4th Instar Larvae Research Articles

Larvacidal effects of methanolic and ethanolic leaf extracts of <i>Xienemia americana</i> against female <i>Anopheles gambiae</i> S.L. (Culicidae: Diptera)

Anopheles gambiae complex is the most important vector of malaria in sub-Saharan Africa. It is thought that Nigeria comprises about 45 species of Anopheles mosquitoes of which Anopheles gambiae is the most prevalent. Extract of different concentrations were evaluated at the level of 2.00 3.00, 4.00, 5.00 and 0.00 (Control) mg/ml. Distilled water only was used as control. Twenty (20) larvae were put into four (4) cups containing 100ml of the test solution of each concentration. Larval to pupa mortality were recorded and calculated after 24, 48 and 72h after treatment. Mortality results were used to determine LC50 and LC90 using probit analysis. The larvicidal activity of methanol and Ethanolic extracts of the X. Americana were evaluated on 4th instar larvae of Anopheles gambiae. From the results concentration of X. americana with ethanol has shown high larvicidal effect with 10%, 12%, 3% adult emergence when compare with control. While Methanol concentration reveals low larvicidal effect with 16 % adult emergence. Treatment group X. Americana showed highest survival from pupa to adult (28, 18% and 6%) recorded, this means concentration of ethanol has larvicidal effect against A. gambiae. However, methanol concentration shows low activity with 45, 21 and 16% followed by X. Americana with 18, 15 and 10% recorded the highest larvicidal activity among all the concentrations with methanol respectively. Concentration of 5.0 mL, 12.0 mL, 20.0 mL, 25.0, 30.0mL compare to control group. All the extracts proved to be toxic to the test organism, though there was a remarkable difference in the concentrations and timing of their activity.

Cloning and spatio-temporal expression of CsKr-h1 encoding the juvenile hormone response gene in Coccinella septempunctata L.

The gene encoding juvenile hormone response (Krüppel homolog1, Kr-hl) in Coccinella septempunctata was investigated by cloning and analysing expression profiles in different developmental stages and tissues by quantitative real-time polymerase chain reaction (PCR). C. septempunctata Kr-hl (CsKr-hl) encoded a 1338 bp open reading frame (ORF) with a predicted protein product of 445 amino acids; the latter showed high similarity to orthologs in other species and contained eight highly-conserved Zn-finger motifs for DNA-binding. CsKr-hl was expressed in different developmental stages of C. septempunctata. The expression levels of CsKr-hl in eggs, 2nd, 3rd, 4th instar larvae, and pupa were 3.31, 2.30, 7.09, 0.58, and 7.48 times the number of 1st instar larvae, respectively. CsKr-hl expression levels in female adults gradually increased at 25-30 days and were significantly higher than expression at 1-20 days. CsKr-hl expression in 20-30 days-old male adults was significantly higher than males aged 1-15 days. CsKr-hl expression levels in heads of male and female adults were significantly higher than expression levels in the thorax, adipose, and reproductive system. Interestingly, CsKr-hl expression levels in the adipose and reproductive system of female adults were significantly higher than in adult male corresponding organs, which suggest that CsKr-hl plays an important role in regulating reproductive development in C. septempunctata.

Sprayable RNAi for silencing of important genes to manage red palm weevil, Rhynchophorus ferrugineus (Coleoptera: Curculionidae).

The red palm weevil, Rhynchophorus ferrugineus (Oliver, 1970) (Coleoptera: Dryophthoridae) is the most devastating insect-pest of palm trees worldwide. Synthetic insecticides are the most preferred tool for the management of RPW. Alternatively, RNA interference (RNAi) mediated silencing of crucial genes provides reasonable control of insect pests. Recently, we have targeted four important genes; ecdysone receptor (EcR), serine carboxypeptidase (SCP), actin and chitin-binding peritrophin (CBP) in the 3rd and 5th instar larvae RPW. The results from 20 days trial showed that the survival rate of 3rd instar larvae fed on SCP and actin dsRNAs exhibited the lowest survival (12-68%). While, in the 5th instar larvae, the lowest survival rate (24%) was recorded for SCP after 20 days of incubation. Similarly, the weight of the 3rd and 5th instar larvae treated with SCP and actin was significantly reduced to 2.30-2.36 g and 4.64-4.78 g after 6 days of dsRNA exposure. The larval duration was also decreased significantly in the larvae treated with all the dsRNA treatments. The qRT-PCR results confirmed a significant suppression of the targeted genes as 90-97% and 85-93% in the 3rd and 5th instar larvae, respectively. The results suggest that the SCP and the actin genes can be promising targets to mediate RNAi-based control of RPW.

Entomopathogenic bacteria and fungi as eco-safe substitutes to chemical insecticides against leaf eating caterpillars of Spodoptera litura

The present study was carried out in laboratory conditions (25 ± 10°C and 70% humidity) for studying the bioefficacy of entomopathogenic fungi and Bacillus thuringiensis against Spodoptera litura using the leaf dip method. The insecticidal attributes of three different commercial bioinsecticides (Bacillus thuringiensis 0.5% W.P., Beauveria bassiana 1.0% W.P., and Metarhizium anisopliae 1.0% W.P.) at different concentrations (0.5, 1.0, and 1.5%) were evaluated against the 3rd and 4th larval instars of S. litura. The analysis of variance results revealed that the highest concentration (1.5% concentration) of B. thuringiensis against the 3rd instar larvae of S. litura caused a maximum 80 ± 0.28% larval mortality, followed by B. bassiana and M. anisopliae, which caused 72 ± 0.21 and 64 ± 0.20% larval mortality after 120 h exposure. The calculated median lethal concentration in probit analysis demonstrated the lowest median lethal concentration of 1.22/10 larvae (95% fiducial limit 4.71–11.45) in the 3rd instar larvae after 72 h. Similarly, in 4th instar larvae of S. litura, the highest concentration (1.5% concentration) of B. thuringiensis caused maximum 76 ± 0.23% larval mortality, followed by B. bassiana and M. anisopliae, causing 70 ± 0.21% and 64 ± 0.20% larval mortality after 120 h. The calculated median lethal concentration in probit analysis demonstrated the lowest LC50 = 1.59/10 larvae (95% FL: 1.08–2.36) in the 4th instar larvae after 72 h. Based on these studies, it was revealed that B. thuringiensis and B. bassiana showed maximum efficacy against S. litura larvae. Although M. anisopliae also exhibits insecticidal properties, all of these bioinsecticides can be used to manage the population of S. litura. These bioinsecticides can be included in integrated pest management programs as they do not pose any toxic hazards to the environment.

Sublethal Doses of Clove Oil Deplete the Energy Reserves and Downregulate the Carbohydrate Metabolizing Enzymes in the 4th Instar Larvae of Trogoderma granarium

Sublethal Doses of Clove Oil Deplete the Energy Reserves and Downregulate the Carbohydrate Metabolizing Enzymes in the 4th Instar Larvae of Trogoderma granarium

Transcriptome Analysis Reveals the Response of Cryptomeria japonica to Feeding Stress of Dendrolimus houi Lajonquière Larvae

The Japanese fir, Cryptomeria japonica, is ecologically and commercially vital in China. However, infestations by Dendrolimus houi Lajonquière larvae cause widespread dieback, mimicking mechanical damage effects, with unclear differential impacts and mechanisms. To address this, 6th instar larvae of D. houi were introduced to three-year-old C. japonica seedlings to induce pest infestation, while mechanical damage and non-infested pests were controlled. Then, next-generation sequencing techniques were employed, and transcriptome sequencing was conducted to analyze the distinct damage mechanisms responding to C. japonica. This study revealed 10,412 DEGs between pest infestation and controls and 5535 DEGs comparing pest infestation to mechanical damage. Functional enrichment analysis highlighted the involvement of these DEGs in crucial processes such as photosynthesis, amino acid and nucleotide metabolism, flavonoid biosynthesis, and plant hormone signaling pathways. In particular, 786 unique DEGs were discerned in pest-infested samples. Key enriched pathways, such as pyruvate and propionate metabolism, were pinpointed, with flavonoid biosynthesis potentially closely linked to pest-feeding inductions. These findings provided valuable insights into the molecular responses of C. japonica to D. houi infestation, laying the foundation for future research aimed at developing pest-resistant varieties of Japanese fir.

Endophytic fungus Alternaria macrospora: A promising and eco-friendly source for controlling Aedes aegypti and its toxicity assessment on non-targeted organism, zebrafish (Danio rerio) embryos

Fungal compounds are believed to be the most efficient method of addressing challenges with pesticide resistance and contamination of the environment. The present study was aimed to evaluate the larvicidal, pupicidal, ovicidal, histopathology profile, antibacterial, cytotoxic effects of cervical cancerous cells and its toxicity assessments using zebrafish embryo (Danio rerio). The isolates were confirmed by macroscopic, microscopic and PCR using a universal internal transcribed spacer primer for the molecular identification of the isolated fungus at the species level (GenBank - MN049541). The isolated fungus was first tested for its ability to produce toxic compounds in Aedes aegpti larvae in the 1–4th instar. For each instar of determined mosquito larvae, the secondary metabolites were evaluated in different bioassays at different test concentrations (100–500 μg/mL). The lethal concentrations of A. macrospora mycelial ethyl acetate extract that kill 50% of exposed larvae (LC50) and 90% of exposed larvae (LC90) were found in the first, second, third, and fourth instar larvae of A. aegypti (LC50 = 96.167, 131.370, 217.595, and 143.864 μg/mL and (LC90 = 395.16, 483.692, 882.545, and 655.722 μg/mL). After 120 h of exposure, the ovicidal bioassay's mean (%) was observed. A dose-dependent pattern was found in the enzymatic level of acetylcholinesterase in 4th instar larvae exposed to fungal mycelial metabolites. The treatment of 500 μg/mL of mycelia metabolites produced significant histopathological damage in the 4th instar mosquito larvae. The highest growth inhibition zones were observed during the antibacterial investigation of Alternaria macrospora metabolites against E. coli (22 mm) and S. aureus (20 mm). Also, the detected mycelium metabolites were tested for docking studies to identify their binding ability towards the E. coli FimH and S. aureus tyrosyl-RNA synthetase protein. The mycelium metabolites with different concentrations were further tested in the in-vivo zebrafish model to evaluate developmental toxicity. This is the first report on mosquito larvicidal and pupicidal activity of ethyl acetate metabolites produced by A. macrospora species. The study findings demonstrate that A. macrospora metabolites might be an ideal, cheap, small, and environmentally suitable source for controlling A. aegypti larvae.

Permethrin Contamination of Sawgrass Marshes and Potential Risk for the Imperiled Klot's Skipper Butterfly (Euphyes pilatka klotsi).

Nontarget effects from mosquito control operations are possible in habitats adjacent to areas targeted by ultra-low-volume (ULV) sprays of permethrin for adult mosquito control. We assessed the risks of permethrin exposure to butterflies, particularly the imperiled Klot's skipper, when exposed to ground-based ULV sprays. Samples of larval host plant leaves (sawgrass) were collected in June (in mosquito season) and January (outside mosquito season) of 2015 from sawgrass marsh habitats of the National Key Deer Wildlife Refuge (Big Pine Key, FL, USA) and analyzed for permethrin. Permethrin detection was higher in June (detected on 70% of samples) than in January (30%), and concentrations were significantly higher in June (geomean = 2.1 ng/g, median = 2.4) relative to January (0.4 ng/g, median = 0.2). Dietary risk for 4th to 5th-instar larvae was low based on the measured residues. The AGricultural DISPersal model (Ver. 8.26) was used to estimate permethrin residues on sawgrass following ULV sprays (deposited residues) to estimate immediate postspray risk. Estimated deposited residues (33-543 ng/g) were much higher than measured residues, which leads to a higher risk likelihood for butterfly larvae immediately after ULV sprays. The difference between estimated and measured residues, and between the two risk estimations, reflects uncertainty in risk estimates based on the measured residues. Research on modeling deposited pesticide residues following ground-based ULV spray is limited. More research on estimating deposited pesticide residues from truck-mounted ULV sprayers could help reduce uncertainty in the risk predictions for nontarget insects like butterflies. Environ Toxicol Chem 2024;43:267-278. Published 2023. This article is a U.S. Government work and is in the public domain in the USA. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Biocontrol potential of entomopathogenic nematode, Heterorhabditis indica against pink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae)

BackgroundThe emergence of pink bollworm (PBW), Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae), in cotton due to Bt resistance and concealed feeding habit has created a need for alternative, eco-friendly, and cost-effective control methods. This study aimed to evaluate the bio-efficacy and reproductive potential of two native strains of entomopathogenic nematodes (EPNs), Heterorhabditis indica, namely CICR-HI-CL and CICR-HI-MN, against PBW larvae and pupae under in-vitro conditions.ResultsThe larval assay revealed that strain CICR-HI-CL exhibited higher potency than strain CICR-HI-MN against 2nd, 3rd, and 4th instar larvae, with median lethal dose (LD50) values of 5.45, 4.45, and 4.60 infective juveniles (IJs) per larva, respectively. In case of pupal bioassay, both EPN strains demonstrated greater virulence when applied directly (LD50 values: 29.65 and 73.88 IJs per pupa for strains CICR-HI-CL and CICR-HI-MN, respectively) compared to soil application (147.84 and 272.38 IJs per pupa). Both EPN strains successfully penetrated and reproduced on 4th instar larvae, resulting in maximum production of 19.28 and 20.85 lakh IJs per larva in the next generation when inoculated at 30 IJs per larva.ConclusionThe present study has generated useful information on the virulence and reproductive potential of two strains of EPN H. indica (CICR-HI-CL and CICR-HI-MN) against PBW, a dreaded pest of cotton. Higher virulence and reproductive potential of EPN strains demonstrated their ability to multiply, sustain and perpetuate on larval and pupal stages of PBW. The knowledge generated will help formulate effective management strategies for PBW with the inclusion of EPN as a potential biological control candidate. The soil-dwelling life stages viz., last instar hibernating larvae and pupae of PBW can be the ideal weak links to make a successful use of H. indica for sustainable management of PBW in the cotton ecosystem. However, before taking these EPN strains to field for managing PBW, detailed studies investigating their biocontrol potential against PBW under field conditions are needed.

Distribution and accumulation of Cadmium in different trophic levels affecting Serangium japonicum, the predatory beetle of whitefly Bemisia tabaci, biologically, physiologically and genetically: An experimental study

Cadmium (Cd) is a heavy metal that is of great concern in agroecosystems due to its toxicity to plants, herbivores, carnivores, and human beings. The current study evaluated the allocation and bioaccumulation of Cd from soil to cotton plants, cotton plants to herbivore pests, and herbivorous pests to a natural enemy predator. When soil was spiked with 100 mg/kg Cd, results demonstrated that cotton roots accumulated more Cd than the stems and leaves. The bioaccumulation of Cd was less in 4th instar larvae, pupa, and adults of Serangium japonicum than in Bemisia tabaci adults. The bioaccumulation in S. japonicum elongated the immature development period and reduced adult longevity, oviposition days, fertility, and total pre-oviposition duration. The net reproduction of S. japonicum was also reduced, as was female mature weight and feeding potential; as a result, Cd exposure could reduce the future population size compared to uncontaminated populations. There was decreased activity of the antioxidant enzymes (SOD, CAT, and POD) and energy-conserving lipids (glycogen, triglyceride, and total cholesterol) in Cd-contaminated S. japonicum compared to controls. The detoxifying enzyme activity of GST and P450 increased while AChE activity did not change. The qRT-PCR research showed that SOD1, CAT, POD, glycogen, and triglyceride gene expression was higher than in controls, whereas detoxification gene expression did not change. Our results indicate that Cd exposure has a physiological trade-off between its adverse effects on life history traits and elevated detoxification and antioxidation of S. japonicum, which could result from gene expression alteration. Further studies are needed to assess whether Cd exposure causes irreversible DNA damage in S. japonicum.

Design, Characterization and SAR Studies of Novel Bioactive Benzylideneacetophenone Derivatives as Insecticidal Agents against Spodoptera frugiperda (Lepidoptera: Noctuidae).

Unintentional environmental effects brought on by insecticides encourage the creation of safer substitutes. A very polyphagous migrating lepidopteran pest species in Africa called S. Frugiperda causes terrible damage. In the current paper, treatment of 4-acetylphenyl 4-methylbenzenesulfonate with different aromatic aldehydes in the presence of NaOH afforded benzylideneacetophenones. The structure of the newly prepared compounds were proved by different spectroscopic techniques such as IR, 1 H-NMR, 13 C NMR, and elemental analysis. We looked at the association between contact with S. frugiperda and stricture reaction to examine their harmful effect. Additionally, S. frugiperda was used for testing the newly created compounds for their ability to kill insects. The majority of substances have been proven to be effective and promising. It has been found that 4-[3-(4-Methylphenyl)prop-2-enoyl]phenyl-4-methyl benzenesulfonate (4) was the most active with an LC50 =3.46 mg/L of 2nd instar larvae and LC50 =9.45 mg/L of 4th instar larvae. Moreover, some of biological and histopathological aspects of the synthesized products were investigated under laboratory conditions.

Effect of Diatomaceous Earth (DE) Against the Stored Product Beetles, Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae) under Laboratory Conditions

Studies on the control of the saw-toothed grain beetle Oryzaephilus surinamensis with a commercial formulation of the Diatomaceous Earth or diatomite (D); (silicon dioxide made up of fossilised diatoms) were carried out at the Entomology Laboratory at a relative humidity of 50 ± 5%, and ambient temperature of 28 ± 2 °C. Laboratory experiments were applied to assess the efficacy of Diatomaceous Earth dust; silicon dioxide commercially on 2nd-5th instar larvae and adults of O. surinamensis. Three concentrations of Diatomaceous Earth (DE) were weighed (2, 3, and 4 grams), and each concentration was mixed with 100 grams of amber rice grains. Beetles were fed on amber rice grains treated with (DE). The results showed that Diatomaceous Earth (DE) was significantly effective at all tested concentrations after 7 days post-treatment. Nevertheless, susceptibility showed visible significant differences in the mortality level on the last day of the tests between adults, 2nd, 5th instar larvae which were treated with three (DE) concentrations. Adults were least susceptible, while 2nd and 5th instar larvae were most susceptible to DE. All Diatomaceous Earth (DE) was significant and more effective on insect life at a higher concentration of 4 g/100 kg, where the mortality proportion was 100%, 99.50% for 2nd, and 5th instar larvae, respectively, and 97.50% for an adult after 5 days post-treatment. However, all O. surinamensis life stages’ mortality percentages reached 100% after 7 days post-treatment. Consequently, due to the effectiveness of this Diatomaceous Earth on different life stages of O. surinamensis, they could be recommended for the management of this insect. Furthermore, to achieve more effective control over this beetle, formulation of the Diatomaceous Earth (DE); Silicon dioxide, could be used since it appeared to be most effective and consistence in its action against different life stages of the beetle. Lastly, the possibility of using Diatomaceous earth to manage stored-product insects has been debated.

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.

A green alternative: Evaluation of Solanum torvum (Sw.) leaf extract for control of Aedes aegypti (L.) and its molecular docking potential

Due to the unavailability of effective vaccines and treatments, mosquito-borne diseases continue to pose a threat to global public health. Insecticide-treated mosquito nets and room sprays have both been successfully treated with plant-based biopesticides to protect people from mosquito bites. The extensive use of chemical pesticides is known to cause serious harm to human and animal health. From this point of view, the demand for plant extracts has recently increased worldwide. The aim of the current study was to determine the effectiveness of a Solanum torvum (Sw.) leaf extract as a larvicidal, adulticidal and in silico study against the mosquito Aedes aegypti. The plant extract from S. torvum was obtained using a simple method. Preliminary qualitative analysis shows the presence of steroids, saponins, phenol, flavonoids, tannins, and anthraquinones in the aqueous leaf extract of S. torvum. A total, 15 compounds were identified using GC–MS. The larvicidal activity, observed during 24-h and 48-h exposure cycles of 4th instar larvae, exhibits a maximum (100 ​%) mortality rate at 200 ​μg/ml. The adulticidal activity, observed during the 24-h exposure cycle of adult mosquitoes, exhibits a maximum (92 ​%) mortality rate at 2 ​mg/mL. The molecular docking observation of Protease Sterol Carrier Protein-2 (IPZ4) was noted campesterol had the most favourable docking score with a value of −10. This finding suggests that campesterol may have a high affinity for the target molecule under study. Based on the results, the current study suggests that the use of S. torvum leaf extract could serve as an environmentally friendly alternative to chemical insecticides in controlling mosquito populations and controlling mosquito bone diseases.

Phenolics from Nigella sativa L. straw: Characterization and insecticidal activity against Agrotis ipsilon (Hüfnagel)

The excessive production of food and agro-waste has become a significant problem for society, the economy, and the environment. To meet the growing demand for food free from harmful synthetic insecticides, a recent study has investigated the potential use of an ethanolic extract obtained from the straw of Nigella sativa L., a byproduct of seed collection, as a bioinsecticide. The study also evaluated its in-vitro and in-silico acetylcholinesterase (AChE) inhibitory potential against the Agrotis ipsilon (Hufnagel) moth species, which is known to cause damage to various crops and ornamental plants. The high-performance liquid chromatography examination revealed that the ethanolic N. sativa straw extract contained 18 phenolics, including 3 simple phenols, 8 phenolic acids, and 7 flavonoids. Catechol (330.14 μg/ml), chlorogenic (169.23 μg/ml), and gallic (110.93 μg/ml) acids were the predominant phenolics. On the other hand, catechin (94.07 μg/ml), naringenin (91.99 μg/ml), and rutin (78.16 μg/ml) were the major flavonoids identified in the extract. The insecticidal activity of the extract against the 4th larval instar of A. ipsilon was evaluated using four concentrations (1.25–10 %). The study found that higher extract concentrations led to increased mortality in the larvae. Specifically, the concentration of 10 % resulted in the highest mortality rate of 96.67 %. Lower concentrations of 5 %, 2.5 %, and 1.25 % resulted in mortality rates of 51.11 %, 18.89 %, and 9.17 %, respectively. The extract also showed higher activity against AChE in larval tissue, with an inhibition percentage of 65.2 % after 24 h of treatment. Docking experiments confirmed that ellagic acid and apigenin had higher binding affinity than the control (lanate). These results demonstrate the potential of utilizing agricultural waste like N. sativa straw to create innovative and sustainable bioinsecticides.

Will climate affect the establishment and efficacy of Agnippe sp. #1 (Lepidoptera: Gelechiidae), a promising biological control agent of Mesquite in South Africa?

Several spiny leguminous tree species within the genus Neltuma Raf. (formerly Prosopis L.) (Fabaceae) occur as widespread invasive alien plants in South Africa, exerting severe negative socio-economic and ecological impacts. Given these impacts, South Africa recently released the leaf-tying moth Agnippe sp. #1 (syn. Evippe sp. #1) (Lepidoptera: Gelechiidae) as a biological control agent against invasive Neltuma species in 2021. The widespread invasion of Neltuma spp. across a vast and climatically diverse range of South Africa has led to concerns regarding the establishment and impact of the agent. Therefore, this study aimed to assess the constraints posed by climate to the potential establishment and efficacy of Agnippe sp. #1 using both climatic matching (CLIMEX) and thermal-physiology assessments. Climatic analyses revealed relatively high (71%) and moderate (66%) matches of South Africa to the native (Argentina) and introduced (Australia) ranges of Agnippe sp. #1 respectively. Thermal assessments of Agnippe sp. #1, particularly the 4th instar larvae, determined a CTmin = 0.9 ± 0.3 °C and LLT50 = −11.1 ± 0.4 °C, which suggest the moth is suited mainly to warmer regions of South Africa. Overall, these assessments propose that the establishment and performance of Agnippe sp. #1 is likely to be constrained by climate in parts of South Africa, particularly within the cold semi-arid and temperate provinces of the country. Promisingly, these climatic comparisons suggest that Agnippe sp. #1 may become more widely established in the hottest parts of the Northern Cape province, which remains a major biological control target region for Mesquite in South Africa.

Synthesis and Insecticidal Assessment of Some Innovative Heterocycles Incorporating a Pyrazole Moiety

The compound 1,3-diphenyl-1H-pyrazole-4-carbaldehyde (1) was utilized as a fundamental component in the synthesis of novel N-phenyl pyrazole derivatives. Substituted N-phenyl pyrazole compounds including 2-cyano-3-(1,3-diphenyl-1H-pyrazol-4-yl)-N-Substituted-acrylamide derivatives (4a–h), 4-(hydrazineylidenemethyl)-1,3-diphenyl-1H-pyrazole (6) and 2-cyano-N'-((1,3-diphenyl-1H-pyrazol-4-yl)methylene)-acetohydrazide (11) were obtained in moderate yields through the reaction of 1 with 2-cyano-N-substituted acetamide derivatives 3a–h, hydrazine hydrate, and cyanoacetohydrazide under basic-catalyzed conditions, respectively. Moreover, hydrazinyl-pyarzole 6 reacted with 4,5,6,7-tetrabromoisobenzofuran-1,3-dione (7) to afford 4,5,6,7-tetrabromo-2-(((1,3-diphenyl-1H-pyrazol-4-yl)methylene)amino)- isoindoline-1,3-dione (8). Furthermore, pyrazoloacetohydrazide 11 is condensed with salicylaldehyde derivatives 12a–e to give pyrazolochromene carbohydrazide derivatives 13a–e. Also, acetohydrazide 11 refluxed with N, N-dimethylformamide dimethyl acetal to produce 2-cyano-3-(dimethylamino)-N'-((1,3-diphenyl-1H-pyrazol-4-yl)methylene)acrylohydrazide (15), which upon exposure to acidic conditions underwent cyclization to form 4-((dimethylamino)methylene)-6-(1,3-diphenyl-1H-pyrazol-4-yl)pyridazine-3,5(4H,6H)-dione (16). The newly synthesized compounds were identified and confirmed using elemental and spectral data analyses as IR, MS, 1H NMR, 13C NMR, and 2D NMR analysis (H-H COSY, HSQC, HMBC, and NOSEY), Also, DFT studies were done to prove the geometrical optimization and spatial distributions orbitals of compounds 4a and 11. The toxicity of N-phenylpyrazole compounds was tested against the corn leaf aphid (Rhopalosiphum maidis) and the mealy plum aphid (Hyalopterus pruni). Compounds 4c, 13c, and 13d were found to be the most potent to control the two insects compared with acetamiprid 20% SP recommended by the Ministry of Agriculture. The biochemical investigation of insects was studied to the most effective compounds on insects as well, and the toxicity of compounds 4c, 13c, and 13d was studied on the predators (Hippodamia variegata, Cydonia vicina isis, Cydonia vicina nilotica, and 4th instar larvae H. variegata) under laboratory conditions.

Evaluation of the Efficacy of Commercial and Local Entomopathogenic Fungi Metarhizium anisopliae Against Ephestia cautella (Lepidoptera: Pyralida) under Lab Conditions

The Ephestia cautella (Walk) (Lepidoptera: Pyralida) is a crucial insect of storage products worldwide. The experiments were conducted to assess Entomopathogenic Fungi (EPFs) (two isolates) with commercial formulations, Met 52 EC (Metarhizium anisopliae strain F52) and local entomopathogenic fungal isolates against Ephestia cautella. Commercial formulations of entomopathogenic fungal M. anisopliae affected the main mortality levels in the E.cautella adult at all three sporal concentrations (2×104, 2×106, 2×108 spore/ml), compared to the local isolates of M. anisopliae. Corrected mortality of E.cautella adult caused by both Commercial and local M. anisopliae 7 days after exposure at 2 × 108 spore/ml was 32±1.3 and 48 ± 1.4 %, respectively. 2nd, 5th instar larvae had a higher mortality level than the adults of E. cautella. The results reveal that Entomopathogenic Fungi isolated from the UK and Iraq can be applied as the microbial bio-agent control against E. castella. Consequently, more studies are required to develop commercial Entomopathogenic Fungi of naturally isolated.

Larvicidal effect of <i>Pongamia pinnata</i> plant extracts against <i>Papilio demoleus</i> Linnaeus (Insecta: Lepidoptera: Papilionidae)

Larvae of the citrus butterfly, Papilio demoleus are serious pests in citrus orchards. Since synthetic pesticides have several ill effects on human health and the ecosystem, biopesticides are feasible alternative to synthetic pesticides. Indian beech tree, Pongamia pinnata plant extracts are well known for their medicinal and pesticidal properties. So, a study was carried out to evaluate P. pinnata plant’s aqueous leaf and seed extracts, and seed oil nanoemulsion at 25, 50, 100, 200, and 400 PPM concentrations against the 4th instar larvae of P. demoleus. All three test compounds showed concentration-dependent larvicidal activity. Comparatively, leaf extracts showed better larvicidal activity than seed extracts and nanoemulsion of the seed oil. The highest mortality was observed with leaf, seed extracts, and seed oil emulsions at 82.61%, 78.26%, and 73.91% respectively, at 400 PPM concentration. LC50 and LC90 values were lowest for leaf extracts (57.97 and 855.93 PPM), while the highest for seed oil nanoemulsion (107.09 and 1947.90 PPM). This is the first report of the efficacy P. pinnata leaf and seed extracts and seed oil nano emulsions against 4th instar larvae of P. demoleus.

Insecticidal Efficiency of Some Pesticides Against Spodoptera Frugiperda (J.E. Smith) (Noctuidae: Lepidoptera) Under Laboratory Conditions

The "fall armyworm," also known as Spodoptera frugiperda, is a maize pest that is native to North America. It invaded Africa in 2019 and caused serious economic damage, forcing the continent's nations to take swift action to protect off this new invading pest. In Egypt, a variety of chemical insecticides were promoted, but farmers quickly and repeatedly reported control failures. Fall armyworm samples were collected from five different maize-growing regions. Five widely available pesticide formulations: emamectin benzoate, chlorantraniliprole, indoxacarb, methomyl, and chlorpyriphos were tested under laboratory conditions against the 2nd and 4th instar larvae. The results demonstrated that S. frugiperda second-instar larvae were more vulnerable to all tested pesticides than fourth-instar larvae. Under laboratory circumstances, the LC50 values for the various substances were 0.090, 0.165, 0.243, 0.908, and 2.55 ppm, respectively. Furthermore, the insecticide emamectin benzoate was more effective than other pesticides. However, chlorpyriphos pesticide was the least harmful insecticide for controlling this bug. To determine how well these treatments perform against this pest, further trials are required.