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17 pages, 4500 KiB

Open AccessArticle

The Frequency and Spread of a GABA-Gated Chloride Channel Target-Site Mutation and Its Impact on the Efficacy of Ethiprole Against Neotropical Brown Stink Bug, Euschistus heros (Hemiptera: Pentatomidae)

by Ana C. P. Cuenca, Bettina Lueke, Renato Vicentini and Ralf Nauen

Insects 2025, 16(4), 422; https://doi.org/10.3390/insects16040422 - 17 Apr 2025

Viewed by 317

Abstract

The Neotropical brown stink bug (NBSB), Euschistus heros, is the most prevalent sucking soybean pest in Brazil, and control of it largely relies on the application of synthetic insecticides such as ethiprole, a phenylpyrazole insecticide targeting GABA-gated chloride channels encoded by the [...] Read more.

The Neotropical brown stink bug (NBSB), Euschistus heros, is the most prevalent sucking soybean pest in Brazil, and control of it largely relies on the application of synthetic insecticides such as ethiprole, a phenylpyrazole insecticide targeting GABA-gated chloride channels encoded by the Rdl (resistant to dieldrin) gene. This study monitored 41 NBSB populations collected between 2021 and 2024 and revealed, for the first time, the presence of a mutation, A301S, in NBSB RDL receptors commonly known to confer target-site resistance to channel blockers such as phenylpyrazoles. Laboratory contact bioassays with ethiprole at 150 g a.i./ha (ethiprole label dose) revealed that most populations were quite susceptible, despite rather high resistance allele frequencies in some populations. Genotyping results confirmed that susceptible and A301S heterozygous genotypes largely dominate in frequency compared to homozygous resistant individuals, which exhibited high survivorship (84%) when exposed to discriminating rates of ethiprole in laboratory bioassays, while susceptible and heterozygote individuals showed lower survival rates (13% and 34%, respectively), suggesting an incompletely recessive trait conferring ethiprole resistance. Furthermore, we developed a TaqMan assay for molecular genotyping to monitor the spread of resistance allele frequency and to inform resistance management strategies for sustainable NBSB control using highly effective phenylpyrazole insecticides such as ethiprole. Full article

(This article belongs to the Special Issue Chemical Toxicology and Insecticide Resistance on Insect Pests)

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12 pages, 1771 KiB

Open AccessArticle

Direct and Indirect Effects of Ivermectin on Phytophagous, Frugivorous and Parasitoid Insects

by Lars Laber, Nico Blüthgen and Karsten Mody

Insects 2025, 16(4), 366; https://doi.org/10.3390/insects16040366 - 1 Apr 2025

Viewed by 467

Abstract

Ivermectin, an anthelmintic used in livestock, is excreted in faeces and can therefore affect non-target organisms. While its effects on coprophagous insects have been well studied, recent research suggests that it can be taken up by plants, raising the possibility that it may [...] Read more.

Ivermectin, an anthelmintic used in livestock, is excreted in faeces and can therefore affect non-target organisms. While its effects on coprophagous insects have been well studied, recent research suggests that it can be taken up by plants, raising the possibility that it may affect a much wider range of invertebrates than previously known. Our study investigated the effects of ivermectin on insects from different feeding guilds. First, we tested its effects on the larvae of the noctuid moths Spodoptera frugiperda and Helicoverpa armigera (chewing herbivores) using an artificial diet. Secondly, we investigated the effects of its presence in the soil of pea plants Pisum sativum on the pea-feeding aphid Acyrthosiphon pisum (phloem-feeding herbivore). Thirdly, we tested ivermectin in an artificial diet for Drosophila melanogaster used as a host for the parasitoid Pachycrepoideus vindemmiae. Our results showed that ivermectin reduced pupal weight and survival in moth larvae, inhibited aphid colony establishment and reduced parasitoid emergence rates from ivermectin-exposed Drosophila pupae. These results highlight the potential of ivermectin to affect multiple trophic levels and emphasise the need for sustainable veterinary practices in the use of anthelmintics in free-ranging livestock and companion animals. Full article

(This article belongs to the Special Issue Chemical Toxicology and Insecticide Resistance on Insect Pests)

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12 pages, 935 KiB

Open AccessArticle

Toxicity and Sublethal Effects of Lambda-Cyhalothrin Insecticide on Parent and Filial Generations of Henosepilachna vigintioctomaculata (Coleoptera: Coccinellidae)

by Wenbo Li, Muhammad Naeem, Juan Cui, Guochuan Du and Huanhuan Chen

Insects 2025, 16(3), 259; https://doi.org/10.3390/insects16030259 - 3 Mar 2025

Viewed by 662

Abstract

Lambda-cyhalothrin is a synthetic pyrethroid insecticide that is widely used to control leaf-eating pests. Because of increased insecticide resistance, an understanding of sublethal cross-generational effects of insecticides is important. We examine the effects of sublethal concentrations (SLCs) (LC₁₀, LC₂₀, [...] Read more.

Lambda-cyhalothrin is a synthetic pyrethroid insecticide that is widely used to control leaf-eating pests. Because of increased insecticide resistance, an understanding of sublethal cross-generational effects of insecticides is important. We examine the effects of sublethal concentrations (SLCs) (LC₁₀, LC₂₀, and LC₄₀) of lambda-cyhalothrin on the growth, reproduction, and detoxification enzyme activities of F₀ and F₁ generation Henosepilachna vigintioctomaculata. Lambda-cyhalothrin is toxic to adult H. vigintioctomaculata, with an LC₄₀ at 48 h of 0.355 mg L⁻¹. At SLCs, lambda-cyhalothrin significantly reduces the longevity and average fecundity of F₀ and F₁ adults, and prolongs the durations of the egg, larval, and pupal stages and adult preoviposition period. Additionally, an increased lambda-cyhalothrin concentration significantly decreases net reproductive rates, and both finite and intrinsic rates of increase in the F₁ generation, and significantly increases the average generation cycle. The detoxification enzyme activity of F₁ adults treated with SLCs of lambda-cyhalothrin for 48 h trends upwards. Results indicate that low concentrations of lambda-cyhalothrin induce glutathione S-transferase and carboxylesterase activities and inhibit multifunctional oxidase activity. The growth, development, and reproduction of the H. viltioctomaculata F₁ population remain inhibited by lambda-cyhalothrin treatment in the adult stage, and inhibitory effects increase with increased lambda-cyhalothrin concentration. The control efficacy of lambda-cyhalothrin against H. viltioctomaculata shows cross-generational effects. Full article

(This article belongs to the Special Issue Chemical Toxicology and Insecticide Resistance on Insect Pests)

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16 pages, 3952 KiB

Open AccessArticle

The Impact of Systemic Insecticides: Cyantraniliprole and Flupyradifurone on the Mortality of Athalia rosae (Hymenoptera: Tenthredinidae) Based on the Biophoton-Emission of Oilseed Rape

by Bálint Gerbovits, Ildikó Jócsák and Sándor Keszthelyi

Insects 2025, 16(1), 35; https://doi.org/10.3390/insects16010035 - 1 Jan 2025

Viewed by 916

Abstract

The selection of an appropriate and targeted crop protection technology for winter oilseed rape is crucial for the economic production of this crop. Insecticides belonging to the group of diamides and butenolides are available as seed treatments for winter oilseed rape and serve [...] Read more.

The selection of an appropriate and targeted crop protection technology for winter oilseed rape is crucial for the economic production of this crop. Insecticides belonging to the group of diamides and butenolides are available as seed treatments for winter oilseed rape and serve as effective tools for chemical crop protection. The objective of this study was to determine the multi-directional applicability of the active ingredients cyantraniliprole and flupyradifurone. Furthermore, the phenotypic detection of stress was conducted for these systemic insecticides. The results of our study show that these active ingredients acropetal and basipetal translocation are both effective against Athalia rosae (L. 1758) (Hymenoptera: Tenthredinidae). The findings from our laboratory studies indicated that the insecticidal active ingredients are effective against Athalia rosae (Hymenoptera: Tenthredinidae) via both acropetal and basipetal translocation. However, differences in the time of exertion of lethal effect were recorded. In both experimental groups, mortality was observed to reach 100% at the 96-h mark, regardless of the specific experimental conditions or the insecticide employed. An examination of the bio-photon emission of the experimental plants revealed a statistically verifiable correlation between the applied active ingredients and the photon emission intensity per unit plant surface area. The findings of our study indicate that due to their insecticidal activity, systemic insecticides also affect plant life processes by increasing photosynthetic activity per unit leaf area. Full article

(This article belongs to the Special Issue Chemical Toxicology and Insecticide Resistance on Insect Pests)

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15 pages, 3073 KiB

Open AccessArticle

Impacts of Sublethal Doses of Spinetoram on the Biological Traits and Detoxifying Enzymes of the Tomato Leaf Miner, Tuta absoluta (Lepidoptera: Gelechiidae)

by Mingjun Jiang, Xiujuan Qian, Zhaoxu Zhou, Yueying Liu, Meijiao Zhang and Yaxian Yang

Insects 2024, 15(12), 990; https://doi.org/10.3390/insects15120990 - 13 Dec 2024

Cited by 3 | Viewed by 1170

Abstract

Tuta absoluta is a major pest, damaging tomato crops in many countries. Spinetoram, a novel insecticide, is increasingly used for the management of various insect pests. However, limited information is available on its lethal effects on T. absoluta. Therefore, this study was [...] Read more.

Tuta absoluta is a major pest, damaging tomato crops in many countries. Spinetoram, a novel insecticide, is increasingly used for the management of various insect pests. However, limited information is available on its lethal effects on T. absoluta. Therefore, this study was carried out to evaluate the toxicity of spinetoram concentrations in T. absoluta by exposing third-instar larvae to this insecticide through leaf-dipping bioassays under laboratory conditions. The results showed that sublethal spinetoram concentrations (LC₁₀ and LC₂₀) extended the developmental duration of the larval and pupal stage, as well as the oviposition period, and decreased the pupal weight, pupation and eclosion rates, fecundity, sex ratio, and egg-hatching rate compared to the control group. LC₁₀ and LC₂₀ treatments up-regulated the activity of superoxide dismutase and catalase antioxidant enzymes in T. absoluta larvae by 51.14–88.72% and 39.34–87.76% at 12 h, 62.71–96.68% and 37.38–39.92% at 24 h, and 41.78–53.34% and 19.44–48.39% at 48 h, respectively, compared to the control. Conversely, the LC₁₀ and LC₂₀ treatments inhibited the activities of detoxifying enzymes, i.e., carboxylesterase (14.72–34.95%), acetylcholinesterase (9.02–48.86%), glutathione S-transferase (19.40–43.19%), and mixed-function oxidase (18.18–25.93%). These findings indicate that lethal concentrations of spinetoram influence the population dynamics of T. absoluta by reducing their survival and developmental potential and inhibiting the activity of detoxifying enzymes. Full article

(This article belongs to the Special Issue Chemical Toxicology and Insecticide Resistance on Insect Pests)

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13 pages, 2567 KiB

Open AccessArticle

Toxicity and Sublethal Effect of Chlorantraniliprole on Multiple Generations of Aedes aegypti L. (Diptera: Culicidae)

by Nimra Batool, Muhammad Abubakar, Ahmed Noureldeen, Muhammad Nadir Naqqash, Akram Alghamdi, Zamzam M. Al Dhafar, Fadi Baakdah and Raimondas Mozūratis

Insects 2024, 15(11), 851; https://doi.org/10.3390/insects15110851 - 30 Oct 2024

Cited by 1 | Viewed by 1251

Abstract

Due to the quick development of insecticide resistance, it is crucial to optimize management programs by understanding the sublethal effects of effective insecticides like chlorantraniliprole on Aedes aegypti L. populations. Using age-stage and two-sex life tables, we investigated the sublethal impacts of chlorantraniliprole [...] Read more.

Due to the quick development of insecticide resistance, it is crucial to optimize management programs by understanding the sublethal effects of effective insecticides like chlorantraniliprole on Aedes aegypti L. populations. Using age-stage and two-sex life tables, we investigated the sublethal impacts of chlorantraniliprole on Ae. aegypti. Larval duration in the progeny of exposed parents was reduced by 0.33–0.42 days, whereas, the longevity of male and female adults was decreased by 1.43–3.05 days. Similarly, the egg-laying capacity of F₁ and F₂ progeny of the exposed parents was significantly reduced from 27.3% to 41.2%. The mean generation time (T) increased up to 11.8% in exposed populations, and the net reproduction rate (Ro) decreased by 51.50–55.60%. After 24 h of chlorantraniliprole treatment, there was a significant increase in cytochrome P450 activity. Contrarily, the activity of glutathione S-transferase (GST) initially declined but started increasing after 48 h of treatment. This research highlights the importance of chlorantraniliprole in mosquito management, as well as the importance of considering sublethal effects when developing strategies to handle them. Having a thorough understanding of the harmful effects of insecticides on mosquito populations can greatly enhance the effectiveness of insecticide-based interventions, while also minimizing the risk of pest resurgence. Full article

(This article belongs to the Special Issue Chemical Toxicology and Insecticide Resistance on Insect Pests)

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16 pages, 3272 KiB

Open AccessArticle

RNAseq-Based Carboxylesterase Nl-EST1 Gene Expression Plasticity Identification and Its Potential Involvement in Fenobucarb Resistance in the Brown Planthopper Nilaparvata lugens

by Murtaza Khan, Changhee Han, Nakjung Choi and Juil Kim

Insects 2024, 15(10), 743; https://doi.org/10.3390/insects15100743 - 26 Sep 2024

Cited by 2 | Viewed by 1061

Abstract

Carbamate insecticides have been used for over four decades to control brown planthopper, Nilaparvata lugens, but resistance has been reported in many countries, including the Republic of Korea. The bioassay results on resistance to fenobucarb showed that the LC₅₀ values were [...] Read more.

Carbamate insecticides have been used for over four decades to control brown planthopper, Nilaparvata lugens, but resistance has been reported in many countries, including the Republic of Korea. The bioassay results on resistance to fenobucarb showed that the LC₅₀ values were 3.08 for the susceptible strain, 10.06 for the 2015 strain, and 73.98 mg/L for the 2019 strain. Compared to the susceptible strain, the 2015 and 2019 strains exhibited resistance levels 3.27 and 24.02 times higher, respectively. To elucidate the reason for the varying levels of resistance to fenobucarb in these strains, mutations in the acetylcholinesterase 1 (ACE1) gene, the target gene of carbamate, were investigated, but no previously reported mutations were confirmed. Through RNA-seq analysis focusing on the expression of detoxification enzyme genes as an alternative resistance mechanism, it was found that the carboxylesterase gene Nl-EST1 was overexpressed 2.4 times in the 2015 strain and 4.7 times in the 2019 strain compared to the susceptible strain. This indicates a strong correlation between the level of resistance development in each strain and the expression level of Nl-EST1. Previously, Nl-EST1 was reported in an organophosphorus insecticide-resistant strain of Sri Lanka 2000. Thus, Nl-EST1 is crucial for developing resistance to organophosphorus and carbamate insecticides. Resistance-related genes such as Nl-EST1 could serve as expression markers for resistance diagnosis, and can apply to integrated resistance management of N. lugens. Full article

(This article belongs to the Special Issue Chemical Toxicology and Insecticide Resistance on Insect Pests)

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12 pages, 1008 KiB

Open AccessArticle

Repellent Effects of Coconut Fatty Acid Methyl Esters and Their Blends with Bioactive Volatiles on Winged Myzus persicae (Sulzer) Aphids (Hemiptera: Aphididae)

by Félix Martín, Pedro Guirao and María Jesús Pascual-Villalobos

Insects 2024, 15(9), 731; https://doi.org/10.3390/insects15090731 - 23 Sep 2024

Viewed by 1324

Abstract

Myzus persicae (Sulzer) (Hemiptera: Aphididae) is one of the most important aphid crop pests, due to its direct damage and its ability to transmit viral diseases in crops. The objective is to test whether spraying nanoemulsions of botanical products repels winged individuals of [...] Read more.

Myzus persicae (Sulzer) (Hemiptera: Aphididae) is one of the most important aphid crop pests, due to its direct damage and its ability to transmit viral diseases in crops. The objective is to test whether spraying nanoemulsions of botanical products repels winged individuals of M. persicae in a bioassay in culture chambers. The bioactive volatiles were applied on pepper plants at a dose of 0.2% alone or at 0.1% of each component in blends. A treated plant and a control plant were placed at each side of an entomological cage inside a growth chamber. The winged individuals were released between the plants, in a black-painted Petri dish suspended by wires in the upper half of the cage. The most repellent products were farnesol (repellency index, RI = 40.24%), (E)-anethole (RI = 30.85%) and coconut fatty acid methyl ester (coconut FAME) (RI = 28.93%), alone or in the following blends: farnesol + (E)-anethole + distilled lemon oil (RI = 36.55%) or (E)-anethole + distilled lemon oil + coconut FAME (RI = 30.63%). The observed effect of coconut FAME on aphids is the first report of this product having a repellent effect on a crop pest. Repellent substances for viral disease vectors should be further investigated to develop new strategies for plant protection. Full article

(This article belongs to the Special Issue Chemical Toxicology and Insecticide Resistance on Insect Pests)

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15 pages, 975 KiB

Open AccessArticle

Monitoring and Detection of Insecticide Resistance in Spodoptera frugiperda (Lepidoptera: Noctuidae): Evidence for Field-Evolved Resistance in Egypt

by Moataz A. M. Moustafa, Nourhan A. El-Said, Nawal AbdulAziz Alfuhaid, Fatma M. A. Abo-Elinin, Radwa M. B. Mohamed and Ahmed A. A. Aioub

Insects 2024, 15(9), 705; https://doi.org/10.3390/insects15090705 - 16 Sep 2024

Cited by 7 | Viewed by 2080

Abstract

Spodoptera frugiperda (J.E. Smith) (Noctuidae: Lepidoptera) is a notable insect pest that invades major cereal crops, causing significant damage and loss. Resistances of 2nd instar larvae of two Egyptian field populations of S. frugiperda, collected from the Fayoum and Giza governments, were [...] Read more.

Spodoptera frugiperda (J.E. Smith) (Noctuidae: Lepidoptera) is a notable insect pest that invades major cereal crops, causing significant damage and loss. Resistances of 2nd instar larvae of two Egyptian field populations of S. frugiperda, collected from the Fayoum and Giza governments, were measured against eight insecticides, including traditional insecticides (profenofos and cypermethrin), bio-insecticides (emamectin benzoate, spinosad, and Bacillus thuringiensis), and insect growth regulators (IGRs) (lufenuron, diflubenzuron, and methoxyfenozide). In addition, the synergistic effects of three synergists (Piperonyl butoxide (PBO), diethyl maleate (DEM), and triphenyl phosphate (TPP) were assessed, and the activities of detoxification enzymes (acetylcholine esterase (AChE), cytochrome P-450 (CYP-450), carboxylesterase (CarE), and glutathione-s-transferase (GST) were also determined. Resistance surveillance revealed that the Fayoum field population showed moderate resistance to cypermethrin (RR = 5.75-fold), followed by spinosad (RR = 2.62-fold), and lufenuron (2.01-fold). On the other hand, the Giza population exhibited significant resistance to cypermethrin only (RR = 3.65-fold). Our results revealed that emamectin benzoate was the most effective insecticide, with an LC₅₀ value of 0.003 mg/L for the Fayoum population and 0.001 mg/L for the Giza population, compared to the susceptible strain (0.005 mg/L). Among the biological insecticides, Bacillus thuringiensis was the least toxic insecticide of all the tested strains. Synergism assays indicated that DEM and TPP had the most synergistic effect on spinosad (SR = 8.00-fold for both), followed by PBO (SR = 5.71-fold) for the Fayoum population, compared with spinosad alone. The assay of detoxification enzymes showed that GST activity significantly (p < 0.05) increased in the two field strains compared to the susceptible strain. However, no significant changes were observed among the tested strains in CYP-450, CarE, or AChE. The findings of this study provide substantial insights into tracking and managing the development of insecticide resistance in S. frugiperda in Egypt. Full article

(This article belongs to the Special Issue Chemical Toxicology and Insecticide Resistance on Insect Pests)

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15 pages, 1162 KiB

Open AccessArticle

The Effects of Natural Insecticides on the Green Peach Aphid Myzus persicae (Sulzer) and Its Natural Enemies Propylea quatuordecimpunctata (L.) and Aphidius colemani Viereck

by Francesco Lami, Giovanni Burgio, Serena Magagnoli, Laura Depalo, Alberto Lanzoni, Elettra Frassineti, Ilaria Marotti, Mattia Alpi, Dario Mercatante, Maria Teresa Rodriguez-Estrada, Giovanni Dinelli and Antonio Masetti

Insects 2024, 15(7), 556; https://doi.org/10.3390/insects15070556 - 22 Jul 2024

Cited by 1 | Viewed by 1844

Abstract

Botanical insecticides and soaps are frequently proposed as environmentally safer alternatives to synthetic insecticides. However, the efficacy and selectivity of these products are often only partially supported by empirical evidence. Here, we tested the effectiveness of five botanical insecticides, belonging to different categories, [...] Read more.

Botanical insecticides and soaps are frequently proposed as environmentally safer alternatives to synthetic insecticides. However, the efficacy and selectivity of these products are often only partially supported by empirical evidence. Here, we tested the effectiveness of five botanical insecticides, belonging to different categories, on the green peach aphid Myzus persicae (Sulzer) and their selectivity towards two natural enemies, the ladybird beetle Propylea quatuordecimpunctata (L.) and the parasitoid Aphidius colemani (Dalman). White thyme essential oil (EO), sweet orange EO, crude garlic extract and Marseille soap were tested and compared with a pyrethrin-based commercial product. Both direct spray assays and residual contact assays on treated cabbage leaf disks were carried out. The tested products had low efficacy against aphids when compared to pyrethrins but were in general less detrimental to ladybird beetle larvae, meaning that if applied against other pests, they have a lower chance of harming this agent of aphid biocontrol. Some of the products (soap, orange EO) did, however, show direct exposure toxicity toward ladybird larvae, and thyme EO had extensive phytotoxic effects on cabbage leaves, possibly indirectly leading to higher mortality in ladybird adults. These results underline the necessity for case-by-case evaluations of botanical insecticides. Full article

(This article belongs to the Special Issue Chemical Toxicology and Insecticide Resistance on Insect Pests)

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13 pages, 4197 KiB

Open AccessArticle

Insecticidal Activity of Allium sativum Essential Oil-Based Nanoemulsion against Spodoptera littoralis

by Gaetano Giuliano, Orlando Campolo, Giuseppe Forte, Alberto Urbaneja, Meritxell Pérez-Hedo, Ilaria Latella, Vincenzo Palmeri and Giulia Giunti

Insects 2024, 15(7), 476; https://doi.org/10.3390/insects15070476 - 26 Jun 2024

Cited by 6 | Viewed by 3935

Abstract

Spodoptera littoralis, commonly known as the Egyptian or African cotton leafworm, is a significant agricultural threat. It is widely distributed in Africa, Mediterranean Europe, and Middle Eastern countries. This polyphagous pest infests numerous crop plants across 44 families, including cotton, soybeans, alfalfa, [...] Read more.

Spodoptera littoralis, commonly known as the Egyptian or African cotton leafworm, is a significant agricultural threat. It is widely distributed in Africa, Mediterranean Europe, and Middle Eastern countries. This polyphagous pest infests numerous crop plants across 44 families, including cotton, soybeans, alfalfa, sweet potato, pepper, eggplant, tomato, maize, lettuce, strawberry, wheat, and hibiscus. The damage caused by S. littoralis on different plant organs, such as young leaves, shoots, stalks, bolls, buds, and fruits, often determines substantial product losses. Current control strategies predominantly rely on synthetic insecticides, which, despite their efficacy, have notable drawbacks, including insecticide resistance, environmental contamination, consumer concerns, and adverse effects on non-target organisms and beneficial insects. In response to these challenges, in this study, we developed and evaluated a garlic EO-based nanoemulsion with a high EO concentration (15%) and low surfactant content to mitigate the possible negative impact on plants and to enhance efficacy against S. littoralis larvae. Laboratory bioassays demonstrated promising larvicidal activity and reduced larval feeding, although some phytotoxicity symptoms were observed. This study underscores the potential of botanical insecticides as sustainable alternatives to synthetic chemicals, emphasizing the importance of balancing efficacy with environmental and ecological considerations in pest management strategies. Full article

(This article belongs to the Special Issue Chemical Toxicology and Insecticide Resistance on Insect Pests)

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16 pages, 1334 KiB

Open AccessArticle

Topical Toxicity and Repellency Profiles of 17 Essential Oil Components against Insecticide-Resistant and Susceptible Strains of Adult Musca domestica (Diptera: Muscidae)

by Yuexun Tian, Jerome A. Hogsette, Edmund J. Norris and Xing Ping Hu

Insects 2024, 15(6), 384; https://doi.org/10.3390/insects15060384 - 24 May 2024

Cited by 3 | Viewed by 2344

Abstract

The house fly is a significant pest in agriculture and human health that is increasingly difficult to manage due to multiple limitations including resistance development. To explore alternative pesticides, the topical toxicity and repellency profiles of 17 essential oil components (EOCs) were evaluated [...] Read more.

The house fly is a significant pest in agriculture and human health that is increasingly difficult to manage due to multiple limitations including resistance development. To explore alternative pesticides, the topical toxicity and repellency profiles of 17 essential oil components (EOCs) were evaluated against a resistant and a susceptible strain of house fly, Musca domestica L., using topical application and Y-tube olfactometers, respectively. Six of the most toxic EOCs based on the LD₅₀ were further investigated against a susceptible strain of house fly. Thymol, (+)-pulegone, eugenol, and carvacrol were always the top four most toxic chemicals tested against the resistant house fly strain. Little to no resistance was observed to the top six EOCs based on the comparison of the results between resistant and susceptible house fly strains. P-Cymene, citronellic acid, R-(+)-limonene, linalool, γ-terpinene, estragole, and eugenol were repellent to adult house flies at certain concentrations while (-)-carvone and thymol were attractive to adult house flies. This screening of a wide variety of individual EOCs provides a stronger foundation of information for further research. This should encourage further investigation into the topical toxicity and repellency in field studies, which will provide more insight into the performance of biopesticides for house fly management and potential commercialization. Full article

(This article belongs to the Special Issue Chemical Toxicology and Insecticide Resistance on Insect Pests)

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12 pages, 1780 KiB

Open AccessArticle

Evaluation of Cotton Fleahopper (Pseudatomoscelis seriatus (Reuter)) Feeding on Mpp51Aa2-Traited Cotton Utilizing Electrical Penetration Graph (EPG) Waveforms

by Brady P. Arthur, Charles P.-C. Suh, Benjamin M. McKnight, Megha N. Parajulee, Fei Yang, Thomas M. Chappell and David L. Kerns

Insects 2024, 15(5), 316; https://doi.org/10.3390/insects15050316 - 29 Apr 2024

Viewed by 2398

Abstract

Prior to the recent implementation of the Mpp51Aa2 pesticidal protein (ThryvOn), transgenic cotton cultivars have historically offered no control of the cotton fleahopper (Pseudatomocelis seriatus (Reuter)). To evaluate the feeding behavior of cotton fleahoppers on ThryvOn cotton, electropenetrography (EPG) using a Giga-8 [...] Read more.

Prior to the recent implementation of the Mpp51Aa2 pesticidal protein (ThryvOn), transgenic cotton cultivars have historically offered no control of the cotton fleahopper (Pseudatomocelis seriatus (Reuter)). To evaluate the feeding behavior of cotton fleahoppers on ThryvOn cotton, electropenetrography (EPG) using a Giga-8 DC instrument was used to monitor the probing activity of fourth- and fifth-instar cotton fleahopper nymphs on both ThryvOn and non-ThryvOn cotton squares. Nymphs were individually placed on an excised cotton square for 8 h of EPG recording, after which resulting waveforms were classified as non-probing, cell rupturing, or ingestion. Although there were significantly more cell rupturing events per insect on ThryvOn (mean ± SEM, 14.8 ± 1.7) than on non-ThryvOn squares (mean ± SEM, 10.3 ± 1.6), there was no difference attributable to ThryvOn in the average number of ingestion events per insect. However, the average duration of ingestion events was significantly shorter on squares with ThryvOn (mean ± SEM, 509 ± 148 s) than on squares without (mean ± SEM, 914 ± 135 s). This suggests that cotton fleahoppers continued to probe despite their inability to sustain ingestion. These results provide conclusive evidence that the Mpp51Aa2 pesticidal protein affects the feeding behavior of cotton fleahopper nymphs. Full article

(This article belongs to the Special Issue Chemical Toxicology and Insecticide Resistance on Insect Pests)

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18 pages, 3857 KiB

Open AccessArticle

The Synergistic Effect of Lemongrass Essential Oil and Flometoquin, Flonicamid, and Sulfoxaflor on Bemisia tabaci (Genn.) (Hemiptera: Aleyrodidae): Insights into Toxicity, Biochemical Impact, and Molecular Docking

by Moataz A. M. Moustafa, Fatma S. Ahmed, Nawal Abdulaziz Alfuhaid, Nourhan A. El-Said, El-Desoky S. Ibrahim and Mona Awad

Insects 2024, 15(5), 302; https://doi.org/10.3390/insects15050302 - 24 Apr 2024

Cited by 7 | Viewed by 3157

Abstract

The whitefly, Bemisia tabaci (Genn.), is one of the most dangerous polyphagous pests in the world. Eco-friendly compounds and new chemical insecticides have gained recognition for whitefly control. In this study, the toxicity and biochemical impact of flometoquin, flonicamid, and sulfoxaflor, alone or [...] Read more.

The whitefly, Bemisia tabaci (Genn.), is one of the most dangerous polyphagous pests in the world. Eco-friendly compounds and new chemical insecticides have gained recognition for whitefly control. In this study, the toxicity and biochemical impact of flometoquin, flonicamid, and sulfoxaflor, alone or combined with lemongrass essential oil (EO), against B. tabaci was studied. In addition, a molecular docking study was conducted to assess the binding affinity of the tested compounds to AchE. Based on the LC values, the descending order of the toxicity of the tested compounds to B. tabaci adults was as follows: sulfoxaflor > flonicamid > flometoquin > lemongrass EO. The binary mixtures of each of the tested compounds with lemongrass EO exhibited synergism in all combinations, with observed mortalities ranging from 15.09 to 22.94% higher than expected for an additive effect. Sulfoxaflor and flonicamid, alone or in combination with lemongrass EO, significantly inhibited AchE activity while only flonicamid demonstrated a significant impact on α-esterase, and none of the tested compounds affected cytochrome P450 or GST. However, the specific activity of P450 was significantly inhibited by the lemongrass/sulfoxaflor mixture while α-esterase activity was significantly inhibited by the lemongrass/flometoquin mixture. Moreover, the lemongrass EO and all the tested insecticides exhibited significant binding affinity to AchE with energy scores ranging from −4.69 to −7.06 kcal/mol. The current findings provide a foundation for utilizing combinations of essential oils and insecticides in the integrated pest management (IPM) of B. tabaci. Full article

(This article belongs to the Special Issue Chemical Toxicology and Insecticide Resistance on Insect Pests)

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27 pages, 1679 KiB

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Insect Pest Control from Chemical to Biotechnological Approach: Constrains and Challenges

by Stefano Civolani, Massimo Bariselli, Riccardo Osti and Giovanni Bernacchia

Insects 2025, 16(5), 528; https://doi.org/10.3390/insects16050528 - 15 May 2025

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Abstract

The large growth in the global population requires new solutions for the control of harmful insects that compete for our food. Changing regulatory requirements and public perception, together with the continuous evolution of resistance to conventional insecticides, also require, in addition to innovative [...] Read more.

The large growth in the global population requires new solutions for the control of harmful insects that compete for our food. Changing regulatory requirements and public perception, together with the continuous evolution of resistance to conventional insecticides, also require, in addition to innovative molecules with different modes of action, new non-chemical control strategies that can help maintain efficient integrated pest management programs. The last 30 years have inaugurated a new era characterised by the discovery of new mechanisms of action and new chemical families. Although European programs also promote a green deal in the crop protection sector, the existing thorough regulations slow down its spread and the adoption of new products. In light of these changes, this review will describe in more detail the dynamics of discovery and registration of new conventional insecticides and the difficulties that the agrochemical industries encounter. Subsequently, the different innovative control strategies alternative to conventional insecticides based on natural substances of different origin, entomopathogenic microorganisms, semiochemical and semiophysical compounds, and classical and augmentative biological control will be described. The advantages of these green strategies will be illustrated and also the constrains to their diffusion and commercialisation. Finally, the main biotechnological discoveries will be described, from transgenic plants to symbiotic control, classical genetic control, and, more recently, control based on insect genomic transformation or on RNAi. These new biotechnologies can revolutionise the sector despite some constrains related to the regulatory restrictions present in different countries. Full article

(This article belongs to the Special Issue Chemical Toxicology and Insecticide Resistance on Insect Pests)

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14 pages, 606 KiB

Open AccessReview

The Role of Chemosensory Proteins in Insecticide Resistance: A Review

by Angeliki Tsouri and Vassilis Douris

Insects 2025, 16(5), 496; https://doi.org/10.3390/insects16050496 - 5 May 2025

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Abstract

Chemosensory proteins (CSPs) are small soluble proteins found predominantly in insects, with a conserved structure that contains a hydrophobic cavity. While originally associated with chemosensation, they were soon implicated to several other functions related to their ability to bind hydrophobic molecules. Research in [...] Read more.

Chemosensory proteins (CSPs) are small soluble proteins found predominantly in insects, with a conserved structure that contains a hydrophobic cavity. While originally associated with chemosensation, they were soon implicated to several other functions related to their ability to bind hydrophobic molecules. Research in the last decade has shown that CSPs may play a role in insecticide resistance. Several CSP genes are upregulated upon induction by sublethal insecticide doses or are highly expressed in resistant populations. RNA interference of CSP genes can restore susceptibility to insecticides. In vitro binding assays and molecular docking simulations suggest that CSPs can strongly bind to insecticides and can accommodate even large molecules in their hydrophobic cavities. Some cases of CSP overexpression in transgenic insects conferring insecticide resistance are reported. Taken together, these results indicate a role for CSPs in insecticide resistance, presumably through a sequestration mechanism, perhaps in combination with other mechanisms like metabolic resistance. This article reviews the evidence for CSP involvement in resistance and discusses ongoing research in the field. Full article

(This article belongs to the Special Issue Chemical Toxicology and Insecticide Resistance on Insect Pests)

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