Effects Of Insecticides Research Articles

Genome-wide identification of G-protein coupled receptors (GPCRs) and their expression profile in response to β-cypermethrin stress in Zeugodacus cucurbitae

G-protein coupled receptors (GPCRs) are the largest and most diverse transmembrane receptor family in the cell. They are involved in regulating a wide range of biological processes, including behavior, reproduction, and development. However, GPCRs have not yet been identified in Zeugodacus cucurbitae. The current study focuses on the GPCRs identification, classification, distribution, and their expression analysis under β-cypermethrin stress to uncover novel targets for pest management and assist in the development of effective strategies for controlling the melon fly population. We identified 80 GPCRs genes including 50 GPCRs identified in family A, 17 GPCRs identified in family B, 8 identified in family C, and 5 identified in family F. Z. cucurbitae GPCRs showed significant differences in both the number of genes in families or subfamilies, as well as the sequencing of the genes. Interestingly, newly identified GPCRs genes are expressed differently at various developmental stages of Z. cucurbitae. Further, we evaluated these 80 GPCRs using Realtime quantitative PCR to confirm their expression between β-cypermethrin-resistant (RS) strain and susceptible strain (SS) of Z. cucurbitae. We identified 50 GPCR genes were highly overexpressed in a RS. Among these genes, eight genes were strongly induced by the 30% lethal concentration (LC) while two genes were significantly increased by the 50% LC of β-cypermethrin. This first genome-wide profiling and characterization of GPCRs could lay foundation for unraveling detoxification mechanism and target site modifications which may improve the insect resistance and could be effective insecticide targets for Z. cucurbitae management.

Evaluation of Fermented Plant Extracts as Bioinsecticides in Controlling Phenacoccus solenopsis Colonies on Hibiscus rosa-sinensis under Laboratory Conditions

The mealybug, Phenacoccus solenopsis, is a serious pest of Hibiscus rosa-sinensis. The waxy coating on its body may hinder pesticide penetration, and the extensive use of pesticides is risky to humans and the environment. Considering these drawbacks, fermented plant extracts (FPEs) were explored for their potential use in controlling this pest in a more user and environmentally-friendly manner. FPEs derived from eleven plant materials were evaluated against P. solenopsis for their insecticidal activity, mealybug wax removal potential and phytotoxicity effect on H. rosa-sinensis. Five concentrations of FPE [5, 10, 15, 20, and 25% (w/v)] were prepared. Among the 11 FPEs, FPE derived from ficus, kaffir lime, and turmeric were effective in suppressing P. solenopsis with lethal concentration at 50% (LC50 value) less than 20% concentration. Although ficus FPE was the top performer in the insecticidal assay, it induced medium to very high levels of leaf damage after being treated with 15–25% concentration at 24 and 72 hr post-treatment. A low level of leaf damage was observed in treatment with turmeric and kaffir lime FPEs at 72 hr post-treatment. FPEs could remove wax from the body of P. solenopsis with no significant difference among them. In conclusion, the FPE of ficus, kaffir lime, and turmeric showed promising insecticidal effects against P. solenopsis.

Transcriptome analyses in juvenile yellow perch (Perca flavescens) exposed in vivo to clothianidin and chlorantraniliprole: Possible sampling bias.

The St. Lawrence River is an important North American waterway that is subject to anthropogenic pressures including intensive urbanization, and agricultural development. Pesticides are widely used for agricultural activities in fields surrounding the yellow perch (Perca flavescens) habitat in Lake St. Pierre (Quebec, Canada), a fluvial lake of the river where the perch population has collapsed. Clothianidin and chlorantraniliprole were two of the most detected insecticides in surface waters near perch spawning areas. The objectives of the present study were to evaluate the transcriptional and biochemical effects of these two pesticides on juvenile yellow perch exposed for 28d to environmental doses of each compound alone and in a mixture under laboratory/aquaria conditions. Hepatic mRNA-sequencing revealed an effect of chlorantraniliprole alone (37 genes) and combined with clothianidin (251 genes), but no effects of clothianidin alone were observed in perch. Dysregulated genes were mostly related to circadian rhythms and to Ca2+ signaling, the latter effect has been previously associated with chlorantraniliprole mode of action in insects. Moreover, chronic exposure to clothianidin increased the activity of acetylcholinesterase in the brain of exposed fish, suggesting a potential non-target effect of this insecticide. Further analyses of three clock genes by qRT-PCR suggested that part of the observed effects of chlorantraniliprole on the circadian gene regulation of juvenile perch could be the result of time-of-day of sacrifice. These results provide insight into biological effects of insecticides in juvenile perch and highlight the importance of considering the circadian rhythm in experimental design and results analyses.

Toxicity of Cry- and Vip3Aa-Class Proteins and Their Interactions against Spodoptera frugiperda (Lepidoptera: Noctuidae).

The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith), is one of the most important insect pests affecting corn crops worldwide. Although planting transgenic corn expressing Bacillus thuringiensis (Bt) toxins has been approved as being effective against FAW, its populations' resistance to Bt crops has emerged in different locations around the world. Therefore, it is important to understand the interaction between different Bt proteins, thereby delaying the development of resistance. In this study, we performed diet-overlay bioassays to evaluate the toxicity of Cry1Ab, Cry1Ac, Cry1B, Cry1Ca, Cry1F, Cry2Aa, Cry2Ab, Vip3Aa11, Vip3Aa19, and Vip3Aa20, as well as the interaction between Cry1Ab-, Cry1F-, Cry2Ab-, and Vip3Aa-class proteins against FAW. According to our results, the LC50 values of Bt proteins varied from 12.62 ng/cm2 to >9000 ng/cm2 (protein/diet), among which the Vip3Aa class had the best insecticidal effect. The combination of Cry1Ab and Vip3Aa11 exhibited additive effects at a 5:1 ratio. Cry1F and Vip3Aa11 combinations exhibited additive effects at 1:1, 1:2, and 5:1 ratios. The combination of Cry1F and Vip3Aa19 showed an antagonistic effect when the ratio was 1:1 and an additive effect when the ratio was 1:2, 2:1, 1:5, and 5:1. Additionally, the combinations of Cry1F and Vip3Aa20 showed antagonistic effects at 1:2 and 5:1 ratios and additive effects at 1:1 and 2:1 ratios. In addition to the above combinations, which had additive or antagonistic effects, other combinations exhibited synergistic effects, with variations in synergistic factors (SFs). These results can be applied to the establishment of new pyramided transgenic crops with suitable candidates, providing a basis for FAW control and resistance management strategies.

A novel albumin-based supramolecular biosensor for ratiometric on-site determination of buprofezin

Buprofezin (BUP) is an effective insecticide against Homopteran and Thysanoptera pests. However, exposure to BUP may result in several harmful effects on the non-target organism including human body, such as hepatotoxicity and DNA damage. Therefore, development of a reliable analytical method for BUP holds paramount importance. This study presents a novel albumin-based supramolecular biosensor, DPP@ALB, designed for the sensitive detection of BUP in environmental matrices, including water, soil, and real food samples. The features of this biosensor include a fast response, high sensitivity, and visually detectable fluorescence color change, enabling on-site detection of BUP based on the portable paper strips and 3D-printed miniaturized testing system. Overcoming challenges associated with the low chemical reactivity of BUP, this supramolecular biosensor emerges as the very first fluorescent sensor for efficient and reliable monitoring of BUP with applications in broader areas of environmental analysis and food safety.

Antenna-Biased Odorant Receptor PstrOR17 Mediates Attraction of Phyllotreta striolata to (S)-Cis-Verbenol and (-)-Verbenone.

Phyllotreta striolata, the striped flea beetle, is one of the most destructive pests in Brassicaceae plants worldwide. Given the drawbacks associated with long-term use of chemical insecticides, green strategies based on chemical ecology are an effective alternative for beetle control. However, the lack of information on beetle ecology has hindered the development of effective biocontrol strategies. In this report, we identified two odorants, (S)-cis-verbenol and (-)-verbenone, which displayed significant attraction for P. striolata (p < 0.05), indicating their great potential for P. striolata management. Using the Drosophila "empty neuron" system, an antenna-biased odorant receptor, PstrOR17, was identified as responsible for the detection of (-)-verbenone and (S)-cis-verbenol. Furthermore, the interactions between PstrOR17 and (-)-verbenone or (S)-cis-verbenol were predicted via modeling and molecular docking. Finally, we used RNAi to confirm that PstrOR17 is essential for the detection of (-)-verbenone and (S)-cis-verbenol to elicit an attraction effect. Our results not only lay a foundation for the development of new and effective nonchemical insecticide strategies based on (S)-cis-verbenol and (-)-verbenone, but also provide new insight into the molecular basis of odorant recognition in P. striolata.

Enhance the physicochemical properties of the citronella oil -SLNPs to improve the insecticidal activity against Spodoptera littoralis (Boisd) (Lep. Nactuidae)

The Nano-formulation of citronella essential oil (Cymbopogon nardus (L.) and their mixtures of three adjuvants (Provecta®, Top film®, and PEG600-dioleate) were studied to enhance physico-chemical properties of the Nano-formulation and improve the insecticidal effect against Spodoptera littoralis (Boisd). Characterisation of physicochemical properties of Nano-formulation was studied by calculating droplet size, polydispersity index (PDI), and Zeta-potential parameters. The results showed that the Solid Lipid Nanoparticles (SLNs) mixtures of three adjuvant mixtures had more toxic activity and stability than the Nano-formulation alone. Before storage the acidity, alkalinity (pH), and viscosity exhibited an acidic pH value in the range (4.11–5.34), whereas after three months of storage was recorded high pH, a shift in the pH on storage can indicate the instability of active substances or product under semi field-laboratory conditions. Nano-formulation of the citronella oil mixed with the three adjuvants increased the mortality percentage of S. littoralis larvae.

Efficacy of some botanical insecticides against &lt;em&gt;Aphis gossypii&lt;/em&gt; Glover (Hemiptera: Aphididae) on chrysanthemum

An evaluation of various botanical insecticides to control Aphis gossypii and its impact on aphid population dynamics on chrysanthemum plants was investigated. In order to control A. gossypii on chrysanthemum, the effectiveness of several botanical insecticides extracted from Melia azedarach, Toona sinensis, and Chrysanthemum cinerariaefolium was investigated in the current study. The research was carried out in the experimental field of the Indonesian Ornamental Crops Research Institute under plastic house conditions. Five concentrations, i.e., 1.5, 2.0, 2.5, 3.0, and 3.5 g/L of three plant extracts, M. azedarach, T. sinensis, and C. cinerariaefolium, were sprayed on chrysanthemum cultivar White Fiji after 28 to 84 days after planting. A. gossypii had a dynamic population that changed according to the plant’s developmental stages. In vegetative growth, the alate adult and nymphal stages were dominant, and the population of nymphs increased along the plant ages. The insect colonized young leaf surfaces in the terminal apices. During the reproductive stages, the population of alate adults diminished, and the distribution of the insect extended to mature, old leaves, flower buds, and bloomed flowers. The application of several botanical insecticides revealed various responses of aphid populations. Among the tested insecticides, C. cinerariaefolium extract at 3.0 and 3.5 g/L demonstrated the highest average percentage efficacy (76 and 72%) and was the most consistent in suppressing the population. The results of this study indicate the potential efficacy of botanical insecticides against A. gossypii suggesting a different approach to efficient and environment-friendly chrysanthemum pest management.

Moslae Herba: Botany, Traditional Uses, Phytochemistry, and Pharmacology.

Moslae Herba (MH) can be used for both medicine and food and has a long history of medicine. MH has the effects of sweating and relieving the exterior, removing dampness and harmonizing, and is mainly used for colds caused by damp heat in summer. It is called "Xiayue Zhi Mahuang" in China. So far, 123 chemical compounds have been isolated and identified from MH, including flavonoids, terpenoids, phenolic acids, phenylpropanoids, and other chemical compounds. Its chemical components have a wide range of pharmacological activities, including antibacterial, antiviral, anti-inflammatory, antioxidant, analgesic sedation, antipyretic, immune regulation, insecticidal, and other effects. In addition, because of its aromatic odor and health care function, MH also has development and utilization value in food, chemical, and other fields. This paper reviewed the research progress of MH in botany, traditional uses, phytochemistry, and pharmacology and provided a possible direction for further research.

Biosynthesis of Copper Nanoparticles from Acacia cornigera and Annona purpurea and Their Insecticidal Effect against Tribolium castaneum

Diverse studies have showed that the pesticides can cause important damages in ecosystem. Therefore, the development of bio pesticides through nanotechnology can increase efficacy and limit the negative impacts in the environmental that traditionally seen through the use of chemical pesticides. Nanoparticles obtained from plants’ extracts can be used for effective pest management as a combined formulation of metal and some other organic material present in the plants. In the present study, our evaluated biosynthesis of nanoparticles of copper used two plant extracts (Acacia cornigera and Annona purpurea), and the Taguchi method was adopted for the synthesis optimization of the following variables of biosynthesis: temperature, pH, extract concentration, and reaction times to maximize the insecticidal activity on Tribolium castaneum. Our results showed that the nanoparticles were successfully synthesized using Acacia cornigera and Anona purpurea extract under optimum conditions under Taguchi L 9 orthogonal design, where copper nanoparticles were obtained with a size of 63–153 nm for using A. cornigera extract, 87–193 nm for A. purpurea extract, and a zeta potential of 9.6 mV and −32.7 mV, respectively. The nanoparticles of copper from A. cornigera showed effective insecticidal activity against Tribolium castaneum, and 90% mortality compared to the 76.6% obtained from nanoparticles of copper from A. purpurea. The results suggest that Cu-nanoparticles derived from both plants could be used as a biocontrol agent of Tribolium castaneum, a pest of stored grain with great economic importance.

Lethal and sublethal effects of insecticides on Bathycoelia distincta (Heteroptera: Pentatomidae)

Bathycoelia distincta is one of the most dominant stink bug pests associated with macadamia orchards in South Africa. Understanding the toxicity and sublethal effects of insecticides on this pest is essential for its effective management. This study tested four commercial insecticide formulations, consisting of one organophosphate (acephate) and three pyrethroids (lambda-cyhalothrin, beta-cyfluthrin and tau-fluvalinate). The toxicity of these insecticides and their behavioural effects on mobility were assessed. The sublethal effects of lambda-cyhalothrin on the biological parameters of parent B. distincta (F0) and offspring generations (F1) were also determined by treating B. distincta adults with sublethal concentrations (LC10 and LC30). In toxicity bioassays, acephate was more toxic to B. distincta than lambda-cyhalothrin, beta-cyfluthrin and tau-fluvalinate. Behavioural changes were only observed in bugs exposed to pyrethroids, resulting in an increase in the distance walked and decrease of angular velocity. In the F0 generation, LC30 reduced the fecundity whereas the LC10 and LC30 accelerated development of the F1 generation. These results suggest that pyrethroids may enhance the dispersal of this pest and stimulate the growth of offspring populations. Further experiments should be conducted to confirm these results and understand the mechanism of action of pyrethroids on B. distincta.

Testing the Sensitivity of the Tropical Bed Bug Cimex hemipterus (Hemiptera: Cimicidae) to Deltamethrin, Phoxim and Propetamphos in Eastern Iran.

Bedbugs are nocturnal ectoparasites that have made a comeback after 20 years and have become one of the main challenges for pest control methods worldwide. Monitoring chemical pesticide resistance is crucial for identifying the best bed bugs management strategies to effectively manage arthropods. This study aims to assess the susceptibility of Cimex hemipterus (Hemiptera: Cimicidae) collected from different parts of Khorasan-Razavi Province, (northeast of Iran) to deltamethrin (pyrethroid), phoxim (organothiophosphate) and propetamphos (phosphoramidate). This study was conducted from Dec 2020 to May 2021. The efficacy of three insecticides (deltamethrin, phoxim, and propetamphos) on adult C.hemipterus was assessed using a bioassay method recommended by the World Health Organization (WHO),. Concentrations of deltamethrin used were 10, 20, 40, 80, 160, 320, 640, 1280, and 2560 ppm, while concentrations of phoxim and propetamphos were 10, 40, 160, and 320 ppm. The bed bugs were continuously exposed to the insecticide for 24 hours, and mortality was assessed at regular intervals during the observation period. The concentration-response data were subjected to POLO-PC software and data were analyzed by the one-way and two-way ANOVA procedures. The lethal concentration fifty values of deltamethrin, phoxim and propetamphos on the examined bed bugs were 0.551, 0.148 and 0.237 ppm, respectively. Insecticide effects of phoxim were significantly higher (P≤ 0.05) compared to each of either deltamethrin and propetamphos agents. The insecticide effects of phoxim against bed bugs were significantly higher compared to each of either deltamethrin or propetamphosinsecticides.

Nicotinic Acetylcholine Receptor Alpha6 Contributes to Antiviral Immunity via IMD Pathway in Drosophila melanogaster.

Currently, insecticides that target nicotinic acetylcholine receptors (nAChR) are widely used. Studies on the sublethal effects of insecticides have found that they can affect the amount of virus in insects. The mechanism by which insecticides affect insect virus load remain unclear. Here, we show that nAChR targeting insecticide can affect viral replication through the immune deficiency (IMD) pathway. We demonstrate that a low dose of spinosad (6.8 ng/mL), acting as an antagonist to Drosophila melanogaster nicotinic acetylcholine receptor α6 (Dα6), significantly elevates Drosophila melanogaster sigmavirus (DMelSV) virus titers in adults of Drosophila melanogaster. Conversely, a high dose of spinosad (50 ng/mL), acting as an agonist to Dα6, substantially decreases viral load. This bidirectional regulation of virus levels is absent in Dα6-knockout flies, signifying the specificity of spinosad's action through Dα6. Furthermore, the knockdown of Dα6 results in decreased expression of genes in the IMD pathway, including dredd, imd, relish, and downstream antimicrobial peptide genes AttA and AttB, indicating a reduced innate immune response. Subsequent investigations reveal no significant difference in viral titers between relish mutant flies and Dα6-relish double mutants, suggesting that the IMD pathway's role in antiviral defense is dependent on Dα6. Collectively, our findings shed light on the intricate interplay between nAChR signaling and the IMD pathway in mediating antiviral immunity, highlighting the potential for nAChR-targeting compounds to inadvertently influence viral dynamics in insect hosts. This knowledge may inform the development of integrated pest management strategies that consider the broader ecological impact of insecticide use.

Nornicotine‐Typed Insecticides: The Potential Insecticides with Strong Activity Against Aedes Albopictus

AbstractAedes albopictus, the main vector of dengue, yellow fever, chikungunya, and Zika, has caused significant public health concerns, but there are still few effective insecticides. Nicotine and nornicotine‐typed compounds are well‐known for their potential as an insecticide, which has potential activity against Ae. albopictus. Here we report the effects of nornicotine‐typed insecticide against larvae of Ae. albopictus. We developed a novel synthetic strategy for nicotine and nornicotine‐typed compounds. Novel compounds A1‐A8 and B1‐B26 were synthesized by the synthesized nornicotine. And bioassays indicated that most of these compounds exhibited good effects against larvae of Ae. albopictus, and compounds A3, B4, B20, and B26 had excellent activity against Ae. albopictus, and they were not toxic to humans according to other reports. After considering the cost, compounds B4, B20, and B26 could be potential lead compounds against Ae. albopictus and other Aedes mosquitoes.

Chronic Effects of Mixture Two Pesticides on kidney of Common Carp Fish (Cyprinus carpio L. 1758)

Pesticides are man-made chemical compounds, widely used in agriculture to control different types of pests, product crops and prevent diseases which damage them. The excessive and unwarranted use of pesticides at various stages of crop production may pose a great danger to the aquatic environment, especially to fish. In this research, an effort has been made to comparative the effect of herbicide (Goldate), insecticide (Alexander) and mixture of them on common carp (Cyprinus carpio) through chronic toxicity bioassay.In chronic exposure, Toxicological effects of Goldate and Alxander individual and combine as mixture observed by monitoring hematological parameters on common carp fish. There was prepared 3 concentration groups (1/10, 1/100 and 1/200) for every pesticides (Goldate, Alxander and mixture Goldate + Alxander), exposed to juvenile fish (60-80 gm. in weight) for 6 weeks. During the experimental period the result showed a significant increase in the mean value of blood urea and createnine compared with control. There was not found any histological alterations in kidney tissues, in all groups and all concentrations. All groups were similar to control group which show normal appearance of renal glomerulus, renal collecting tubules and hemopoietic tissue.

Removal of neonicotinoids present in secondary effluents by ferrate(VI)-based oxidation processes

The persistence in the environment and possible harmful effects of neonicotinoid insecticides have raised some concerns, which have led to the proposal of various measures for their remediation. The aim of this work was to study the elimination of five neonicotinoids (thiamethoxam (THM), imidacloprid (IMI), clothianidin (CLO), thiacloprid (THC), and acetamiprid (ACE)) using ferrate (Fe(VI)) as the oxidizing agent. Firstly, second-order rate constants for the reactions of neonicotinoids with Fe(VI) were determined at different pHs. The most reactive compound was THC, with a rate constant of 400 ± 43 M−1 s−1 at pH 8 (the optimum pH considering the predominance of the most reactive species (HFeO4−) and the decreasing self-decomposition of Fe(VI) with pH), followed by CLO (10.7 ± 1.7 M−1 s−1), THM (9.7 ± 0.7 M−1 s−1), and IMI (2.5 ± 0.6 M−1 s−1). ACE did not significantly react with Fe(VI). The oxidation of the selected pollutants in secondary effluents by Fe(VI) was rather slow, and only THC could be efficiently removed. The presence of natural organic matter (NOM) exerted a negative influence on the removal of the neonicotinoids of moderate reactivity with Fe(VI) (CLO, THM, and IMI). The additional presence of peroxymonosulfate (Fe(VI)/PMS system) slightly increased the removal of neonicotinoids due to the formation of hydroxyl and sulfate radicals. Finally, the application of the Fe(VI)/sulfite system considerably increased the oxidation rate of the selected pollutants, with enhanced formation of hydroxyl and, especially, sulfate radicals. Overall, these results suggest that the Fe(VI)/sulfite system has significant potential to address environmental and health concerns associated with neonicotinoids in water sources with low NOM content.Graphical abstract

Cereal leaf beetle-associated bacteria enhance the survival of their host upon insecticide treatments and respond differently to insecticides with different modes of action.

The cereal leaf beetle (CLB, Oulema melanopus) is one of the major cereal pests. The effect of insecticides belonging to different chemical classes, with different mechanisms of action and the active substances' concentrations on the CLB bacterial microbiome, was investigated. Targeted metagenomic analysis of the V3-V4 regions of the 16S ribosomal gene was used to determine the composition of the CLB bacterial microbiome. Each of the insecticides caused a decrease in the abundance of bacteria of the genus Pantoea, and an increase in the abundance of bacteria of the genus Stenotrophomonas, Acinetobacter, compared to untreated insects. After cypermethrin application, a decrease in the relative abundance of bacteria of the genus Pseudomonas was noted. The dominant bacterial genera in cypermethrin-treated larvae were Lactococcus, Pantoea, while in insects exposed to chlorpyrifos or flonicamid it was Pseudomonas. Insecticide-treated larvae were characterized, on average, by higher biodiversity and richness of bacterial genera, compared to untreated insects. The depletion of CLB-associated bacteria resulted in a decrease in larval survival, especially after cypermethrin and chlorpyrifos treatments. The use of a metagenome-based functional prediction approach revealed a higher predicted function of bacterial acetyl-CoA C-acetyltransferase in flonicamid and chlorpyrifos-treated larvae and tRNA dimethyltransferase in cypermethrin-treated insects than in untreated insects.

The Management Strategies against Maize Stem Borer, Chilo partellus (Swinhoe) on Maize (Zea mays L.): A Review

The research provides updated information on the effect of different insecticides and biopesticides against maize stem borer (Chilo partellus Swinhoe) were carried out at different areas by different scientists. Combining Imidacloprid and Trichogramma chilonis resulted in significantly decreased leaf injury m-2 (1.32) and dead hearts (4.16%) in several trials done in different agroclimatic zones. With maximum grain yield (39.5 q/ha), imidacloprid + Karanj oil significantly reduced dead heart (2.8%), plant infestation (14.1%), stem tunneling (2.7%), and number of exit holes per plant (0.6). Results of the field bio-efficacy study showed that at, Chloropyrifos 50% + Cypermethrin 5% @2500 g.a.i./ha recorded significantly lower larval populations (1.18 larvae per plant) and a lower percentage of plant damage (9.00%). As per the findings this study suggests the percentage infestation and larval population of Chilo partellus can be minimized by the application of combinations of insecticides and biopesticides.

Concentration-dependent effects of spinetoram on nontarget freshwater microalgae: A comparative study on Chlorella vulgaris and Microcystis aeruginosa

The rising global demand for agricultural products is leading to the widespread application of pesticides, such as spinetoram, resulting in environmental pollution and ecotoxicity to nontarget organisms in aquatic ecosystems. This research focused on assessing the toxicity of spinetoram at various concentrations (0, 0.01, 0.1, 0.5, 1.0, and 3.0 mg L−1) on two common freshwater microalgae, Chlorella vulgaris and Microcystis aeruginosa, to shed light on the ecotoxicological effects of insecticides. Our findings demonstrate that M. aeruginosa is more sensitive to spinetoram than is C. vulgaris, with a concentration-dependent reduction in the growth rate observed for M. aeruginosa, whereas only the highest concentration of spinetoram adversely affected C. vulgaris. At a concentration of 0.01 mg L−1, the growth rate of M. aeruginosa unexpectedly increased beginning on day 7, indicating a potential hormetic effect. Although initial exposure to spinetoram improved the photosynthetic efficiency of both microalgae strains at all concentrations, detrimental effects became apparent at higher concentrations and with prolonged exposure. The photosynthetic efficiency of C. vulgaris recovered, in contrast to that of M. aeruginosa, which exhibited limited recovery. Spinetoram more significantly inhibited the effective quantum yield of PSII (EQY) in M. aeruginosa than in C. vulgaris. Although spinetoram is not designed to target phytoplankton, its toxicity can disrupt primary productivity and modify phytoplankton-consumer interactions via bottom-up control mechanisms. This study enhances our understanding of spinetoram's ecotoxicity and potential effects on aquatic ecosystems.

Insecticidal effects of the fast pyrolysis bio-oil against Spodoptera littoralis and Aphis gossypii insect pests

The detrimental effects of agricultural pesticides on human and environmental health necessitate the development of alternatives to conventional pesticides. In the laboratory, the cotton leafworm (Spodoptera littoralis) and aphid (Aphis gossypii) insects were used to evaluate the insecticidal activity of bio-oil derived from olive cake. The application of bio-oil by leaf dipping against S. littoralis demonstrated no mortality at a concentration of 1 % bio-oil. In contrast, the bio-oil showed better results against A. gossypii by slide dip method with LC50 = 1310.40 mg/l and LC90 = 3117.40 mg/l. The combined activity of bio-oil and the biopesticide Beauveria bassiana (bio-oil/B.b) was comparable, with LC50 = 1386.94 mg/L and LC90 = 3142.05 mg/L. The field application (two sprays) of bio-oil, bio-oil/B.b, and a commercial insecticide (alpha super) on aphids revealed a reduction of 52 %, 74.33 %, and 74.67 % in the first spray and 59.67 %, 63.33 %, and73.67 % in the second spray for, bio-oil, bio-oil/B.b, and super alpha respectively. The bio-oil and bio-oil/B.b had significantly less effect on the population densities of two predators (predator mite Amblyseius swirskii and aphid lion Chrysoperla carnea) than the insecticide used. Analyses of bio-oil by gaschromatography–mass spectrometry (GC–MS) identified 30 compounds possibly have pesticidal activity. The most abundant compounds are 9 octadecenoicacid methyl ester, hexadecanoic acid, methyl ester, 6 octadecenoic acid, methyl ester and Phenol, 2methoxy. The pyrolysis byproduct (bio-oil) of olive cake biomass contains bioactive compounds that can be used as biopesticide.