Simulating the residual magnitudes of pesticides applied to crops during cultivation is essential for determining appropriate harvest timing to guarantee safe agricultural products. In this study, field experiments were performed to evaluate the time-dependent persistence of pesticides captan (CT), lufenuron (LF), tebufenozide (TB), and teflubenzuron (TF) applied to apples at recommended and three-fold higher doses. Subsequently, various kinetic models were applied to the residual data for calculating pre-harvest residue limits (PHRLs) which indicate permissible pesticide concentrations during the pre-harvest period. The double-exponential model best fitted persistence trends of all tested pesticides in apples (R2 = 0.67 - 1.00), outperforming zero-, first-, and second-order models. TB, vulnerable to sunlight, exhibited shortest half-lives in apples (0.2 - 0.4 days). Systemic insecticide TF showed longest half-lives in apples (24.6 - 29.3 days), while CT and LF ranged 8.6 - 9.9 and 11.3 - 16.1 days, respectively. Double-exponential parameters enabled PHRL estimation for determining safe apple harvest dates ensuring pesticide concentrations below maximum residue limits. This model provides accurate PHRL calculations, helping farmers produce safer apples from pesticide residues.

Spodoptera exigua (Lepidoptera, Noctuidae) poses significant threats to global agriculture, necessitating the management of resistance through sustainable alternatives such as Insect growth regulators (IGRs), including Methoxyfenozide (MET) and Lufenuron (LUF). This study elucidates the potential regulatory mechanisms between 20-hydroxyecdysone (20E) and immune signaling under IGR exposure. Sublethal doses of MET, LUF, and their mixture (MML) significantly downregulated the 20E titer by upregulating SeShd and SeCYP18A1. Silencing SeShd decreased 20E, whereas knockdown SeCYP18A1 increased 20E; both delayed development and increased susceptibility to IGRs. Furthermore, IGRs activated immune pathways (Toll/IMD), elevating SeDif and SePGRP-LB (SePLB) expression while simultaneously suppressing 20E. Silencing SeDif and SePLB stimulated 20E biosynthesis and heightened susceptibility to IGRs. These findings offer novel insights into the intricate interplay between 20E biosynthesis and the immune response to IGRs. Our work enhances the understanding of the IGRs' molecular mechanism and offers actionable strategies for combating resistance in S. exigua.

The fate and risk identification of cyantraniliprole (CYA) and lufenuron (LUF) in pak choi were systematically analyzed through an investigation comprising field trials, dissipation kinetics, and dietary risk assessment. Initially, field experiments across ten Chinese provinces revealed half-lives of 3.04–5.41 d for CYA and 2.02–5.13 d for LUF, with dissipation following single first-order (SFO) kinetics or double first-order in parallel (DFOP) kinetics. Terminal residues (<limit of quantification (LOQ) to 0.29 mg/kg) were below maximum residue limits. Dissipation rates were significantly influenced by temperature, climate, and crop growth stage. Additionally, the multidimensional dietary assessment using deterministic and probabilistic models revealed acceptable long-term risk levels for CYA and LUF among consumer groups (risk quotients < 28.4%). Overall, this first comprehensive study from cultivation to consumption provides crucial insights for rational pesticide use in pak choi.

Sporotrichosis caused by Sporothrix brasiliensis is a globally emerging infectious disease with limited therapeutic options. Thus, we aimed to evaluate the in vitro activity of amlodipine (AML) and lufenuron (LUF) alone and their interaction with itraconazole (ITZ), the first-choice drug against S. brasiliensis. Twenty clinical isolates of S. brasiliensis from two hyperendemic regions were tested through a microdilution assay to evaluate the minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) of AML and LUF. Checkerboard assay was performed with 10 isolates for both drug interactions with ITZ. AML showed inhibitory and fungicidal activity against all isolates included, with MIC values ranging from 32 to 256 µg/mL, and MFC from 64 to 256 µg/mL. However, none of the S. brasiliensis isolates were inhibited by the highest soluble concentration of LUF (MIC >64 µg/mL for all strains). Synergic interaction of AML and LUF with ITZ occurred in 50% and 40% of the isolates tested, without any antagonistic effects. Both repurposing drugs evaluated in our study showed a promising in vitro activity, especially in synergy with ITZ against S. brasiliensis, warranting future in vivo investigations regarding its activity.

Management of khapra beetle, Trogoderma granarium Everts, using binary combinations of chitin synthesis inhibitors and inert dusts

Lufenuron (LUF) and Methoxyfenozide (MET) as Insect Growth Regulators (IGRs) contribute to the current control of the catastrophic crop pest, Spodoptera exigua (Lepidoptera, Noctuidae). Yet S. exigua has evolved resistance to LUF and MET, which is possibly mediated by cytochrome P450 monooxygenases (P450s), particularly from the CYP3 clade family, as it plays a key role in the detoxification of insecticides. However, a mixture of LUF and MET (MML) (optimal ratio: 6:4) remains highly insecticidal. Here, we analysed the response of S. exigua to sublethal concentrations of LUF, MET, and MML via transcriptomics. Twelve differentially expressed genes (DEGs) encoding CYP3 clade members were observed in transcriptomes and CYP9A9 was significantly upregulated after treatment with LUF, MET, and MML. Further, CYP9A9 was most highly expressed in the midgut of L4 S. exigua larvae. RNAi-mediated knockdown of CYP9A9 reduced the activity of CYP450 and increased the susceptibility of S. exigua larvae to LUF, MET, and MML. Thus, CYP9A9 plays a key role in the detoxification of LUF, MET, and MML in S. exigua. These findings provide new insights into insecticidal actions of IGRs, which can be applied to the establishment of novel pest management strategies.

Knockdown of UDP-N-acetylglucosamine pyrophosphorylase and chitin synthase A increases the insecticidal efficiency of Lufenuron to Spodoptera exigua

Background: Chrysomya albiceps is of medical and veterinary importance as larvae cause cutaneousmyiasis in both man and animals. Chitin synthesis inhibitors (CSI) are commonly used in control ofdipterous flies causing myiasis. Several compounds are utilized to interfere with chitin deposition andmolting processes during development.Objectives: In comparison to chlorfluazuron (CF), the current study aims to investigate the toxicologicaland ultrastructural effects of the CSI, lufenuron (LF) on the biological parameters of the third larval instar(L3) of C. albiceps.Material and Methods: Early L3 of C. albiceps were fed on diets mixed with four concentrations of LF andCF. Average larval mortality rates were subjected to probit model analysis for calculating LC25, LC50, andLC90. Larval deformation and mortality, percent pupation, adult emergence and chitinase enzyme activitywere recorded. Using transmission electron microscope (TEM), ultrastructural study was carried out onnon-treated and treated L3 to evaluate LF effects on the integument and muscle layer.Results: By recording LC50 values for LF and CF (146 and 194 ppm, respectively), LF showed more toxiceffects on L3 than CF, and at a lower concentration. Reduction in pupation percentage, complete cessationof adult emergence from pupae and decrease in chitinase activity were observed after treatment withall concentrations of both compounds. Ultrastructural changes after treatment with LC50 of LF indicatedtegumental, nuclear and mitochondrial toxicological effects, and muscle fibers disorganization.Conclusion: LF proved to be a successful CSI in controlling myiasis causing C. albiceps L3.

The aim of this study was to investigate plasma proteins, total immunoglobulin (Ig), lysozyme and complement (ACH50) levels, and gill superoxide dismutase (SOD) and catalase (CAT) gene expression in common carp (Cyprinus carpio), following exposure to lufenuron (LUF) and flonicamide (FL). Fish were distributed in 12 tanks as three quadrupled treatments: control (fish were kept in pesticide-free water), LUF [fish exposed to 10% of LUF LC50 (4.3mg/L)], and FL [fish exposed to 10% of FL LC50 (0.1mg/L)]. The plasma parameters were assessed after 7 and 21days exposure to pesticides, whereas the gene expressions were assessed after 21days. The results showed that LUF exposure significantly decreased plasma total protein and globulin levels compared to the control group. Both pesticide significantly decreased plasma total Ig levels compared to the control group; however, LUF exhibited a greater effect. There were no significant effects of pesticides or sampling time on plasma ACH50 activity. Pesticides and sampling time interacted to affect plasma lysozyme activity. Seven days after exposure, both pesticides significantly increased lysozyme activity, and the effect of FL was greater than LUF. Nevertheless, there was no significant difference in plasma lysozyme activities among the pesticides, 21days after the exposure. Both pesticides significantly decreased SOD and CAT gene expression, nevertheless, FL exhibited greater effects than LUF. In conclusion, both pesticides induced immunosuppression in the fish, though such effects were more severe in LUF group, compared to the FL. These pesticides negatively affect expression of gill antioxidant genes, and the FL effects were greater than the LUF.

The salmon louse (Lepeophtheirus salmonis) is an ectoparasite infecting Atlantic salmon (Salmo salar), which causes substantial problems to the salmon aquaculture and threatens wild salmon. Chitin synthesis inhibitors (CSIs) are used to control L. salmonis in aquaculture. CSIs act by interfering with chitin formation and molting. In the present study, we investigated the action of four CSIs: diflubenzuron (DFB), hexaflumuron (HX), lufenuron (LF), and teflubenzuron (TFB) on larval molt. As the mode of action of CSIs remains unknown, we selected key enzymes in chitin metabolism and investigated if CSI treatment influenced the transcriptional level of these genes. All four CSIs interfered with the nauplius II molt to copepodids in a dose-dependent manner. The EC50 values were 93.2 nM for diflubenzuron, 1.2 nM for hexaflumuron, 22.4 nM for lufenuron, and 11.7 nM for teflubenzuron. Of the investigated genes, only the transcriptional level of L. salmonis chitin synthase 1 decreased significantly in hexaflumuron and diflubenzuron-treated larvae. All the tested CSIs affected the molt of nauplius II L. salmonis larvae but at different concentrations. The larvae were most sensitive to hexaflumuron and less sensitive to diflubenzuron. None of the CSIs applied had a strong impact on the transcriptional level of chitin synthesis or chitinases genes in L. salmonis. Further research is necessary to get more knowledge of the nature of the inhibition of CSI and may require methods such as studies of protein structure and enzymological studies.

In accordance with Article 43 of Regulation (EC) 396/2005, EFSA received a request from the European Commission to provide support for the preparation of the EU position for 51st session of the Codex Committee on Pesticide Residues (CCPR). In 2018, JMPR evaluated 15 active substances regarding the setting of toxicological reference values to be used in consumer risk assessment (chlorfenapyr, ethiprole, fenpicoxamid, fluazinam, fluxapyroxad, imazalil, kresoxim‐methyl, lambda‐cyhalothrin, mandestrobin, mandipropamid, norflurazon, pydiflumetofen, pyraclostrobin, pyriofenone, tioxazafen) and 27 active substances regarding the setting of maximum residue limits (MRLs) (abamectin, bentazone, chlorfenapyr, cyantraniliprole, cyazofamid, diquat, ethiprole, fenpicoxamid, fenpyroximate, fluazinam, fludioxonil, fluxapyroxad, imazalil, isofetamid, kresoxim‐methyl, lufenuron, mandipropamid, norflurazon, oxathiapiproline, profenofos, propamocarb, pydiflumetofen, pyraclostrobin, pyriofenone, pyriproxyfen, sulfoxaflor and tioxazafen); EFSA prepared comments on the Codex MRL proposals and the proposed toxicological reference values. In addition, EFSA provided comments on follow‐up assessments of JMPR on pesticides where specific concerns were raised in the previous CCPR meetings. The current report should serve as the basis for deriving the EU position for the CCPR meeting.

Laboratory evaluation on a potential birth control diet for fruit fly sterile insect technique (SIT)

Lufenuron (LFN), a chitin synthase inhibitor, impacts the fertility of Ceratitis capitata, Bactrocera dorsalis, B. cucurbitae, and B. latifrons. We posed the hypothesis that LFN curtails egg hatch in the solanaceous fruit fly, B. latifrons. In this study, newly emerged virgin adults were sexed and fed for 12 days with varying concentrations of LFN-laced agar diets until sexual maturation. Eggs were collected from 12-d-old adults and the egg hatch was assessed. Egg hatch decreased in adults reared on LFN-treated diets. LFN-treated media did not influence fertility after one gender was reared on experimental and the other on control media before mating. Exposure to LFN-treated medium after mating led to reduced egg hatch. We infer that LFN is not a permanent sterilant, and reduced egg hatch depends on continuous exposure to dietary LFN after mating. Proteomic analysis identified two differentially expressed proteins, a pheromone binding protein and a chitin binding protein, between adults maintained on LFN-treated and control diets. Expression of two genes encoding chitin synthase 2, and chitin binding protein, was altered in adults exposed to dietary LFN. LFN treatments also led to increased expression of two odorant binding proteins one in females and one in males. We surmise these data support our hypothesis and provide insight into LFN actions.

Chrysoperla carnea (Stephens) is a general biocontrol agent of several insect pests in greenhouses. The lethal effects of four compounds, imidacloprid, lufenuron, thiametoxam and thiodicarb, on the eggs and 1st instar larvae of C. carnea were studied in laboratory conditions. Dipping bioassay tests were used for eggs and the residual contact method for larvae. Positive relationships were detected between the concentrations of insecticides and mortality rates of various stages. However, there were considerable variations in toxicity of insecticides. Thiodicarb had no effect on eggs, whereas thiametoxam with an LC50 value of 1.90 μg ai. L-1 showed the highest ovicidal activity. On larvae, thiametoxam was the most toxic (LC50= 0.55 μg ai. L-1) and lufenuron proved to be the least toxic (LC50 = 44.02 μg ai. L-1). The use of thiametoxam should be carefully evaluated if employed in combination with C. carnea in IPM programs

A laboratory bioassay was used to evaluate the effect of residues from 10 orchard pesticides on mortality of Dolichogenidea tasmanica a parasitoid of leafrollers Adult parasitoids were caged in Petri dishes that had been sprayed with the field rate of the pesticides Mortality was assessed over 7 days and classified using the laboratory criteria defined by the International Organization for Biological and Integrated Control of Noxious Animals and Plants Residues of buprofezin emamectin benzoate lufenuron tebufenozide and thiacloprid were harmless (lt;30 mortality) to D tasmanica adults in the 7 days after treatment Indoxacarb and lime sulphur residues were moderately harmful (8099 mortality) while carbaryl diazinon and spinosad residues were harmful (>99 mortality) The implications for leafroller control in pipfruit production programmes are discussed

Photochemical-spectrofluorimetric method for the determination of benzoylurea insecticides: applications in river water samples and in technical formulations