Chemical Insecticides Research Articles

Alternatives for controlling insect pests in crops of agronomic interest using Bacillus thuringiensis and Brevibacillus laterosporus

The bacteria Bacillus subtilis and Bacillus thuringiensis have been the main target of research for a long time, making it necessary to identify new microorganisms capable of being used and that accompany the rapid development of biotechnology. The work aims to evaluate the efficiency of isolates of B. thuringiensis and B. laterosporus in controlling caterpillars in crops of agronomic interest. Experiments were conducted with the cultivation of Cotton, Sugarcane, Citrus, Bean, Cabbage, Maize, Soybean and Wheat in different environments to evaluate the efficiency of B. thuringiensis and B. laterosporus isolates in controlling caterpillars. Analysis of variance took place at 5% probability using the F test. Subsequently, the Scott-Knott grouping of means was used at 5% probability. The synergistic use of chemical and biological insecticides promotes satisfactory rates of pest control in crops of agronomic interest. Isolates of B. thuringiensis and B. laterosporus are efficient in controlling caterpillars when applied at the highest dosages tested.

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.

Potential of zodia (Evodia suaveolens) as natural repellents for Culex sp

Background: Adult Culex sp mosquitoes as disease vector also cause discomfort around humans. Various efforts have been made to prevent the transmission of diseases carried by mosquitoes, including the use of mosquito nets and the use of chemical insecticides in the larval and adult stages. Objectives: This Reserach aim to investigates the potential of Zodia (Evodia suaveolens) as natural repellents. Materials and Methods: An experimental study was conducted to test the effectiveness of Zodia extract at concentrations of 1%, 2%, and 3% against Culex sp. mosquitoes. The tests were conducted under controlled conditions in the Laboratory of Parasitology, University of Binawan. The effectiveness was measured by the percentage of mosquitoes repelled after exposure. Results: The effectiveness of Zodia repellent increased with concentration, showing 76.4% effectiveness at 1%, 81.3% at 2%, and 91.05% at 3%. These results indicate a concentration-dependent increase in repellency, with the highest concentration approaching typical efficacy rates of synthetic repellents. Conclusions: The Zodia repellent (Evodia suaveolens) with a concentration of 1%, 2% and 3% has been demonstrated to be effective as a natural repellent against Culex sp. mosquitoes.

Neurotoxicity, Cytotoxicity, and Genotoxicity of Phyto-radio Synthesized Selenium Nanoparticles in Culex pipiens Complex.

Effective mosquito management strategies are crucial to minimize the number of mosquito-borne diseases. Selenium nanoparticles (SeNPs) are promising in mosquito control because they are effective and eco-friendly rather than synthetic insecticides. The current study was conducted to evaluate the impact of SeNPs on the detoxification enzymes, acetylcholine esterase (AChE), glutathione S-transferase (GST), and α-carboxyl esterase (α-CarE), in larval instars of Culex pipiens complex at the LC50 concentration. In 3rd instar larvae treated with microwave-assisted selenium nanoparticles (SeNPs-MW) and gamma-assisted selenium nanoparticles (SeNPs-G), it was found that AChE activity was significantly inhibited. On the other hand, significant increases in GST and α-CarE activities were observed. Additionally, genotoxic and ultrastructure studies of midgut epithelial cells in 3rd instar larvae revealed DNA damage and cell lysis, including destruction of the cell membrane, microvilli, and nuclei. These findings suggest that SeNPs have an adverse effect on AChE gene expression, resulting in its downregulation. This downregulation can be attributed to the formation of reactive oxygen species induced by SeNPs that can modulate the host defense mechanism leading to apoptosis and subsequent larval mortality. The present study was the first to use phyto-microwave-assisted and gamma-assisted synthesis of SeNPs which provides an eco-friendly and cost-effective solution to reduce the risk of chemical insecticides. Furthermore, an integrated pest management program (IPM) using nanocides can be successfully developed for mosquito control.

Biological efficacy of selected insecticides for the control of the green apple aphid Aphis pomi (de Geer, 1773) on apple in Bulgaria

The aim of this study was to evaluate the biological efficacy of chemical insecticides, from different chemical classes, recommended for the control of the apple aphid Aphis pomi in apple orchards in Bulgaria. The experiment was carried out in 2023 in the experimental field of Agricultural University-Plovdiv. The insecticides tested were spirotetramat (Movento 100 SC), flonikamid (Teppeki) and acetamiprid (Mospilan 20 SG). The insecticides were applied at the concentrations recommended for the control of this and other pests. All the tested chemical insecticides showed very high biological efficacy, therefore they can be recommended as suitable for efficient control of Aphis pomi on apple. Keywords: Chemical insecticides, Movento, Teppeki, Mospilan, Aphis pomi, Аpple, Bulgaria

Utilization of Gomophia egyptiaca (Red Starfish) in the Biological Control of Aedes aegypti Larvae

Background: Aedes aegypti mosquito spreads many vital diseases to humans. Traditionally, chemical insecticides were used for control. Recently, interest has grown in using aquatic predators, such as the Red Starfish (Gomophia egyptiaca), to target mosquito larvae in water, offering a potential biological control method. Methods: This study investigates the larvicidal potential of G. egyptiaca against Ae. aegypti larvae, a key vector for dengue and other mosquito-borne diseases after 24 hours. Result: The results demonstrate a significant increase in mortality rates with prolonged exposure to G. egyptiaca. After 2 hours, the mortality rate was 6.66%, increasing to 20% at 4 hours, 60% at 12 hours and peaking at 80% after 24 hours. Statistical analysis using one-way ANOVA revealed a highly significant p-value of 3.93, confirming the effectiveness of G. egyptiaca over time. LT50 was determined to be 14.91 hours, with a confidence interval of 12.40 to 18.65 hours. These findings indicate that G. egyptiaca could serve as a powerful alternative to chemical insecticides, offering a sustainable approach to mosquito control. However, field trials and evaluations of non-target impacts are necessary to fully assess its potential in diverse ecological settings. This study supports the integration of G. egyptiaca into mosquito management strategies, particularly where chemical resistance and environmental concerns are prevalent.

Biological Control of Aedes aegypti Larvae using Sea Shell Powder

Background: The Aedes aegypti mosquito is a primary vector for several arboviral diseases, including dengue, Zika, chikungunya and yellow fever, posing significant public health challenges, especially in tropical and subtropical regions. Traditional chemical insecticides have been the mainstay for controlling Aedes aegypti populations, but their extensive use has led to the development of insecticide resistance, environmental pollution and adverse effects on non-target organisms. This study explores the potential of sea shell powder as a natural larvicide against Aedes aegypti larvae. Methods: Sea shell powder, derived from the calcified exoskeletons of marine mollusks, was tested for its larvicidal activity against fourth instar larvae of Ae. aegypti at concentrations ranging from 100 to 600 ppm. Result: The results demonstrated a concentration and time-dependent increase in larval mortality, with LC50 values of 407.01 ppm at 24 hours and 327.55 ppm at 48 hours. The findings suggest that sea shell powder could serve as an effective, environmentally sustainable alternative to chemical insecticides, offering advantages such as biodegradability, low cost and reduced risk of resistance development. This study supports the potential inclusion of sea shell powder in integrated mosquito management programs, particularly in areas with prevalent insecticide resistance.

Essential oil-loaded polymeric nanoparticles as a viable alternative to control storage grain insects -a review

The loss of stored grains is becoming a major issue globally because of insect infestation. The extensive usage of chemical insecticides for insect control has caused enormous harm to the worldwide ecology. Hence, it is essential to look for more environmentally sustainable solutions. Several essential oils (EOs) and bioactive chemicals have been adopted as natural insecticides due to their considerable insecticidal activity, diversified mechanism of action, and nontoxicity to other organisms. Meanwhile, despite their potential features, EOs have certain disadvantages, including being extremely volatile, less water-soluble, more rapidly degradable and the cost of production in some cases. Encapsulating EOs as nanoemulsions into polymers has recently been recognized as a potential technique for increasing their stability, selective release, and usefulness in various domains. These EOs and nanoemulsions displayed insect-deterrent behaviour by acting as fumigants, contact repellents, antifeedants, egg development deterrents, and larval agents, in addition to inhibiting chemical messengers such as acetylcholinesterase (AChE) and octopamine and transforming enzyme performance. This review article summarizes recent trends and innovations to define polymeric nano-formulated EOs as environment-friendly substitutes for harmful conventional insecticides. It also provides opportunities for more secure and profitable methods of controlling agricultural insects. Along with this, the insecticidal activity and mechanism of action for various essential oils and essential oil-loaded polymeric nanoparticles on various insects of stored grains are thoroughly discussed.

Biodegradation of insecticides: oligonucleotide insecticides and double-stranded RNA biocontrols paving the way for eco-innovation

Each new class of insecticides that emerged during the development of plant protection gradually found the most suitable group of insect pests for application. At the same time, for each individual insecticide, a balance was sought between its effectiveness, on the one hand, and its safety for non-target organisms and the ecosystem as a whole, on the other hand. Neonicotinoids, diamides and pyrethroids, as effective control agents, dominate the insecticide market, but do not have outstanding performance in selectivity and biodegradation. The biodegradation of insecticides is one of the most important indicators, representing what will be said about the hidden costs for the resulting harvest paid by the environment and human health. Oligonucleotide insecticides (contact unmodified antisense DNA (CUAD) biotechnology, or ‘genetic zipper’ method) and RNA biocontrols (double-stranded RNA technology) as natural polymers and the next-generation classes of insecticides possess unique characteristics in fast biodegradation and high selectivity in action. While current chemical insecticides require days, months and even years for biodegradation by bacteria and fungi, oligonucleotide insecticides and RNA biocontrols are substantially biodegraded within hours in the presence of nucleases. Nucleic acid-based insecticides have the potential to complement the existing insecticide market and set an eco-precedent for crop protection products where the effectiveness of the insecticide will be determined by its safety for non-target organisms, and other factors being equal, the choice of a particular control agent will be determined by its biodegradability. It should be noted that not a single class of insecticides that once appeared has completely disappeared; rather, it has occupied its niche, gradually declining under the pressure of new classes of insecticides. At the same time, the common trend in plant protection is towards use of insecticides with higher biodegradability, which gives hope for a safer future of the planet.

Maize plants can recover from fall armyworm damage under optimum crop production conditions in humid tropical agro-ecologies.

Farmers in Africa perceive the impact of fall armyworm (FAW) on maize to be significant, but field assessments have shown that yield losses are not significant enough to warrant pesticide interventions. This suggests that relationships between the crop stages, time, and duration of attack can affect the yield. Therefore, assessing the plant's recovery from damage using individual plants based on defoliation levels could guide whether and when pesticides should be applied. To study this, we selected 120 labeled maize plants corresponding to six levels of FAW defoliation, replicated 20 times, based on an initial damage rating. The rating scale ranged from 1 (no defoliation) to 5 (>75% defoliation) during four planting seasons. Plants with a rating scale of 1 were replicated and treated with a chemical insecticide to keep them undefoliated, and that served as a control. Damage severity was recorded weekly on all plants, starting from emergence until maturity, using the same damage rating scale. Results showed that damage severity varied significantly among different defoliation levels during all seasons. Higher levels of defoliation during dry seasons resulted in significant yield loss only for plants with damage levels 4 and 5, with damage severity ranging from 38.7% to 57.5%. These results indicate that FAW control is unnecessary in the rainy season. In contrast, pesticide interventions should be envisaged in seasons of erratic rainfall, with a significant defoliation threshold level of around 50%, occurring at 8 and 5wk after planting weeks after planting, respectively for the early and late dry season.

Structural Derivatives of β-Asarone from Acorus calamus Linn. as Insecticide Candidates and the Insecticidal Mechanism Against Small Brown Planthopper

The small brown planthopper (SBPH), Laodelphax striatellus (Fallén) (Hemiptera: Delphacidae), is an increasing threat to Gramineae crops, posing significant risks to both the environment and food safety. β-asarone, as a promising green alternative to chemical insecticides, possesses wide application prospects in the crop protection field. To enhance the insecticidal activity of β-asarone, a series of derivatives were prepared through an active substructure splicing strategy, and their insecticidal activities against SBPH were evaluated. Among the 7 commercial compounds with chemical structures similar to β-asarone and 12 structural derivatives of β-asarone, compound 10, which incorporates the 2-chloropyridine functional group from flupyrimin, exhibited the most potent insecticidal activity against SBPH, with an 8.31-fold increase in insecticidal activity compared to β-asarone. Furthermore, transcriptome analysis showed that among the selected genes that may play important roles in insecticidal activity, an ABC transporter gene, MDR49, was most significantly down-regulated. MDR49 was highly expressed in the 4th-instar nymphs, with the highest expression level in the fat body, midgut, and abdomen. RNA interference (RNAi) against MDR49 significantly reduced susceptibility to compound 10 in SBPH, which revealed that MDR49 may be the candidate insecticidal target of compound 10. Additionally, the insecticidal spectrum revealed that compound 10 showed excellent efficacy against Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) and Tetranychus cinnabarinus (Boisduval) (Acarina: Tetranychidae). This study indicates that compound 10 could be further developed as a novel eco-friendly pesticide.

A study on the effectiveness of (+)-usnic acid as oral toxic sugar bait against adult male and female Anopheles gambiae

BackgroundDespite the application of various tools for the control of vectors of Plasmodium falciparum, malaria remains the major killer disease in sub-Saharan Africa accounting for up to 90% of deaths due to the disease. Due to limitations of the useage of chemical insecticides such as resistance, negative impact on the environment and to nontarget organisms, the World Health Organization (WHO) requires that affected countries find alternative vector control tools. This study evaluated the effectiveness of ( +)-usnic acid (UA) as an insecticide through oral administration to male and female Anopheles gambiae as an alternative or additional active ingredient to be used in toxic sugar bait.Methods( +)-usnic acid was diluted using acetone at 5, 10, and 15 mg/ml concentrations in three replicates. A 5 ml mixture of 2% food dye and 10% sugar using chlorine-free water mixed with the dilutions of the ( +)-usnic acid and negative control was made containing 2% food dye and 10% sugar solution. The preparations were soaked on a ball of cotton wool and placed over the net of a cup. 5 male and 5 non-blood-fed female newly hatched starved An. gambiae Kisumu strain were introduced together into a cup and monitored for knockdown and mortalities after 4, 24 48, and 72 h. The data were analysed using a multiple linear regression model using the lm function, a base R function and a posthoc test were conducted on the significant main effects and interaction terms using the emmeans function from the emmeans R package. All analyses were performed in RStudio using base R (version 4.3.3).ResultsThere was high mortality of both male and female An. gambiae after ingestion of the toxic sugar bait. 15 mg/ml usnic acid caused the highest mortality (50%) within the first 4 h compared to 5 and 10 mg/ml ( +)-UA. There was a decline in the mortality rate with increased exposure time from 24 to 72 h, however, there was a significant difference in mortality at 5, 10 and 15 mg/ml. Acute toxicity was associated with ingestion of 15 mg/ml after 24 h. 72 h post-mortality was lower in all concentrations than in the control. High mortality was observed among females over the first 4 h (60%) compared to males (40%) due to higher feeding rate of the toxic agent. The proportion of dead males and females was equal after 24 h while after 48 h, the proportion of dead males was high.There was a significantly lower mortality rate after 72 h for both males and females (0 to 13.3%). Compared to all the treatments, high mortality of males was observed.ConclusionsThe results of this study indicate that ( +)-UA when administered as oral sugar bait to An. gambiae has insecticidal properties and is a suitable ingredient to be used as a toxic agent in the novel attractive toxic sugar bait for the control of malaria vectors. ( +)-UA may be an alternative active ingredient as toxic bait in the effort to reduce and eliminate the transmission of Plasmodium falciparum in Africa.

Trap cropping for insect pests in the Canadian Prairies: a review and a case study

AbstractThe Canadian Prairies are one of the major agricultural regions of the world in terms of cereal, oilseed and pulse crop production. With few exceptions, major insect pests like grasshoppers, flea beetles, Lygus bugs, wireworms and pea leaf weevils are controlled with insecticides. Wheat stem sawfly is managed through host plant resistance and endemic natural enemies, whereas cereal leaf beetle is managed through classical biological control. Large farms and short growing seasons in the region present logistical challenges to adopt time intensive pest management systems such as trap crops. Therefore, there is no adoption of trap crops even though some research has demonstrated their potential. In this article we present a brief overview of the pest status and management, and we summarize research on trap crops in the Prairies Ecozone and adjacent ecoregions. We conclude the review with some innovative research ideas to make trap cropping a more appealing pest management system in our quest to reduce dependency on chemical insecticides and increase the environmental resilience of Canadian agroecosystems.

Future semiochemical control of codling moth, Cydia pomonella

Codling moth (CM), Cydia pomonella, is a significant pest of apple (Malus domestica) and other orchard crops worldwide, posing challenges due to the decrease in registered insecticides, rising resistance, and a changing climate. The pest exhibits a strong resistance capacity to both synthetic and natural insecticides, while shifting seasonal temperatures disrupt the reliability of phenology-temperature models for predicting targeted control strategies. Alternative control strategies are necessary to future-proof control of this pest. Current control methods primarily rely on chemical insecticide sprays or granulosis virus applications during egg hatching. This review focuses explicitly on semiochemical-based manipulation of CM adults and larvae for control in orchards. Topics covered include the role of semiochemicals in integrated pest management, area-wide control, mating disruption, female attractants, larval kairomones, and incorporation into monitoring and control strategies. The potential of CM repellents in a push–pull strategy is also discussed. Primary sources for identifying relevant literature included GoogleScholar and ResearchGate, with a focus on papers published since 2013 but also include relevant papers from 2003. Nine review papers and 119 papers were reviewed. The review emphasizes that effective control necessitates an area-wide approach targeting all life stages (eggs, larvae, pupae, and adults). Comprehensive monitoring is crucial for identifying CM “hot-spots” and enhancing targeted interventions. Growers must consider landscape context when designing control programs. Lastly, recommendations are provided for future research and CM management strategies. There are opportunities to explore and exploit female kairomone attractants and repellents in control strategies and modify monitoring traps to be more attractive and autonomous.

Evaluation of transplant drench and foliar insecticide applications for wireworm (Coleoptera: Elateridae) management in sweetpotato.

The revocation of chlorpyrifos tolerances in 2022 left sweetpotato growers without their most important tool to combat a complex of soil-borne root pests that includes wireworms (Coleoptera: Elateridae). Since then, growers have reported increased root damage despite a rapid pivot to pyrethroid-based management systems to replace mechanically incorporated preplant chlorpyrifos broadcast sprays. Our goal was to evaluate the efficacy of alternative insecticide chemistries and application methods to expand the portfolio of management options for wireworms, specifically Conoderus spp. and Melanotus communis (Gyllenhal). We tested (i) insecticidal transplant water drenches and (ii) a foliar spray program targeting adult elaterids. We found that incorporating insecticides into transplant water reduced wireworm damage when compared to untreated transplant water. Our treatments included a recently registered meta-diamide, broflanilide, which represents a promising path to diversify active ingredients and shift away from an overreliance on preplant and post-directed pyrethroid soil sprays. Foliar spray plots had less damage than plots that did not receive foliar sprays. One benefit of adult-focused management is the availability of effective monitoring tools such as sex pheromones and blacklight trapping. Developing a robust adult monitoring program would enable more precise applications of foliar insecticides versus season-long prophylactic soil sprays targeting larvae. Our results demonstrated a significant benefit to both alternative delivery methods. These management alternatives could expand treatment options beyond traditional preplant and post-directed pyrethroid sprays.

Assessing the multifaceted repercussions of chemical insecticides on vegetable yield and human population: A modeling study

Vegetables stand out as invaluable reservoirs of essential vitamins, minerals, antioxidants, and vital dietary elements, yet their production faces a considerable threat due to insects. To tackle this challenge, farmers spray chemical insecticides to enhance vegetable yields by controlling the insect population. Nevertheless, the presence of insecticide residues in vegetables stands as a primary contributor to acute illnesses and chronic health conditions in humans. In the present research work, we formulate a novel nonlinear mathematical model meticulously designed to scrutinize the multifaceted repercussions of chemical insecticides on vegetable yield and the human population. In our model formulation, we adopt a dynamic approach where insecticide application on vegetables in agricultural fields correlates with the insect population. However, we acknowledge the consequential impact of insecticide usage on human health, which in turn reduces the growth rate of the human population. This study determines the critical value of the spraying rate of insecticide at which the human population reaches its maximum, ensuring that human needs for vegetables are met while minimizing the adverse effects of insecticide. Since various species of insects attack vegetables in the field and different insect species have different natural mortality rates, therefore we also identify the range of natural mortality rates of insects for which vegetable yield is minimal and fluctuates with time. Further, our research reveals that if the natural mortality rate of insects in a certain crop field lies within this identified range, then farmers should increase the insecticide spraying rate to avoid this upheaval situation and stabilize vegetable yield at a higher level.

Entomopathogenic nematodes as a lethal bioagent to deter <i>Pieris brassicae</i> L. (Lepidoptera: Pieridae) infesting different cole crops: A review

Cole crops are the most important and attractive vegetables, belonging to the family Cruciferae are extremely grown all over the world. In India, their annual production has been reported to be about 191.77 million metric tons so chips into the economy by a huge amount. Pieris brassicae, one of the dreaded insect pests incur damage to different vegetables to a tune of 40%. To curb this pest damage various synthetic insecticides are applied, albeit showing promising results yet posing drastic negative imprints on non-target organisms, environment and pest resistance. These drawbacks demand a perfect alternative which seals all the glitches created by the chemical insecticides. For this Infective Juveniles (IJs) of Entomopathogenic Nematodes (EPNs) act as perfect biological agents. So, work done in these lines has been reviewed to facilitate students and researchers for advanced research related to entomopathogenic nematodes and P. brassicae.

First Report of <i>Tetrastichus howardi</i> (Olliff) and <i>Chelonus formosanus</i> Sonan as parasitoids of fall armyworm, <i>Spodoptera frugiperda</i> (J.E. Smith), in Pakistan

Fall armyworm, Spodoptera frugiperda (J.E. Smith), an invasive agricultural pest, causes substantial economic losses in Pakistan. This study reports the first record of Tetrastichus howardi (Olliff) and Chelonus formosanus Sonan as natural enemies parasitising S. frugiperda within the country. Parasitoids were collected from infested maize fields and identified through morphological analysis. This discovery enhances our understanding of the natural enemy complex associated with S. frugiperda in Pakistan and provides a foundation for investigating their potential as biological control agents. These findings underscore the potential of these parasitoids as components of integrated pest management systems to diminish reliance on chemical insecticides and foster sustainable agricultural practices.

Biocontrol of Phenacoccus solenopsis Tinsley using entomopathogenic fungi and bacteria

IntroductionPhenacoccus solenopsis Tinsley, poses a significant threat to a range of crops worldwide. This study aimed to evaluate the efficacy of entomopathogenic fungi (Alternaria murispora and Alternaria destruens) and bacteria (Streptomyces bellus-E23-2) against adult females of P. solenopsis under laboratory (26 ± 2°C) and greenhouse conditions.MethodsLaboratory trials tested A. murispora, A. destruens (104–1010 conidia mL−1), and S. bellus E23-2 (104–1010 cfu mL−1), alone and in combination, recording mortality rates and LC50 values. Greenhouse trials tested the best lab treatments on infested potato plants, monitoring pest density and plant quality.Results and discussionIn laboratory trials, A. murispora at 1010 conidia mL−1 was the most effective, achieved 79.7% mortality (LC50 = 1.338 × 108 conidia mL−1 after 14 days). Combination treatments significantly enhanced efficacy, with A. murispora + S. bellus E23-2 (1010 conidia mL−1 + 1010 cfu mL−1) reaching 85.3% mortality. In greenhouse trials, the combination treatments notably reduced P. solenopsis densities and increased the number of infected mealybugs, with A. murispora + S. bellus E23-2 being the most effective. These treatments did not harm plant quality, unlike imidacloprid, which reduced visual quality despite its high efficacy. Alternaria murispora and S. bellus E23-2 effectively control P. solenopsis, providing a sustainable, plant-safe alternative to chemical insecticides.

Comparative Study of the Efficacy of Two Biological Insecticides (Azadirachta indica and Bacillus thuringiensis) and a Chemical insecticide (Diflubenzuron WP) against Fall Armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae) in Maize Crop, Western Bur

Aims: This study aimed at comparing the biological efficacy of Diflubenzuron WP, a chemical insecticide, and two biopesticides, one based on neem oil (Azadirachta indica) and an entomopathogen (Bacillus thuringiensis) against the fall armyworm on maize. Place and Duration of Study: The work was carried out on the irrigated scheme of Bama, western Burkina Faso during the 2022 and 2023 wet seasons. Methodology: The experimental design was a Fisher block with 4 treatments: T0: untreated or control; T1: Bacillus thuringiensis; T2: neem oil; T3: Diflubenzuron WP, in 4 replications. Entomological observations focused on the score and severity of attacks, as well as the pest's infestations rate. Results: The results showed that the different insecticides tested over the two wet seasons of 2022 and 2023 induced better control of S. frugiperda populations, with larval density being kept lower with the treatment of Diflubenzuron WP (4.25±1.2%), neem oil (14.28±1.6%) and Bacillus thuringiensis (24.5±3.2%). The insect damage severity rates and scores of damaged ears were also low for the three treatments respectively (1.09±0.2, 0.9±0.26 and 0.27±0.71) over the two cropping seasons. Diflubenzuron WP insecticide treatment not only reduced pest pressure, but also significantly improved maize yield. No surprisingly the highest yield (5.14 t/ha) was recorded with Diflubenzuron WP, followed by neem oil (4.62kg/ha) and finally Bacillus thuringiensis (3.92kg/ha). Conclusion: Further studies are needed to determine the optimal doses of neem oil and Bt for the control of Fall Armyworm. Neem oil can be considered as a good alternative to a chemical insecticide like Diflubenzuron WP.