Biopesticide Formulations Research Articles

Recent Advances in Biopesticide Research and Development with a Focus on Microbials.

Biopesticides are pest control products derived from natural sources such as microbes, macro-organisms (insects and pathogens), plant extracts, and certain minerals. Many biopesticides are considered environmentally safe and can complement or substitute conventional chemical pesticides. They can also be highly specific or broad spectrum with a unique mode of action controlling a wide range of pest species. Due to their target-specificity and low to no environmental residuality, biopesticides conform to the 3 pillars of Climate-Smart Agriculture, the Sustainable Development Goals, and, ultimately, the Paris Agreement. This review focuses largely on microbial biopesticides derived from fungi, bacteria, viruses, and nematodes. It discusses (i) the various microbial biopesticide formulations, (ii) the mode of microbial biopesticide action, (iii) the factors that affect the potential efficacy of biopesticides, (iv) challenges to the adoption of microbial biopesticides, and (v) the role of microbial biopesticides in Integrated Pest Management programs. Finally, advancements in application techniques, as well as future research directions and gaps, are highlighted.

Composition of biopesticides for crop protection – current state and prospects (review)

Aim. To summarise and analyse available information on research into biopesticide compositions aimed at enhancing their effectiveness and to assess prospects for the development of this field so as to determine the influence of components on the effectiveness of biopesticides for agricultural crop protection.This review article presents the results of studies of components included in the compositions of microorganism‐based biopesticides based on a system analysis. It is noted that the selection of biopesticide components must be carried out in accordance with the requirements for products recommended for use in ecological and organic farming systems. It is indicated that the choice of optimal formulation is associated with the characteristics of the producer strains, their trophic needs and resistance to biotic and abiotic factors and with the characteristics of the biopesticide application technology (seed treatment, application to the soil or treatment of plants during vegetation), as well as the type of equipment used.Knowledge of the basic requirements for biopesticide formulations will help maintain the viability and biological activity of microbial agents during storage of biopesticides, taking into account the sensitivity of producer strains to environmental conditions. Selection of optimal carriers, adhesives, stabilisers, thickeners and synergists, taking into account the technology of application of the biopesticide and the target pathogen, will facilitate the development and appearance on the market of new biopesticides for protecting agricultural crops from diseases.

Development of point-of-need colourimetric, isothermal diagnostic assays for specific detection of Bacillus subtilis using shikimate dehydrogenase gene.

The largest obstacle in the promotion of biopesticides is the existence of counterfeit products available in the market. Identification and quantification of antagonistic organisms in biopesticide products are the key to the reduction of spurious microbial pesticides. In this study, we have developed a simple, sensitive, isothermal-based colourimetric assay for specific detection of Bacillus subtilis from the biopesticide formulations and soil samples. A region specific to B. subtilis which codes for shikimate dehydrogenase was identified through in silico analysis. We employed conventional PCR, loop-mediated isothermal amplification (LAMP), recombinase polymerase amplification (RPA), and qPCR for specific detection of B. subtilis in soil samples and biopesticide formulations. Specificity tests showed that the PCR primers amplified an amplicon of 521bp in four strains of B. subtilis only, and no amplification was found in negative control samples. Similarly, the LAMP assay showed sky blue colour in all four strains of B. subtilis and violet colour in negative control samples. Whereas in the RPA assay, upon the addition of SYBR Green dye, a bright green colour was seen in B. subtilis strains, while a brick-red colour was observed in negative control samples by visualizing under a UV transilluminator. The qPCR assay showed specific amplifications with a Ct value of 12 for B. subtilis strains and no amplification in negative control samples. In the sensitivity test, PCR could amplify DNA of B. subtilis up to 500pg/µL. DNA concentration as low as 10pg/µL was enough to show the colour change in the LAMP as well as the RPA assays, whereas the qPCR assay showed sensitivity till 100pg/µL. All four diagnostic assays developed in the study have been validated in soil samples and B. subtilis-based biopesticides. Compared to conventional PCR, the qPCR assay has the advantage of quantification and visualizing the result in real-time, whereas LAMP and RPA assays have the benefits of being colourimetric and less time-consuming. The other advantages are that the results can be visualized with the naked eye, and these assays do not require a costly thermal cycler and gel documentation system. Hence, LAMP and RPA assays are highly suitable for developing point-of-need diagnostic kits and, in turn, help regulators assess the quality of biopesticides in the market.

Recent Advances in Biopesticide Research and Development: A Focus on Microbial: A Review

Biopesticides are pest control products derived from natural sources such as microbes, macro-organisms (insects and pathogens), plant extracts, and certain minerals. Many biopesticides are considered environmentally safe and can complement or substitute conventional chemical pesticides. They can also be highly specific or broad spectrum with a unique mode of action controlling a wide range of pest species. Due to their target-specificity and low to no environmental residuality, biopesticides conform to the 3 pillars of Climate-Smart Agriculture, the Sustainable Development Goals, and ultimately, the Paris Agreement. This review focuses largely on microbial biopesticides derived from fungi, bacteria, viruses, and nematodes. It discusses (i) the various microbial biopesticide formulations, (ii) the mode of microbial biopesticide action, (iii) the factors that affect the potential efficacy of biopesticides, (iv) challenges to the adoption of microbial biopesticides, and (v) the role of microbial biopesticides in Integrated Pest Management programs. Finally, advancements in application techniques, as well as future research directions and gaps are highlighted.

Recent Advances in Biopesticide Formulations for Targeted Insect Pest Management: A Review

The increasing environmental and health concerns associated with the use of synthetic chemical pesticides have driven the need for alternative, eco-friendly pest management solutions. Biopesticides, derived from natural sources such as plants and microorganisms, offer a promising solution, as they are less toxic, decompose quickly, and target specific pests with minimal impact on non-target organisms. Recent advancements in biopesticide formulations, including nano pesticides, controlled release formulations (CRFs), hydrogels, polymer-coated granules, and tablets, are enhancing the effectiveness, stability, and environmental safety of these products. The integration of nanotechnology and controlled release systems in biopesticides is opening new avenues for sustainable agriculture. This review discusses the various biopesticide formulation technologies, highlighting their advantages, disadvantages, and future prospects.

Cell Penetrating Peptide Enhances the Aphidicidal Activity of Spider Venom-Derived Neurotoxin.

HxTx-Hv1h, a neurotoxic peptide derived from spider venom, has been developed for use in commercial biopesticide formulations. Cell Penetrating Peptides (CPPs) are short peptides that facilitate the translocation of various biomolecules across cellular membranes. Here, we evaluated the aphidicidal efficacy of a conjugated peptide, HxTx-Hv1h/CPP-1838, created by fusing HxTx-Hv1h with CPP-1838. Additionally, we aimed to establish a robust recombinant expression system for HxTx-Hv1h/CPP-1838. We successfully achieved the secretory production of HxTx-Hv1h, its fusion with Galanthus nivalis agglutinin (GNA) forming HxTx-Hv1h/GNA and HxTx-Hv1h/CPP-1838 in yeast. Purified HxTx-Hv1h exhibited contact toxicity against Megoura crassicauda, with a 48 h median lethal concentration (LC50) of 860.5 μg/mL. Fusion with GNA or CPP-1838 significantly enhanced its aphidicidal potency, reducing the LC50 to 683.5 μg/mL and 465.2 μg/mL, respectively. The aphidicidal efficacy was further improved with the addition of surfactant, decreasing the LC50 of HxTx-Hv1h/CPP-1838 to 66.7 μg/mL-over four times lower compared to HxTx-Hv1h alone. Furthermore, we engineered HxTx-Hv1h/CPP-1838 multi-copy expression vectors utilizing the BglBrick assembly method and achieved high-level recombinant production in laboratory-scale fermentation. This study is the first to document a CPP fusion strategy that enhances the transdermal aphidicidal activity of a natural toxin like HxTx-Hv1h and opens up the possibility of exploring the recombinant production of HxTx-Hv1h/CPP-1838 for potential applications.

Biopesticide formulation based on essential oils in Drosophila suzukii management as a future of pest control

Biopesticide formulation based on essential oils in Drosophila suzukii management as a future of pest control

The Role of Agrotechnology in Pest Management: Assessing the Effectiveness of Biopesticides, Integrated Pest Management, and Genetic Engineering

This qualitative study investigates the role of agrotechnology in pest management by assessing the effectiveness of biopesticides, integrated pest management (IPM), and genetic engineering. Through an extensive review of existing literature and case studies, the research aims to elucidate how these technological advancements contribute to sustainable agricultural practices and effective pest control. Biopesticides, derived from natural materials such as microorganisms, plants, and certain minerals, are highlighted as a key component in modern pest management. The study finds that biopesticides offer an environmentally friendly alternative to conventional chemical pesticides, reducing the ecological impact and the risk of pesticide resistance. They are effective against a broad spectrum of pests while being safe for non-target species, including humans and beneficial insects. The research underscores the importance of developing and optimizing biopesticide formulations to enhance their efficacy and acceptance among farmers. In conclusion, the study suggests that the integration of biopesticides, IPM, and genetic engineering in pest management strategies can lead to more sustainable and effective agricultural practices. It advocates for continued research and collaboration among scientists, policymakers, and farmers to develop and implement these technologies responsibly. Future research should explore the long-term impacts of these technologies on agricultural ecosystems and their potential to adapt to changing environmental conditions.

Evaluation of Lysinibacillus formulations against banana pseudostem weevil (BPW) Odoiporus longicollis [Olivier.]

ABSTRACT Odoiporus longicollis [Olivier], commonly known as banana pseudostem weevil or BPW has been a predominant pest of bananas, resulting in devastating losses in banana cultivation across India. The current research explores the use and effectiveness of the microbial biopesticide – Lysinibacillus sphaericus against banana pseudostem weevils in field and laboratory conditions. The LC50 value of L.sphaericus was found to be 9.92% of 1 OD (optical density at 600 nm) culture after 24 h of treatment against grubs at in-vitro conditions. L.sphaericus cultures were formulated as liquid, solid, and capsule formulations, and analysed parameters such as viability, shelf life, and pest control efficiency against banana pseudostem weevils. The capsule-based formulation (8 ± 2 × 102a CFU/ml) was most effective against the grubs with a storage period of 120 days to six months under room temperature in air-free containers. The efficacy of a capsule-based formulation at in vivo conditions in the pseudostem revealed that the gelatine coat of the capsule disintegrated within 24hrs after application, leading to the easy release of active ingredients to the pseudostem. The field evaluation observed that in L.sphaericus-based capsule formulations treated plants, there was more than an 80% reduction in the infestation of grubs over control treatments. The current paper describes the application of L.sphaericus against the weevil, its unique formulation as a capsule increasing bacterial shelf life, and ease of application. The development of an easily applicable and effective capsule with a better shelf life of 6 months would increase the marketing possibilities of this biopesticide formulation against Odoiporus longicollis.

Development of Bacillus thuringiensis-based liquid and paste formulations for controlling invasive pest species Spodoptera frugiperda J. E. Smith

Spodoptera frugiperda J.E. Smith (Spodoptera: Noctuidae) is an invasive pests of maize that has been reported around the world. Control efforts using biological agents continue to be developed, including the use of entomopathogen bacteria such as Bacillus thuringiensis. To boost the efficacy and efficiency of biological control, formulations are required. The objective of this study was to develop biopesticide formulations and evaluate their efficacy. The research was carried out by formulating B. thuringiensis strain BtJ2 (1010 cfu mL -1) in liquid and paste formulations. The effectiveness of the formulations was evaluated using the feed dipping method. The results showed that paste formulations at a concentration of 10% caused 100% mortality, whereas the liquid formulation resulted in 85% mortality. The LC90 for the paste formulation was 6.66%, while the LC90 for the liquid formulation was 12.90%. Both the liquid and paste formulations had similar effects on mortality and viability. Based on the LC90 and LT90, the paste formulation was more efficient and faster in killing S. frugiperda than the liquid formulation. The results of this study provide recommendations that B. thuringiensis as a bioinsecticide is better formulated in a paste than in a liquid form.

Development of Bacillus thuringiensis-based liquid and paste formulations for controlling invasive pest species Spodoptera frugiperda J. E. Smith

Spodoptera frugiperda J.E. Smith (Spodoptera: Noctuidae) is an invasive pests of maize that has been reported around the world. Control efforts using biological agents continue to be developed, including the use of entomopathogen bacteria such as Bacillus thuringiensis. To boost the efficacy and efficiency of biological control, formulations are required. The objective of this study was to develop biopesticide formulations and evaluate their efficacy. The research was carried out by formulating B. thuringiensis strain BtJ2 (1010 cfu mL -1) in liquid and paste formulations. The effectiveness of the formulations was evaluated using the feed dipping method. The results showed that paste formulations at a concentration of 10% caused 100% mortality, whereas the liquid formulation resulted in 85% mortality. The LC90 for the paste formulation was 6.66%, while the LC90 for the liquid formulation was 12.90%. Both the liquid and paste formulations had similar effects on mortality and viability. Based on the LC90 and LT90, the paste formulation was more efficient and faster in killing S. frugiperda than the liquid formulation. The results of this study provide recommendations that B. thuringiensis as a bioinsecticide is better formulated in a paste than in a liquid form.

Influence of environmental factors on stability and anti-feedant activity of biopesticide formulations of Pachygone laurifolia (DC.) L.Lian & Wei Wang (Cocculus laurifolius) against Spodoptera litura (Lepidoptera : Noctuidae)

Influence of environmental factors on stability and anti-feedant activity of biopesticide formulations of Pachygone laurifolia (DC.) L.Lian & Wei Wang (Cocculus laurifolius) against Spodoptera litura (Lepidoptera : Noctuidae)

First report of native Beauveria bassiana and Trichoderma ghanense as bio-control agents against Spodoptera frugiperda in Ghana

Signs of mycosis on mummified Spodoptera frugiperda cadavers were found in maize fields in the Ejura-Sekyedumase and Wa Municipalities in the Ashanti Region and Upper West Region of Ghana, respectively, during the 2019 to 2022 growing seasons. Two major signs were observed on two sets of cadavers that were collected. These were dense white powdery colony encapsulating cadavers, and green powdery growth engulfing cadavers. The causal fungi were confirmed as Beauveria bassiana from white cadaver mummies and Trichoderma ghanense from green cadaver mummies based on morphological and molecular characteristics. The two fungi were assessed for their lethal effect against 3rd instar larvae of S. frugiperda by artificial inoculation. The inoculation was performed with conidia suspension of 1 × 108 conidia/ml for each fungi. B. bassiana caused 55% larval mortality, which was significantly higher (p < 0.05) than the 32.5% caused by T. ghanense. No larval mortality was recorded for the control. Artificially inoculated 3rd instar S. frugriperda larvae exhibited signs similar to those observed on infected larvae collected from the field. The respective pathogens were re-isolated and the morphology matched B. bassiana and T. ghanense, respectively. The findings indicate the potential of the two fungi as bio-control agents for management of S. frugiperda on maize. The obtained result could find application in the formulation of bio-pesticides for S. frugiperda management.

Valorisation of essential oil of Eucalyptus populifolia Desf, Eucalyptus woollsiana and Eucalyptus exserta for agro-industrial purposes

ABSTRACT Forest species are characterized by their wealth of essential oils (EOs), which play key requested for alternative control methods against weeds, fungi and pests. This study reports the chemical composition and highlight the antioxidant, antifungal and phytotoxic properties of the EOs obtained from Eucalyptus populifolia Desf, Eucalyptus woollsiana and Eucalyptus exserta. The EOs were analyzed by gas chromatography coupled to mass spectrometry (GC/MS). Their antioxidant, antifungal and phytotoxic properties were investigated. All EOs displayed a specific richness in eucalyptol (75.94-7.01%), camphene (6.97-0.4%) globulol (5.20-5.83%) and α-pinene (0.71-12.82 %). EOs isolated from E. populifolia exhibited significant antioxidant activity. Furthermore, all investigated EOs displayed significant antifungal properties against four phytopathogenic fungi belonging to Fusarium genus. The phytotoxic activity against five weeds showed varying effectiveness on seed germination and seedling growth, which exhibited greater effectiveness compared to glyphosate. Eucalyptus EOs have the potential to be used in the formulation of biopesticides.

Encapsulation of Fennel and Basil Essential Oils in β-Cyclodextrin for Novel Biopesticide Formulation.

β-cyclodextrin (β-CD) is a good host for the encapsulation of fennel and basil essential oils (FEO and BEO, respectively) and the formation of inclusion complexes (ICs) using the co-precipitation method. According to the results of the GC/MS analysis conducted in this study, monoterpenes and monoterpenoids were the dominant chemical groups in total FEO, while in BEO, these two groups occurred along with sesquiterpenes and sesquiterpenoids. The presence of dominant compounds from both EOs was validated using the FT-IR spectra of ICs, which indicated successful complexation. Analyses conducted using SPME/GC-MS showed the continuous emission of volatiles over 24 h from both ICs. Under SEM, particles of both ICs appeared to have a rectangular or rhomboid morphology and few aggregates. The insecticidal properties of EOs and ICs with β-CD were tested on the Colorado potato beetle (CPB) as a model pest. The inclusion complex of β-CD with FEO altered the developmental dynamic and body mass of the CPB. The initial increase in the proteolytic activity of CPB larvae fed with potato plants sprayed with ICs was not maintained for long, and the proteolytic efficacy of treated larvae remained in line with that of the control larvae. Future investigations will focus on manipulating the volume of EOs used and the treatment duration for optimal efficacy and potential application.

Performance insights into spray-dryer microencapsulated Bacillus thuringiensis cry pesticidal proteins with gum arabic and maltodextrin for effective pest control

Bacillus thuringiensis (Bt) produces crystals composed mainly of Cry pesticidal proteins with insecticidal activity against pests but are highly susceptible to degradation by abiotic factors. In this sense, encapsulation techniques are designed to improve their performance and lifetime. However, the effects of polymeric matrix encapsulation such as gum arabic and maltodextrin by spray-dryer in the mechanisms of action of Bt kurstaki and Bt aizawai are unknown. We analyzed crystal solubilization, protoxin activation, and receptor binding after microencapsulation and compared them with commercial non-encapsulated products. Microencapsulation did not alter protein crystal solubilization, providing 130 kDa (Cry1 protoxin) and 70 kDa (Cry2 protoxin). Activation with trypsin, chymotrypsin, and larval midgut juice was analyzed, showing that this step is highly efficient, and the protoxins were cleaved producing similar ~ 55 to 65 kDa activated proteins for both formulations. Binding assays with brush border membrane vesicles of Manduca sexta and Spodoptera frugiperda larvae provided a similar binding for both formulations. LC50 bioassays showed no significant differences between treatments but the microencapsulated treatment provided higher mortality against S. frugiperda when subjected to UV radiation. Microencapsulation did not affect the mechanism of action of Cry pesticidal proteins while enhancing protection against UV radiation. These data will contribute to the development of more efficient Bt biopesticide formulations.Key points• Microencapsulation did not affect the mechanisms of action of Cry pesticidal proteins produced by Bt.• Microencapsulation provided protection against UV radiation for Bt-based biopesticides.• The study’s findings can contribute to the development of more efficient Bt biopesticide formulations.Graphical

Phytochemical composition and biopesticidal potential of Pinus mugo Turra essential oil

Pinus mugo Turra (sensu lato) is an alpine species distributed at high altitudes in the mountains. The species represents a resource for obtaining essential oil (EO). Pinus essential oils (EOs) show great potential as biopesticides in agriculture. To date, there is no comparative study of the EO from various plant parts of P. mugo across the Bulgarian flora. This study aimed to investigate the phytochemical compositions of P. mugo EOs from different plant parts; leaves, twigs, wood, and cones, and evaluate their bioactivity. The botanical pesticides potential of twigs EO against Sitobion avenae, Rhopalosiphum padi, and seeds of weed species Agrostemma githago L., Anthemis arvensis L., Avena fatua L., and Papaver rhoeas L. were tested in Petri dishes. The statistical analysis results showed different EOs yield in different plant parts (0.10–0.63% in leaves, 0.40–1.00% in tips of twigs, 0.1–0.71% in twigs, 0.2–1.43% in wood of one-two year twigs, 0.21–0.6% in male cones, and 0.17% in female cones). The predominant constituents in P. mugo EO were α-pinene, α-phellandrene, β-phellandrene and β-caryophyllene. These constituents were found in all analyzed shrubs from the six populations but in different amounts, depending on the plant part. The tested twigs EO at concentrations of 5%, 4.5%, 3.5%, 2.5%, 1.5%, and 1% had significant insecticidal activity against two aphid species. The efficacy of all concentrations of the EO was 100% on both aphids 24 h after the treatment. The EO demonstrated repellent activity only in high concentrations of 3.5%, 4.5%, and 5% for S. avenae, and 4.5%, and 5% for Rh. padi, respectively. The germination energy, germination, sprouts length, and root length of A. githago, A. arvensis, A. fatua, and P. rhoeas seeds were completely inhibited by low, and high doses (1 µL, 2 µL, 5 µL, 10 µL, and 20 µL) of P. mugo EO. Furthermore, the botanical pesticide capabilities of EOs against six phytopathogens; Alternaria alternata, Botrytis cinerea, Diaporthe nobilis, Fusarium oxysporum, Rhizoctonia solani, and Phytophthora cryptogea were evaluated. The EOs of all investigated parts of the species had strong antimicrobial effect against Salmonella enterica subsp. enterica, and Escherichia coli. The needles tissues extract of P. mugo contained polyphenolic compounds with pronounced antioxidant activity. The findings of this study provide strong support for considering P. mugo EO as a valuable ingredient in the formulation of diverse biopesticides.

Bioactive metabolites of licorice and thyme as potential inhibitors of Cox1 enzyme of phytopathogens of Capsicum annuum L.: In-silico approaches

Cytochrome c oxidase subunit 1 (Cox1), a key enzyme, has a crucial role in cellular respiration in eukaryotes and prokaryotes. Generally, respiratory inhibitors are considered one of the types of chemical pesticides. Thyme oil and licorice aqueous extract have been reported to have antifungal activities against fungal phytopathogens of Capsicum annuum L., i.e., Colletotrichum capsici, Fusarium oxysporum, and Pythium aphanidermatum. The present study focuses on identifying the key bioactive molecules of thyme and licorice botanicals inhibiting the activity of the Cox1 enzymes of the above mentioned phytopathogens, employing the in-silico approach. From a wide range of bioactive molecules screened, the molecular docking indicated trans-carveol, carvacrol, kaempferol 3-rhamnoside 7-xyloside, kaempferitrin, and astragalin 7-rhamnoside as the potential inhibitors for Cox1 of C. capsici, β-Caryophyllene, Caryophyllene acetate, hispaglabridin A, kaempferol 3-rhamnoside 7-xyloside and licorice glycoside A for Cox1 of F. oxysporum and (+)-Longifolen, Caryophyllene acetate, Hispaglabridin A, Neoliquiritin 2''-apioside and Licorice-saponin A3 for Cox1 of P. aphanidermatum. Most of the top-scoring bioactive molecules exhibited higher binding affinity with the targets than the chemical compound, i.e., carbendazim. Density functional theory (DFT) analysis confirmed the reactivity of the top-docked compounds. Molecular dynamic simulations confirmed the stability of docked complexes when evaluated through multiple descriptors. Additionally, MM/PBSA analysis supported the findings, indicating the spontaneous binding of the enzymes to the screened ligands. ADMET analysis revealed the safety of the selected bioactive compounds. The present findings could be useful in developing biopesticidal formulations as efficient and sustainable alternatives to chemical pesticides. Communicated by Ramaswamy H. Sarma

Biopesticide Nanoformulations Based on Clove Essential Oil for the Growth Inhibition of Lichens

Clove essential oil with eugenol as the major compound was used to develop a biopesticide formulation for lichens. Due to the suboptimal effectiveness and high volatility, the present research aimed to prepare a stable and effective deliverable nano biopesticide formulation by adding AgNO3 powder to clove essential oil. The analysis was carried out with several variations: Storage time, AgNO3 concentration, and the effect of adding emulsifiers like Tween 80 and PEG 400. Biopesticide formulations were characterized using a ultraviolet-visible spectrophotometer, Fourier transform infrared, pore size analyzer, and scanning electron microscope-energy dispersive X-ray. The effectiveness of inhibiting lichen growth was determined through an inhibition test. The results showed that the effective biopesticide formulation with AgNO3 was obtained at 429?475 nm wavelength, with a particle size of 217 nm and a PI value below 0.5. To reduce the particle size further, the addition of Tween 80 and PEG 400 in the process showed that the particle size achieved was 111.8?172.2 nm with round and irregular morphology, close to the nanoparticle size, and a suitable nanoemulsion formulation. Clove essential oil biopesticide modified with AgNO3, Tween 80, and PEG 400 effectively inhibited lichen growth with an average inhibition zone diameter of 33?37 mm compared to 36.4 mm in positive control and no inhibition in negative controls.. KEYWORDS :Biopesticides, Clove essential oil, Eugenol, Growth inhibition, Lichen, Silver

Insecticidal potential of Streptomyces sp. dichloromethane extracts against the cactus cochineal Dactylopius opuntiae (Cockerell)

Destructive damages caused by Dactylopius opuntiae (Cockerell) to cactus worldwide require an ecofriendly IPM approach. Streptomyces sp. produce wide range of biologically active secondary metabolites that can be an interesting alternative to chemical insecticides for pest control, as they are less toxic and easily biodegradable. The efficacy of dichloromethane extracts of four Moroccan Streptomyces sp. strains: Streptomyces bellus- E23-2, Streptomyces galilaeus- E23-9, Streptomyces africanus- E23-3, and Streptomyces bellus- E25-12 (applied at 11, 13, 15, 17 and 20 mg mL-1) against D. opuntiae nymphs and adult females was evaluated under laboratory and greenhouse conditions. Results showed that Streptomyces bellus- E23-2 and Streptomyces galilaeus- E23-9 dichloromethane extracts applied at 20 mg mL-1 were more effective, causing higher mortality against nymphs (92% and 91%, respectively) and adult females (90% and 95%, respectively) after 8 days of exposure, resulting in an LT50 value of 3.0 days (nymph), and 3.0 and 6.0 days (adult female), respectively. Streptomyces bellus- E25-12 extract had the lowest mortalities [88% (nymph) and 68% (adult female)]. In greenhouse experiment, the highest first instar nymph mortality was achieved by Streptomyces bellus- E23-2 (55.5%) and Streptomyces galilaeus- E23-9 (50.5%) dichloromethane extracts at 20 mg mL-1. The metabolites found in dichloromethane extracts of Streptomyces bellus- E23-2 and Streptomyces galilaeus- E23-9 show considerable potential to be used in the development of new biopesticide formulations for use in integrated pest management programs against D. opuntiae.