Pesticides Research Articles

Phytochemical Analysis and Antioxidant and Antifungal Activities of Powders, Methanol Extracts, and Essential Oils from Rosmarinus officinalis L. and Thymus ciliatus Desf. Benth.

Chemical residues in food pose health risks such as cancer and liver issues. This has driven the search for safer natural alternatives to synthetic fungicides and preservatives. The aim of this study was to characterize the chemical composition of the essential oils (EO), determine the polyphenolic contents, and evaluate the in vitro antioxidant and antifungal activities of methanol extracts (ME), essential oils (EO), and powders from Rosmarinus officinalis L. (rosemary) and Thymus ciliatus (Desf) Benth. (thyme) from the M'sila region, Algeria. The chemical composition of the EOs was determined by GC-MS. R. officinalis EO was composed of 31 components, mainly camphor (41.22%), camphene (18.14%), and α-pinene (17.49%); T. ciliatus EO was composed of 58 components, mainly, in percentage, α-pinene (22.18), myrcene (13.13), β-pinene (7.73), β-caryophyllene (10.21), and germacrene D (9.90). The total phenols and flavonoids were determined spectrophotometrically, and the rosemary ME was found to possess the highest polyphenolic content (127.1 ± 2.40 µg GAE/mg), while the thyme ME had the highest flavonoid content (48.01 ± 0.99 µg QE/mg). The antioxidant activity was assessed using three methods: rosemary ME was the most potent, followed by DPPH (IC50 = 13.43 ± 0.14 µg/mL), β-carotene/linoleic acid (IC50 = 39.01 ± 2.16 μg/mL), and reducing power (EC50 = 15.03 ± 1.43 µg/mL). Antifungal activity was assessed for 32 pathogenic and foodborne fungi. Four methods were applied to the solid medium. Incorporating the powdered plant into the culture medium (at 10%) reduced the fungal growth to greater than 50% in 21.88% and 6.25% of all fungal isolates, for R. officinalis and T. ciliatus, respectively. The ME, applied by the well diffusion method (0.1 g/mL), was less effective. Different concentrations of EO were tested. Incorporating the EO into the culture medium (1500 μL/L) inhibited 50% of the molds to levels of 50 and 75% for R. officinalis and T. ciliatus, respectively, with the complete inhibition of four fungi. Fumigated EO (15 μL) inhibited 65% of the molds to levels of 65 and 81.25% for R. officinalis and T. ciliatus, respectively, with the complete inhibition of five fungi. There was little to no sporulation in conjunction with the inhibition. Our results revealed some of the potential of the studied plants to fight foodborne molds and presented their promising characteristics as a source of alternatives to chemical pesticides and synthetic preservatives. Further studies are needed to find adequate application techniques in the food safety area.

Actinobacteria mediated synthesis of silver nanoparticles using Streptomyces diastaticus and their biological efficacy against human vector mosquitoes and agricultural insect pests

Mosquitoes and agricultural insects were harmful to both public health and crops. Prolonged use of synthetic chemical pesticides for insect pest control was associated with resistance development and negative human and ecological effects. This study investigates the larvicidal activity of Ag-NPs produced using Streptomyces diastaticus against Culex quinquefasciatus, Anopheles stephensi, Aedes aegypti, Spodoptera litura, and Plutella xylostella. UV-Vis spectroscopy, XRD, SEM-EDX, FT-IR, TEM, DLS, and Zeta potential analysis were used to characterize the biosynthesized Ag-NPs. The results showed that biosynthesized Ag-NPs were more toxic to, A. stephensi, C. quinquefasciatus, and A. aegypti with LC50 values of 15.70, 11.10, and 17.53 µg/mL, respectively. Biosynthesized Ag-NPs exhibited the highest antifeedant effects against S. litura (88.73 %) and P. xylostella (92.36 %) at 50 µg/mL concentration. The mortality bioassay revealed considerable larvicidal activity against S. litura and P. xylostella larvae at greater doses of 50 µg/mL, 80.67 and 84.05 %, respectively. Morphogenetic variations were observed on treated larvae of C. quinquefasciatus, A. aegypti, and A. stephensi, S. litura, and P. xylostella with Ag-NPs. In the present investigation the impact of Ag-NPs on the antioxidant enzymes (SOD, CAT, and GPx), the activity of each enzyme were dramatically increased with higher concentrations resulting in significant differences. The study also found that Ag-NPs inhibited the detoxifying enzyme (GST and AChE) activity of target organisms. The histological structure of the treated and untreated larvae revealed structural changes between the midgut epithelial cells. As a consequence of these findings, the S. diastaticus-mediated Ag-NPs serve as a possible, eco-friendly biopesticide and alternative to synthetic chemicals for the control of human vector mosquitoes and destructive arthropod insect pests.

Separation of plant protection products from complex aqueous bodies using carbon-mineral composites incorporated with double metals (Ni/Mn or Ni/Fe)

Due to the extensive application of pesticides and their hazardous effects on organisms, there is an urgent need to remove them effectively from wastewater. Metal-incorporated carbon-mineral composites (Ni/Mn-CMC and Ni/Fe-CMC) described in this paper can certainly be applied for this purpose. They were synthesized by combining mechanochemical and pyrolytic processes and their physicochemical properties were investigated using numerous methods (SEM-EDS, N2 adsorption/desorption, XRD, surface charge, FTIR). Adsorption capacity towards diuron and carboxin with and without impurities commonly detected in natural ecosystems, cadmium ions or arsenite, was measured. The obtained results indicated that Ni/Fe-CMC is more efficient adsorbent of pesticides due to its well-developed surface. It was able to bind 158.34 mg g−1 of diuron and 133.58 mg g−1 of carboxin in the solutions, where only one pesticide was present. In turn, these values for the Ni/Mn-CMC sample were 126.49 mg g−1 and 102.08 mg g−1, respectively. It should be noted that the composites maintained their high adsorption capacity in the multicomponent solutions, i.e., containing both pesticide and metal ions. Then, the maximum reduction in pesticide adsorption was only 8.36. Ni/Mn-CMC and Ni/Fe-CMC were successfully regenerated with ethanol without changing their structure and adsorption capacity. Also, the extracts from investigated materials did not have negative impact on plant growth. This confirmed suitability of carbon-mineral composites for repeated multiple use without toxic effects to organisms.

Applications of chitosan in the agri-food sector: A review

Chitosan is a natural and renewable polysaccharide that can form biopolymers. It is derived from the deacetylation of chitin mainly from crustaceans' shells, but also from fungi and insects. Thanks to unique characteristics such as antimicrobial effects, antioxidant properties or film forming capacities, it has triggered an important amount of research in the last decade about possible applications in industrial fields. The main application field of chitosan is the food industry where it can be used for preservation purposes and shelf-life improvement for fresh food products such as fruits or meat. For beverages, it is used for clarification and fining as well as elimination of spoilage flora in beverages like fruit juices or wine. And in agriculture, it can be used as a plant protection product through different mechanisms like the elicitation of plant defences. The mechanisms of action of chitosan on microorganisms are multiple and complex but revolve mostly around the disturbance of microorganisms’ membranes and cell walls resulting in the leakage of cell material. The use of chitosan is still minor but is promising in finding environmentally friendly alternatives to synthetic chemicals and plastics. Therefore, its characterization is primordial for the future of sustainable production and preservation processes.

MODELING THE EFFECTS OF PESTS AND PESTICIDE ON CROP YIELDS IN A MULTIPLE CROPPING SYSTEM

Pest infestation poses a significant threat to agricultural crop yields, and to control it, farmers spray chemical pesticides. The persistent use of these chemical agents not only leads to pesticide residues within crops but also exerts collateral damage on the beneficial pest population. In this research work, we formulate a nonlinear mathematical model to assess the impacts of pesticide on crop yields within a multiple cropping system. Model analysis illustrates that crop consumption rates destabilize, and the spraying rate of pesticide stabilizes the system. Furthermore, we determine conditions for the global stability of the coexisting equilibrium and conduct a global sensitivity analysis to identify model parameters that significantly influence pest population density. Our findings emphasize that, for effective pest population control and enhanced crop yields, farmers should choose either pesticides with a high pest abatement rate or those with a higher pesticide uptake rate. Considering the spraying rate of pesticide as time-dependent, we also suggest an optimal control strategy to minimize the pest population and associated costs. We provide analytical results backed by numerical simulations implemented through the non-standard finite difference scheme to support our findings.

A novel approach to managing facility airborne diseases: suppressing air pathogens with smoke aerosols generated from fungicide phase transition.

Environmental microorganisms are major contributors to the development and spread of disease. Chemical disinfection can inhibit pathogens and play a preventive role against diseases. In agriculture, prolonging the floating time of chemical pesticides in the air has a positive effect on the control of airborne diseases. However, the interaction of chemical pesticides with airborne pathogens is not yet known. Here, triazole fungicide was transformed into stable smoke aerosols in order to assess the feasibility of employing phase transition release pesticides for air disinfection. The phase transition had a minimal impact on hexaconazole (Hexa) and myclobutanil (Mycl), with their smoke formation rates remaining consistently >90%. In microscopic morphology, triadimenol (Tria) and epoxiconazole (Epox) are solid, and tebuconazole (Tebu), Hexa, Mycl and difenoconazole (Dife) are liquid. Liquid smoke has advantages over solid smoke in the inhibition of environmental pathogens. The floatability and spatial distribution of fungicide aerosol were optimized by the combination of smoke particles with different properties, so that the fungicide aerosol could meet the conditions of practical application. In practical applications, smoke exhibits a gentler deposition process at the target interface compared to spray, along with a more homogeneous distribution of fungicides. Moreover, fungicide smoke demonstrates superior control efficacy and leaves behind lower residual amounts on fruit. In conclusion, the implementation of fungicide phase transition as a smoke aerosol offers a viable approach to effectively suppress pathogen aerosols and enhance the control of airborne diseases. © 2024 Society of Chemical Industry.

Comparison between Liquid Immersion, Laser Diffraction, PDPA, and Shadowgraphy in Assessing Droplet Size from Agricultural Nozzles

Spray droplet diameters play a key role in the field of liquid plant protection product (PPP) application technology. However, the availability of various measurement techniques, each with its unique operating principles for evaluating droplet size spectra, can lead to different interpretations of spray characteristics. Therefore, in this study, four measurement techniques—Liquid Immersion (LI), Laser Diffraction (LD), Phase Doppler Particle Analysis (PDPA), and Shadowgraphy (SG)—were utilized to evaluate the droplet size distribution of agricultural spray nozzles. Additionally, PDPA and SG were used to assess the average velocity of spray droplets. Experiments were conducted in three different laboratories with the main aim of comparing results obtained with various types of equipment utilized under ordinary practical conditions. Spraying tests were carried out using three flat fan nozzles and an air-induction flat fan nozzle. As a general trend, the lowest values for droplet diameters were measured using the Laser Diffraction technique, followed by Shadowgraphy. The PDPA technique provided the highest values for mean diameters (D10, D20, and D30) and the numeric median diameter (Dn0.5), whereas the Liquid Immersion method yielded the highest values for the Sauter mean diameter (D32) and volumetric diameters (Dv0.1, Dv0.5, and Dv0.9). Importantly, all measurement techniques were able to discriminate the four nozzles based on their Dv0.5 diameter. Average droplet velocities showed a similar pattern across the four nozzles with the PDPA and the SG measurement techniques. The differences in diameter values observed with the four measurement techniques underline the necessity of always including reference nozzles in spray quality assessments to base classifications on relative rather than absolute values.

Biopesticide effect on crops for the bioactive components extracted from Tagetes erecta and Tagetes patula

Botanicals from Marigold, Chrysanthemum, Basil, Rosemary and other medicinal plants have been analysed as potential replacements of chemical pesticides as they are effective and non-hazardous to the environment. The bioactive components thiophene is present in large amount in Tagetes sp. which have a wide range of biocidal properties. In this study the crude extracts of different parts of Tagetes erecta and Tagetes patula were obtained by Soxhlet extraction method. The leaf extracts were subjected to GC–MS to identify their components and to confirm the presence of thiophenes. Two major disastrous crop pests namely, Spodoptera litura and Corcyra cephalonica belongs to Order Lepidoptera, Family Noctuidae and Pyralidae were used for the experimental study. The effect of bioactive extract was tested by direct and indirect methods for their larvicidal effect. The S. litura larvae was allowed to feed on castor leaves coated with spraying different concentrations of methanolic sample extracts as indirect method. In the direct spraying method, the S. litura and C. cephalonica larvae were sprayed with low and high concentrations of crude sample extracts of both T. patula and T. erecta. Significant decrease in larval activity and survival rate within 24 h to 48 h were recorded for both the methods. The trials were performed using variousvolumes from 10 to 1000 µl to check larvicidal activity. The roots and stem extracts of T. erecta for 25 µl kill 100% larvae within 24 h whereas 50 µl of T. patula flowers, roots and stem extract effectively kill only 50% of the larvae in 48 h. A mini nursery evaluation were conducted by direct spraying method on larvae growing on jowar saplings, which displayed 100% mortality of larvae within 24 h for 25 µl of T. erecta leaf and flower extracts and T. patula flower extract. From these trials, it can be inferred that the extracts of T. patula and T. erecta provided effective outcomes as larvicides of S. litura and C. cephalonica.

Optimizing the production of dsRNA biocontrols in microbial systems using multiple transcriptional terminators.

Crop pests and pathogens annually cause over $220 billion in global crop damage, with insects consuming 5%-20%of major grain crops. Current crop pest and disease control strategies rely on insecticidal and fungicidal sprays, plant genetic resistance, transgenes, and agricultural practices. Double-stranded RNA(dsRNA) is emerging as a novel sustainable method of plant protection as an alternative to traditional chemical pesticides. Successful commercialization of dsRNA-based biocontrols requires the economical production of large quantities of dsRNA combined with suitable delivery methods to ensure RNAi efficacy against the target pest. In this study, we have optimized the design of plasmid DNA constructs to produce dsRNA biocontrols in Escherichia coli, by employing a wide range of alternative synthetic transcriptional terminators before measurement of dsRNA yield. We demonstrate that a 7.8-fold increase of dsRNA was achieved using triple synthetic transcriptional terminators within a dual T7 dsRNA production system compared to the absence of transcriptional terminators. Moreover, our data demonstratethat batch fermentation production dsRNA using multiple transcriptional terminators is scalable and generates significantly higher yields of dsRNA generated in the absence of transcriptional terminators at both small-scale batch culture and large-scale fermentation. In addition, we show that application of these dsRNA biocontrols expressed in E. coli cells results in increased insect mortality. Finally, novel mass spectrometry analysis was performed to determine the precise sites of transcriptional termination at the different transcriptional terminators providing important further mechanistic insight.

The Influence of Low Pesticide Doses on Fusarium Molds

The agricultural sector is a large consumer of synthetic chemical products, especially fertilizers and plant protection products. Therefore, an emerging concern nowadays is to reduce chemicals’ use in agriculture. One of the approaches is to reduce the doses of plant protection products, as much as possible, while keeping the treatments’ efficacy. The present work presents the antifungal action of three commercial plant protection products, tested at recommended as well as reduced doses, against important phytopathogenic molds of the Fusarium genus. In vitro, results have shown that two of the tested products could be used at reduced doses while keeping their antifungal activity. The commercial pesticide containing prothioconazole 53 g/L, spiroxamine 224 g/L, and tebuconazole 148 g/L mixture was able to inhibit completely the growth of three virulent F. culmorum strains, even when fungicide treatment was applied in 25% reduced dose. Lower efficacy was seen on F. graminearum strains, however, there were no significant differences (p < 0.05) between the commercially recommended dose and the 25% reduced dose. Another efficient pesticide in Fusarium control contains triadimenol 43 g/L, spiroxamine 250 g/L, and tebuconazole 167 g/L. Tested in a reduced dose (28.6% less than the commercial recommended dose) it completely inhibited the F. graminearum Fg183 (DSM 4527) strain and inhibited the growth of various F. culmorum strains with at least 97.50% efficacy. However, there are some fungal strains, such as the aggressive F. graminearum Fg96 strains that were less susceptible to pesticide treatments even at commercially recommended doses of fungicides.

Peasant perception of beekeeping constraints and practices in large honey production areas in Burkina Faso

BackgroundIn recent decades, agricultural landscapes have been profoundly modified due to the intensification of agriculture, therefore leading to significant disturbances in all components of biodiversity. A survey on the knowledge of beekeeping realities and the use of phytosanitary products in areas of high honey production in Burkina Faso was carried out. Beekeeping realities design the state of beekeeping activities in the study localities.MethodsThe objective of this survey was to characterize Beekeeping operations and to assess the level of knowledge of beekeepers on the effects of the use of phytosanitary products through different beekeeping and agricultural practices. In this sense, 113 farmer beekeepers from the Boucle du Mouhoun, Hauts-Bassins and Nord regions in Burkina Faso were surveyed about their different beekeeping practices.ResultsThe results obtained indicated that beekeeping is a secondary activity (96.47%) and is mainly practiced by men (90.27%). The respondents have mostly an average of 22 traditional hives. The majority of beekeepers have not received training (84.07%) on the hazards of plant protection products on their beekeeping farms. However, a large amount of beekeepers (70.73%) acknowledged that the use of plant protection products could be harmful to their activity. Hives are usually installed in or near the fields. The plant protection products used for crop protection are herbicides (27%), insecticides (23%), fungicides (8%), but especially mixed (42%).ConclusionThe results show that beekeeping in Burkina Faso remains traditional and is practiced for sociocultural reasons. The use of pesticides close to beekeeping could play a role in bee colony collapse taking place in these regions. Training beekeepers on the dangers of the chemicals they use in fields near hives is therefore essential.

Analysis of glycoalkaloid distribution in the tissues of mealworm larvae (Tenebrio molitor)

Solanine (SOL) and chaconine (CHA) are glycoalkaloids (GAs) produced mainly by Solanum plants. These plant secondary metabolites affect insect metabolism; thus, they have the potential to be applied as natural plant protection products. However, it is not known which GA concentration induces physiological changes in animals. Therefore, the aim of this study was to perform a quantitative analysis of SOL and CHA in the larvae of Tenebrio molitor using LC‒MS to assess how quickly they are eliminated or metabolised. In this experiment, the beetles were injected with 2 μL of 10−5 M SOL or CHA solution, which corresponds to a dosage range of 0.12–0.14 ng/mg body mass. Then, 0.5, 1.5, 8, and 24 h after GA application, the haemolymph (H), gut (G), and the remainder of the larval body (FB) were isolated. GAs were detected in all samples tested for 24 h, with the highest percentage of the amount applied in the FB, while the highest concentration was measured in the H sample. The SOL and CHA concentrations decreased in the haemolymph over time, while they did not change in other tissues. CHA had the highest elimination rate immediately after injection, while SOL slightly later. None of the GA hydrolysis products were detected in the tested samples. One possible mechanism of the detoxification of GAs may be oxidation and/or sequestration. They may be excreted by Malpighian tubules, with faeces or with cuticles during moulting. The results presented are significant because they facilitate the interpretation of studies related to the effects of toxic substances on insect metabolism.

NanoBioProtectors: Role of plant derived magnetic nanoparticles as a potent biocontrol agent against Fusarium oxysporum ciceris

In the current scenario, where demand for food production is constantly increasing with the rise in population, the threat of plant pathogens has also increased. The destruction of crops due to diseases caused by plant pathogens has become difficult to control with conventional physical and chemical methods. Traditional agriculture often depends on use of chemical pesticides, which have had negative impacts on both living organisms and ecosystems. As a fundamental principle of sustainable agriculture, it is important to limit the use of chemical pesticides in order to safeguard the environment and preserve diverse species. Additionally, sustainable agriculture should operate as a low input system, characterised by reduced production costs and increased net returns. Here, nanotechnology stands as a new weapon against rising challenges in agriculture. Nanotechnology may greatly improve the effectiveness of agricultural inputs, making it a valuable tool for promoting sustainable growth in agroecosystems via the use of nanoparticles. Using magnetic nanoparticles for controlling plant pathogenic fungi can be developed as a potent method for disease management in plants. In the present study, the effect of plant (Carica papaya) -based Fe3O4 magnetic nanoparticles was synthesized and studied against Fusarium oxysporum f.sp. ciceris, a chickpea pathogen. The antifungal effect of these nanoparticles and their minimum inhibitory concentration were studied using a soft agar assay and broth assay. Plant-synthesized nanoparticles were able to inhibit Fusarium oxysporum f.sp. ciceris by up to 87 %. It’s in vivo effect was checked with pot trials on chickpeas. Fe3O4 magnetic nanoparticles have shown adequate inhibition of fungus both in vitro and in vivo.

FTIR Characterization of Bioactive Functional Groups Present in Crude Extract of Mycoherbicides Produced from Consortium Culture of Rhizosphere Fungal Isolates

ABSTRACT Consortium culture can be a relatively cheap and environment-friendly technology for producing secondary metabolites like pesticides (herbicides). This study produced some metabolites from a consortium culture of fungal isolates obtained from the rhizospheres of Panicum maximum, Ipomoea involucrata and Amaranthus viridis. The isolates from rhizospheres of the above-named plants were co-cultured using Czapek broth and were incubated in an incubator shaker for 28 days. The co-culture combinations were: Aspergillus welwitschiae and Trichoderma hamatum (consortium 1), Aspergillus welwitschiae and Aspergillus aculeatus (consortium 2), and Aspergillus aculeatus and Trichoderma hamatum (consortium 3). Crude extracts from each consortium were characterized using Fourier Transform Infrared Spectroscopy (FTIR). The FTIR results showed that consortium 1 had peak spectra range from 418.57 cm−1 (S–S stretch of aryl disulfides) to 3462.34 cm−1 (alcohol, aliphatic primary amine), consortium 2 had peak spectra range from 420.5 cm−1 (halo compound) to 3456.65 cm−1 (alcohol, aliphatic primary amine) and consortium 3 had peak spectra from 457.14 cm−1 (halo compound) to 3448.84 cm−1 (alcohol, aliphatic primary amine). Some of the compounds produced by the consortia were pesticidal in nature and are hence, considered a potential technology in developing organic pesticides.

Climate-Smart Agriculture as an Adaptation Measure to Climate Change in Togo: Determinants of Choices and Its Impact on Rural Households’ Food Security

Climate-smart agriculture is one of the most important actions for agricultural climate change adaptation, especially in Togo, a sub-Saharan African country with a fragile ecology and where agriculture is profoundly impacted by climate change. Using a multinomial endogenous switching regression (MESR) and a multinomial endogenous treatment effect (METE) approach, we conducted empirical research to identify the factors influencing the adoption decisions of climate-smart agricultural practices (CSAPs) and their impact on household food security among smallholder farmers in Togo. The findings of this study revealed that the adoption of CSAPs by farmers is influenced by a range of factors, such as age, marital status, the household head’s gender, engagement in off-farm activities, level of education, farm size, agroecological zone, regional location, land ownership, distance between homestead and farm, access to credit, the presence of agricultural associations and cooperatives, and access to extension agents. On the one hand, the MESR analysis demonstrated a positive correlation between the number of adopted CSAPs and households’ food consumption score. Similarly, greater adoption of CSAPs resulted in a significant reduction in the food insecurity experience scale. On the other hand, the METE model portrayed an increase in acceptable food consumption when households adopted up to three CSAPs. Likewise, it significantly alleviated severe food insecurity. Further results based on the propensity score matching technique showed that the adoption of a crop rotation system, utilization of improved varieties of seeds, plant protection products, inorganic fertilizer, organic fertilizer, and irrigation improved adopters’ food consumption scores while reducing their level of food insecurity.

Morphological characteristics and density of Bracon (Habrobracon) concolorans Marshall,1900 (Hymenoptera: Braconidae), a native Turkish parasitoid of Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae), on greenhouse-grown tomatoes in Antalya, Türkiye

Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae) is one of the most significant pests of tomato. Chemical pesticides are prioritized in pest control, and this poses risks to both the environment and human health. Although commercial biological agents are occasionally?increasingly? used for control, understanding the density of existing parasitoids and predators of the pest is crucial for the effectiveness of integrated pest management. In this study, the parasitism rate of the native parasitoid Bracon (Habrobracon) concolorans Marshall, 1900 (Hymenoptera:Braconidae) collected from T. absoluta infesting tomato plants Antalya was investigated. Tomato leaf samples were collected weekly from a greenhouse in Elmalı/Antalya in October-November 2019, and cultured. The samples were monitored daily to record the number of pests and parasitoids that reached the adult stage. According to the results, 2004 T. absoluta and 478 B. (H.) concolorans adults were obtained from 221 infedted leaves. The number of parasitoids reaching the adult stage ranged from 1.7 adults to 2.6 adults per leaf. The study also included determinationss of the morphological characteristics of the Antalya population of the parasitoid. Accordingly, the average body length of the parasitoid was 2.13 mm in males and 2.37 mm in females. The average antenna length in males and females was 2.04 mm and 1.80 mm, respectively,and the number of antenna segments was 20-23 and 18-21, respectively.The average ovipositor length was 0.59 mm.

Exploring the Potential of Crotalaria juncea L. for Phytoremediation: Insights from Gas Exchange, Pigment Quantification, and Growth Measurements under Copper Stress

Soil contamination by trace elements is a worldwide concern that can result from several sources, such as mining, smelting, car traffic exhaust, agriculture plant protection products such as fungicides, and fertilizers. Among the metals involved, copper can cause alterations in the photosynthetic, respiratory, and enzymatic processes of plants, leading to reduced growth of roots and shoots. An alternative to dealing with metals present in the soil is phytoremediation, which consists of using plants to extract or stabilize these elements. The leguminous Crotalaria juncea is widely used as a green manure and may be advantageous due to its capacity for biological nitrogen fixation and biomass accumulation. This research aimed to evaluate the growth and physiological behaviour of C. juncea in copper-contaminated soil and its potential use as a phytoremediation plant. For the fresh and dry mass of shoots and roots, compared with 30 mg.dm−3 of Cu, there was a decrease in values with the increase in concentrations up to a dose of 480 mg.dm−3. The roots were less sensitive to increased Cu concentrations than the shoots. The tolerance index decreased as copper concentrations in the soil increased. From 60 mg.dm−3, its vegetative growth decreased, but C. Juncea was able to tolerate and accumulate copper in the root system, presenting high potential as a phytostabilizing species.

Towards sustainable biocontrol: inhibition of soil borne fungi by microalgae from harsh environments.

Using microorganisms as biocontrol agents against soilborne plant pathogens is a promising alternative to chemical pesticides. However, only some biocontrol agents have proven effective under field conditions. This study explores the potential of highly resilient microalgae isolated from harsh environments, such as Biological Soil Crusts and agricultural fields in semi-arid regions, as a novel and sustainable approach to biocontrol. Fifty-nine microalgal strains, including thirteen cyanobacteria and forty-six green algae, were isolated and identified. Dual-culture plate assays and toxicity tests of microalgal growth media were conducted to evaluate the antifungal activity of the isolates against eight representative soilborne pathogens. The results showed that many microalgae strains exhibited significant inhibitory effects on the growth of specific fungal pathogens, although the activity varied among different microalgal strains and pathogen species. Some strains even promoted the growth of certain fungi. The lack of a clear pattern in the antifungal activity highlights the complexity and specificity of the interactions between microalgae and soilborne pathogens. An "Inhibition Effectiveness" metric was developed to quantify biocontrol potential based on fungal growth inhibition. The green algal genus Desmodesmus, particularly Desmodesmus subspicatus isolates, showed higher antifungal efficacy than other genera. While the inhibitory mechanisms remain unclear, the results demonstrate the promising biocontrol capabilities of microalgae from extreme environments like BSCs. Further research could unlock novel opportunities for sustainable disease management by harnessing specific microalgal strains or synergistic strain combinations targeting soilborne pathogens.

Comparative evaluation of biological control programs and chemical pesticides for managing insect and mite pests in cucumber greenhouses: a sustainable approach for enhanced pest control and yield

BackgroundCucumber plants are susceptible to several economically damaging pests, including whiteflies, aphids, thrips and spider mites. This study aimed to evaluate the efficacy of two biological control programs, utilizing different releases of bio-agents, in comparison with chemical control method. The bio-agents used were the aphid parasitoid Aphelinus albipodus Hayat and Fatima (Hymenoptera: Aphelinidae), the green lacewing Chrysoperla carnea (Steph.) (Neuroptera: Chrysopidae) and the predatory mite Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae) in two release rates; low and high. Additionally, a chemical pesticides treatment was included for comparison in managing the pests in cucumber greenhouses during the winter seasons of 2022 and 2023, in Egypt. Abundances of whitefly, aphids, thrips and spider mites were recorded weekly throughout the study.ResultsThe aphid population in the greenhouse with high release rate (BIO 2) showed the highest reduction, with percentages of 84.55 and 89.88% in 2022 and 2023, respectively. Both greenhouse with low release rate (BIO 1) and BIO 2 exhibited significant reductions in the whitefly population, with proportions of 71.31 and 72.01% in 2022, and 82.05 and 85.94% in 2023, respectively. The thrips population also experienced notable reductions in both BIO 1 and BIO 2 greenhouses, with percentages of 72.08 and 75.71% in 2022, and 59.93 and 61.38% in 2023, respectively. However, the pesticide treatment demonstrated the lowest reduction in populations of aphids, whitefly and thrips in both seasons. Nevertheless, in all treatments in the two evaluated seasons, the high release rate of the predatory mite, P. persimilis (15 individuals/m2), proved to be highly effective in maintaining the mite populations below the economic threshold level. However, the population density of the two-spotted spider mite, Tetranychus urticae Koch. (Acari: Tetranychidae), increased in the pesticide-treated greenhouse, indicating the development of resistance to pesticides. Although the tested programs resulted in similar yields, the biological control approach offered the advantage of pesticide-free produce and reduced production costs.ConclusionFor pest management in cucumber growing in greenhouses during winter, it is recommended to use biological control agents at a low release rate at the early occurrence of pests. This approach can help minimize pest populations effectively.

Real-time precision spraying application for tobacco plants

This paper introduces a precision agriculture application aimed at mitigating the excessive utilization of agricultural chemicals, including pesticides and fungicides during crop spraying. The prevailing spraying techniques face two principle challenges: first, the indiscriminate dispensation of chemicals irrespective of plant size and requirements and second, the farmer's exposure to health hazards. To tackle these issues, a detection and segmentation model employing both YOLOv5 and YOLOv6 architectures is proposed and a comparative assessment of their accuracies within the same model category is conducted. The training dataset originates from a subset of the TobSet dataset, while the evaluation of the trained models is executed using publicly accessible aerial videos/images from available repository. The best detection accuracy achieved for the tobacco plant model size is observed with YOLOv6s and the YOLOv5-segmentation model, yielding accuracies of 95% and 94.8%, respectively. Additional performance metrics such as precision, recall, area under the PR-curve, inference time, and NMS per image are also compared between the two models. The YOLOv5-segmentation model excels by outperforming the YOLOv6s model in precision, recall score, and area under the PR-curve whereas slightly extended inference time and NMS per image duration are noted for the YOLOv5-segmentation model and the speed performance is comparable for the two models. Subsequently, the evaluation of these two models is conducted on the drone videos, which were recorded during drone traversal at a speed of 2 km/hr. The results demonstrate superiority of YOLOv5-segmentation model over the YOLOv6s model, with detection accuracies of 98.1% and 97.3%, respectively. These findings indicate the potential of integrating YOLOv5 segmentation models in precision spraying applications and contribute in improving the overall agricultural practices.