Effects Of Insecticides Research Articles

Bioinsecticidal potential of rose essential oil against the cowpea beetle, Callosobruchus maculatus (Fabricius) (Coleoptera: Chrysomelidae)

AbstractCallosobruchus maculatus (Fabricius), also known as the cowpea beetle or pulse beetle, is the most important pest of stored cowpea. The beetle causes both qualitative and quantitative losses in the grains, all of which result in low crop yields. The objective of this work was to investigate the insecticidal effect of rose essential oil (REO) on adult Callosobruchus maculatus in terms of mortality and oviposition. In addition, the viable mesophilic aerobic bacteria of C. maculatus were evaluated, and surface molecular electrostatic potential (MEP) maps were examined to determine the interaction domains of the bioactive components of REO. The interaction mechanism between the AChE enzyme (PDB ID: 6XXY, 4EY6, 4EY7 and 6O4W) and the REO components was investigated using the molecular docking method. The highest mortality of 92.40 ± 0.03% was obtained at 16 μL within 72 h of exposure. Higher concentrations of the essential oil decreased the laying performance of C. maculatus. A significant decrease of 91.33% in the number of eggs laid was observed. Gas chromatography–mass spectrometry (GC/MS) results showed that the major constituents of Rosa damascena Miller essential oil (REO) were citronellol (46.15%), geraniol (16.19%), nonadecane (8.80%) and nerol (7.43%). Treatments of 4, 8, 12 and 16 μL of REO significantly reduced the viable mesophilic aerobic bacteria of C. maculatus samples compared with the control. It was found that the most effective binding was between the REO components and the 4EY7 protein, with binding energies ranging from −6.9 to −8.9 kcal/mol. Although the major component of REO was citronellol (46.15%), the best interaction was observed with farnesol isomer B (0.80%). Overall, these results suggest that REO has the potential to control C. maculatus as an environmentally friendly alternative to synthetic pesticides.

Effects of Some Plant Powders on Immatures of Corcyra cephalonica (Stainton) (Lepidoptera: Pyralidae) on Stored Cocoa Beans

Rice moth, Corcyra cephalonica, an important insect pest of many stored food products has been reported as one of the most important pest of cocoa bean, which causes significant reduction in weight and quality of beans. High pesticides level in cocoa beans pose danger to human health and may hinder its acceptance in the global market due to regulations on Maximum Residue Limit (MRL). This study therefore, evaluated the insecticidal effects of the powders of Piper guineense, Aframomum melegueta, Eugenia aromatica and Rice husk on egg hatchability and larva mortality of C. cephalonica. Powder efficacies as insecticides were tested by applying varying rates (0.0, 0.1, 0.2, 0.3 and 0.4g) on petri dish lined with filter paper and the developmental stages (20 eggs and 10 larvae) of the insect were introduced in a Completely Randomized Design experiment. Egg hatchability was recorded at 24 h interval for 96 h. Larvae mortality was recorded at every 24 and 48 h of introduction. All powders completely inhibited egg hatchability at 0.3 and 0.4g rates. P. guineense and A. melegueta recorded 60% and 50% larva mortality at 48hour post treatment. Mean adult emergence was zero at higher rates in all treatments. Powders of P. guineense and A. melegueta were effective as contact bio-insecticide against C. cephalonica immature stages

Bioaccumulation mediated by water solubility leads to differences in the acute toxicity of organophosphorus insecticides to zebrafish (Danio rerio).

The use of some organophosphate insecticides is restricted or even banned in paddy fields due to their high toxicity to aquatic organisms. The aim of this study is to elucidate the main pathways and target organs of organophosphate insecticide toxicity to fish exposed via different routes by integrating histopathological and biochemical techniques. Using malathion as the model drug, when the dosage is 20-60 mg/L, the toxicity of whole body and head immersion drugs to zebrafish is much higher than that of trunk immersion drugs. A dose of 21.06-190.44 mg/kg of malathion feed was fed to adult zebrafish. Although the dosage was already high, no obvious toxicity was observed. Therefore, we believe that the drug mainly enters the fish body through the gills. When exposed to a drug solution of 20 mg/L and 60 mg/L, the fish showed significant neurological behavioral abnormalities, and the pathological damage to key organs and brain tissue was the most severe, showing obvious vacuolization and the highest residual amount (8.72-47.78 mg/L). The activity of acetylcholinesterase was the most inhibited (54.69-74.68%). Therefore, brain tissue is the key toxic target organ of malathion in fish. In addition, we compared the bioaccumulation effects of different water-soluble organophosphorus insecticides in fish and their toxic effects. We found that the higher the water solubility of organophosphorus insecticides, the lower their toxicity to fish.

Nasturtium leaf compounds, diphenyl disulfide and lyral, against Atta sexdens (Hymenoptera: Formicidae) and their symbiotic fungi.

Social insect pests, particularly leaf-cutting ants, present a considerable challenge in terms of control. Leaf-cutting ants are significant agricultural, forestry, and pasture pests, and understanding their behavior and defense mechanisms is essential for managing their colonies effectively. While toxic ant baits are a primary control method, the limited availability of effective insecticides and concerns over their hazardous nature has spurred the search for alternative solutions, particularly natural compounds, which aligns with the goals of forest certification groups. In the light of previous evidence demonstrating the efficacy of nasturtium leaves (Tropaeolum majus L. (Brassicales: Tropaeolaceae)) in suppressing leaf-cutting ant colonies, this study investigates 2 active components of nasturtium leaf extracts: diphenyl disulfide and lyral. We tested their impact on Atta sexdens (L.) (Hymenoptera: Formicidae), the most prevalent leaf-cutter ant species in Brazil, and their symbiotic fungus, Leucoagaricus gongylophorus (Möller) Singer (Agaricales: Agaricaceae). We conducted experiments with increasing concentrations of diphenyl disulfide and lyral, assessing their effects on the symbiotic fungus and on forager workers and gardeners of A. sexdens colonies. Our findings revealed no fungicidal activity, and ant mortality was minimal in both topical and ingestion bioassays with the exception of gardeners topically exposed to diphenyl sulfide. Furthermore, the compounds did not affect leaf ingestion, but diphenyl disulfide did increase interactions among foragers. These results suggest that neither diphenyl disulfide nor lyral are the primary contributors to the suppression of leaf-cutting ant colonies by nasturtium leaves. However, they may enhance the formicidal activity of other compounds present in nasturtium leaves.

Insecticidal Effect of Two Chemotypes of the Essential Oil of Eucalyptus camaldulensis Dehnh against Aphis fabae Scopoli

Background: The objective of this study was to study the insecticidal and repellent effect of the essential oil of the plant Eucalyptus camaldulensis Red Dehnh extracted by hydrodistillation method planted in the Ouargla region against the black aphid. Methods: The insecticidal effect of essential oils against aphid mortality by the introduction of bean leaflets in the different oily extracts with different concentrations and the count of dead individuals after 3, 6 and 24 h at the physiology laboratory in Ghardaïa University. Result: Through this study, the leaves treated with the major compounds of Eucalyptus camaldulensis essential oil such as Benzene,1-methyl-4-(1-methylethyl) at 35 per cent concentration after 24 hours, a 65 per cent aphid mortality was recorded which is more effective compared to Sabinene and essential oils of Eucalyptus camaldulensis at different concentrations (5; 35%; and 50 per cent). As for the repellent effect is 87 per cent after 6 hours for the pure essential oil of E. camaldulensis.

Insecticidal Properties and Chemical Characterization of Laurus nobilis L. Essential Oils from Two Regions of Morocco against Callosobruchus maculatus (Coleoptera: Bruchinae)

Morocco is a significant botanical reservoir that boasts a wealth of raw materials with promising applications across various industrial sectors, notably in pharmaceuticals and food. The objective of this study was to assess the effectiveness of essential oils (EOs) derived from Laurus nobilis L. leaves originating from the Tanger (EOT) and Meknes (EOM) regions in combating Callosobruchus maculatus infection. The chemical compositions of these oils were examined using Fourier transform infrared (FTIR) spectroscopy and gas chromatography–mass spectrometry (GC-MS). The biological activity of the EOs was evaluated via repulsion and fumigation tests against C. maculatus at varying concentrations. FTIR analysis revealed distinct vibrational bands indicative of various chemical compounds. GC-MS analysis was used to delineate the major chemical constituents of the EOs. The three predominant compounds in the EOT were 1,8-cineole (37.64%), linalool (16.40%), and adamantane (12.00%), whereas 1,8-cineole (47.84%), toluene (17.60%), and α-phellandrene (8.44%) were the most abundant in the EOM. Notably, the EOs exhibited significant repellent activity against C. maculatus, with repulsion percentages ranging from 51.11 to 90.00% in Tanger and 67.78 to 93.33% in Meknes. Mortality rates varied from 0 to 100% depending on the treatment. However, the mean concentrations showed mortality rates ranging from 29.44 to 65.56% for the EOT and from 21.11 to 67.78% for the EOM, with LD50 values of 11.96 μL/L and 5.22 μL/L. Docking studies revealed that 1,8-cineole had the highest binding affinity for the active site of acetylcholinesterase, thus confirming its toxic activity against C. maculatus. The findings of this study highlight the ability of EOs extracted from L. nobilis in the Moroccan regions of Tanger and Meknes to act as effective insecticides and repellents against C. maculatus, thereby highlighting avenues for further exploration of pest management and agricultural practices.

Heterologous expression of distinct insecticidal genes in potato cultivars encodes resistance against potato tuber moth, Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae)

AbstractThe potato tuber moth, Phthorimaea operculella (Zeller), is a notorious insect pest of potato incurring substantial yield losses in the field as well as in storage. Chemical control is difficult to exercise due to the latent feeding of the caterpillars and their ability to develop resistance against insecticides. One of the essential components of efficient insect-resistant management is using two or more different insecticidal genes in transgenic crops to effectively avoid and delay the resistance development in insect pests. Two constructs, namely DS-1 (cry3A + SN-19 genes) and DS-2 (OCII + SN-19 genes) in pCAMBIA1301 binary vector, were developed and were transformed in potato cultivars (Agria and Lady Olympia) via Agrobacterium-mediated transformation. The molecular analysis confirmed gene integration and expression of the introduced genes in transgenic plants. The insecticidal effects of incorporated genes in transgenic plants were assessed against 1st, 2nd, 3rd, and 4th instar potato tuber moth (PTM) larvae. The transgenic plants endured significantly high mortalities (100%) of larval stages of PTM within 72 h. Our results show that these transgenic potato plants have the potential to control populations of PTM and are also useful tools in managing PTM that would ultimately reduce the dependency on conventional chemical pesticides with potentially less or minimal hazards. These lines can also serve as an excellent source of germplasm for potato breeding program.

Insecticidal potential and risk assessment of diamide pesticides against Spodoptera frugiperda in maize crops

The effectiveness, tolerance, and safety of pesticides must be established before their scientific or rational. This study evaluates the field control efficacy of broflanilide, tetraniliprole, and chlorantraniliprole in combating Spodoptera frugiperda in maize crops, as well as the resistance of S. frugiperda to these three diamide pesticides after exposure. By assessing field control efficiency, toxicity, effects on development and reproduction, and detoxification enzyme activity of these diamide pesticides on S. frugiperda, highlights broflanilide's significant insecticidal potential. A highly sensitive and efficient method using QuEChERS/HPLCMS/MS was developed to simultaneously detect residues of these three pesticides on maize. Initial concentrations of broflanilide, tetraniliprole, and chlorantraniliprole ranged from 2.13 to 4.02 mg/kg, with their respective half-lives varying between 1.23 and 1.51 days. Following foliar application, by the time of harvest, the terminal residue concentrations of these pesticides were all under 0.01 mg/kg. Chronic dietary intake risk assessments and cumulative chronic dietary exposure for three pesticides indicated that the general population's terminal residue concentration was within acceptable limits. Not only does this research provide valuable insights into field control efficiency, insecticidal effects, resistance, residues, and risk assessment results of broflanilide, tetraniliprole, and chlorantraniliprole on maize, but additionally, it also paves the way for setting suitable Maximum Residue Limits (MRLs) values based on pre-harvest interval values, rational dosage, and application frequency.

Evaluating foliar insecticides and economic thresholds for Tychius picirostris (Coleoptera: Curculionidae) management in Oregon white clover seed production.

The clover seed weevil, Tychius picirostris Fabricius (Coleoptera: Curculionidae), is a major pest in Oregon white clover seed crops. Reliance on synthetic pyrethroid insecticides and limited availability of diverse modes of action (MoAs) has increased insecticide resistance selection in regional T. picirostris populations, emphasizing the need to evaluate novel chemistries and rotational strategies for effective insecticide resistance management (IRM). The efficacy of 8 foliar insecticide formulations for managing T. picirostris adult and larval life stages was determined in small and large-plot field trials across 2 crop years. In both years, bifenthrin (Brigade 2EC), the grower's standard, showed negligible adult and larval suppression. Insecticide formulations with isocycloseram and cyantraniliprole active ingredients reduced adult and larval populations when applied at BBCH 59-60 (prebloom) and BBCH 65-66 (full bloom) growth stages, respectively. While differences in T. picirostris abundance were observed among insecticide treatments, seed yield differences were not detected in large-plot trials. Larval abundance was correlated with reduced seed yield, and an economic threshold of ≥3 larvae per 30 inflorescences was determined as a conservative larval threshold to justify foliar applications of diamide insecticides. Additional commercial white clover seed fields were surveyed to compare larval scouting techniques, including a standard Berlese funnel and a grower's do-it-yourself funnel. Both larval extraction techniques were correlated and provided similar estimates of larval abundance. These findings demonstrate new MoAs, optimal insecticide application timing, and larval monitoring methods that can be incorporated into an effective T. picirostris IRM program in white clover seed crops.

Antibiotics suppress the expression of antimicrobial peptides and increase sensitivity of Cydia pomonella to granulosis virus

Cydia pomonella granulovirus (CpGV) is a highly specific and environmentally friendly pathogenic virus successfully used as a biological insecticide against codling moth larvae. Continuous application of CpGV has led to high levels of resistance in codling moth, Cydia pomonella (C. pomonella). Nevertheless, the specific molecular mechanisms underlying the development of resistance in codling moths to CpGV have been rarely investigated. This study explored the potential antiviral immune roles of codling moth antimicrobial peptides (AMPs) against CpGV. A total of 11 AMP genes classified in cecropin, defensin, gloverin, and attacin subfamilies, were identified in the codling moth genome. The cecropin and gloverin subfamilies were found to be the ancestral genes of the AMP gene family. The expression of two AMP genes (CmGlo1 and CmAtt1) significantly increased following CpGV challenge, and CmGlo1 and CmAtt1 gene silencing resulted in a significant increase in CpGV replication in codling moth larvae. The hemolymph and fat body serve as major viral immune functional tissues in codling moth larvae. Moreover, zhongshengmycin significantly reduced the diversity and abundance of codling moth larvae gut microbiota, thereby suppressing the expression of CmAtt1 AMP gene. We also found that the combination of the virus with zhongshengmycin would enhance the insecticidal effects of CpGV. This study provides the first explanation of the molecular mechanisms driving CpGV immune function development in codling moths, approached from the perspective of the codling moth itself. Additionally, we introduced an alternative approach to combat codling moth in the field by combining antibiotics with biopesticides to amplify the insecticidal effects of the latter.

Current prospects of green-metallic nanoparticles in mosquito control: A brief review.

Mosquitoes (Diptera: Culicidae) transmit many pathogens and parasites such as viruses, bacteria, protozoans and nematodes, which cause serious diseases such as malaria, dengue, yellow and Chikungunya fever, encephalitis or filariasis etc. Traditionally, control of these mosquitoes has relied on the use of several chemical insecticides. These insecticides have been used to control the various life stages of mosquitoes, but some of these insecticides are causing harm to the environment, human, plants and animals which in turn cause environmental pollution. Presently, NPs are thought to be used as an effective insecticide. Most of the NPs having insecticidal properties are prepared through green synthesis method, where extracts from plants, fungi, bacteria, and even dead insects have been efficaciously employed to decrease or to kill mosquito population. Biological and green synthesis method has resulted in the production of less toxic or nontoxic and sustainable NPs for further application in mosquito control. The evaluation of green chemistry or biological techniques for synthesizing metal NPs from plant extracts and other biological organisms has drawn the attention of many researchers. This review explores the usefulness of green synthesized various metal NPs on larvae, pupae and adults of mosquitoes.

Assessment of sublethal effects of permethrin on adult life characteristics and resistance dynamics in Aedes albopictus (Diptera: Culicidae)

Mosquitoes are regularly exposed to adverse effects of insecticides employed in field during vector control campaigns. Its primary goal is to eliminate the vector population; nevertheless, this practise typically ignores the residual impacts and long-term repercussions on the remaining population. Here, the current study analysed how sublethal exposure of insecticides alter the life qualities, genotypic and biochemical characteristics of mosquitoes. The resistance ratio value in Laboratory Resistant (Lab-R) larvae increased 10 times (0.010 mg/l to 0.108 mg/l) compared to Laboratory Susceptible (LabS) larvae. It also revealed that the surviving mosquitoes had 50% reduction in hatchability but had longer larval and pupal periods (15 days and 2 days), respectively. The survival rates decrease in female by 2 days but increase in male by 7 days which is of concern and necessitates additional study. Moreover, major role of monooxygenase was confirmed behind resistance development which was further supported by piperonyl butoxide assay where reduction in Tolerance Ratio (TR50) by 12-fold occurred and gene expression profile also showed high expression level of CYP6P12 gene. In resistant strain, cuticular thickness increased by 1.23 times and alteration at codon 1532 (ATC to TTC) on VGSC gene leads to mutation I1532F. The data gleaned from our work highlights the threat of sublethal insecticides on vector control techniques and offers ample evidence that the larval selection alters adult life qualities, metabolic properties and transgenerational features which contributes to the damage caused by resistance.

Insecticidal Activity of Some Major Essential Oil Components against Metopolophium dirhodum and Its Predators.

Essential oils (EOs) are plant metabolites with important insecticidal effects. Nevertheless, information on the efficacy of the major substances on aphids and their natural enemies is still missing. The objective of this paper is, therefore, to identify the efficacy of selected EO majority substances-β-citronellol, carvacrol, isoeugenol, and linalool, including their binary mixtures-on the mortality and fertility of the aphid Metopolophium dirhodum, an important cereal pest. The best efficacy was proven for the binary mixture of β-citronellol and linalool (1:1 ratio), for which the estimated LC50(90) is 0.56(1.58) mL L-1. This binary mixture applied in sublethal concentrations significantly reduced aphid fertility. It was found that the phenomenon can be attributed to β-citronellol, as the females treated with LC30 laid 45.9% fewer nymphs, on average, compared to the control. Although β-citronellol and linalool, including their 1:1 mixture, showed very good efficacy on aphid mortality, they were, on the other hand, very friendly to the larvae of Aphidoletes aphidimyza and Chrysoperla carnea, which are important aphid predators. Based on our results, the newly discovered synergically acting binary mixture β-citronellol/linalool can be recommended as an efficient substance suitable for the further development of botanical insecticides used against aphids.

Insecticidal, physiological, and biochemical effects of Schinus molle essential oil on the adults of Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae)

Rhyzopertha dominica (F.) is considered as a major stored product pest. Conventional insecticides induce adverse effects on the environment. Plant derivative products constitute a promising alternative for pest control. The purpose of our research was to identify the chemical profile of essential oil (EO) extracted from Schinus molle L. (Anacardiaceae) and to evaluate the fumigant and the contact toxicity, and the repellent activity of this oil on adults of Rhyzopertha dominica F. (Coleoptera), a major pest in products that are stored around the world. The effects of this oil were examined on biochemical profile (energy reserves and Proteins), selective biomarkers like acetylcholinesterase (AChE), glutathione S-transferases (GST) and glutathione (GSH), and nucleic acids (DNA and RNA). Digestive enzymes were also investigated. The major chemical compounds identified by the GC-MS were α-phellandrene (16.613%), ß-phellandrene (12.104%), elemol (9.028%) and β-eudesmol (5.872%). Then, we evaluated the repellent activity, and also the effects in nutritional reserves and some biomarkers. This EO exhibited an insecticidal and repellent activity as a function of the exposure time and concentrations. Contact (LC50 at 24 h: 19.99 μL/mL) is the most effective mode of application compared to fumigation (LC50 at 24h: 174.30 μL/L air). S. molle EO was also investigated in digestive enzymes’ activities (α-amylase, lipase, chitinase and protease). Our results revealed a decrease in both α-amylase, lipase, protease and chitinase activities in treated adults compared to controls. In addition, we noticed a neurotoxic activity of S. molle EO traduced by a decrease of AChE. An induction of the detoxification system was observed via a decrease in GSH rate and an increase in GST activity. Moreover, the treatment induces an alteration of biochemical profile of R. dominica adults. Lastly, essential oil was examined on nucleic acids. Results showed an increase in DNA and RNA amount in treated adults when compared with control. Due to their effective source of bioactive compounds, the EO from the studied plant could be used as an alternative strategy for the management of stored product pests.

Combined effects of herbicides and insecticides reduce biomass of sensitive aquatic invertebrates

The structure and biomass of aquatic invertebrate communities play a crucial role in the matter dynamics of streams. However, biomass is rarely quantified in ecological assessments of streams, and little is known about the environmental and anthropogenic factors that influence it. In this study, we aimed to identify environmental factors that are associated with invertebrate structure and biomass through a monitoring of 25 streams across Germany. We identified invertebrates, assigned them to taxonomic and trait-based groups, and quantified biomass using image-based analysis. We found that insecticide pressure generally reduced the abundance of insecticide-vulnerable populations (R2 = 0.43 applying SPEARpesticides indicator), but not invertebrate biomass. In contrast, herbicide pressure reduced the biomass of several biomass aggregations. Especially, insecticide-sensitive populations, that were directly (algae feeder, R2 = 0.39) or indirectly (predators, R2 = 0.29) dependent on algae, were affected. This indicated a combined effect of possible food shortage due to herbicides and direct insecticide pressure. Specifically, all streams with increased herbicide pressure showed a reduced overall biomass share of Trichoptera from 43 % to 3 % and those of Ephemeroptera from 20 % to 3 % compared to streams grouped by low herbicide pressure. In contrast, insecticide-insensitive Gastropoda increased from 10 % to 45 %, and non-vulnerable leaf-shredding Crustacea increased from 10 % to 22 %. In summary, our results indicate that at the community level, the direct effects of insecticides and the indirect, food-mediated effects of herbicides exert a combined effect on the biomass of sensitive insect groups, thus disrupting food chains at ecosystem level.

Comparative effect of biopesticides against the fall armyworm Spodoptera frugiperda (J.E. Smith)

Summary The current study evaluated the effect of microbial-derived insecticides (abamectin and spinosad), two microbials (Beauveria bassiana (Balsamo) Vuillemin, Bacillus thuringiensis Berliner), and three chitin synthesis inhibitors (CSIs) (chlorfluazuron, hexaflumuron and lufenuron) against Spodoptera frugiperda larvae. Spinosad and abamectin caused pronounced mortality against second larval instar of S. frugiperda using the leaf dipping method. Spinosad induced higher toxicity (LC50 = 4.01 mg/L) than abamectin (LC50 = 8.33 mg/L) one day after treatment. The treatments with B. bassiana and B. thuringiensis caused higher mortality of S. frugiperda larvae 7 days after treatment with LC50 values of 3.0 × 105 spores/ml and 8.2 × 106 cells/ml, respectively. In the case of the CSIs, hexaflumuron showed higher toxicity than chlorfluazuron and lufenuron with LC50 values of 0.01, 0.009 and 0.005 mg/L 3, 7 and 10 days after treatment, respectively.

Gelatin Nanoparticles can Improve Pesticide Delivery Performance to Plants.

Nanomaterials associated with plant growth and crop cultivation revolutionize traditional concepts of agriculture. However, the poor reiterability of these materials in agricultural applications necessitates the development of environmentally-friendly approaches. To address this, biocompatiblegelatin nanoparticles (GNPs) as nanofertilizers with a small size (≈150nm) and a positively charged surface (≈30mV) that serve as a versatile tool in agricultural practices is designed. GNPs load agrochemical agents to improve maintenance and delivery. The biocompatible nature and small size of GNPs ensure unrestricted nutrient absorption on root surfaces. Furthermore, when combined with pesticides, GNPs demonstrate remarkable enhancements in insecticidal (≈15%) and weed-killing effects (≈20%) while preserving the efficacy of the pesticide. That GNPs have great potential for use in sustainable agriculture, particularly in inducing plant growth, specifically plant root growth, without fertilization and in enhancing the functions of agrochemical agents is proposed. It is suggested conceptual applications of GNPs in real-world agricultural practices.

Insecticidal effects of some plant extracts against Khapra beetle [Trogoderma granarium Everts (Coleoptera: Dermestidae)

The study aims to determine the toxicity of extracts in three different solvents (methanol, hot water, and cold water) obtained from 10 different plants [Rosmarinus officinalis L. (Lamiaceae), Nigella sativa L. (Ranunculaceae), Laurus nobilis L. (Lauraceae), Anethum graveolens L. (Apiaceae), Origanum onites L. (Lamiaceae), Lavandula angustifolia Mill. (Lamiaceae), Foeniculum vulgare Mill. (Apiaceae), Hypericum perforatum L. (Clusiaceae), Mentha piperita L. (Lamiaceae), and Nicotiana tabacum L. (Solanaceae)] against the larvae of the third instar of Trogoderma granarium Everts (Coleoptera: Dermestidae) collected from different provinces of Türkiye. The results of the study varied depending on the plant species and the solvent used. Based on the observations, methanol was found to be the most effective solvent, followed by hot water and then cold water. On the 14th day of application, the highest mortality rate of 100% was observed when methanol was used as a solvent at a concentration of 20% (w/v) of the plant extracts. In contrast, this rate was 44% when cold water was used and 56% when hot water was used. According to the research results, extracts of A. graveolens, N. tabacum, and N. sativa showed a highly toxic effect on the pest, suggesting that these extracts are promising for the control of storage pests. However, more extensive studies are still needed to confirm the applicability and feasibility of these applications on an industrial scale.

THE INFLUENCE OF MULTICOMPONENT WINTER WHEAT SEED PROTECTANTS ON ITS PRODUCTIVITY AND QUALITY

We studied combined suspension compositions prepared by liquid-phase mechanical treatment based on the fungicides difenoconazole, tebuconazole, imazalil, fludioxanil, thiabendazole, prochloraz, sedoxan and the insecticides thiamethoxam, imidacloprid, plant growth regulators Enershanse, which showed a wide range of biological activity in field conditions. It was established that the main indicators of the quality of the final product - the nature of the grain, the amount of protein and gluten, glassiness, and the quality of gluten - depended on the fungicidal and insecticidal effects on the phytosanitary condition of winter wheat crops. All studied drugs had a protective effect. They contributed to the disinfection of winter wheat seeds from seed and soil pathology and harmful insects of the early period of plant development. It was found that for effective treatment of winter wheat seeds, it is best to use insectofungicidal preparations containing several components of different chemical classes. It was found that pre-sowing treatment of winter wheat seeds with a suspension composition of thiamethoxam + sedaxan + fludioxonil + tebuconazole in the form of Vibranse Integral, suspension concentrate provided the greatest increase in grain yield by 0.49 t/ha (7.3%) with a control yield of 6.74 t/ha. The use of this drug ensures a particularly high protein content in the grain (16.07%) and gluten (36.8%) of the first quality group. We have established diverse positive effects of the drug Vibranse Integral, manifested in enhancing the growth processes of the root system due to the presence of the sedaxane molecule, the purpose of which is aimed at the formation of a healthy and well-developed root system, increasing the stress resistance of plants to abiotic factors, and the manifestation of a good protective effect in relation to soil and seed infections. We determined the lowest, relative to other studied drugs, yield (6.17 t/ha) from the use of a suspension composition of thiamethoxam (262.5 g/l) + difenoconazole (25 g/l) + fludioxonil (25 g/l (Celest Top), but the grain was of high quality. All other seed protectants occupied an intermediate position between the above-mentioned drugs.

TOXICITY OF SOME INSECTICIDES AND THEIR SUBLETHAL EFFECTS ON NUTRITIONAL INDICES OF FALL ARMYWORM IN SWEET CORN PLANT

Corn is a vital cereal crop in Bangladesh, significantly contributing to food security and economy. However, the fall armyworm Spodoptera frugiperda, poses a severe threat to corn cultivation. This study evaluates the toxicity of four insecticides and their effect on the nutritional indices of fall armyworm. Experiment was conducted from November 2022 to April 2023 with sweet corn variety BU Misty Vutta 1 at Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur, Bangladesh. In this research four insecticides: Winmax 40 WDG, Ripcord 10 EC, Marshal 20 EC, and Shobicron 425 EC, were tested on fall armyworm larvae at multiple concentrations. The mortality of fall armyworm larvae was observed at 24, 48, 72, and 96 hours after treatment. Results indicated significant differences in larval mortality across treatments, with Shobicron 425 EC showing the highest mortality rate (100% at 72 hours after treatment), while Winmax 40 WDG showed the lowest. The median lethal concentration (LC50) and lethal concentration for 95% mortality (LC95) values supported the findings, with Shobicron 425 EC demonstrating superior efficacy. Additionally, Shobicron 425 EC resulted in the lowest food consumption (0.1), consumption index (0.2), Approximate digestibility (19.5%), Efficiency of conversion of ingested food (3.9%) and Efficiency of conversion of digested food (1.1%). The study concludes that Shobicron 425 EC is the most effective insecticide for controlling fall armyworm in sweet corn, suggesting its potential for integrated pest management strategies.