Concentrations Of Insecticides Research Articles

Selectivity of Abamectin Against Chrysoperla carnea (Stephens) (Chrysopidae, Neuroptera)

Relative toxicities of abamectin along with spinosad, cypermethrin and chlorpyrifos currently used in cotton fields to control bollworms on the general predator, Chrysoperla carnea (Stephens) at egg, larvae and adult stages were evaluated under laboratory conditions in Tamil Nadu, India. The insecticide concentrations studied were equivalent to those prescribed for field application inclusive of various doses for abamectin. The results revealed that there was no significant adverse effect on hatchability of C. carnea caused by abamectin 1.9 EC. However, the fecundity and longevity of adults were significantly reduced at higher concentrations (2 and 2.4 ml l-1) of abamectin. The larva upon direct exposure to insecticides recorded a maximum 40.0 per cent mortality at the highest dose of abamectin (2.4 ml l-1). When the larva were fed with the insecticides treated eggs at 2.4 ml l-1, the larval mortality was 36.7 per cent and the pupation and adult emergence were 68.4 and 61.5 per cent, respectively. Abamectin at lower doses had caused very little impact upon C. carnea. All the doses of abamectin were comparatively safer than chlorpyrifos and cypermethrin. Thus, abamectin is found harmless to C. carnea and can provide selectivity in an integrated control programme for cotton bollworms.

Comparing simulated aerial and chemigation insecticide applications to manage western bean cutworm (Lepidoptera: Noctuidae) in corn.

The efficacy of aerial application and chemigation of insecticides is not well explored for western bean cutworm, Striacosta albicosta (Smith), management in corn. In the short term, inadequate application of insecticides can lead to control failures when insect pests are not effectively targeted. In the longer term, exposure to sublethal insecticide concentrations can contribute to the evolution of insecticide resistance. The goal of this study was to compare aerial application and chemigation under simulated conditions to determine the most effective insecticide application method for managing S. albicosta. Three larval stages were exposed to the highest and lowest label rates of commercial formulations of bifenthrin (36.8 and 112.1g a.i. ha-1) and chlorantraniliprole (52.7 and 75.1g a.i. ha-1). Experiments were conducted in spray chambers, utilizing a carrier volume of 18.7L ha-1 for aerial application and 1.57cm ha-1 for chemigation. Mortality was recorded at 16, 24, and 41h after infestation. The simulated aerial application was more effective than simulated chemigation in controlling S. albicosta, resulting in 100% mortality 24h after infestation. Within the chemigation applications, chlorantraniliprole treatments were effective at both rates for all instars, while the high rate of bifenthrin exhibited greater efficacy than the lower rate. In conclusion, it was evidenced that the same insecticide active ingredients do not yield equivalent efficacy when applied via aerial application compared to chemigation. The present study highlights the importance of selecting appropriate insecticide application methods in controlling S. albicosta larvae.

Lethal and sublethal effects of flupyradifurone and cyantraniliprole on two neotropical stingless bee species.

Stingless bees are important pollinators in tropical regions, but their survival and behavior have been impacted by various factors, including exposure to insecticides. Here, we evaluated the lethal and sublethal effects of commercial formulations of two widely used insecticides, flupyradifurone (FPF formulation), and cyantraniliprole (CY formulation), on Melipona beecheii and Nannotrigona perilampoides. The study involved oral exposure of bees to insecticides, calculation of the lethal concentration (LC50) and the lethal time (LT50), and evaluation of walking and flight take-off activities. The LC50 values showed that the largest bee, M. beecheii, was more sensitive than N. perilampoides to both insecticides and that the FPF formulation had faster lethal effects in both species (N. perilampoides, 9.6 h; M. beecheii, 5 h) compared to the effects of the CY formulation (N. perilampoides, 17 h; M. beecheii, 24.7 h). Sublethal concentrations (LC50/10 and LC50/100) of both insecticides affected walking and flight take-off activities. After 6-24 h of exposure, both FPF and CY formulations significantly reduced the mean walking speed of N. perilampoides (0.962-1.402 cm/s) and M. beecheii (2.026-2.589 cm/s) compared to the control groups (N. perilampoides: 1.648-1.941 cm/s; M. beecheii: 2.759-3.471 cm/s). Additionally, the FPF and the CY formulation impaired individual flight take-off in both species. This study provides the first comprehensive evaluation of the lethal and sublethal effects of flupyradifurone and cyantraniliprole on M. beecheii and N. perilampoides, offering valuable information for future research on insecticide toxicity in stingless bees.

Resistance of Aphids (Aphis gossypii) to Different Types and Concentrations of Synthetic Insecticides

Resistance of Aphids (Aphis gossypii) to Different Types and Concentrations of Synthetic Insecticides

High prevalence of veterinary drugs in bird's nests.

The environmental impact of insecticides used as ectoparasitic treatments for companion animals is not well understood, since they are not subject to detailed environmental risk assessment. Many of these treatments include active ingredients such as fipronil and imidacloprid that are banned from agricultural use in the EU. These treatments are applied topically and can remain on the animal's fur for an extended period of time. Birds (adults, eggs, and nestlings) using fur as an inner layer for their nests have the potential of being exposed dermally to these chemicals. In this study, we collected 103 nests from blue and great tits, which were lined with fur. Using UHPLC-MS/MS, we detected 17 out of the 20 insecticides we screened for, with the number of insecticides detected per nest ranging from 2 to 11. Fipronil, imidacloprid, and permethrin were detected in 100%, 89.1%, and 89.1% of samples, respectively. The average concentration of fipronil, imidacloprid and permethrin were respectively 115.5ppb, 376.3ppb, and 231.1ppb. Dinotefuran was found at the highest concentration of 7198ppb in a single sample. Overall, a higher number of either dead offspring or unhatched eggs was found in nests containing a higher number of insecticides, higher total concentration of insecticides or a higher concentration of fipronil, imidacloprid or permethrin, suggesting that contact exposure of eggs to insecticides in nest lining may lead to mortality and lower reproductive success. This highlights the need for a re-evaluation of the environmental risks associated with use of these potent and persistent insecticides on companion animals.

Negative cross-resistance to chlorfenapyr in pyrethroid-resistance house flies

The purpose of the research is to evaluate the susceptibility to deltamethrin and the pro-insecticide chlorfenapyr in a field population of Musca domestica L. compared to a laboratory strain Lab UF and to clarify a possible mechanism of crossresistance to chlorfenapyr.Materials and methods. The study was carried out on the adults of the laboratory strain Lab UF and the field population Nik of the housefly M. domestica collected from a livestock farm in the Tyumen region, where pyrethroid insecticides had been used for a long time. The toxicity of the pyrethroid deltamethrin (Delcid, 4%) and the pyrrole chlorfenapyr (Pyrafen EC, 360 g/l) against insects was estimated by the no-choice feeding test. Based on the dose-mortality response, lethal concentrations of insecticides were calculated by the probit analysis and the resistance ratio was determined. To clarify the possible mechanism of cross-resistance to chlorfenapyr in the Nik population of M. domestica, the activity of the main detoxification enzymes was determined depending on sex of the insects. In addition, the presence of the kdr-mutation providing resistance to pyrethroids was assessed by the Sanger sequencing.Results and discussion. The lethal concentrations of insecticides and the resistance ratios revealed the moderate resistance to deltamethrin and high susceptibility to chlorfenapyr in the field Nik population. A statistically significant increase in the activity of monooxygenases by 2.25–4.36 times, glutathione-S-transferase by 2.02–2.18 times, acetylcholinesterase by 1.45–1.46 times and alpha-naphthyl esterase by 1.41–1.46 times was noted in females and males of the Nik population compared to these parameters of the Lab UF strain. The presence of the kdr-mutation (L1014F) in houseflies of the field population was confirmed by the Sanger sequencing, while the kdr-his mutation (L1014H) was not detected. The results obtained allow us to suggest that resistance to deltamethrin and high susceptibility to chlorfenapyr in the field population of M. domestica are caused by the L1014F mutation and the increased P450 monooxygenase activity. Negative crossresistance can be used to develop insecticidal formulations that reduce the risk of rapid development of insecticidal resistance in M. domestica L.

RNAi-mediated knockdown of Gastric lipase gene response to spirobudiclofen stress in Panonychus citri

Panonychus citri is a globally distributed pest that is currently controlled using insecticides. However, alternative strategies are needed to minimize the use of chemicals. Given that the enormous potential of RNA interference pesticides in pest control development, lipases also have key roles in underpinning insect reproduction, development, defence from pathogens and oxidative stress, and pheromone signalling.Therefore, studying the function of Gastric lipase as a control measure for P. citri may be a promising approach. In this study, we cloned PcGTGL from the genome and studied its transcriptional response to spirobudiclofen, as well as its response after PcGTGL was knocked down. The results showed that the expression level of PcGTGL was higher during the larval、deutonymph and adult stage compared to the stage of egg. Additionally, under the stress of spirobudiclofen, the expression level decreased with the concentration of insecticides increased. We silenced PcGTGL through RNAi, and the results indicated an increase in mortality rate of P. citri, as well as a lethal phenotype characterized by body folding and darkening. Additionally, we found that treatment with spirobudiclofen on PcGTGL-silenced P. citri not only increased mortality rates and the mRNA expression of hormone-sensitivelipase(HSL), but also led to lower expression levels of PcGTGL、PcVg 、PcVgR and accumulation of TAG. These results indicate that the silencing of PcGTGL effectively inhibits the population growth of P. citri. Following the inhibition of PcGTGL, P. citri helps them obtain the energy needed to resist insecticide stress by triggering HSL action. The results provide a new RNAi-based target for control of P. citri.

Resistance of Anopheles gambiae s.s. against commonly used insecticides and implication of cytochrome P450 monooxygenase in resistance to pyrethroids in Lambaréné (Gabon)

BackgroundInsecticides are a crucial component of vector control. However, resistance constitute a threat on their efficacy and the gains obtained over the years through malaria vector control. In Gabon, little data on phenotypic insecticide resistance in Anopheles vectors are published, compromising the rational implementation of resistance management strategies. We assessed the susceptibility to pyrethroids, carbamates and organophosphates of Anopheles gambiae sensu lato (s.l.) and discuss the mechanisms involved in the pyrethroid resistance-phenotype.MethodsA. gambiae s.l. larvae were collected from breeding sites in Lambaréné. Emerging adults were used in WHO tube assays at an insecticide concentration that defines resistance (diagnostic concentration). Subsequently, deltamethrin and permethrin were used at 5x and 10x diagnostic concentrations and after preexposure with the cytochrome p450 (and glutathione S-transferase) inhibitor piperonyl butoxide (PBO). A subset of mosquitoes was typed by molecular methods and screened using Taqman assays for mutations conferring target site resistance at the Voltage-gated sodium channel 1014 (Vgsc-1014) locus and the acetylcholinesterase (Ace-1) gene.ResultsAll mosquitoes were A. gambiae sensu stricto (s.s.) and resistant to permethrin, deltamethrin and alphacypermethrin (mortality less than 98%). However, mosquitoes were susceptible to malathion but resistant to bendiocarb. The level of resistance was high for permethrin and at least moderate for deltamethrin. Pre-exposure to PBO significantly increased the mortality of resistant mosquitoes (P < 0.0001). They became fully susceptible to deltamethrin and permethrin-induced mortality increased 4-fold. The G119S Ace-1 resistance allele, which confers resistance to both organophosphates and carbamates, was not present. All sampled mosquitoes were either homozygous for the Vgsc-L1014F or heterozygous for Vgsc-L1014F/L1014S, a marker for resistance to pyrethroids and organochlorides.ConclusionThese findings demonstrate a role of cytochrome P450 monooxygenases in the pyrethroid-resistance of A. gambiae s.s. from Lambaréné. Combining PBO with pyrethroids, as done in second generation bednets, may be used to revert resistance. In addition, malathion could also be used in combination with pyrethroids-based methods for resistance management.

Insecticide Resistance and Target-Site Mutations kdr, N1575Y, and Ace-1 in Anopheles gambiae s.l. Populations in a Low-Malaria-Transmission Zone in the Sudanian Region of Senegal.

Background/Objectives: Significant progress in malaria control has been achieved through long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS), raising hopes for malaria elimination. However, emerging insecticide resistance threatens these gains. This study assessed the susceptibility of Anopheles gambiae s.l. populations to public health insecticides, examined the frequencies of kdr, Ace-1, and N1575Y mutations, and explored their associations with phenotypic resistance in Dielmo and Ndiop, Senegal. Methods: Anopheles larvae collected between September and December 2022 were reared to adulthood. Adult mosquitoes were exposed to discriminating concentrations of various insecticides following WHO guidelines. Knockdown times (KDT50 and KDT95) for pyrethroids were calculated using the Probit model. RT-qPCR detected target-site mutations (kdr: L1014F and L1014S, Ace-1, N1575Y) and assessed correlations with phenotypic resistance. Species-specific PCR identified species within the An. gambiae complex. Results/Conclusions: The populations of Dielmo and Ndiop showed susceptibility to pirimiphos-methyl and bendiocarb, with no Ace-1 mutation detected. Resistance to DDT and pyrethroids was observed. The knockdown times indicated that alphacypermethrin and lambdacyhalothrin were more effective than permethrin and deltamethrin. The L1014F allele was widespread, while L1014S was absent in Ndiop and low in Dielmo. The N1575Y mutation occurred only in populations with L1014F. The L1014S mutation was significantly associated with resistance to lambdacyhalothrin in both villages and to deltamethrin in Ndiop.

Improving Sphenophorus levis Adult Mortality Through Solid Insecticide Applications and Increased Insecticide Dose.

The sugarcane weevil (Sphenophorus levis Vaurie, 1978) is currently considered the most important sugarcane pest in Brazil, causing significant yield losses. Application methods of insecticides for S. levis control have not been effective, mostly due to the insect's cryptic behavior below the soil surface which suppresses the correct placement of insecticide active ingredients on target. Two experiments were conducted using an innovative bioassay methodology that simulates sugarcane field conditions to effectively evaluate S. levis adult mortality and insecticide residues in the soil under different treatments. The first experiment aimed to assess the efficacy of two liquid- and solid-applied insecticides, while the second aimed to examine the effect of increasing the dose of lambda-cyhalothrin + thiamethoxam on S. levis adult control. The novel bioassays simulated liquid and solid insecticide applications on sugarcane by exposing S. levis adults to chemical residuals on rhizomes and in soil after insecticide application. In the first experiment, low S. levis adult control was detected (< 53% mortality) across all treatments, where both solid and liquid applications of lambda-cyhalothrin + thiamethoxam provided greater efficacy levels than imidacloprid and control treatments, respectively. Solid applications maintained higher insecticide concentrations in the soil for longer periods than liquid insecticide applications, providing maximum insect control levels 7days after application. The second experiment revealed that solid applications at higher insecticide doses significantly improved control of S. levis adult (76.7% mortality) and resulted in greater insecticide concentrations in the soil compared to the recommended label rate (58.8% mortality).

Neonicotinoid Insecticide Concentrations Upstream and Downstream of the Sendai River, Tottori Prefecture, Japan

Neonicotinoid Insecticide Concentrations Upstream and Downstream of the Sendai River, Tottori Prefecture, Japan

Plant versus pollinator protection: balancing pest management against floral contamination for insecticide use in Midwestern US cucurbits.

Controlling crop pests while conserving pollinators is challenging, particularly when prophylactically applying broad-spectrum, systemic insecticides such as neonicotinoids. Systemic insecticides are often used in conventional agriculture in commercial settings, but the conditions that optimally balance pest management and pollination are poorly understood. We investigated how insecticide application strategies control pests and expose pollinators to insecticides with an observational study of cucurbit crops in the Midwestern United States. To define the window of protection and potential pollinator exposure resulting from alternative insecticide application strategies, we surveyed 62 farms cultivating cucumber, watermelon, or pumpkin across 2 yr. We evaluated insecticide regimes, abundance of striped and spotted cucumber beetles (Acalymma vittatum [Fabricius] and Diabrotica undecimpunctata Mannerheim), and insecticide residues in leaves, pollen, and nectar. We found that growers used neonicotinoids (thiamethoxam and imidacloprid) at planting in all cucumber and pumpkin and approximately half of watermelon farms. In cucumber, foliar thiamethoxam levels were orders of magnitude higher than the other crops, excluding nearly all beetles from fields. In watermelon and pumpkin, neonicotinoids applied at planting resulted in 4-8wk of protection before beetle populations increased. Floral insecticide concentrations correlated strongly with foliar concentrations across all crops, resulting in high potential exposure to pollinators in cucumber and low-moderate exposure in pumpkin and watermelon. Thus, the highest-input insecticide regimes maintained cucumber beetles far below economic thresholds while also exposing pollinators to the highest pollen and nectar insecticide concentrations. In cucurbits, reducing pesticide inputs will likely better balance crop protection and pollination, reduce costs, and improve yields.

Effect of Insecticides on Generative Potential of Entomopathogenic Nematode, Steinernema abbasi PN-1 in Spodoptera litura Fabricius

This study aimed to evaluate the effects of different insecticides at varying concentrations on the progeny production of the entomopathogenic nematode Steinernema abbasi PN-1 in Spodoptera litura larvae, with a focus on determining the insecticides' compatibility with biological control agents. S. litura larvae were treated with a mixture of S. abbasi PN-1 and insecticides (fipronil, emamectin benzoate, cyantraniliprole, indoxacarb, and chlorantraniliprole) at three different concentrations (lower, medium, and higher). Progeny production of S. abbasi PN-1 was assessed and compared across treatments, with control groups consisting of larvae treated with S. abbasi PN-1 alone. The study found that progeny production was significantly influenced by the type and concentration of insecticides. Fipronil exhibited the least negative impact on progeny production across all concentrations, followed by emamectin benzoate, cyantraniliprole, indoxacarb, and chlorantraniliprole, with the latter showing the most significant inhibitory effects. Higher concentrations of insecticides resulted in a greater reduction in progeny production, indicating a dose-dependent relationship. The results suggest that certain insecticides, particularly at higher concentrations, can negatively affect the progeny production of S. abbasi PN-1, potentially compromising the effectiveness of EPNs in integrated pest management (IPM) programs. The study highlights the importance of selecting compatible insecticides and their appropriate concentrations to enhance the success of biological control strategies involving EPNs.

Non-conventional endpoints show higher sulfoxaflor toxicity to Chironomus riparius than conventional endpoints in a multistress environment

Evidence grows that standard toxicity testing might underestimate the environmental risk of neurotoxic insecticides. Behavioural endpoints such as locomotion and mobility have been suggested as sensitive and ecologically relevant additions to the standard tested endpoints. Possible interactive effects of chemicals and additional stressors are typically overlooked in standardised testing. Therefore, we aimed to investigate how concurrent exposure to environmental stressors (increased temperature and predation cues) and a nicotinic acetylcholine receptor (nAChR)-modulating insecticide (‘sulfoxaflor’) impact Chironomus riparius across a range of conventional and non-conventional endpoints. We used a multifactorial experimental design encompassing three stressors, sulfoxaflor (2.0–110 µg/L), predation risk (presence/absence of predatory cues), and elevated temperature (20 °C and 23 °C), yielding a total of 24 distinct treatment conditions. Additional stressors did not change the sensitivity of C. riparius to sulfoxaflor. To assess potential additive effects, we applied an Independent Action (IA) model to predict the impact on eight endpoints, including conventional endpoints (growth, survival, total emergence, and emergence time) and less conventional endpoints (the size of the adults, swimming abilities and exploration behaviour). For the conventional endpoints, observed effects were either lower than expected or well-predicted by the IA model. In contrast, we found greater than predicted effects of predation cues and temperature in combination with sulfoxaflor on adult size, larval exploration, and swimming behaviour. However, in contrast to the non-conventional endpoints, no conventional endpoints detected interactive effects of the neurotoxic insecticide and the environmental stressors. Acknowledging these interactions, increasing ecological context of ecotoxicological test systems may, therefore, advance environmental risk analysis and interpretation as the safe environmental concentrations of neurotoxic insecticides depend on the context of both the test organism and its environment.

Sensitivity of the Mosquito Culex pipiens Diptera: Culicidae towards Temephos in Southern Central Morocco

Mosquito species are responsible for the transmission of many parasitic diseases and their control leads to the phenomenon of resistance to insecticides including temephos, mostly used by hygienic services. This article reports the results of studies conducted using WHO sensitivity tests on larvae local populations of Culex pipiens collected in three lodging in the city of Marrakesh (Southern-Central, Morocco), towards temephos. Five concentrations of insecticide in addition to a control, were used to determine the DC50 and DC 90 of Culex pipiens species towards temephos. Sensitivity tests were carried out at the entomology unit and monitoring of insect sensitivity towards insecticides installed at the Regional Diagnostic Laboratory Epidemiological and Environmental Hygiene (LRDEHM), Marrakesh, under the Regional Directorate of Health of Marrakesh-Safi. The bioassay results affirmed the presence of resistance in Culex pipiens larvae towards temephos. This species has also developed similar and comparable resistance levels in the three lodgings studied, with resistance rates recorded varying between 15.2 and 128.5. This study results can be used as database for the control of mosquito resistance to insecticides at local and national level.

Effect of indoor residual spraying on sandfly abundance and incidence of visceral leishmaniasis in India, 2016–22: an interrupted time-series analysis and modelling study

Efforts to eliminate visceral leishmaniasis in India mainly consist of early detection and treatment of cases and indoor residual spraying with insecticides to kill the phlebotomine sandfly Phlebotomus argentipes that transmits the causative Leishmania protozoa. In this modelling study, we aimed to estimate the effect of indoor residual spraying (IRS) on vector abundance and transmission of visceral leishmaniasis in India. In this time-series analysis and modelling study, we assessed the effect of IRS on vector abundance by using indoor vector-abundance data (from 2016 to 2022) and IRS quality-assurance data (from 2017-20) from 50 villages in eight endemic blocks in India where IRS was implemented programmatically. To assess a potential dose-response relation between insecticide concentrations and changes in sandfly abundance, we examined the correlation between site-level insecticide concentrations and the site-level data for monthly sandfly abundances. We used mathematical modelling to link vector data to visceral leishmaniasis case numbers from the national Kala-Azar Management Information System registry (2013-21), and to predict the effect of IRS on numbers of averted cases and deaths. IRS was estimated to reduce indoor sandfly abundance by 27% (95% CI 20-34). Concentrations of insecticides on walls were significantly-but weakly-associated with the degree of reduction in vector abundance, with a reduction of -0·0023 (95% CI -0·0040 to -0·0007) sandflies per mg/m2 insecticide (p=0·0057). Reported case numbers of visceral leishmaniasis were well explained by trends in vector abundance. Village-wide IRS in response to a newly detected case of visceral leishmaniasis was predicted to reduce disease incidence by 6-40% depending on the presumed reduction in vector abundance modelled. Indoor residual spraying has substantially reduced sandfly abundance in India, which has contributed to reductions in visceral leishmaniasis and related deaths. To prevent the re-emergence of visceral leishmaniasis as a public health problem, surveillance of transmission and sandfly abundance is warranted. Bill & Melinda Gates Foundation. For the Hindi translation of the abstract see Supplementary Materials section.

Multiresidues of pesticides in the particulate matter (PM10) emitted by rural soils of the semiarid pampas, Argentina. A potential source of air pollution

The aim of this work was to evaluate the presence of 40 pesticides in the PM10 emitted by rural soils of the semiarid region of Argentina. Six agricultural soils for grain production under no till and with high use of pesticides (AG), 5 agricultural soils for forage and grain production under conventional tillage (AFG) and 5 unpaved rural roads (RR) were sampled. The PM10 was generated using the Easy Dust Generator and it was collected with an electrostatic precipitator. The presence of 20 herbicides, 14 insecticides and 6 fungicides was analyzed in the soil and in the PM10. More than 70% of the pesticides analyzed were detected in the soil and in the PM10. All agricultural soils and 87% of RR soils showed at least one residue of pesticides. Multiresidues of pesticides were found in the 100% of PM10 emitted by rural soils. The mean number of pesticides was higher in the PM10 (7) than in the soil (5). Some pesticides were not detected in the soils but they were detected in the PM10 (triticonazole, carbofuran, metsulfuron methyl) and vice versa. In general, the concentrations of herbicides were higher in the PM10 than in the soil, while the concentrations of insecticides and fungicides were lower in the PM10 than in the soil. These results suggest that the concentrations of pesticide in the PM10 (inhalable fraction) should be used instead the concentrations of pesticide in the soil to calculate the exposure factor to pesticides by dust inhalation. This study provides the initial evidence of the presence of multiple pesticide residues in PM10 emitted by rural soils under different land management. Also confirms that the PM10 is a potential source of air contamination with pesticides. Future studies should be driven to measure the concentrations of pesticides and their dynamics in the PM10.

Terbium-benzoyl acetate complex encored indium-MOFs through post-synthetic modification for luminescent sensitive detection of organophosphorus insecticides

Metal-organic frameworks (MOFs) are represented ideal candidate materials for chemical sensing of different kinds of species because they contain optically active sites may be in organic linker or ions node, moreover, MOFs have high porosity that capture different types of guests. Lanthanide MOFs (Ln-MOFs) was very common in sensing chemical species due to identical light emission characteristics. The problem of Ln-MOFs was the difficulty of its preparation; therefore, post-synthetic modification (PSM) technique was excellent for incorporation of lanthanide site in the network. Unlike other MOFs, In-MOF can be post-synthesized because of its free amino group in the network, therefore, it was chosen in the current work. Here, Tb-In-MOF-EBA was generated by PSM of In-MOF in two steps: (1) formation of the amide by the reaction of In-MOF with ethyl benzoyl acetate; (2) chelation of Tb3+ cations by the diketone fragment. The main challenge of present work is not to give another luminescent MOF based sensor rather than using decorative technique based PSM route to tune optically active sensors for organophosphorus (OP) insecticides (dimethoate, chlorpyrifos, and pirimiphos-methyl) identification quantitatively and qualitatively. The emission intensity of Tb-In-MOF-EBA were reduced with 8 %, 50 %, and 81 %, after adding dimethoate, chlorpyrifos, and pirimiphos-methyl for the parent compounds, respectively. Tb-In-MOF-EBA showed interesting selectivity toward dimethoate, chlorpyrifos, pirimiphos-methyl, therefore, it can be used in measuring the concentration of OP insecticide with high accuracy.

Correlation between Coleoptera abundance in cattle excrements and pesticide contamination of nature conservation areas grazed by cattle

The aim of this study was to explore the relationship between pesticide contamination at 16 locations in 14 Dutch nature conservation areas and the abundance of Coleoptera (among which dung beetles) in excrements of grazing cattle. A wide spectrum of pesticides was measured in soil, vegetation and excrements of cattle, obtained from all locations. In the fresh dung pats sampled for chemical analysis, beetle numbers were counted and beetle species were identified. In total, 31 different pesticides (including some metabolites) were detected: 14 in fresh excrements, 17 in soil and 20 in vegetation. Total pesticide concentrations in soil, vegetation and excrements varied between 2.6 and 200 μg kg −1 dry matter. In vegetation, the most frequently encountered classes of pesticides (including some of their metabolites) were fungicides (9), herbicides (4) and insecticides (6). The total number of Coleoptera beetles in dung pats correlated negatively with the total concentration of insecticides in vegetation (Kendall's τ −0.501 at p < 0.05). The total concentrations of herbicides and fungicides were not statistically significant correlated with Coleoptera beetle numbers in the dung pats. Yet, the concentration of one single herbicide, viz. chlorpropham in vegetation correlated significantly negative with Coleoptera counts (Kendall's τ −0.603 at p < 0.01).

The combined effect of sublethal concentrations of insecticides and local entomopathogenic nematode isolates on larval and pupal stages of Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae)

The black cutworm (BCW), Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae), is an economically significant pest affecting numerous crops and turf grasses. Despite employing various methods, such as chemical and biological control, to mitigate this pest, the efficacy of these methods often fails to reach the desired level. Hence, the integration of diverse strategies is a key to sustainable management. In this study, we assessed the toxicity of four insecticides (indoxacarb, pyridalyl, lufenuron, and methoxyfenozide) and three local EPN isolates (two isolates of Heterorhabditis indica and one of Heterorhabditis bacteriophora) in targeting the fifth instar larval (L5) and pupal stages of BCW. After demonstrating their potential use in BCW control, we explored the combined use of sublethal concentrations of insecticides (LC15 or LC30) alongside the LC20 values of EPNs. The findings revealed that lufenuron and methoxyfenozide, when combined with EPNs, exhibited a synergistic effect on the L5 stage of BCW, whereas the same combination displayed antagonism on pupae. On the other hand, the combination of indoxacarb and pyridalyl with EPNs demonstrated a synergistic effect on the pupal stage of BCW. These results highlight the potential of employing a combination of insecticides and EPNs at sublethal concentrations to control BCW effectively. This approach shows promise for designing sustainable pest management strategies within the framework of integrated pest management (IPM).