Properties, toxicity and current applications of the biolarvicide spinosad

Microbial biopesticides: A one health perspective on benefits and risks

Controlling insect pests that destroy crop and spread diseases will become increasingly crucial for addressing the food demands of a growing global population and the expansion of vector-borne diseases. A key challenge is the development of a balanced approach for sustainable food production and disease control in 2050 and beyond. Microbial biopesticides, derived from bacteria, viruses, fungi, protozoa, or nematodes, offer potentially significant benefits for promoting One Health and contributing to several United Nations Sustainable Development Goals (SDGs). This narrative review examines the benefits and risks of microbial biopesticides from a One Health perspective, focusing on the Americas and Europe, and aligned with respective SDGs. The value of biopesticides in sustainable agriculture and integrated pest management (IPM) approaches for food security, particularly SDG 2 (Zero Hunger) and SDG 1 (No Poverty) has been widely recognized, with relatively fewer adverse effects to people and the environment than synthetic pesticides. With increased demand and usage, microbial biopesticides can be expected to contribute further to additional SDGs such as SDG 12 (responsible consumption and production) through waste recycling for biopesticide production and remediation of polluted ecosystems, and by reducing vector-borne disease burdens such as malaria and dengue. Nevertheless, the prudent and judicious application of microbial biopesticides is crucial to ensuring their effectiveness and maximizing their One Health benefits while minimizing pest resistance and unintended impacts. From a One Health perspective, this goal involves incorporating microbial biopesticides into a comprehensive biological control strategy within an IPM framework for sustainable agriculture and for controlling vector-borne diseases.

Residue pattern and risk assessment of validamycin A and spinosyn A in tea using hydrophilic interaction liquid chromatography coupled with tandem mass spectrometry

Validamycin A (VA) and spinosyn A (SA) have been utilized as antibiotic pesticides in tea plantations for the control of pests and diseases. Both pesticides pose significant risks to human health and have been listed as key controlled new pollutants in China. So far, there have been few reports for the risk assessment of antibiotic pesticides in tea. In this study, a hydrophilic interaction liquid chromatography coupled with tandem mass spectrometry (HILIC-MS/MS) method was developed for the simultaneous detection of VA and SA residues in tea. Method validation demonstrated good accuracy and precision. During tea planting, SA and VA in tea shoots degraded fast, with the half-life of 0.36 to 0.43 days for SA and 0.72 to 0.92 days for VA. SA and VA in tea shoots degraded fast initially and then followed by a slower phase. Both SA and VA degraded rapidly during the withering and drying stages. Compared to green tea, the degradation rates of both pesticides were faster during black tea manufacturing. Transfer rates of VA and SA from tea into infusions had transfer rates of 76.7 % to 99.5 % and 1.5 % to 2.7 %, respectively. The chronic risk quotient (RQc) < 1 for both antibiotic pesticides indicated negligible consumer risk from tea.

History and future perspectives of spinosad for mosquito control

Since the initial discovery of the soil-dwelling actinomycete Saccharopolyspora spinosa in 1982, its metabolites spinosyns and modified spinosoids have been developed to control a wide variety of arthropod pests of economic importance. The most intensively studied are spinosad consisting of natural spinosyn A and D, as well as spinetoram comprising modified spinosyn J and L. The unique mode-of-action, high bioactivity and generally benign environmental safety profile of spinosyns add significant value to this class of pesticides of natural origin. Currently, products based on spinosad and spinetoram are available in >85 countries since initial global registration in 1996. In the US, spinosad and spinetoram are found in >80 registered pesticide products, mostly being used on agricultural crops, ornamental plants, stored grains, urban environments, and pets. Some spinosad products are approved for use in organic farming. Since the earliest recognition and registration of spinosad products for mosquito control in the 2000s, numerous customized formulations have been developed and registered for controlling different mosquito species in diverse habitats. Thus far, satisfactory bioactivities and effectiveness against mosquitoes by available products have been documented worldwide. At the same time, concerns over nontarget aquatic invertebrate fauna have gradually emerged when considering spinosad as a relatively selective pesticide. Resistance and cross-resistance following repeated applications, and their management are of pressing concern. © 2025 Society of Chemical Industry.

Acute contact toxicity of insecticides for the chemical control of the invasive yellow-legged hornet Vespa velutina nigrithorax (Hymenoptera: Vespidae)

The yellow-legged hornet, Vespa velutina subs. nigrithorax Buysson, 1905, originally from Southeast Asia, has become an invasive species in Europe since its introduction in France around 2004. Its rapid proliferation and voracious predatory behavior pose a significant threat to native insects, particularly honeybees and other pollinators, impacting agricultural production, biodiversity, and human safety. Eradication in Europe seems now impossible, and the control efforts are hindered by the lack of standardized application protocols, including for insecticide use, leading to potential indiscriminate pesticide application and, consequently, environmental damages. Our study evaluated the acute contact toxicity on V. v. nigrithorax workers of four commercially available formulations containing acetamiprid, cypermethrin, a mix of natural pyrethrins, and Spinosad as active ingredients. These tests were performed in laboratory conditions, offering novel data for the chemical control of this invasive species. Our results suggest acetamiprid and spinosad as promising candidates for the yellow-legged hornet control. Further research is needed to validate their efficacy under field conditions and assess ecological impacts of these pesticides on non-target organisms. Integrated pest management strategies should prioritize insecticides with low non-target toxicity and minimal environmental persistence to mitigate resistance development and ensure effective pest control. Comprehensive assessments considering multiple factors beyond mortality are essential for informing sustainable pest control strategies.

An organic solvent-free self-assembly strategy for scalable preparation of nanobiopesticides with enhanced insecticidal activity against houseflies

The abuse of toxic organic solvents has caused great harm to human health and the environment. Therefore, developing an environmentally friendly nano-based pesticide formulation without using harmful solvents is urgent to improve the efficacy of pesticides and minimize environmental and health risks. Herein, by combining aspartic acid (Asp) with spinosad (SSD) as an attractive building unit, a self-assembly and carrier-minimized strategy was applied to construct a nanobiopesticide (Asp-SSD) simultaneously. To further improve the storage stability of the formulation, the biogenic surfactant alkyl polyglucoside (APG) was subsequently added to afford a more stable and smaller nano-delivery system (Asp-SSD-APG). Bioactivity assays showed that Asp-SSD-APG exhibited good quick-acting performance against Musca domestica in the spray assay, and the insecticidal activities of Asp-SSD and Asp-SSD-APG were better than that of the SSD nano-suspension concentrate (Nano-SC). Compared to CK, Asp-SSD-APG reduced the activity of GST, SOD, and CAT in M. domestica, which contributed to the enhanced insecticidal effect of SSD. The cell viability evaluation in 4T1 cells showed that Asp-SSD-APG posed a low risk to the mammalian cells. This study provides an alternative approach for developing environmentally benign nanobiopesticides with a self-assembly and carrier-minimized strategy, which has the potential to improve the efficacy and safety of pesticides in the public health field.

4(3H)-Quinazolinone: A Natural Scaffold for Drug and Agrochemical Discovery

4(3H)-quinazolinone is a functional scaffold that exists widely both in natural products and synthetic organic compounds. Its drug-like derivatives have been extensively synthesized with interesting biological features including anticancer, anti-inflammatory, antiviral, antimalarial, antibacterial, antifungal, and herbicidal, etc. In this review, we highlight the medicinal and agrochemical versatility of the 4(3H)-quinazolinone scaffold according to the studies published in the past six years (2019-2024), and comprehensively give a summary of the target recognition, structure-activity relationship, and mechanism of its analogs. The present review is expected to provide valuable guidance for discovering novel lead compounds containing 4(3H)-quinazolinone moiety in both drug and agrochemical research.

Micro and nanobubbles enhanced ozonation technology: A synergistic approach for pesticides removal

Pesticides production, consumption, and disposal around the world are raising concerns day by day for their human and environmental health impacts. Among developing treatment technologies, ozonation has attracted the attention of many researchers in recent years. It is an emerging and promising technology for removing pesticides in the aqueous environment and degrading the residual pesticides from the fruits and vegetables (F&V) surfaces. This systematic review presents an extensive study of the degradation of different types of residual pesticides from F&V using ozonation, micro- and nanobubble (MNB) ozonation, or other advanced techniques such as microwaves/ultrasonication and advanced oxidation process. This review compiles the studies that reported the effect of MNB size on the dissolution of ozone gas in the washing medium and its effect on the degradation of residual pesticides from F&V. The mechanism and routes of pesticide degradation and how integrating MNB technology (MNBT) can help overcome economic losses, reduce health issues for consumers, and save the environment from harmful chemicals used in the pesticides are also discussed. The article encourages the development and utilization of MNBT not only in agriculture, but aquaculture, fisheries, food industries, food storage, and packing, for reducing/degrading the residual pesticides from foods and support environmental sustainability as well as improve international trade.

The Inevitable Fate of Tetranychus urticae on Tomato Plants Treated with Entomopathogenic Fungi and Spinosad

Tetranychus urticae (Acari: Tetranychidae) is a pervasive and damaging mite pest of tomato crops, leading to important economic losses globally. This study evaluated the acaricidal efficacy of spinosad, alone and in combination with Beauveria bassiana (Bb) WG-21 and Metarhizium robertsii (Mr) WG-04, in the laboratory (application to tomato leaf discs) and greenhouse (application to tomato plants), considering mortality and establishment, respectively. The combination treatments of Bb WG-21 or Mr WG-04 with spinosad achieved 100% mortality of T. urticae nymphs within 2 days on leaf discs, while individual applications of each control agent resulted in lower mortalities, ranging between 62.91 and 86.25% after 3 days. The paired treatment of Mr WG-04 + spinosad killed all exposed adults within 5 d, while that of Bb WG-21 + spinosad achieved the same results after 7 d. However, spinosad, Mr WG-04, and Bb WG-21 alone killed ≥77.08% of adults after 7 d. In the greenhouse, the combination treatment of WG-04 + spinosad deterred the presence of T. urticae (adults, immatures, and eggs) on either surface of the tomato leaves, while Bb WG-21 + spinosad suppressed the populations only on the adaxial surface. These findings indicate that combined treatments of the tested EPF + spinosad, especially Mr WG-04, on tomato plants under greenhouse conditions can provide substantially enhanced control of T. urticae life stages compared to each treatment applied alone.

The PurR family transcriptional regulator promotes butenyl-spinosyn production in Saccharopolyspora pogona

Butenyl-spinosyn, derived from Saccharopolyspora pogona, is a broad-spectrum and effective bioinsecticide. However, the regulatory mechanism affecting butenyl-spinosyn synthesis has not been fully elucidated, which hindered the improvement of production. Here, a high-production strain S. pogona H2 was generated by Cobalt-60 γ-ray mutagenesis, which showed a 2.7-fold increase in production compared to the wild-type strain S. pogona ASAGF58. A comparative transcriptomic analysis between S. pogona ASAGF58 and H2 was performed to elucidate the high-production mechanism that more precursors and energy were used to synthesize of butenyl-spinosyn. Fortunately, a PurR family transcriptional regulator TF00350 was discovered. TF00350 overexpression strain RS00350 induced morphological differentiation and butenyl-spinosyn production, ultimately leading to a 5.5-fold increase in butenyl-spinosyn production (141.5 ± 1.03 mg/L). Through transcriptomics analysis, most genes related to purine metabolism pathway were downregulated, and the butenyl-spinosyn biosynthesis gene was upregulated by increasing the concentration of c-di-GMP and decreasing the concentration of c-di-AMP. These results provide valuable insights for further mining key regulators and improving butenyl-spinosyn production. KEY POINTS: • A high production strain of S. pogona H2 was obtained by 60Co γ-ray mutagenesis. • Positive regulator TF00350 identified by transcriptomics, increasing butenyl-spinosyn production by 5.5-fold. • TF00350 regulated of butenyl-spinosyn production by second messengers.

Molluscicidal assessment of certain toxicants: Impact on biochemical alterations and electrophoretic protein patterns in Massylaea vermiculata (O. F. Müller, 1774) snails

Massylaea vermiculata snails are a significant gastropod pest in Egypt, threatening agriculture. Due to increasing concerns about conventional pesticides, it is imperative to find effective alternatives that are less harmful. We assessed the molluscicidal activity of abamectin, methoxyfenozide, and spinosad using the leaf-dipping method in vitro and the effect of LC50 of these compounds on biochemical aspects and protein electrophoresis. Results showed that these compounds exhibited molluscicidal activity, with LC50 values of 0.21, 0.63, and 0.65 mg/l for abamectin, methoxyfenozide and spinosad, respectively. Biochemical assays on treated snails showed increased aspartate and alanine aminotransferase and alkaline phosphatase activities and reduced total protein compared to controls. For the most effective compound (abamectin), these values were 195.36, 105.82, 276.76, and 2.49, compared to control values of 88.00, 47.67, 124.67, and 5.52, after 10 days post-treatment. Protein electrophoresis revealed variations in protein bands. Thus, these compounds can be effective within integrated control programs.

The LysR family transcriptional regulator ORF-L16 regulates spinosad biosynthesis in Saccharopolyspora spinosa

Spinosad, a potent broad-spectrum bioinsecticide produced by Saccharopolyspora spinosa, has significant market potential. Despite its effectiveness, the regulatory mechanisms of spinosad biosynthesis remain unclear. Our investigation identified the crucial role of the LysR family transcriptional regulator ORF-L16, located upstream of spinosad biosynthetic genes, in spinosad biosynthesis. Through reverse transcription PCR (RT-PCR) and 5'-rapid amplification of cDNA ends (5'-Race), we unveiled that the spinosad biosynthetic gene cluster (BGC) contains six transcription units and seven promoters. Electrophoretic mobility shift assays (EMSAs) demonstrated that ORF-L16 bound to seven promoters within the spinosad BGC, indicating its involvement in regulating spinosad biosynthesis. Notably, deletion of ORF-L16 led to a drastic reduction in spinosad production from 1818.73 mg/L to 1.69 mg/L, accompanied by decreased transcription levels of spinosad biosynthetic genes, confirming its positive regulatory function. Additionally, isothermal titration calorimetry (ITC) and EMSA confirmed that spinosyn A, the main product of the spinosad BGC, served as an effector of ORF-L16. Specifically, it decreased the binding affinity between ORF-L16 and spinosad BGC promoters, thus exerting negative feedback regulation on spinosad biosynthesis. This research enhances our comprehension of spinosad biosynthesis regulation and lays the groundwork for future investigations on transcriptional regulators in S. spinosa.

ARTP/NTG Compound Mutagenesis Improved the Spinosad Production and the Insecticidal Virulence of Saccharopolyspora Spinosa

Spinosad is an efficient and broad-spectrum environmentally friendly biopesticide, but its low yield in wild-type Saccharopolyspora spinosa limits its further application. ARTP/NTG compound mutagenesis was used in this study to improve the spinosad titer of S. spinosa and obtain a high-yield mutant-NT24. Compared with the wild-type strain, the fermentation cycle of NT24 was shortened by 2 days and its maximum titer of spinosad reached 858.3 ± 27.7 mg/L, which is 5.12 times more than for the same-period titer of the wild-type strain. In addition, RT-qPCR, resequencing, and targeted metabolomics showed that the upregulation of the key differential genes accD6, fadD, sdhB, oadA, and gntZ caused increased metabolic flux in the tricarboxylic acid cycle and pentose phosphate pathway, suggesting that the accumulation of pyruvate and short-chain acyl-CoA was the primary cause of spinosad accumulation in NT24. This study demonstrates the effectiveness of ARTP mutagenesis in S. spinosa, and provides new insights for the mechanism of spinosad biosynthesis and metabolic engineering in S. spinosa.

Persistence of widespread moderate Spinosad resistance among wild melon fly (Zeugodacus cucurbitae) and oriental fruit fly (Bactrocera dorsalis) populations on the major Hawaiian islands

BACKGROUND

Insecticide resistance among invasive tephritid fruit flies poses a great risk to national food security and has the potential to disrupt quarantine and eradication programs, which rely on the efficacy of Spinosad to prevent widespread establishment in North America. During 2022 to 2023 we surveyed the extent of Spinosad resistance of two key species, oriental fruit fly Bactrocera dorsalis, and melon fly Zeugodacus cucurbitae, from 20 sites across five Hawaiian Islands including Kaua'i, O'ahu, Maui, Molokai and the "Big Island" (Hawai'i).

RESULTS

We used topical thoracic applications of eight concentrations of Spinosad ranging from 0.028 to 3.6 mg/mL to evaluate the lethal concentration (LC50 and LC99) required to kill wild-caught males. Resistance ratios (RR) were calculated by comparing the LC50 of wild flies to laboratory susceptible lines maintained in colony. Our results identified at least two new sites of concern for melon fly resistance on the Big Island, and at least four sites of concern for oriental fruit fly, all of which were located on the Big Island. At these locations RRs were >5. On O'ahu, melon fly RRs were >10.

CONCLUSIONS

The persistence of Spinosad resistance is concerning, yet it is a reduction compared to the values reported previously and before changes to Spinosad use recommendations by local extension agents beginning in 2017. For oriental fruit fly, these RR values are the highest levels that have been detected in wild Hawai'i populations. These data suggest that expanded Spinosad reduction and replacement programs are warranted given the ongoing issues with Spinosad resistance in Hawai'i and expansion in the number of species affected. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Agricultural Pest Management: The Role of Microorganisms in Biopesticides and Soil Bioremediation

Pesticide use in crops is a severe problem in some countries. Each country has its legislation for use, but they differ in the degree of tolerance for these broadly toxic products. Several synthetic pesticides can cause air, soil, and water pollution, contaminating the human food chain and other living beings. In addition, some of them can accumulate in the environment for an indeterminate amount of time. The agriculture sector must guarantee healthy food with sustainable production using environmentally friendly methods. In this context, biological biopesticides from microbes and plants are a growing green solution for this segment. Several pests attack crops worldwide, including weeds, insects, nematodes, and microorganisms such as fungi, bacteria, and viruses, causing diseases and economic losses. The use of bioproducts from microorganisms, such as microbial biopesticides (MBPs) or microorganisms alone, is a practice and is growing due to the intense research in the world. Mainly, bacteria, fungi, and baculoviruses have been used as sources of biomolecules and secondary metabolites for biopesticide use. Different methods, such as direct soil application, spraying techniques with microorganisms, endotherapy, and seed treatment, are used. Adjuvants like surfactants, protective agents, and carriers improve the system in different formulations. In addition, microorganisms are a tool for the bioremediation of pesticides in the environment. This review summarizes these topics, focusing on the biopesticides of microbial origin.

Physiological responses of the stingless bee Partamona helleri to oral exposure to three agrochemicals: impact on antioxidant enzymes and hemocyte count

Agrochemicals pose significant threats to the survival of bees, yet the physiological impacts of sublethal doses on stingless bees remain poorly understood. This study investigated the effects of acute oral exposure to three commercial formulations of agrochemicals [CuSO4 (leaf fertilizer), glyphosate (herbicide), and spinosad (bioinsecticide)] on antioxidant enzymes, malondialdehyde content (MDA), nitric oxide (NO) levels, and total hemocyte count (THC) in the stingless bee Partamona helleri. Foragers were exposed to lethal concentrations aimed to kill 5% (LC5) of CuSO4 (120 μg mL-1) or spinosad (0.85 μg mL-1) over a 24-h period. Glyphosate-exposed bees received the recommended label concentration (7400 μg mL-1), as they exhibited 100% survival after exposure. Ingestion of CuSO4 or glyphosate-treated diets by bees was reduced. Levels of NO and catalase (CAT) remained unaffected at 0 h or 24 h post-exposure. Superoxide dismutase (SOD) activity was higher at 0 h compared to 24 h, although insignificantly so when compared to the control. Exposure to CuSO4 reduced glutathione S-transferase (GST) activity at 0 h but increased it after 24 h, for both CuSO4 and glyphosate. MDA levels decreased after 0 h exposure to CuSO4 or spinosad but increased after 24 h exposure to all tested agrochemicals. THC showed no difference among glyphosate or spinosad compared to the control or across time. However, CuSO4 exposure significantly increased THC. These findings shed light on the physiological responses of stingless bees to agrochemicals, crucial for understanding their overall health.

Spinosad blocks CHRNA5 mediated EGFR signaling pathway activation to inhibit lung adenocarcinoma proliferation

Lung adenocarcinoma (LUAD) is the leading cause of cancer death worldwide, with high incidence and low survival rates. Nicotinic acetylcholine receptors play an important role in the progression of LUAD. In this study, a screening of 17 nicotinic acetylcholine receptor allosteric agents revealed that spinosad effectively suppressed the proliferation of LUAD cells. The experiments demonstrated that spinosad induced cell cycle arrest in the G1 phase and stimulated apoptosis, thereby impeding the growth of LUAD and enhancing the responsiveness to gefitinib in vitro and vivo. Mechanistic insights obtained through transcriptome sequencing, Co-IP, and protein immunoblots indicated that spinosad disrupted the interaction between CHRNA5 and EGFR, thereby inhibiting the formation of downstream complexes and activation of the EGFR signaling pathway. The supplementation of exogenous acetylcholine showed to mitigate the inhibition of LUAD cell proliferation induced by spinosad. This study elucidates the therapeutic effects and mechanisms of spinosad in LUAD, and offers a theoretical and experimental foundation for novel LUAD treatments.

Spanish Academy of Dermatology and Venereology (AEDV) expert recommendations for the management of sexual transmitted parasitosis. Scabies, and pediculosis pubis

Sexually transmitted infections are communicable diseases where the pathogen is transmitted through sexual contact. The Sexually Transmitted Infections Working Group of the Spanish Academy of Dermatology and Venereology (AEDV) is engaged in the drafting of documents to guide dermatologists and health care personnel who treat Spanish patients with these infections. This document analyzes the epidemiological, clinical, therapeutic, and control characteristics of 2 sexually transmitted parasitosis: scabies due to Sarcoptes scabiei var. hominis, and pubic pediculosis due to Phthirus pubis. Both parasitoses share a sort of mixed spread through sexual and community transmission regardless of the route through which the infection was initially acquired. This specific feature creates particularities in the management and control of the infestation.

[Translated article] Spanish Academy of Dermatology and Venereology (AEDV) expert recommendations for the management of sexual transmitted parasitosis. Scabies, and pediculosis pubis

Sexually transmitted infections are communicable diseases where the pathogen is transmitted through sexual contact. The Sexually Transmitted Infections Working Group of the Spanish Academy of Dermatology and Venereology (AEDV) is engaged in the drafting of documents to guide dermatologists and health care personnel who treat Spanish patients with these infections. This document analyzes the epidemiological, clinical, therapeutic, and control characteristics of 2 sexually transmitted parasitosis: scabies due to Sarcoptes scabiei var. hominis, and pubic pediculosis due to Phthirus pubis. Both parasitoses share a sort of mixed spread through sexual and community transmission regardless of the route through which the infection was initially acquired. This specific feature creates particularities in the management and control of the infestation.

Exploration of Streptomyces fradiae J1-021 as a Potential Host for the Heterologous Production of Spinosad

Spinosad is a potent insecticide produced by Saccharopolyspora spinosa. However, it harbors certain limitations of a low growing rate and unfeasible genetic manipulation that can be overcome by adopting a superior platform, such as Streptomyces. Herein, we exploited the industrial tylosin-producing Streptomyces fradiae J1-021 for the heterologous production of spinosad. An engineered strain (HW01) with deletion of the tylosin biosynthetic gene cluster (BGC) was constructed and then transformed with the natural spinosad BGC. The distribution and expression levels of the tylosin BGC operons were assessed to construct a natural promoter library. The rate-limiting steps of spinosad biosynthesis were identified by analyzing the transcriptional expression of the spinosad biosynthetic genes. The stepwise engineering work involved the overexpression of the biosynthetic genes participating in rate-limiting pathways using strong promoters, affording an increase in spinosad production to 112.4 μg/L. These results demonstrate that strain HW01 has the potential to be used as a chassis for the heterologous production of polyketides.

Uridine diphosphate glucosyltransferases are involved in spinosad resistance in western flower thrips Frankliniella occidentalis (Pergande)

Uridine diphosphate glucosyltransferases (UGTs) play crucial roles in the insect detoxification system and are associated with pesticide resistance. Our previous transcriptomic analysis of spinosad-susceptible (Ivf03) and resistant (NIL-R) Frankliniella occidentalis revealed numerous upregulated UGT genes in the NIL-R strain, suggesting their potential contribution to spinosad resistance. To investigate this hypothesis, here we conducted UGT activity assays and spinosad induction experiments, employing RNA interference (RNAi) techniques for gene function validation. We found significantly elevated UGT activity in the NIL-R strain compared to Ivf03, with 5-nitrouracil showing a substantial synergistic effect on the resistant strain. Eighteen UGT genes were identified in F. occidentalis, with gene expansion and duplication observed within families UGT466, 467, and 468. Ten out of the eighteen UGTs exhibited higher expression levels in NIL-R, specifically FoUGT466B1, FoUGT468A3, and FoUGT468A4 consistently being upregulated across nymphs, males, and females. RNAi-based functional validation targeting these three UGT genes led to increased susceptibility to spinosad in a life stage-, sex-, and dose-dependent manner. These results indicate that UGTs are indeed involved in spinosad resistance in F. occidentalis, and the effects are dependent on life stage, sex, and dose. Therefore, sustainable control for F. occidentalis resistance should always consider these differential responses.

The Perpetual Vector Mosquito Threat and Its Eco-Friendly Nemeses

Mosquitoes are the most notorious arthropod vectors of viral and parasitic diseases for which approximately half the world's population, ~4,000,000,000, is at risk. Integrated pest management programs (IPMPs) have achieved some success in mitigating the regional transmission and persistence of these diseases. However, as many vector-borne diseases remain pervasive, it is obvious that IPMP successes have not been absolute in eradicating the threat imposed by mosquitoes. Moreover, the expanding mosquito geographic ranges caused by factors related to climate change and globalization (travel, trade, and migration), and the evolution of resistance to synthetic pesticides, present ongoing challenges to reducing or eliminating the local and global burden of these diseases, especially in economically and medically disadvantaged societies. Abatement strategies include the control of vector populations with synthetic pesticides and eco-friendly technologies. These "green" technologies include SIT, IIT, RIDL, CRISPR/Cas9 gene drive, and biological control that specifically targets the aquatic larval stages of mosquitoes. Regarding the latter, the most effective continues to be the widespread use of Lysinibacillus sphaericus (Ls) and Bacillus thuringiensis subsp. israelensis (Bti). Here, we present a review of the health issues elicited by vector mosquitoes, control strategies, and lastly, focus on the biology of Ls and Bti, with an emphasis on the latter, to which no resistance has been observed in the field.

Evaluating the Compatibility of Spinosad and Alpha-Cypermethrin for Controlling Six Insect Pests Infesting Stored Wheat

The deterioration of stored wheat due to pest infestations is a significant concern, with pests like Rhyzopertha dominica, Tribolium castaneum, Cryptolestes ferrugineus, Sitophilus oryzae, Oryzaephilus surinamensis, and Trogoderma granarium being major contributors. This study examined the efficacy of spinosad and alpha-cypermethrin, individually and in combination, against these pests under laboratory conditions. Spinosad was tested at two concentrations (0.05 and 0.1 mg/kg), while alpha-cypermethrin was applied at 0.05 mg/kg. The combined application of both insecticides led to significantly higher pest mortality compared to single treatments. Importantly, all treatments caused substantial pest mortality and exhibited the ability to suppress pest progeny production over time, as observed in both laboratory and persistence trials. Among the various treatment combinations, the joint application of 0.1 mg/kg spinosad and 0.05 mg/kg alpha-cypermethrin emerged as the most effective, resulting in elevated mortality and a marked reduction in pest progeny. Rhyzopertha dominica exhibited the highest susceptibility among the pests, followed by S. oryzae, T. castaneum, C. ferrugineus, O. surinamensis, and T. granarium. The remarkable performance of the joint action of alpha-cypermethrin and spinosad at low doses highlights this combination as an efficacious approach for safeguarding stored grain against these destructive insect pests, warranting further exploration.

Characterization of three succinyl-CoA acyltransferases involved in polyketide chain assembly

Polyketides are a class of natural products with astonishing structural diversities, fascinating biological activities, and a versatile of applications. In polyketides biosynthesis, acyltransferases (ATs) are the 'gatekeeping' enzymes selecting the specific CoA-activated acyl groups as building blocks and transferring them onto the phosphopantetheine arm of acyl carrier proteins (ACPs) to enable the following condensation reactions to assemble the polyketide chain. Herein, the Art2 protein from aurantinins, a group of the antibacterial polyketides, is characterized in vitro as an AT that can load a CoA-activated succinyl unit onto the first ACP domain of Art17 (ACP_Art17-1). In addition, another two proteins, GbnB and EtnB, involved in the biosynthesis of gladiolin and etnangien respectively, were traced by literature mining, homologous searching, and product structure analysis and then identified as functional succinyl-CoA ATs by the ACP_Art17-1 assays. Taken together, by the assay method employing ACP_Art17-1 as an acyl acceptor, we identified three ATs that can introduce a succinyl unit into the polyketide assembly line, which enriches the toolbox of polyketide biosynthetic enzymes and sets a stage for incorporating a succinyl unit into polyketide backbones in synthetic biological manners. KEY POINTS: • Three acyltransferases that are able to load ACP with a succinyl unit were characterized in vitro. • ACP_Art17-1 can be used as an acceptor to assay succinyl-CoA AT from different polyketides. • The succinyl unit can be incorporated into polyketides assembly process.

Colupulone, colupone and novel deoxycohumulone geranyl analogues as larvicidal agents against Culex pipiens

BACKGROUND

As climate change proceeds, the management of the population of mosquitoes becomes more and more challenging. Insect adulticides and larvicides constitute significant control techniques, with the latter being considered the leading mosquito control method. However, the development of mosquito resistance development and the adverse side effects caused by the extensive use of synthetic insecticides have turned research towards the discovery of environmentally-friendly solutions. Plants and bacteria have historically proven to be a good source of insecticidally active compounds, which may possess novel modes of action to overcome current resistance mechanisms and could also possess favorable human and environmental safety profiles. A previous study demonstrated that the naturally occurring prenylated acyl phloroglucinol deoxycohumulone is a potent larvicidal agent against Culex pipiens. Herein the structural characteristics that improve it are explored by evaluating colupulone and novel geranylated analogues.

RESULTS

Colupulone, a prenylated acyl phloroglucinol isolated from Humulus lupulus, colupone, and novel geranylated acyl phloroglucinol congeners, were synthesized and evaluated against Cx. pipiens larva. Results indicated that selected derivatives exhibited superior potency than deoxycohumulone (LC₅₀ 43.7 mg L^-1 ). Thus, strong activity was observed for colupulone (LC₅₀ 19.7 mg L^-1 ), and some novel geranyl analogues of deoxycohumulone reaching at LC₅₀ 17.1 mg L^-1 , while colupone and similar compounds were almost inactive.

CONCLUSION

The results determined the relationship between the target activity and the chemical structure of the tested compounds, and they revealed significantly improved larvicidal candidates. These results highlight the potential of the acyl phloroglucinol chemistry for further development of mosquito larvicides. © 2022 Society of Chemical Industry.

Biological activities and gene expression of detoxifying enzymes in Tribolium castaneum induced by Moutan cortex essential oil

Tribolium castaneum is one of the most harmful storage pests in the world. The aim of this study was to determine the chemical composition, repellent, and contact activities of Moutan cortex essential oil against this insect pest. In addition, the effects of Moutan cortex were examined on the expressions of three major detoxifying enzyme genes in T. castaneum. Four components were identified in this essential oil by gas chromatography-mass spectrometry (GC-MS), which was predominantly paeonol (99.13%). Paeonol exerted significant repellent activity against T. castaneum, which was more potent than the positive control N.N-diethyl-meta-toluamide (DEET). The most significant contact toxicity was observed at 24 h after exposure to paeonol. Further, quantitative real-time PCR (qRT-PCR) was used to assess expression changes in three detoxification enzyme genes in T. castaneum, including carboxylesterase (CarE), glutathione S-transferase (Gst) and cytochrome P4506BQ8 (Cyp6bq8). Among these, Gst was most highly up-regulated after treatment with paeonol with the highest expression level of 4.9-fold (Rps18 as internal reference gene) greater than control at 24 h following treatment. Data indicated that Gst might play a critical role in metabolic detoxification of toxic xenobiotics. Taken together, our findings might lay a foundation for development of paeonol as a potential natural repellent or pesticide to control storage pests.

Mortality of Orius insidiosus by contact with spinosad in the laboratory as well as in the field and a perspective of these as controllers of Frankliniella occidentalis

Orius insidiosus, known as the pirate bug, is widely distributed throughout the Americas. It is employed for the biological control of Frankliniella occidentalis in organic berry crops in Mexico. In conventional crops, spinosad is the main control method for this pest. The LD₅₀ of spinosad on O. insidiosus was determined. In addition, we monitored the population density of F. occidentalis in blackberry crops under two types of management (biochemical+mass trapping, and biological control). The LD₅₀ was 225.65 ppm 3.8 times greater than the 60 ppm dose commonly used in blackberry crops. Both types of control are efficient; however, spinosad is less effective and should be combined with other environmentally friendly strategies. The possibility of combining chromatic traps+spinosad application and chromatic traps+strategic release of O. insidiosus to effectively control thrips without compromising fruit quality is discussed.

Pollution impacts on water bugs (Nepomorpha, Gerromorpha): state of the art and their biomonitoring potential

As water pollution poses an increasing risk worldwide, it is timely to assess the achievements of the aquatic macroinvertebrate ecotoxicology to provide a sound basis for the discipline's future and support the development of biomonitoring. Aquatic and semi-aquatic bugs (Hemiptera: Nepomorpha, Gerromorpha) are ubiquitous in almost all water types, sometimes in high densities, and play a significant role in organic material turnover and energy flow. Nevertheless, they are ignored in the water pollution biomonitoring schemes. Here, based on 300 papers, we review and evaluate the effects of chemical pesticides, microorganism-derived pesticides, insecticides of plant origin, heavy metals, eutrophication, salinisation and light pollution which are summarised for the first time. Our review encompasses the results of 100 laboratory and 39 semi-field/field experiments with 47 pesticides and 70 active ingredients. Pyrethroids were found to be more toxic than organochlorine, organophosphate and neonicotinoid insecticides to water bugs, like other macroinvertebrate groups. Additionally, in 10 out of 17 cases, the recommended field concentration of the pesticide was higher than the LC50 values, indicating potential hazards to water bugs. The recommended field concentrations of pesticides used in mosquito larvae control were found non-toxic to water bugs. As very few replicated studies are available, other findings on the effects of pesticides cannot be generalised. The microorganism-derived pesticide Bti appears to be safe when used at the recommended field concentration. Data indicates that plant-derived pesticides are safe with a high degree of certainty. We have identified three research areas where water bugs could be better involved in water biomonitoring. First, some Halobates spp. are excellent, and Gerris spp. are promising sentinels for Cd contamination. Second, Micronecta and, to a certain extent, Corixidae species composition is connected to and the indicator of eutrophication. Third, the species composition of the Corixidae is related to salinisation, and a preliminary method to quantify the relationship is already available. Our review highlights the potential of water bugs in water pollution monitoring.

Evaluation of a Spinosad Controlled-Release Formulation Based on Chitosan Carrier: Insecticidal Activity against Plutella xylostella (L.) Larvae and Dissipation Behavior in Soil

Controlled-release pesticide formulations using natural polymers as carriers are highly desirable owing to their good biocompatibility, biodegradability, and improved pesticide utilization. In this study, the application potential of our previously prepared spinosad/chitosan controlled-release suspension (SCCS) was evaluated through both toxicity and dissipation tests. A comparison with the spinosad suspension concentrate and the commercial spinosad emulsion in water showed that the insecticidal activity of SCCS against Plutella xylostella larvae displayed the best quick-acting performance as well as long-term efficacy of more than 20 days. The 48 h LC50 for a 20-day efficacy was calculated to be 29.36 mg/L. The dissipation behavior of spinosad in the spinosad/chitosan microparticles in soil was found to follow the first-order kinetics, with a relatively shorter half-life (2.1 days) than that observed for the unformulated spinosad (3.1 days). This work showed the positive effect of chitosan on spinosad in improving insecticidal activity and reducing environmental risks in soil, which provided useful information on the application potential of pesticide-carrier systems based on natural polymer materials in crop protection and food safety.

Prospects and Pitfalls: Next-Generation Tools to Control Mosquito-Transmitted Disease

Mosquito-transmitted diseases, including malaria and dengue, are a major threat to human health around the globe, affecting millions each year. A diverse array of next-generation tools has been designed to eliminate mosquito populations or to replace them with mosquitoes that are less capable of transmitting key pathogens. Many of these new approaches have been built on recent advances in CRISPR/Cas9-based genome editing. These initiatives have driven the development of pathogen-resistant lines, new genetics-based sexing methods, and new methods of driving desirable genetic traits into mosquito populations. Many other emerging tools involve microorganisms, including two strategies involving Wolbachia that are achieving great success in the field. At the same time, other mosquito-associated bacteria, fungi, and even viruses represent untapped sources of new mosquitocidal or antipathogen compounds. Although there are still hurdles to be overcome, the prospect that such approaches will reduce the impact of these diseases is highly encouraging.

Comparative transcriptomic analysis of two Saccharopolyspora spinosa strains reveals the relationships between primary metabolism and spinosad production

Saccharopolyspora spinosa is a well-known actinomycete for producing the secondary metabolites, spinosad, which is a potent insecticides possessing both efficiency and safety. In the previous researches, great efforts, including physical mutagenesis, fermentation optimization, genetic manipulation and other methods, have been employed to increase the yield of spinosad to hundreds of folds from the low-yield strain. However, the metabolic network in S. spinosa still remained un-revealed. In this study, two S. spinosa strains with different spinosad production capability were fermented and sampled at three fermentation periods. Then the total RNA of these samples was isolated and sequenced to construct the transcriptome libraries. Through transcriptomic analysis, large numbers of differentially expressed genes were identified and classified according to their different functions. According to the results, spnI and spnP were suggested as the bottleneck during spinosad biosynthesis. Primary metabolic pathways such as carbon metabolic pathways exhibited close relationship with spinosad formation, as pyruvate and phosphoenolpyruvic acid were suggested to accumulate in spinosad high-yield strain during fermentation. The addition of soybean oil in the fermentation medium activated the lipid metabolism pathway, enhancing spinosad production. Glutamic acid and aspartic acid were suggested to be the most important amino acids and might participate in spinosad biosynthesis.

Low toxicity and high efficacy in use of novel approaches to control Aedes aegypti

Arthropod-borne viruses are a group of etiologic agents accounting for different incapacitating diseases that progress to severe and lethal forms in animal and human targets consequently representing a significant burden on public health and global economies. Although attempts were undertaken to combat Aedes aegypti, the primary urban mosquito vector of several life-threatening diseases, the misuse of chemical pesticides, development of resistance, and toxicity on non-target species still need to be overcome. In this context, it is imperative for development of long-lasting, novel approaches envisioning effective control of Aedes aegypti, mainly in endemic regions. Thus, the present review was undertaken to describe safe and eco-friendly approaches as potential weapons against Aedes aegypti. Accordingly, the findings discussed indicated that biological larvicides and genetic engineering technologies constitute noteworthy alternatives of future mosquito-borne arbovirus disease control efforts.