Insect Growth Regulator Research Articles

Machine learning-based rational design for efficient discovery of allatostatin analogs as promising lead candidates for novel IGRs.

Insect neuropeptide allatostatins (ASTs) play a vital role in regulating insect growth, development, and reproduction, making them potential candidates for new insect growth regulators (IGRs). However, the practical use of natural ASTs in pest management is constrained by their long sequences and high production costs, thus the development of AST analogs with shorter sequences and reduced cost is essential. Traditional methods for designing AST analogs are often time-consuming and resource-intensive. This study aims to employ new computational methodologies to understand the structure-activity relationship and efficiently discover potent AST analogs. Two machine learning models, utilizing multiple linear regression and support vector machine, were constructed to reveal the key structural factors that influence the juvenile hormone-inhibiting activity of AST analogs. These models suggested that a potent AST analog should contain styrene, hydrophilic, and aromatic groups, and rotatable bonds at positions 1, 2, 3, and 4, respectively. Six analogs (A52-A57) were designed and synthesized, and they exhibited potent juvenile hormone-inhibiting activity (IC50 < 16 nM). Notably, analog A53 showed the best activity (IC50 = 2.07 nM), surpassing that of most natural Dippu-ASTs, making it a potential lead candidate for IGRs. These models promote the efficient design, screening, and prioritization of new or untested AST analogs. The study clarifies how a machine learning-based strategy facilitates the development of AST analogs as novel IGR lead candidates, offering a useful reference for pest management. © 2024 Society of Chemical Industry.

Demographic toxicology of insect growth regulators on the nontarget ectolarval parasitoid Habrobracon hebetor

Habrobracon hebetor Say (Hymenoptera: Braconidae) is one of the most important parasitoids of many pyralid moths, including the olive leaf moth, Palpita unionalis Hubner (Lepidoptera: Pyralidae). The widespread use of insecticides threatens natural enemies. Assessing the side effects of insecticides on nontarget organisms supports the rational use of insecticides during field application. The present study evaluates the lethal and sublethal effects of three insect growth regulators (IGRs), novaluron, methoxyfenozide, and pyriproxyfen, on P. unionalis and the demographic toxicology of these IGRs on its parasitoid H. hebetor. The LC50 values of these IGRs on P. unionalis were 0.97, 0.176, and 0.00009 ppm, respectively, indicating that pyriproxyfen was the most toxic. When H. hebetor adults were exposed to these LC50 levels under laboratory conditions to determine possible side effects. The IGRs did not affect the paralysis and parasitism rates of the parasitoid nor the sex ratio of its offspring. IGR treatments slightly reduced hatching rates and immature survival by 15–25%, indicating moderate effects on the early developmental stages of H. hebetor. The longevity and fecundity of treated females were each reduced to < 50% of their respective values in untreated females. Additionally, some demographic parameters of the parasitoid were significantly affected by the IGRs. Nevertheless, despite these observed effects, the positive net reproductive rate (R0 > 0) and intrinsic rate of increase (rm > 1) of H. hebetor indicated an exponential population increase that reflects the compatibility of the IGRs with the parasitoid. Our results demonstrated that the tested IGRs could be categorized as relatively harmless compounds to the parasitoid. Following these laboratory assessments, field studies will be required to confirm the effects of the tested IGRs on H. hebetor as well as other nontarget organisms.

Scaffold hopping approach to the novel hexacyclic pyrazol-3-amide derivatives as potential multi-target insect growth regulators candidates

Ecdysone receptor (EcR) and three insect chitinases (OfChtI, OfChtII, and OfChi-h) are considered as attractive targets for the development of novel insect growth regulators (IGRs) since they are closely related to the insect molting. In this study, to develop potent multi-target IGRs, a series of hexacyclic pyrazol-3-amide derivatives were rationally designed by utilizing the scaffold hopping strategy with the previously reported compound 6j (N-(4-bromobenzyl)-2-phenyl-4,5,6,7-tetrahydro-2H-indazole-5-carboxamide) as a lead compound. The bioassay results indicated that most of the target compounds exhibited obvious insecticidal activity. Especially, compounds a5 and a21 displayed excellent insecticidal activities against P. xylostella with LC50 values of 82.29 and 69.45 mg/L, respectively, exceeding that of 6j (263.78 mg/L). Compounds a5 and a21 also dramatically disturbed the growth and development of O. furnacalis larvae, and their LC50 values were 124.71 and 127.54 mg/L, respectively, superior to the lead 6j (267.33 mg/L). The action mechanism study revealed that the most active compound a21 could act simultaneously on EcR (21.4 % binding activity at 8 mg/L), OfChtI (94.9 % inhibitory at 10 μM), OfChtII (23.1 % inhibitory at 10 μM), and OfChi-h (94.3 % inhibitory at 10 μM), significantly higher than that of the lead compound 6j. The result of molecular docking indicated that transferring the carboxamide group from pyrazole position 5 to 3 enhanced the interactions of a21 with the key amino acid residues of the OfChtI, OfChtII, and OfChi-h, resulting in stronger affinity to the three targets than 6j. The present work offers a useful guidance for the further development of novel multi-target IGRs.

Acyl Hydrazides as Insecticides: Synthesis, Biochemical, Structure-Activity Relationship Studies and Insecticidal Activity of some IGRs Analogues Against Spodoptera littorallis (Boisd.).

The exponential rise in pesticide resistance to conventional chemical pesticides is another major factor driving the development of novel insecticidal active agents. One approach to solving this problem is to investigate novel classes and environmentally safe insecticidal chemicals with a variety of modes of action. Among these techniques is the creation of novel tebufenozide derivatives. Tebufenozide belongs to the insect growth regulator class of insecticides and is regarded as one of the safest chemical insecticides ever. The toxicological and biochemical efficiency of each analog was assessed against the Spodoptera littoralis pest in both its second and fourth instar larvae. The bioassay results show that compound 7 was the most effective insecticidal agent, with LC50 values of 10.6.5 and 18.7 mg/L against S. littoralis larvae in their second and fourth instar larvae, respectively. Finally, it was shown how treatment with the LC50 of the examined substances affected the activity of many enzymes involved in the cuticle production of S. littoralis larvae in their fourth instar. From this study, it was concluded that Acyl hydrazide are helpful for the management of S. littoralis and will be an effective replacement for other synthetic insecticides.

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

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

Novel 5-alkenylthiothiazolidinone scaffold discovery as Multi-Chitinases inhibitors to arrest the molting of Asian corn borer

Chitinases are crucial enzymes in insect growth and development processes and have thus become potential targets for the control of insect pests. Rhodanine (5-alkenylthiothiazolidinone) is an important fragment with various biological activities in agriculture. Therefore, 24 novel 5-alkenylthiothiazolidinone derivatives were designed and synthesized by introducing a hydrophobic hydrocarbon chain and a benzylformamide group on the basis of the conserved binding cavity of three chitinases, OfChtI, OfChtII and OfChi-h. These 5-alkenylthiothiazolidinone analogs were found for the first time to have inhibitory effects on OfChtII, except for their ability to inhibit the other two known chitinases, OfChtI and OfChi-h. The inhibitory activities of the target compounds against OfChtI and OfChi-h ranged from 40 % to 95 % at a concentration of 100 μM. In particular, some compounds were also found to have an inhibitory rate of 50 % against OfChtII. Among them, the Ki values of the most potent compound 5e-9 were 5.82, 27.5 and 6.77 μM against OfChtI, OfChtII and OfChi-h, respectively. The inhibition mechanism studies revealed that both π stacking interactions and hydrophobic interactions were vital for the binding of Compound 5e-9 with the three chitinases. A lethal and sublethal bioassay study revealed that Compound 5e-9 could affect the growth and development of Asian corn borers. This work suggested that 5-alkenylthiothiazolidinone could be a novel inhibitor scaffold against multichitinase for the development of insect growth regulators.

Structural and biological studies on beta – alanine substituted Sulfonamide derivatives: A new class of Juvenile hormone mimics as insect growth regulators

A series of naphthyl-sulfonamide juvenile hormone analogs has been synthesized through one-pot synthesis route using thionyl chloride as an activating agent for carboxylic functional group. The structures of synthesized compounds with general formula C10H7-SO2NH-(CH2)2CON-R1R2 have been confirmed by FT-IR, 1HNMR , 13CNMR , and ESI-MS techniques. The insect growth regulating property of all the synthesized compounds as juvenile hormone analogs (JHAs) has been studied against yellow fever mosquito, Aedes aegypti and tobacco cutworm, Spodoptera litura. The bioassay results demonstrate that the synthesized compounds exhibit insect growth regulating activity in comparison to standard JHAs. The IE50 and IE90 values of B4 are 0.08 and 6.62 ppm, respectively for inhibition of Aedes aegypti and the LC50 and LC90 values of B3 are 11.03 and 45.36 ppm, respectively for Spodoptera litura. Notably, the compounds B3 and B4 showed enhanced efficacy at lower concentrations. Additionally, density functional theory (DFT) technique is used to predict the chemical reactivity and toxicity of the synthesized JHAs in comparison to pyriproxyfen. Further, the DNA-binding study of synthesized JHAs has been carried out using UV–vis spectroscopy for toxicity assessment against DNA and the binding constant values in the range 102 – 103 suggest lower toxicity of all the synthesized molecules in comparison to PYR. All the synthesized JHAs show IGR action and exhibit better reactivity and reduced toxicity as compared to the commercial in use IGRs.

Efficacy of antiparasitic macrocyclic lactone drops against passalurosis and psoroptic mange in rabbits

The purpose of the research is to study the efficacy of a macrocyclic lactone drug using the spot-on method against passalurosis and psoroptic mange in rabbits.Materials and methods. The study was conducted at the Department of Parasitology and Veterinary-Sanitary Expertise of the MVA named after K. I. Skryabin in 2022–2023 to determine the efficacy of antiparasitic drops (active ingredients: phenylpyrazole derivative, pyrazinoisoquinoline derivative, macrocyclic lactone, insect growth regulator, manufactured by AVZ S-P, LLC) against passalurosis and psoroptic mange. The antiparasitic drops were applied by the spot-on method to rabbits of different age and sex groups in doses of 0.5 mL per animal for body weight of up to 4 kg and 1 mL per animal for body weight of 4 to 8 kg against passalurosis and psoroptic mange. Rabbit fecal samples were examined using the Fülleborn method. Skin scrapings from the inner auricle surface were studied for Psoroptes cuniculi mites as per D. A. Priselkova.Results and discussion. The antiparasitic drug was found to have 100 % efficacy against ticks Psoroptes cuniculi and nematodes Passalurus ambigus.

COMPARATIVE LABORATORY ACTIVITY AND SEMI-FIELD EFFICACY OF OMNIPRENE® G AND ALTOSID® PELLETS AGAINST AEDES AEGYPTI.

Mosquito larval control by biorational larvicides plays a crucial role in mosquito and mosquito-borne disease management. However, the availability of larvicides that meet the criteria of efficacy, safety, and quality is limited and conventional pesticides are no longer preferred for larval control. Although efforts are made to research new active ingredients (AIs), it is equally important to innovate new formulations based on currently available AIs such as microbial agents and insect growth regulators. Studies were therefore conducted to compare the laboratory activity and semi-field efficacy of OmniPrene® G and Altosid® Pellets with DR-tech, both containing 4.25% S-methoprene, at 2.8 kg/ha and 11.2 kg/ha against the yellow fever mosquito Aedes aegypti (L.) in outdoor microcosms. Both products performed equally in bioassays against the test species with comparable inhibition of emergence activities. In the semi-field study, the lower dose of Altosid Pellets at 2.8 kg/ha, showed lower efficacy than OmniPrene G during the initial 6 weeks; this difference became negligible on week 7, followed by higher efficacy in Altosid Pellets on weeks 8 and 9. More uniform efficacy was observed at the higher dose of 11.2 kg/ha. Equal performance was revealed during weeks 2 to 6, with the OmniPrene G outperforming the Altosid Pellets in week 1, but the opposite during weeks 7 to 9. Mortality patterns were similar in both products, i.e., majority of mortality occurred before emergence, although more incomplete emergence was noted in lower doses, particularly in Altosid Pellets. Overall, newly available OmniPrene G provided comparable activity and efficacy with Altosid Pellets against the test species, with the advantages of fast initial AI release and even coverage, particularly when applied at low doses.

High concentrations of piperonyl butoxide (PBO) enhance toxicity of S-methoprene against the lesser grain borer, Rhyzopertha dominica.

Insect growth regulators (IGRs) have been playing a major role in the effective management of a range of stored product insect pests including species that have developed resistance to major groups of insecticides, such as organophosphates (OPs) and synthetic pyrethroids (SPs). In the present study, we evaluated the efficacy of S-methoprene alone and in combination with piperonyl butoxide (PBO), an adjuvant component of insecticides for synergy, against two strains, Lab-S (susceptible) and Met-R (Methoprene resistant) of an economically important pest species, the lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae). Adults of both Lab-S and Met-R strains were exposed to wheat treated with multiple concentrations of S-methoprene ranging from 0.001 to 0.01 and 10 to 60 mg/kg, respectively, alone and in combination with PBO. A variety of concentrations, including 0.27, 0.53, 0.80, and 1.07 g/kg, were evaluated for PBO. Mortality of adults and percent reduction in progeny were assessed after 14 and 65 days of treatment, respectively. As anticipated, the adult mortality rates of both strains were not significantly affected by S-methoprene alone. However, the number of progeny produced confirmed that the Met-R strain exhibited a high level of resistance to S-methoprene alone, with over 50 F1 progeny adults surviving in wheat treated with the maximal rate, 10 mg/kg. In contrast, the toxicity of S-methoprene was increased against the same resistant strain (Met-R), by 0.80 or 1.07 g/kg of PBO in combination treatment, resulting in a significant reduction in progeny numbers (25 adults per container). Although the tested concentrations of S-methoprene and PBO were well above the currently registered rate globally, our results highlight the fact that PBO enhances the toxicity of S-methoprene to some extent, reaffirming that the mode of action of the latter involves the inhibition of mixed-function oxidases (MFOs) and highlights the need for further research into developing potential binary or triplet formulations containing these two active ingredients (AIs).

A smartphone-based supramolecular biosensor for portable and rapid detection of buprofezin in real food samples

Buprofezin (BUP) is an insect growth regulator widely used in agriculture to control hemipteran pests, particularly the melon aphid, Aphis gossypii, due to its efficiency and low toxicity. Although approved by the Chinese government, its maximum residue limit (MRL) in food is strictly regulated, and conventional techniques for detecting BUP have several limitations. Our study reports successful BUP detection using a supramolecular fluorescent probe DP@ALB, constructed with chalcone-based fluorescent dye DP and albumin as the host. The probe offers advantages such as low cost, visual signal output with high fluorescence color variation, rapid response, and high sensitivity. Additionally, portable test strips enable convenient on-site BUP detection and simplifying field monitoring of spiked real samples. The study achieves precise qualitative and quantitative BUP analysis in grape fruit, groundwater, and soil with satisfactory recoveries. Further, the biological applicability of sensor for the in vitro detection of BUP in L929 living cells was demonstrated. This research breakthrough overcomes the limitations of traditional analytical methods, offering an efficient and reliable approach for food and environmental monitoring and pesticide residue detection.

Extreme resistance to S-methoprene in field-collected Culex pipiens (Diptera: Culicidae) across the Chicago, IL region

Insect growth regulators, like S-methoprene, are heavily relied upon worldwide for larval mosquito chemical control due to their target specificity and long-lasting effects. In this study, susceptibility to S-methoprene was evaluated in Culex pipiens, a globally important vector species. Populations from 14 sites throughout the Chicago area with a long history of S-methoprene use and two sites with minimal use in Wisconsin were examined. Using a bioassay methodology and probit analyses, LC50 and LC90 values were calculated and compared to a susceptible laboratory strain to develop resistance ratios, then categorized for resistance intensity. The resistance ratios observed required the addition of another category, termed ‘extreme’ resistance, indicating resistance ratios greater than 100. ‘Low’ to ‘extreme’ levels of resistance to S-methoprene were detected throughout Illinois populations, with resistance ratios ranging from 2.33 to 1010.52. Resistance was not detected in populations where S-methoprene pressure has been very limited. These 'extreme’ resistance ratios observed have never been documented in a wild vector species mosquito population. The relationships between historical S-methoprene use, resistance detected with laboratory bioassays, and the potential for field product failure remain unclear. However, the profound resistance detected here demonstrates a potential critical threat to protecting public health from mosquito-borne diseases.

Evaluation of the In2Care Mosquito Station at low deployment density: a field study to manage Aedes aegypti and Culex quinquefasciatus (Diptera: Culicidae) in North Central Florida.

In the last 2 decades, there has been an increase in the geographic range and frequency of vector-borne diseases. Management of mosquito populations has become challenging due to increasing rates of resistance to existing insecticidal products and formulations. Several alternative tools have emerged to suppress or replace mosquito populations. One of these tools is the In2Care Mosquito Station (In2Care station). This dual-action station contains the insect growth regulator pyriproxyfen which disrupts the development of immatures and the entomopathogenic fungus Beauveria bassiana (B. bassiana) strain GHA which kills exposed adult mosquitoes. The In2Care stations have previously been shown to effectively control Aedes aegypti in field settings at a density of 6 stations/acre rather than the label-recommended 10 stations/acre. To further test the efficacy of low station density deployment, we deployed In2Care stations in the Pleasant Street Historic District of Gainesville, Florida, at a density of 3 stations/acre over a period of 2 years in the presence or absence of ground larvicidal applications. The deployment of stations resulted in no measurable impact on Ae. aegypti and Culex quinquefasciatus adult or immature abundance suggesting that the low-density deployment of In2Care stations is insufficient to reduce Ae. aegypti and Cu. quinquefasciatus abundance within treatment areas.

English

Oilseed cultivation is the major source of energy that fulfills the cooking oil requirements of large masses across the globe. Mustard is one of the important members of the brassica family, which is attacked by an aphid, Lipaphis erysimi. This research investigated the field population fluctuations of L. erysimi on different mustard varieties for two growing years. L. erysimi population reached to peak (171.3 nymphs and 141.6 adults) in the Mustard-early variety in early March. Based on Mustard Resistance Index (MRI), the Mardan-Local variety is highly resistant having an Aphid Population Score (APS) and Leaf Damage (LD) of 1 with a pooled annual mean of 1.85 aphids. The varietal preference test results indicated that the highest L. erysimi (8.0 adults) were attracted to the Mustard-early variety while the least (2.80 adults) were attracted to Mardan-local. In the In-vitro bioassay, Lefenuron and Pyriproxyfen caused 100 and 70.4% mortality, respectively. In the field, synchronized experiment, Imidochloprid (control positive) and Lefenuron showed the highest mortalities (100%), respectively. The Pyriproxefen and Runner (Methoxyfenoxid) treated plots had caused 77 and 70.3% mortalities, respectively. The present research is the first attempt to investigate the synchronized effects of Host Plant Resistance and Insect Growth Regulators for the L. erysimi management in Mustard. It is concluded that Mardan-Local variety alongside lefenuron application provides an effective IPM for L. erysimi. These outcomes will help the farmers better understand and manage aphids; it will help the researcher to explore further management tools of Aphids in oilseed crops.

The impact of non-lethal doses of pyriproxyfen on male and female Aedes albopictus reproductive fitness.

Control of the mosquito Aedes albopictus is confounded by its behavior due to females preferring to oviposition in small natural and artificial containers that are often difficult to remove or treat with insecticides. Autodissemination strategies utilizing highly potent insect growth regulators (IGRs) have emerged as promising tools for the control of this container-inhabiting species. The intended goal of autodissemination approaches is to use mosquitoes to self-deliver an IGR to these cryptic oviposition locations. Previous studies have focused on the efficacy of these approaches to impact natural populations, but little focus has been placed on the impacts on mosquitoes when exposed to non-lethal doses of IGRs similar to the levels they would be exposed to with autodissemination approaches. In this study, the impact of non-lethal doses of pyriproxyfen (PPF) on the reproductive fitness of Ae. albopictus was investigated. Female and male Ae. albopictus mosquitoes were exposed to non-lethal doses of PPF and their fecundity and fertility were measured. To examine the impact of non-lethal doses of PPF, the expression of the ecdysone-regulated genes USP, HR3, and Vg, which are involved in vitellogenesis, was determined. Our results demonstrated a significant reduction in female fecundity and in the blood feeding and egg hatching rates upon exposure to non-lethal doses of PPF. Oocyte development was also delayed in PPF-treated females. Furthermore, exposure to non-lethal doses of PPF altered the expression of the genes involved in vitellogenesis, indicating disruption of hormonal regulation. Interestingly, PPF exposure also reduced the sperm production in males, suggesting a potential semi-sterilization effect. These findings suggest that non-lethal doses of PPF could enhance the efficacy of autodissemination approaches by impacting the reproductive fitness of both males and females. However, further research is needed to validate these laboratory findings in field settings and to assess their practical implications for vector control strategies.

Eficacy of Certain Insecticides against Olive Psyllid &lt;i&gt;Euphyllura straminea&lt;/i&gt; (Loginova)

A field study was conducted to assess the effectiveness of six insecticides (with different modes of action) viz, imidacloprid, spirotetramat, sulfoxaflor, buprofezin, pyriproxyfen, and mineral oil, against the olive psyllid Euphyllura straminea (Loginova) (Homoptera: Aphalaridae) on olive trees (Olea europea L.) in Giza Governorate during the 2022 season. The results indicated that all tested insecticidesa significantly reduced the olive psyllids (both nymph and adult stages). Particularly, imidacloprid, sulfoxaflor, and spirotetramat were superior in reducing nymphs (91.37, 89.80, and 89.34% reduction, respectively). Mineral oil was the least effective (only 81.39% reduction). The same order of efficiency was observed with the adults, except for spirotetramat. Buprofezin and pyriproxyfen as insect growth regulators (IGR) displayed good efficacy.

Analytical method for insect growth regulator pyriproxyfen by LC/MS/MS and occurrence in street gully in Tokyo

Analytical method for insect growth regulator pyriproxyfen by LC/MS/MS and occurrence in street gully in Tokyo

Novel Aryl Thioamides Derivatives as Insect Growth Regulators Analogues against Spodoptera littoralis (Lepidoptera: Noctuidae): Design, Synthesis, Insecticidal Activity and Biochemical Impacts.

A significant reason for developing innovative insecticidal active agents is the exponential rise in resistance to traditional chemical pesticides. Exploring new classes of insecticidal compounds with distinct mechanisms of action is one way to address this difficulty. So that, novel aryl thioamides derivatives 3-15 has been synthesized viaone-pot, three-component reaction of aroyl chloride, ammonium thiocyanate, and aromatic amines in dry acetone. The newly synthesized compounds' structures were validated by various spectroscopic methods, including elemental analysis, 1H-NMR, 13C NMR, and infrared spectroscopy. Under laboratory circumstances, the synthesized compounds showed good and broad-spectrum insecticidal activities toward S. littorali. When compared to other synthetic target compounds, 2,4-dichloro-N-[(3-fluorophenyl)carbamothioyl]benzamide 11, 2,4-dichloro-N-[(3-fluorophenyl)carbamothioyl]benzenecarbothioamide 13 showed good insecticidal activity, with 46.33 mg/L and LC50 values of 49.25 mg/L for 2nd instar larvae. Furthermore, the compound 3 was the least toxic in controlling the second and fourth instar larvae of S. littoralis on tomato leaves. Additionally, several histopathological and biochemical features of the some synthesized compounds under laboratory circumstances were also examined.

Potential of secondary metabolites from soil-derived actinomycetes as juvenile hormone disruptor and insecticides

Actinomycetes represent sources of potential alternatives to chemicals as biological pest control agents, and several actinomycetes are known to produce metabolites with insecticidal activities against insect pests. Although these metabolites are eco-friendly and effective, it is necessary to identify a novel insect-specific insecticidal agents that can minimize the occurrence of resistance. Thus, in this study, we screened the juvenile hormone disruptor (JHD) and insecticidal activities of crude acetone extracts derived from various actinomycetes as novel biopesticide candidates. A total of 300 soil-derived actinomycetes were isolated from various sites in Korea, and were screened for their JHD and insecticidal activities against a range of important medical and agricultural pests. Among them, eight extracts showed high levels of JHD activity. The AN120590 strain showed a broad insecticidal spectrum with stably maintained JHD properties. Additionally, the dead larvae of Aedes albopictus and Plutella xylostella treated with acetone extracts of the AN120590 strain displayed morphological deformities similar to those of insects treated with juvenile hormone-based insect growth regulators (IGRs). These findings indicate that actinomycetes represent promising sources of novel IGRs that can be effectively applied as insecticides with a broad insecticidal spectrum.

A new strategy for efficient detection of triflumuron residues in food: An electrochemical sensor derived from a Cu/Fe-BTC MOF-polymer

Triflumuron is an insect growth regulator belonging to the class of insecticides. It finds its primary application in the agricultural sector for the control of various pests, particularly certain beetles, aphids, locusts, and mites. In this paper, a Cu/Fe-BTC composite was synthesized through a straightforward solvothermal approach, subsequently employed as a precursor for the fabrication of an electrochemical sensor denoted as CuFe2O4@C. The latter exhibited a distinctive core-shell architecture achieved through annealing, and its application was focused on the sensitive detection of triflumuron. The electrochemical behaviour of CuFe2O4@C for the detection of triflumuron was evaluated by differential pulse voltammetry (DPV) under optimal conditions in wide concentrations from 1.0 × 10−4 to 1.0 × 10−12 mol·L−1, where there existed a superior linear relationship between the current and the concentration of triflumuron with R2 being 0.995. Meanwhile, CuFe2O4@C had a low limit of detection (LOD) of 922 fM for triflumuron. The CuFe2O4@C/GCE exhibited remarkable sensitivity, long-term stability, excellent reproducibility, and repeatability, as well as effective anti-interference capabilities. Additionally, CuFe2O4@C demonstrated its applicability for the quantitative determination of triflumuron in diverse real samples with commendable recovery rates. In conclusion, the electrochemical sensor not only displayed exceptional performance in terms of stability, reproducibility, and anti-interference, but also showcased its practical utility in quantifying triflumuron across various real-world samples.