Synthetic Chemical Insecticides Research Articles

Evaluation of selected biorational and synthetic chemical insecticides for controlling Phenacoccus solenopsis (Hemiptera: Pseudococcidae) under field conditions

Evaluation of selected biorational and synthetic chemical insecticides for controlling Phenacoccus solenopsis (Hemiptera: Pseudococcidae) under field conditions

The Susceptibility of Malaysian Rice Brands To Sitophilus oryzae and The Potential Application of Zinc Oxide Nanoparticles For Control Purposes

The rice weevil, Sitophilus oryzae, is an insect pest that can pose severe harm to stored grains. Rice weevils, both adults and larvae, cause significant economic losses because they can infest a wide range of plants and stored goods. Nanoparticle insecticides are created and studied to replace the overly-used synthetic chemical insecticides. The purpose of this study is to investigate the susceptibility of several commercialized rice brands towards S. oryzae infestation and to assess the toxicity of different types of zinc oxide (ZnO) against S. oryzae. The study involved twelve rice brands, and S. oryzae infestation rates were observed in the laboratory for 17 weeks. The infestation rates were obtained at the end of the observation period. To obtain the required dosages of 0.1, 0.2, 0.4, and 0.8% (w/w), four different concentrations of each type of ZnO nanoparticle that had undergone various reactivity modifications were mixed with rice for bioassays test. S. oryzae has been proven to be susceptible to almost all commercialized rice brands studied in this research. Based on the data, it can be concluded that the ZnO nanoparticle modified with gamma-ray is the most effective at controlling S. oryzae, as 100% mortality was seen after three days of treatment at concentrations between 0.4 to 0.08% (w/w). The slow emergence of pests in monitored rice brands is attributed to the protectants and their residue, which work by eradicating eggs and adults that have consumed the grain. Zinc oxide type 7A is the most toxic towards S. oryzae because of its exposure to gamma-ray which has the highest energy compared to neutron and beta rays. This results in the release of more active molecules to act on the pest.

Insecticidal activity of Aguaria salicifolia leaf extracts on cowpea bruchid Callosobruchus maculatus (Coleoptera: Chrysomelidae)

The protection of foodstuffs against insect pests constitutes a serious problem across the world. Synthetic chemical insecticides are the most widely used method for grain protection. Unfortunately, the harmful effects of these insecticides on human health and environment have increased the interest of researchers for botanical insecticides which are recognized as eco-friendly products. Therefore, the efficacy of Aguaria salicifolia Hook. f. ex Oliv. leaf extracts was tested against Callosobruchus maculatus F. on cowpea grain, at the dosage of 2, 4, 8 and 16 g/kg. To estimate the biological activity of leaf powder and aqueous extract, adult mortality, insect population growth reduction, grain damage and weight loss reduction tests were carried out. The repellency effect of A. salicifolia was assessed using the aqueous, methanolic and ethyl acetate extracts. The mortality was recorded at 1, 3, 5 and 6 days post-exposure. All treatments were submitted to four replications, and the experiment was carried out in a completely randomised design in the fluctuating laboratory conditions (Temp. = 23.71 ± 1.03 °C; RH. = 81.38 ± 2.03 %). Overall, all the extracts significantly exhibited insecticidal activities against cowpea bruchids. The highest dosage induced the highest mortality rates; 79.26 % and 84.08 % with aqueous extract and leaf powder, respectively. The different plant extracts considerably reduced insect population, grain damage and weight loss. The complete reduction of C. maculatus population was achieved by aqueous extract of A. salicifolia. The different solvent extracts had repellent property with repellency percentage values ranging from 30 % to 73.75 %. Considering these results, insecticidal products derived from A. salicifolia could constitute an alternative to the chemical synthetic insecticides used against C. maculatus. However, further studies are needed to be carried out concerning the mammalian toxicity and evaluation of suitable formulations of the extracts under field conditions before their promotion for grain protection.

The use of combination plant growth promoting rhizobacteria to control chili leaf curl disease in the field

Plant growth-promoting rhizobacteria (PGPR) is a promising technology for controlling viral diseases, including pepper yellow leaf curl disease (PYLCD) of chili pepper caused by Begomovirus infection. The objectives of this research were to investigate the effectiveness of PGPR containing Pseudomonas fluorescens PF1 and Bacillus polymyxa BG25, as well as their combination with other protective agents, to control PYLCD under field conditions in an endemic region. The treatments consisted of a single application of PGPR (a mixture of P. fluorescens PF1 and B. polymyxa BG25), guano tea, endophytic fungus H5, and neem oil; combination of PGPR with guano tea, endophytic fungus H5, and neem oil; conventional pesticide that relies on synthetic chemical insecticide sprayed weekly; and untreated plots. The experiment was arranged in a randomized block design with four replications. Treatment with PGPR alone was able to delay disease onset by 2.25 weeks, but it caused only a slight reduction in disease incidence. The combination of PGPR + guano tea and PGPR + endophyte H5 provided the best results in controlling PYLCD. The combination of PGPR + guano tea and PGPR + endophyte H5 delayed disease onset by 2.75 weeks and 3.25 weeks, respectively, and reduced disease incidence with effectiveness rates of 52.72% and 52.08%, respectively. These two treatment combinations gave the best performance for plant growth and yield.

First report of Telenomus remus Nixon (Hymenoptera: Scelionidae) on Spodoptera frugiperda Smith (Lepidoptera: Noctuidae) in Egypt

BackgroundThe polyphagous alien invasive pest, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), invaded Africa and has so far spread across the continent, causing devastating impacts on maize production. In Egypt, the management of the pest by maize growers has been characterized by the application of broad-spectrum synthetic chemical insecticides, a strategy which is associated with various detrimental effects on the environment and human health. To mitigate the overreliance and excessive use of those synthetic chemicals, biological control using egg parasitoids species provides an ecologically friendly and sustainable management strategy. In that regard, this study had the objective of identifying the natural existing egg parasitoids, which could be effectively used in augmentative biocontrol of the pest in Egypt.ResultsFor the first time in Egypt, natural occurrence and parasitism of Telenomus remus Nixon, 1937 (Hymenoptera: Scelionidae) on S. frugiperda egg masses was recorded. Infested maize farms in Qena Governorate, Egypt, were surveyed, and S. frugiperda egg masses were collected and incubated in the laboratory. Emerging parasitoids’ wasps were grouped based on their morphological similarities. Natural parasitism of the egg parasitoids (Telenomus sp.) was computed from the parasitized field collected egg masses. In addition, to confirm the laboratory parasitism and suitability of the parasitoid, Telenomus sp. to develop on S. frugiperda, the parasitoid was reared on S. frugiperda egg masses for three generations under laboratory conditions. Moreover, both morphological and molecular identifications were conducted. The recovered parasitoid samples from the field S. frugiperda egg masses were Telenomus remus (Nixon) (Hymenoptera: Scelionidae). Moreover, the average field parasitism level by T. remus on S. frugiperda was 15.9%, while under laboratory conditions, the parasitism was 63.5%.ConclusionsThe natural occurrence of T. remus in Egypt and its association with S. frugiperda is an important finding upon which augmentative biocontrol strategy can be leveraged on to sustainably manage the pest populations.

Mentha spp. essential oils: toxicity to Alphitobius diaperinus, activity against poultry pathogenic bacteria, and Beauveria bassiana compatibility.

The botanical insecticide market is growing because of limitations placed on the use of certain synthetic chemical insecticides. In this sense, the lesser mealworm Alphitobius diaperius (Coleoptera: Tenebrionidae) is the main poultry pest. The insect causes weight loss and damage to the digestive system of poultry, and it is a vector and reservoir of pathogens. Consequently, this study explored the following hypotheses: (i) essential oils (EOs) derived from Mentha spp. are toxic to A. diaperius; (ii) these EOs are compatible with Beauveria bassiana, the natural enemy of the poultry pest, that parasite A. diaperinus; (iii) these EOs also exhibit activity against bacteria that are pathogenic to poultry. In topical applications and ingestion tests, EOs from Mentha arvensis, Mentha spicata, and Mentha piperita were toxic to A. diaperinus. Chromatographic analyses revealed that menthol is the predominant compound in M. arvensis and M. piperita, whereas carvone is the major compound in M. spicata. Both (-)- and (+)-menthol, along with (-)- and (+)-carvone, underwent testing with A. diaperinus. Nevertheless, their activity was not as potent as those of the EOs, suggesting a possible synergistic and/or additive effect. The EOs did not have any adverse effects on the conidial germination, vegetative growth, or conidia production per colony of the entomopathogenic fungus B. bassiana. Consequently, these EOs are compatible with this natural enemy. The EO extracted from M. spicata exhibited significant toxicity against Staphylococcus aureus (ATCC 25923), whereas the remaining EOs displayed moderate toxicity against this bacterium. The EOs derived from Mentha spp., as assessed in this study, hold promise for the development of botanical insecticides tailored for the control of A. diaperinus. These insecticides are selective in favor of the natural enemy B. bassiana and can also serve as effective sanitizers, thanks to their antibacterial properties.

Biological control potential of two Beauveria bassiana isolates against the stink bugs Nezara viridula L. and Piezodorus guildinii Westwood (Hemiptera: Pentatomidae) in common bean

BackgroundThe stink bugs, Nezara viridula L. and Piezodorus guildinii Westwood (Hemiptera: Pentatomidae) are the most important and widespread species of polyphagous stink bugs in the tropical and subtropical regions of Latin America, which affect the quality and yield of the common bean (Phaseolus vulgaris L.). The use of synthetic chemical insecticides is the major control strategy to manage stink bugs in common beans and alternatives are needed. In this study, mortality and median Lethal Time (LT50) of two Cuban isolates of the entomopathogenic fungus Beauveria bassiana (18 S-O-R and 96 P-O-E), as well as one commercial Cuban isolate (Bb-18), at a concentration of 1 × 108 conidia/ml were evaluated. These evaluations were conducted against both stink bug species using Petri dish bioassays and a semi-field experiment in common beans.ResultsIn Petri dish bioassays, the isolates 18 S-O-R and 96 P-O-E caused 100% mortality of both N. viridula and P. guildinii. This was significantly higher than for isolate Bb-18, which caused 86.3% N. viridula and 81.3% P. guildinii mortality. In the semi-field experiment, when pooling both stink bug species, total mortality after 14 days was 91.3% for 18 S-O-R, 80.0% for 96 P-O-E and 73.8% for Bb-18 isolates. LT50 value for isolate 18 S-O-R tested under laboratory conditions was 6.04 ± 0.18 days for N. viridula and 5.32 ± 0.14 days for P. guildinii at the same concentration of 1 × 108 conidia/ml. LT50 value for isolate 18 S-O-R in semi field was 6.79 ± 0.37 days for N. viridula and 7.71 ± 0.32 days for P. guildinii at 1 × 108 conidia/ml.ConclusionThe study highlights the potential of B. bassiana 18 S-O-R as a promising candidate for control of stink bugs in common bean under tropical conditions as an alternative to conventional chemical insecticides in integrated pest management (IPM) programs. Moving forward, further research should focus on validating the efficacy under diverse field conditions and integrating application methods into practical IPM approaches. Future use of B. bassiana will enhance sustainability and reduce environmental impacts associated with pesticide use.

The Essential Oils Compounds of Lippia multiflora Moldenke and Cymbopogon schoenanthus (L.) Spreng Repel and Affect the Survival of the Maize Pest Spodoptera frugiperda (Lepidoptera: Noctuidae) Larvae

Plant-derived insecticides, such as essential oils, can be an effective alternative to replace synthetic chemical insecticides against Spodoptera frugiperda, which becomes increasingly resistant to synthetic products. This study aims to evaluate essential oils (EOs) effects on larval growth and development following feeding inhibition, growth regulation, and repellency of EOs of Lippia multiflora (Verbenaceae), Cymbopogon schoenanthus (Poaceae), and their combination. Topical application of EOs was used on S. frugiperda larvae for larvicidal effect or treating filter paper with the EOs to find repellency. The effect of EOs on food intake and larval growth was also evaluated. Several types of compounds have been identified in the EOs, mainly monoterpenes with the appearance of new compounds in the 1 : 1 combination. Bioassay results show that individuals and combinations of EOs significantly influenced S. frugiperda larval development. L. multiflora caused 100% mortality of L2 larvae within 24 hours at 3%. The Lm + Cs (1 : 1) EOs combination was the most effective with LC50 and LC90 of 1.02% and 1.92%, respectively. Lm + Cs (1/4 : 3/4) EOs caused the highest inhibition of food consumption, 0.0160 g consumed after food was treated with 2.2% concentration compared to food consumption of 0.0602 g for the control group at 24 hours. Lower food consumption caused the inhibition of larval growth and weight loss of 0.0005 g/day at the 2.2% EOs concentration. The highest repellency effect of the EOs was found in EOs of L. multiflora, exhibiting a repulsion of 83.33% of the larvae after 3 hours of exposure. This diversity in the biological actions of the EOs tested on S. frugiperda represents valuable options for contributing to integrated pest management and an alternative to synthetic chemical insecticides.

Efficacy and Persistence of Entomopathogenic Fungi against Rhynchophorus ferrugineus on Date Palm: Host to Host Transmission

The red palm weevil (RPW), Rhynchophorus ferrugineus (Olivier) (Coleoptera: Dryophthoridae), is a destructive and voracious pest of palm species worldwide. Due to environmental and regulatory concerns, ecologically safe alternatives to synthetic chemical insecticides are needed to manage this cryptic insect species. Entomopathogenic fungi have the potential to manage this pest. The scope of management and effectiveness can be improved by direct control or horizontal transmission of entomopathogenic fungal isolates. We tested in the laboratory the virulence and pathogenicity of fifteen different entomopathogenic fungal isolates belonging to the following species: Beauveria bassiana, Metarhizium anisopliae, Beauveria brongniartii and Purpureocillium lilacinum. All fungal isolates were found virulent against larvae (14.9 ± 1.06 to 81.5 ± 1.48% mortality) and adults (5.6 ± 1.12 to 51.7 ± 1.51% mortality) at 12 d post-treatment. From a screening bioassay, five M. anisopliae (WG-08, WG-09) and B. bassiana (WG-23, WG-24, WG-25) isolates were tested for their concentration response mortality against larvae and adults after 7, 14 and 21 days (d) of treatment. Mortality was found positively correlated with concentration and time. At 21 d of treatment, WG-23 and WG-25 1 × 108 conidia/mL resulted in 100% mortality against larvae while only WG-25 1 × 109 conidia/mL caused 100% mortality of adults. Along with mortality, all the potential isolates have strong ovicidal effects that reduced 81.49% at 1 × 108 conidia/mL. The horizontal transmission bioassay indicated that the infected adults transmitted the disease to healthy individuals. Horizontal transmission of fungi from infected to non-infected adults not only caused significant mortality but also had a serious sublethal impact on insect development and fitness including reduced number of eggs/d fecundity, egg viability and neonate survival. Isolate WG-25 reduced oviposition (0.5 eggs/d), fecundity (11.7 eggs/female), egg viability (11.6%) along with larval survival 25.9% when infected male mated with normal female. In semi-field trials, all fungal isolates reduced survival of larvae found inside the palms and ultimately reduced infestations over a period of two months. The results of this study indicate that entomopathogenic fungi should be further tested for sustainable and efficient control of RPW in date palm production systems.

A review of entomopathogenic fungi as a potential tool for mosquito vector control: A cost‐effective and environmentally friendly approach

AbstractMosquitoes around the world spread diseases like malaria, dengue, zika, lymphatic filariasis and arboviruses, which are dangerous to human health and the economy. Eventually, mosquitoes develop resistance to synthetic chemical insecticides and, moreover, these insecticides have adverse environmental impacts, accumulating in soils and in the food chain. So, researchers are searching for better vector control tools from biological sources such as plants, bacteria, fungi, viruses and other predators. Eco‐friendly methods that use entomopathogenic fungi to reduce vector‐borne disease burdens are becoming more popular because they are selective and safe for the environment. Based on existing literature, several microbial agents show potential for the biocontrol of mosquitoes. With advances in genetic recombination and transformation techniques, in the ongoing battle against insecticide‐resistant mosquitoes, genetically engineered fungal biopesticides represent a cutting‐edge solution. These biopesticides are the result of novel genetic changes that improve the ability of fungi to target and kill mosquitoes. These fungi can effectively combat mosquito populations by introducing genes that produce insecticidal proteins or toxins. This method has several advantages, including a lower environmental impact, because the fungi are highly specific to mosquitoes and are harmless to non‐target organisms. It also helps to reduce the problem of insecticide resistance because the fungi have a unique mode of action. These biopesticides hold great promise for reducing mosquito‐borne diseases while minimizing environmental damage and combating resistance. This review article discusses various entomopathogenic fungal pathogens that can act as biocontrol agents and their mode of action against mosquitoes. We discus recent advances in entomopathogenic fungi‐secreted effector molecules for suppressing host immunity and progress in the development of transgenic mosquito‐killing fungi.

Application of Two Ocimum Species Powders in the Control of Red Flour Beetles, Tribolium castaneum Herbst (Coleoptera: Tenebronidae), during Wheat Grain Storage

Pest insects on stored goods are a problem everywhere in the world because they lower grain yields and quality. This has the impact of creating a significant danger to global food security, which could negatively affect people's well-being. In the human endeavor to lessen the threat caused by these insects, the use of synthetic chemical insecticides has unfavorable effects. Recently, there has been advancement in the use of botanicals and agricultural wastes in the control of these pests. This research investigated the effects of Ocimum gratissimum (African basil) and O. basilicum (common basil) powders against Tribolium castaneum infesting wheat grains in storage. Powders were tested singly and mixed at doses of 0.2, 0.4, 0.6, 0.8 and 1.0 g per 20 g of wheat grains. The following parameters were determined: adult mortality, adult emergence rates, seed damage %, weight loss %, and beetle perforation index. The data showed that two Ocimum powders were efficacious and their effectiveness increased with increasing the dosage and also the exposure time. The population of adult T. castaneum on treated wheat grains was significantly (p < 0.05) decreased by the two tested Ocimum species powders. After 24 hours of treatment, 1.0 g of O. basilicum powder caused 50% mortality of adult T. castaneum. However, the combination of O. gratissimum and O. basilicum powders caused 40% of beetles' mortality. On the other hand, O. gratissimum powder was the least toxic on adult T. castaneum with 30% only mortality. The lethal doses of both tested powders and their combination required to cause 50% mortality of the T. castaneum population after the first day of exposure were 1.09, 1.44, and 1.45 g, respectively. While, the lethal dose required to cause 90% mortality (LD90) was 4.24, 8.44, and 5.38 g after the first day post exposure. This study demonstrated the toxicity of O. gratissimum and O. basilicum powders on the survival of T. castaneum on wheat grains. The least deadly dose was recorded on O. gratissimum. Therefore, it is recommended that poor resource farmers and food vendors use Ocimum powder as a biocontrol to manage the red-rust flour beetle in stored wheat grains.

Assessments of some animal bones biochar as paddy protectants against rice weevil, Sitophilus oryzae L. [Coleoptera: Curculionidae]

The main insect pest of stored paddy is Sitophilus oryzae (rice weevil). Huge amounts of rice are produced by peasant farmers each year, but the bulk of it is wasted due to insufficient storage facilities and insect pest attacks brought on by careless handling. In this study, the insecticidal effects of biochar on S. oryzae were assessed in femurs from Sus scrofa (pig), Gallus gallus (chicken), and Bos taurus (cattle). Adult mortality, adult emergence, weight loss, seed damage, and weevil perforation index are among the indicators evaluated. To apply the biochar, different dosages were used: 0.2, 0.4, 0.6, 0.8, and 1.0 g/20 g of paddy rice. In this work, the population of adult S. oryzae on paddy rice was dramatically reduced by all animal bones biochar tested for insecticidal activity (p < 0.05). The animal bone biochar became more effective with increasing dosage. After 24 h of treatment, pig biochar induced a 36.67 % mortality rate of adult S. oryzae, followed by cow biochar's 20 % mortality rate of rice weevils. The fatal dose of cattle, pig, and chicken biochar at which 50 % (LD50) of the population of adult S. oryzae responded after 24 h of treatment were 0.83g, 0.43g, and 0.90g, respectively. It should be encouraged to utilize biochar made from animal bones to combat the S. oryzae in stored paddy. They could be utilized as a green control measure to lessen the risk brought on by the usage of synthetic chemical insecticides in the environment.

Exploring bioactive molecules with fumigation toxicity against the red imported fire ant Solenopsis invicta Buren from commercial essential oils by GC–MS combined with chemometrics

Metabolomics approaches are becoming a powerful analytical technique for exploring bioactive molecules in essential oils. The prevalence of imported red fire ants affected the environment, biodiversity of wildlife, infrastructure, and hypersensitivity reactions of people. Due to public health and environmental issues, essential oils as environmentally friendly alternatives to synthetic chemical insecticides in fire ant management have attracted great attention. However, there is a lack of an objective strategy suitable for identifying bioactive molecules that can guarantee the quality of essential oil biopesticides. Therefore, a metabolomics approach with four main steps, including bioassays, GCMS analysis of chemical constitution, construction of multivariate OPLS and univariate Pearson correlation statistical models, and feature selection, was proposed in this study to verify its potential to find bioactive molecules in essential oils that are effective against red imported fire ants. The fumigation mortalities of 20 commercial essential oils ranged from 0 to 100%. A total of 296 mass features were deconvoluted, and 121 of them were identified. Then, 52 potential bioactive molecules were selected by both VIP > 1.0 and P < 0.05. Finally, 6 of these potential bioactive molecules, (+)− 2-bornanone,.beta.-pinene, eucalyptol, isoborneol, linalool, and L-.alpha.-terpineol, have shown good fumigation toxicity against minor and/or major red imported fire ant workers. This study has, in certain aspects, supported the feasibility of this metabolomics approach. It could be helpful for natural molecules to be alternatives to synthetic chemical insecticides, leading to more environmentally friendly and sustainable management policies for red imported fire ants.

Effect of the Essential Oil of Zanthoxylum Armatum DC. (Rutaceae) Against Aphid (Aphis Citricidus)

Aphids have been considered as a major pest of cultivated crops and invade a wide range of vegetables, cereals, and fruits. Use of synthetic chemical insecticides are the common aphid management practices in the world. The use of chemical insecticides/pesticides raises many concerns associated with the environment, biodiversity and human health. Therefore, the use of natural products such as essential oils have been tested extensively to assess their insecticidal and repellent activity. In this study different concentrations (0.1%, 0.2%, 0.3%, 0.4% and 0.5%) of essential oil (EO) from seeds of Zanthoxylum armatum were tested for their insecticidal and repellent activity for aphids using direct toxicity and repellency method. Results revealed that mortality and repellency were concentrations and exposure time dependent. Mean mortality percentage increased with the increasing concentration and exposure time. 100% mortality was observed in 0.5% concentration after 48 hrs exposure time. However, repellent activity increases with the increasing concentration and decreases with the increasing exposure time. The maximum repellence percentage (96.29%) was achieved in 0.5% oil concentration after 24 hrs of exposure time. Gas Chromatography - Mass Spectrometry (GC-MS) analysis of the essential oil revealed the presence of three major compounds such as Eucalyptol (46.47%), Methyl Cis-Cinnamate (11.13%), and D-Limonene (7.10%) reported as insecticidal activity. SAARC J. Agric., 21(2): 183-194 (2023)

Efficacy of Indigenous Entomopathogenic fungi Beauveria bassiana Isolate for the Control Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) under Laboratory Conditions

Spodoptera littoralis is a serious threat to tomato production worldwide as it can cause yield losses. The farmers used to use synthetic chemical insecticides to control this pest, which unfortunately selects resistant populations and entails public health risks. The aim of this study was to evaluate of indigenous entomopathogenic fungi Beauveria bassiana isolate against different stages of S. littolars life. Results show high significant differences between the three concentrations of suspensions and fungi exudates of B. bassiana in addition differences among time of exposure on ratio of eggs hatching of S. littoralis the high rate of affected of B. bassiana suspension registered at concentration of 1×108 and at concentration 75% of B. bassiana exudates it was reached 32.28% and 34.15% respectively. The study showed that the mortality on 1st and 6th instar larvae of S. littoralis increased as concentration of fungi exudates of B. bassiana increased, it had been 20.51%, 24.65%and 33.45% at concertation 25%, 50%and 75% on 1st instar and reached 3.33%,7.78% and 12.67% on 6th instar of S. littoralis larvae respectively. Moreover suspension fungi of B. bassiana superior at the concentration 1×10 8conidia/1ml of distilled water in the mortality of 1st and 6th instar of S. littolaris larvae with a mortality rate 35.41% and 15.37% respectively.the results showed eggs and 1st instar of of S. littolaris larvae more sensitive to suspensions and fungi exudates of B. bassiana than the 6th instar.

EVALUATION OF DIFFERENT STRAINS OF ENTMOPATHOGENIC FUNGI AS POTENTIAL AGENTS FOR THE MANAGEMENT OF TRIBOLIUM CASTANEUM

The global economic significance of wheat (Triticum aestivum) is undeniable, as it serves as a primary food source for 40% of the human population. T. castaneum, a notable economic pest, particularly impacts stored wheat grains and flour. In the pursuit of sustainable pest control, entomopathogenic fungi (EPF) have emerged as advanced microorganisms, providing viable alternatives to harmful synthetic chemical insecticides. This study employed four fungal strains—Beauveria bassiana, Isaria cateniannulata, Trichoderma harzianum, and Metarhizium attenuatum—against mixed adult populations of T. castaneum under controlled laboratory conditions. Different concentrations (1×10², 1×10⁴, 1×10⁶, 1×10⁸, 1×10¹⁰ cfu/ml) for each fungus were employed, and mortality data, LC50, and LT50 were recorded at post-exposure intervals of 4, 6, 8, and 10 days. The application method involved using the fungus through a filter paper dip, and red flour beetle adults were introduced to wheat grains. The highest mortality, observed at the concentration of 1×10¹⁰ cfu/ml, was 80% for both M. attenuatum and B. bassiana. Conversely, the lowest mortality, recorded at the concentration of 1×10² cfu/ml, was 64% for I. cateniannulata, while T. harzianum demonstrated 70% mortality at 1×10¹⁰ cfu/ml. The utilization of entomopathogenic fungi for insect control represents an emerging strategy. B. bassiana and M. attenuatum emerge as promising alternatives for managing T. castaneum in stored grains.

Analysis of the virulence, infection process, and extracellular enzyme activities of Aspergillus nomius against the Asian corn borer, Ostrinia furnacalis guenée (Lepidoptera: Crambidae)

ABSTRACT The control of Ostrinia furnacalis, a major pest of maize in Xinjiang, is challenging owing to the occurrence of resistant individuals. Entomopathogenic fungi (EPF) are natural insect regulators used as substitutes for synthetic chemical insecticides. The fungus Aspergillus nomius is highly pathogenic to O. furnacalis; however, its virulence characteristics have not been identified. This study aimed to analyse the lethal efficacy, mode of infection on the cuticle, and extracellular enzyme activity of A. nomius against O. furnacalis. We found that the mortality and mycosis of O. furnacalis were dose-dependent when exposed to A. nomius and varied at different life stages. The egg-hatching and adult emergence rates decreased with an increase in conidial suspension. The highest mortality (83.33%, 7 d post-infection [DPI]) and mycosis (74.33%, 7 DPI) and the lowest mortality response (8.52 × 103 conidia mL−1) and median lethal time (4.91 d) occurred in the 3rd instar larvae of O. furnacalis. Scanning electron microscopy indicated that numerous conidia germination and infection structure formation may have contributed to the high pathogenicity of A. nomius against O. furnacalis. There were significant correlations between O. furnacalis mortality and the activities of extracellular protease, lipase, and chitinase of A. nomius. This study revealed the infection process of the highly pathogenic A. nomius against O. furnacalis, providing a theoretical basis and reference for strain improvement and field application of EPF.

Evaluation of Phytochemical Compounds in Senna siamea stembark Powders for Insect Pest Control

A laboratory screening was conducted to evaluate the phytochemical compounds in Senna siamea stembark powders and their insecticidal activity on Callosobruchus subinnotatus PIC on stored Bambara groundnut through untargeted Gas Chromatography – Mass Spectrometry (GC- MS) using three different extraction solvents (ethanol, methanol and distilled water). To mention but few, the ethanol extracts revealed Octanoic acid, 4,6-dimethyl-, methyl ester, (4S,6S)-(+)- (C11H22O2); cis-Vaccenic acid (C19H36O2); Z,Z-10,12-Hexadecadien-1-ol acetate (C18H32O2); 2-Methyl-Z,Z-3,13-octadecadienol (C19H36O). Methanol extracts showed Oleic Acid (C18H34O2); Cyclononasiloxane, octadecamethyl- (C18H54O9Si9); Cyclodecasiloxane, eicosamethyl- (C20H60O10Si10); 2-Methyl-Z,Z-3,13-octadecadienol (C19H36O). Distilled water extraction revealed cis-Vaccenic acid (C19H36O2); 1,2-Benzisothiazole,3-(hexahydro- 1H-azepin-1-yl)-, 1,1-dioxide (C13H16N2O2S); Oleic Acid (C18H34O2); 11-Octadecenoic acid, methyl ester (C19H36O2)as compounds with the highest percentage area. Phytochemicals have been used for many years to control insect pest damage in agricultural crops. Pyretre, Nicotine, Rotenone and tobacco have long been used as control agents against insects in some regions of sub-Saharan Africa. Unlike synthetic chemical insecticides that kill both pests and non-target organisms, botanicals pesticides are relatively target specific. They are also biodegradable, environmentally friendly, and can also be used in insecticide resistance management programs. Hence, could serve as good alternatives to chemical insecticides. Further research on the bio insecticidal activity of these compounds is highly advocated.

Effects of konjac glucan-nan/low-acyl gellan edible coatings loaded thymol-β-cyclodextrin microcapsules on postharvest blueberry

This study developed an edible antimicrobial coating using a blend of konjac glucomannan (KGM) and low acyl gellan gum (LAG) hydrogel to incorporate thymol nanoparticles (TKL). The optimized TKL formulation (TKL60) comprised 0.22% thymol microcapsules (TMs), 0.075% total polysaccharide content (KGM:LAG = 1:2), and 99.63% distilled water. When applied to blueberries, TKL60 significantly extended their shelf life to 42 d at 2 ± 0.5 °C, tripling that of control fruit. TKL60 reduced decay rate, weight loss, and respiration rate, delayed softening and senescence during cold storage. It preserved the outer epidermis by retaining cuticular waxes, curbing lipid oxidation, and sustaining defense-related enzyme activities. Flavor analysis revealed altered volatile compound concentrations in TKL60-treated berries, including decreased terpenes and benzaldehyde, and increased esters and aldehydes like 2-methylbutanol, 3-methylbutanol, and linalool. Discriminant Analysis highlighted TKL60′s efficacy in delaying aroma deterioration by over 21 d. TKL60 exhibits potential as a substitute for synthetic coatings and chemical insecticides.

A Systematic Review of the Bioactivity of Jatropha curcas L. (Euphorbiaceae) Extracts in the Control of Insect Pests

The use of botanical extracts of the plant Jatropha curcas (Euphorbiaceae) represents a valuable alternative to control insect pests and avoid the detrimental effects on the environment and health that arise due to synthetic chemical insecticides. Thus, we conducted a systematic review to summarize the published evidence on the bioactivity of J. curcas against insect pests. Electronic databases were searched to identify studies that assessed J. curcas extracts against insect pests in various types of crops. We included 39 articles that reported the insecticidal and insectistatic activity of several botanical extracts from J. curcas against insects of eight different taxonomic orders. The evidence demonstrates that aqueous and methanolic extracts from seeds and leaves, seed oil, and petroleum ether seed extracts were effective against insect pests of stored grains, aphids of cabbage and sorghum, fruit flies, and desert locusts. The extracts caused high mortality, controlled the populations, reduced oviposition, diminished hatchability, and increased the antifeedant effect. However, the type of solvent used to obtain the botanical extract and the method of application (contact or food) are fundamental to increase its bioactivity. Therefore, botanical extracts from seeds and leaves of J. curcas should be considered as an alternative against insect pests and may be incorporated into integrative and sustainable management for insect control.