choices in the past.

Botanical monoterpenes synergise the toxicity of azamethiphos in the vector of Chagas disease, Triatoma infestans (Hemiptera: Reduviidae).

OBJECTIVE: To investigate what toxicological interactions occur when binary combinations of azamethiphos and botanical monoterpenes (eugenol, menthol or menthyl acetate) are applied to Triatoma infestans. METHODS: The toxicity of binary mixtures of azamethiphos and sublethal doses of a monoterpene (eugenol, menthol or menthyl acetate) was evaluated in nymphs of the first stage of T. infestans. Experiments using exposure to filter papers and topical application were carried out. Values of Lethal Concentration 50% (LC50) were calculated in the first case, and values of Lethal Dose 50% (LD50) in the second. RESULTS: The LC50 of azamethiphos applied on filter paper was 50.3 µg/cm2 . However, when it was simultaneously applied with a sublethal concentration of monoterpene, its toxicity increased (LC50 with eugenol = 11.20 µg/cm2 , LC50 with menthyl acetate = 5.30 µg/cm2 , LC50 with menthol = 7.26 µg/cm2 ). When applied topically, the LD50 of azamethiphos was 7.85 µg/insect, but its toxicity drastically increased when it was applied together with sublethal doses of menthol (LD50 = 0.00016 µg/insect) or menthyl acetate (LD50 = 0.00051 µg/insect). The simultaneous application with eugenol did not significantly change azamethiphos toxicity (LD50 = 12.79 µg/insect). CONCLUSIONS: The toxicity of azamethiphos in T. infestans was synergised when it was applied together with eugenol, menthol or menthyl acetate on a filter paper. However, only menthol and menthyl acetate synergysed azamethiphos when mixtures were topically applied. The drastic effects of menthol and menthyl acetate in topical application experiments should be further studied as they could be the basis for developing more efficient triatomicidal products with a lower content of conventional insecticides than those currently used for controlling T. infestans.

OBJECTIF: Etudier les interactions toxicologiques qui se produisent lorsque des combinaisons binaires d'azaméthiphos et de monoterpènes botaniques (eugénol, menthol ou acétate de menthyle) sont appliquées à Triatoma infestans. MÉTHODES: La toxicité de mélanges binaires d'azaméthiphos et de doses sublétales d'un monoterpène (eugénol, menthol ou acétate de menthyle) a été évaluée sur les nymphes du premier stade de T. infestans. Des expériences utilisant une exposition à des papiers filtres et une application topique ont été réalisées. Les valeurs de concentration létale à 50% (CL50) ont été calculées dans le premier cas et les valeurs de dose létale à 50% (DL50) dans le second. RÉSULTATS: La CL50 de l'azaméthiphos appliqué sur papier filtre était de 50,3 µg/cm2 . Cependant, lorsqu'il était appliqué simultanément avec une concentration sublétale de monoterpène, sa toxicité augmentait (CL50 avec eugénol = 11,20 µg/cm2 , CL50 avec acétate de menthyle = 5,30 µg/cm2 , CL50 avec menthol = 7,26 µg/cm2 ). Lorsqu'il était appliqué localement, la DL50 de l'azaméthiphos était de 7,85 µg/insecte, mais sa toxicité augmentait considérablement lorsqu'il était appliqué avec des doses sublétales de menthol (DL50 = 0,00016 µg/insecte) ou d' acétate de menthyle (DL50 = 0,00051 µg/insecte). L'application simultanée d'eugénol n'a pas modifié de manière significative la toxicité de l'azaméthiphos (DL50 = 12,79 µg/insecte). CONCLUSIONS: La toxicité de l'azaméthiphos chez T. infestans a été mise en synergie lorsqu'il a été appliqué avec de l'eugénol, du menthol ou de l' acétate de menthyle sur un papier filtre. Cependant, seuls le menthol et l' acétate de menthyle ont eu un effet synergique avec l'azaméthiphos lorsque les mélanges étaient appliqués localement. Les effets drastiques du menthol et de l' acétate de menthyle dans les expériences d'application topique devraient être plus étudiés car ils pourraient être la base du développement de produits triatomicides plus efficaces avec une teneur inférieure en insecticides conventionnels que ceux actuellement utilisés pour lutter contre T. infestans.

Assessment of Resistance to Organophosphates and Pyrethroids in Aedes aegypti (Diptera: Culicidae): Do Synergists Affect Mortality?

Aedes aegypti (L.) is the primary vector of Zika, dengue, yellow fever, and chikungunya viruses. Insecticides used in mosquito control can help prevent the spread of vector-borne diseases. However, it is essential to determine insecticide resistance (IR) status before control measures are undertaken. Only the most effective insecticides should be used to avoid ineffective control and/or promotion of IR. Pyrethroids and organophosphates are the most commonly used insecticides for mosquito control. Here, the efficacy of two active ingredients (AIs; permethrin [pyrethroid], chlorpyrifos [organophosphate]), two formulated products (FPs; Biomist [AI: permethrin]) and (Mosquitomist [AI: chlorpyrifos]), and three synergists (piperonyl butoxide, diethyl maleate, S-S-S-tributyl phosphorotrithioate) was evaluated in two Ae. aegypti colonies (pyrethroid resistant and susceptible). Mosquitomist was most effective against the pyrethroid-resistant colony (100% mortality at diagnostic time). Pre-exposure to synergists did not increase the efficacy of AIs against the pyrethroid-resistant colony. Further research is needed to discover how synergists may affect the efficacy of insecticides when used on pyrethroid-resistant mosquitoes.

Side effects of insecticidal usage in rice farming system on the non-target house fly Musca domestica in Punjab, Pakistan.

Insecticidal usage in the rice farming system may affect non-target insect species present in the same fields. Musca domestica, a well-known pest of medical and veterinary importance worldwide, is one of the important non-target insect species present in the rice farming system. In this study, five strains of M. domestica were exclusively collected from rice fields in major rice cultivated areas of Punjab, Pakistan, and evaluated for the presence of insecticide resistance against nine commonly used insecticides in the rice farming system. Moreover, the performance of life-history traits was also studied. Compared with a Lab-susceptible reference strain of M. domestica, all the field strains exhibited moderate levels of resistance to carbofuran (RRs = 27.96-46.00 fold) and cartap hydrochloride (RRs = 31.48-48.21 fold), low to moderate levels of resistance to gamma-cyhalothrin (RRs = 19.00-43.00 fold), chlorantraniliprole (RRs = 11.90-27.10 fold), monomehypo (RRs = 14.38-25.84 fold), and fipronil (RRs = 13.23-40.15 fold), low levels of resistance to triazophos (RRs = 11.13-19.83 fold), and very low to low levels of resistance (RRs = 7.83-13.28 fold) to flonicamid. The performance of life-history traits (developmental time, adult eclosion rate, fecundity, egg hatch rate, and longevity of adults) of field strains was weaker as compared with that of the Lab-susceptible strain. These results contribute to the growing knowledge on the effects of insecticidal usage in agriculture on non-target invertebrates, and necessitate the need to explore alternate insecticides that can effectively control insect pests but safe for non-target organisms.

Lysophosphatidic acid receptor LPA3 prevents oxidative stress and cellular senescence in Hutchinson-Gilford progeria syndrome.

Hutchinson-Gilford progeria syndrome (HGPS) is a rare laminopathy that produces a mutant form of prelamin A, known as Progerin, resulting in premature aging. HGPS cells show morphological abnormalities of the nuclear membrane, reduced cell proliferation rates, accumulation of reactive oxygen species (ROS), and expression of senescence markers. Lysophosphatidic acid (LPA) is a growth factor-like lipid mediator that regulates various physiological functions via activating multiple LPA G protein-coupled receptors. Here, we study the roles of LPA and LPA receptors in premature aging. We report that the protein level of LPA3 was highly downregulated through internalization and the lysosomal degradation pathway in Progerin-transfected HEK293 cells. By treating Progerin HEK293 cells with an LPA3 agonist (OMPT, 1-Oleoyl-2-O-methyl-rac-glycerophosphothionate) and performing shRNA knockdown of the Lpa3r transcript in these cells, we showed that LPA3 activation increased expression levels of antioxidant enzymes, consequently inhibiting ROS accumulation and ameliorating cell senescence. LPA3 was shown to be downregulated in HGPS patient fibroblasts through the lysosomal pathway, and it was shown to be crucial for ameliorating ROS accumulation and cell senescence in fibroblasts. Moreover, in a zebrafish model, LPA3 deficiency was sufficient to cause premature aging phenotypes in multiple organs, as well as a shorter lifespan. Taken together, these findings identify the decline of LPA3 as a key contributor to the premature aging phenotypes of HGPS cells and zebrafish.

Insecticide resistance in stable flies (Stomoxys calcitrans) on dairy farms in Germany.

Stable flies (Stomoxys calcitrans Linnaeus, 1758) can have a considerable negative impact on animal well-being, health, and productivity. Since insecticides constitute the mainstay for their control, this study aimed at assessing the occurrence of insecticide resistance in S. calcitrans on dairy farms in Brandenburg, Germany. First, the susceptibility of stable flies from 40 dairy farms to a deltamethrin-impregnated fabric was evaluated using the FlyBox® field test method. Then, S. calcitrans strains from 10 farms were reared in the laboratory, and the offspring was tested against the adulticides deltamethrin and azamethiphos and the larvicides cyromazine and pyriproxyfen. The FlyBox® method indicated 100% resistance in stable flies against deltamethrin. Later, to the offspring of those 10 established laboratory strains previously caught on suspected dairy farms, these field findings could be confirmed with mortalities well below 90% 24 h following topical application of the calculated LD95 of deltamethrin and azamethiphos. The ten strains could therefore be classified as resistant to the tested insecticides. In contrast, exposure to the insect growth regulators cyromazine and pyriproxyfen at their recommended concentrations demonstrated 100% efficacy. Both larvicides inhibited the moulting process of the stable fly larval stages completely, showing that the stable fly strains tested were susceptible to them. The intensive use of insecticides in recent decades has probably promoted the development of insecticide resistance. Systematic surveys in different livestock production systems and vigilance are therefore deemed necessary for estimating the risk of insecticide resistance development on a nationwide scale.

Organophosphorus pesticide triazophos: A new endocrine disruptor chemical of hypothalamus-pituitary-adrenal axis.

The organophosphorus pesticide, triazophos (TAP) was banned to use in agriculture in several countries due to its high toxicity. However, TAP was still widely used and frequently detected in foods. Recently, many studies reported the endocrine-disrupting effect of pesticides, especially the hypothalamic-pituitary-thyroid and hypothalamic-pituitary-gonadal axis. In this study, adult male Wistar rats were exposed to TAP at the dose of 0.164 and 1.64 mg/kg bodyweight (~1/500th and 1/50th of LD50) for 24 weeks and serum contents of hormones were measured. TAP exposure significantly reduced serum contents of adrenocorticotropic hormone, corticosterone and epinephrine in rats (p < .05), leading to the delay in glucose homeostasis during the insulin tolerance test and decrease in serum contents of total cholesterol, triglyceride and low density lipoprotein. Molecular docking results suggested TAP may be an antagonist of glucocorticoid receptor which decreased significantly in the liver of rats, resulting in the decreased expression of 11ß-hydroxysteroid dehydrogenase 1 and PEPCK1. This study revealed that TAP is a potential endocrine disruptor, especially in the hypothalamus-pituitary-adrenal system and may disturb the metabolism by affecting glucocorticoid receptor. This study provided new evidence about the toxicity of TAP and it was necessary to strictly control the usage of TAP in food.

Susceptibility of Caligus rogercresseyi collected from the native fish species Eleginops maclovinus (Cuvier) to antiparasitics applied by immersion.

A major challenge for Chilean salmon farming is infestation by the ectoparasite Caligus rogercresseyi. In addition, there is evidence that a loss of chemotherapeutic treatment efficacy against important fish pathogens is occurring in salmon farming, including antiparasitic efficacy. Currently, there are known techniques that allow the determination of the susceptibility profile of parasites to antiparasitic treatment. However, there is scarce information about both threshold values and categorization of antiparasitic susceptibility for C. rogercresseyi. Bioassay technique allowed the determination of both mean values and the natural variation of EC50%, which were contrasted with available susceptibility thresholds. Results allowed to determine that parasites from the native fish host, Eleginops maclovinus, are susceptible to azamethiphos, deltamethrin and cypermethrin treatments, showing a high susceptibility profile to antiparasitics.

Caligus rogercresseyi acetylcholinesterase types and variants: a potential marker for organophosphate resistance.

BACKGROUND: Control of the sea louse Caligus rogercresseyi in the Chilean salmonid industry is reliant on chemical treatments. Azamethiphos was introduced in 2013, although other organophosphates were previously used. In 2014, reduced sensitivity to azamethiphos was detected in the Los Lagos Region using bioassays. The main target of organophosphates is the enzyme acetylcholinesterase (AChE). Mutations in the AChE gene are the main cause of organophosphate resistance in arthropods, including other sea lice. In the present study, we aimed to characterize C. rogercresseyi AChE(s) gene(s) and to study the association between AChE variants and azamethiphos resistance in this sea louse species. METHODS: Samples of adult male and female C. rogercresseyi were collected in the Los Lagos Region in 2014. Twenty-four hour exposure bioassays with azamethiphos were performed to select sensitive and resistant lice. The full-length cDNA coding sequences encoding for two AChEs in C. rogercresseyi were molecularly characterized. One of the AChE genes was screened by direct sequencing in the azamethiphos-selected lice to search for variants. An additional louse sampling was performed before and after an azamethiphos treatment in the field in 2017 to validate the findings. RESULTS: The molecular analysis revealed two putative AChEs in C. rogercresseyi. In silico analysis and 3D modelling of the protein sequences identified both of them as invertebrate AChE type 1; they were named C. rogercresseyi AChE1a and 1b. AChE1a had the characteristics of the main synaptic AChE, while AChE1b lacked some of the important amino acids of a typical AChE. A missense change found in the main synaptic AChE (1a), F318F/V (F290 in Torpedo californica), was associated with survival of C. rogercresseyi at high azamethiphos concentrations (bioassays and field treatment). The amino acid change was located in the acyl pocket of the active-site gorge of the protein. CONCLUSIONS: The present study demonstrates the presence of two types of AChE1 genes in C. rogercresseyi. Although enzymatic assays are needed, AChE1a is most probably the main synaptic AChE. The function of AChE1b is unknown, but evidence points to a scavenger role. The AChE1a F/V318 variant is most probably involved in organophosphate resistance, and can be a good marker for resistance monitoring.

Resistance to commonly used insecticides and phosphine fumigant in red palm weevil, Rhynchophorus ferrugineus (Olivier) in Pakistan.

The red palm weevil Rhynchophorus ferrugineus (Olivier) is an important pest of date palms in many regions of the world. This paper reports the first survey of insecticide resistance in field populations of R. ferrugineus in Pakistan which were collected from seven date palm growing areas across Punjab and Khyber Pakhtunkhwa (KPK) provinces, Pakistan. The resistance was assessed by the diet incorporation method against the formulated commonly used chemical insecticides profenophos, imidacloprid, chlorpyrifos, cypermethrin, deltamethrin, spinosad, lambda-cyhalothrin and a fumigant phosphine. Elevated levels of resistance were recorded for cypermethrin, deltamethrin and phosphine after a long history of insecticide use in Pakistan. Resistance Ratios (RRs) were 63- to 79-fold for phosphine, 16- to 74-fold for cypermethrin, 13- to 58-fold for deltamethrin, 2.6- to 44-fold for profenophos, 3- to 24-fold for chlorpyrifos, 2- to 12-fold for lambda-cyhalothrin and 1- to 10-fold for spinosad compared to a susceptible control line. Resistant R. ferrugineus populations were mainly found in southern Punjab and to some extent in KPK. The populations from Bahawalpur, Vehari, Layyah and Dera Ghazi Khan were most resistant to chemical insecticides, while all populations exhibited high levels of resistance to phosphine. Of the eight agents tested, lower LC50 and LC90 values were recorded for spinosad and lambda-cyhalothrin. These results suggest that spinosad and lambda-cyhalothrin exhibit unique modes of action and given their better environmental profile, these two insecticides could be used in insecticide rotation or assist in phasing out the use of older insecticides. A changed pattern of both insecticides can be used sensibly be recommended without evidence of dose rates and frequencies used.

Resistance status to deltamethrin pyrethroid of Culex pipiens pipiens (Diptera: Culicidae) collected from three districts of Tunisia.

OBJECTIVES: The aim of the present study was to determine the susceptibility status of Culex pipiens pipiens populations against deltamehtrin insecticide. METHODS: Larvae of Culex pipiens pipiens were collected from three breeding places in Northern and Southern Tunisia between 2003 and 2005. Early third and late fourth instars were tested against deltamethrin pyrethroid insecticide. Cross-resistance with DDT resistance was evaluated in studied samples to estimate the role of target site insensitivity and two synergists including piperonyl butoxide (Pb) and S,S,S-tributyl phosphorotrithioate (DEF) were used to estimate the role of detoxification enzymes. RESULTS: Our results revealed that the level of deltamehtrin resistance ranged from 0.67 to 31.4. We also showed the non-involvement of kdr resistance in pyrethroid resistance and no cross-resistance with DDT resistance was detected in all studied populations including the most resistant one. Synergists study on the resistant population (sample # 1) showed the involvement of CYP450 in the recorded resistance to the deltamethrin insecticide. CONCLUSION: The results obtained from this study should be considered in the current control programs to combat mosquitoes in Tunisia.

Association between blood cholinesterase activity, organophosphate pesticide residues on hands, and health effects among chili farmers in Ubon Ratchathani Province, northeastern Thailand

Background: Use of pesticides has been documented to lead to several adverse health effects. Farmers are likely to be exposed to pesticides through dermal exposure as a result of mixing, loading, and spraying. Organophosphate pesticides (OPs) are widely used in most of the agricultural areas throughout Thailand. OPs are cholinesterase inhibitors and blood cholinesterase activity is used as a biomarker of OP effects. Objective: This study aims to determine the association between blood cholinesterase activity and organophosphate pesticide residues on chili farmer's hands and their adverse health effects. Materials and Methods: Ninety chili farmers directly involved with pesticide applications (e.g. mixing, loading, spraying) were recruited and were interviewed face to face. Both enzymes, erythrocyte acetylcholinesterase (AChE) and plasma cholinesterase (PChE), were tested with the EQM Test-mate Cholinesterase Test System (Model 400). Hand wipe samples were used for collecting residues on both hands and OP residues for chlorpyrifos and profenofos were quantified using gas chromatography equipped with a flame photometric detector (GC-FPD). Results: The average activity (±SD) of AChE and PChE was 2.73 (±0.88) and 1.58 (±0.56) U/mL, respectively. About 80.0% of the participants had detectable OP residues on hands. The median residues of chlorpyrifos and profenofos were found to be 0.02 and 0.03 mg/kg/two hands, respectively. Half of participants reported having some acute health symptoms within 48 hours after applying pesticides. When adjusted for gender, number of years working in chili farming, and frequency of pesticide use, AChE activity (Adjusted OR = 0.03, 95%CI: 0.01-0.13) and detected OP residues on hands (Adjusted OR = 0.15, 95%CI: 0.02-0.95) were significantly associated with having health effects, but no significant association was found in PChE activity (Adjusted OR = 2.09, 95%CI: 0.63-6.99). Conclusions: This study suggests that regular monitoring for blood cholinesterase and effective interventions to reduce pesticide exposure to prevent health effects should be provided to chili farmers.

A selection study on a laboratory-designed population of salmon lic (Lepeophtheirus salmonis) using organophosphate and pyrethroid pesticides.

Resistance towards antiparasitic agents in the salmon louse (Lepeophtheirus salmonis) is a widespread problem along the Norwegian coast, reducing treatments efficacies and slowing down the envisioned expansion of Norwegian salmon production. The present study was conducted in order to assess the efficacies of two of the most widely used anti-parasitic substances-azamethiphos and deltamethrin-as well as assessing the benefit of having a resistant genotype compared to being fully sensitive when exposed to one of these substances. Atlantic salmon were exposed to a mix of salmon lice copepodids from a fully sensitive, a double resistant and a multi-resistant strain. Once the lice reached pre-adult stages, one group was exposed to 100 µg/L azamethiphos for 60 minutes, the other to 2 µg/L deltamethrin for 30 minutes, and the last was kept in a seawater control. Detached lice were collected at a series of time points following exposure, and all lice (immobilized and surviving) were analysed for both pyrethroid (sensitive "S" and resistant "R") and azamethiphos (fully sensitive "SS", heterozygous resistant "RS" and fully resistant "RR") resistance markers. We found that the efficacies of deltamethrin on parasites with genotype S and R were 70.3 and 13.2%, respectively. The overall efficacy of the deltamethrin treatment was 32.3%. The efficacies of azamethiphos on parasites with genotype SS, RS and RR were 100, 80 and 19.1%, respectively. The overall efficacy of the azamethiphos treatment was 80.4%. Survival analyses revealed that the median survival time in deltamethrin-sensitive and-resistant parasites were 16.8 and >172 hours, respectively. The differences were even more pronounced in the azamethiphos-treated group, where SS, RS and RR parasites survived for 0.26, 6.6 and >172 hours, respectively. The substantial differences in survival between sensitive and resistant lice following treatment demonstrate the ability of medicinal treatments to drive genetic selection towards a much more resistant salmon lice population within a very short time span if there is no influx of sensitive genotypes.

Evaluating bath treatment effectiveness in the control of sea lice burdens on Atlantic salmon in New Brunswick, Canada.

The use of medicinal bath treatment for sea lice is becoming more common, due to increasing resistance to in-feed treatments with emamectin benzoate. Common treatment modalities in New Brunswick, Canada, include Salmosan administered by tarpaulin or wellboat, and Paramove administered by wellboat. In this study, we assessed the effectiveness of these treatment modalities in the field between 2010 and 2015 using a web-based sea lice data management system (Fish-iTrends© ). Effectiveness was evaluated for adult female (AF) and for pre-adult and adult male (PAAM) life stages separately. We also investigated the impact of variability in pretreatment lead and post-treatment lag time on effectiveness measures. There were 1185 treatment events at 57 farms that uniquely matched our pre- and post-treatment count criteria. The effectiveness of treatment modality was significantly influenced by season, pretreatment level of sea lice and by lead and lag times. In summer, Salmosan administered by tarpaulin had the greatest effectiveness on both AF and PAAM, when pretreatment levels were above 10 sea lice; whereas in autumn, the performance of treatment modalities varied significantly, depending on the pretreatment levels for the life stages. Ignoring the lead or lag time effect generally resulted in an underestimation of treatment effectiveness.

Indoxacarb biotransformation in the German cockroach.

Insecticides that are used for pest control undergo physical and biological (enzymatic) degradation. Indoxacarb is an oxadiazine class sodium channel blocker insecticide used for German cockroach (Blattella germanica L.) control. At present, no information is available on enzymatic biotransformation or metabolism of indoxacarb in this important urban pest. We studied the biotransformation pathways of indoxacarb in one susceptible and three field strains with varying susceptibility levels using liquid chromatography and high-resolution mass spectrometry. As shown in other insect species we found evidence for hydrolase-based bioactivation of indoxacarb to a toxic decarbomethoxylated metabolite, DCJW. In addition, both indoxacarb and DCJW were further metabolized to hydroxy, oxadiazine ring-opened and hydroxylated ring-opened metabolites. In general, higher indoxacarb disappearance, increased formation of DCJW and the above-mentioned metabolites were observed in the three field strains. In vitro biotransformation studies showed that hydroxylated and oxadiazine ring-opened metabolite formation is NADPH/cytochrome P450-dependent. Bioassays and in vivo metabolism experiments using the enzyme-inhibiting insecticide synergists, piperonyl butoxide (PBO) and S,S,S,-tributyl phosphorotrithioate (DEF), provided insights into potential indoxacarb resistance mechanisms that may proliferate in German cockroach field strains following unchecked selection pressures. The information presented here is an essential step toward developing indoxacarb resistance management programs and also reveals mechanisms of secondary/tertiary indoxacarb toxicity.

Suppressing male spermatogenesis-associated protein 5-like gene expression reduces vitellogenin gene expression and fecundity in Nilaparvata lugens Stål.

In our previous study with the brown planthopper (BPH), Nilaparvata lugens, triazophos (tzp) treatments led to substantial up-regulation of a male spermatogenesis-associated protein 5-like gene (NlSPATA5) compared to untreated controls. Mating with tzp-treated males significantly increased fecundity (as numbers of eggs laid), relative to females mated with untreated males. Because SPATA5 acts in mammalian sperm development and is expressed in testes, we posed the hypothesis that NlSPATA5 occurs in BPH seminal fluid and it operates in fecundity via mating. We tested the hypothesis by investigating the influence of suppressing NlSPATA5 expression in BPH males on fecundity. Reduced expression of NlSPATA5 led to decreased male accessory gland protein content and reproductive system development compared to controls. These changes in males led to prolonged pre-oviposition periods and decreased fecundity in females. For both genders, we recorded no difference in the body weight, oviposition periods, and longevity compared to controls. NlSPATA5 suppression in males also led to decreased fat body and ovarian protein content, yeast-like symbionts abundance and ovarian development as well as vitellogenin gene expression in their mating partners. We infer that increased NlSPATA5 expression may be one molecular mechanism of tzp-driven reproduction and population increases in BPH.

Pharmacological activation of lysophosphatidic acid receptors regulates erythropoiesis.

Lysophosphatidic acid (LPA), a growth factor-like phospholipid, regulates numerous physiological functions, including cell proliferation and differentiation. In a previous study, we have demonstrated that LPA activates erythropoiesis by activating the LPA 3 receptor subtype (LPA3) under erythropoietin (EPO) induction. In the present study, we applied a pharmacological approach to further elucidate the functions of LPA receptors during red blood cell (RBC) differentiation. In K562 human erythroleukemia cells, knockdown of LPA2 enhanced erythropoiesis, whereas knockdown of LPA3 inhibited RBC differentiation. In CD34(+) human hematopoietic stem cells (hHSC) and K526 cells, the LPA3 agonist 1-oleoyl-2-methyl-sn-glycero-3-phosphothionate (2S-OMPT) promoted erythropoiesis, whereas the LPA2 agonist dodecyl monophosphate (DMP) and the nonlipid specific agonist GRI977143 (GRI) suppressed this process. In zebrafish embryos, hemoglobin expression was significantly increased by 2S-OMPT treatment but was inhibited by GRI. Furthermore, GRI treatment decreased, whereas 2S-OMPT treatment increased RBC counts and amount of hemoglobin level in adult BALB/c mice. These results indicate that LPA2 and LPA3 play opposing roles during RBC differentiation. The pharmacological activation of LPA receptor subtypes represent a novel strategies for augmenting or inhibiting erythropoiesis.