Sap-sucking Insects Research Articles

Influence of Previous Infestation of Wheat Leaves and Ears by Sitobion avenae on Interaction with Rhopalosiphum padi.

Different herbivorous species that share a host plant may interact via competition or facilitation, depending on whether the interaction partners are hindered by or benefit from the interaction. Sap-sucking insects, such as aphids, can influence each other indirectly by altering the composition of the shared phloem sap. Aphid-induced changes in the plant may affect aphid performance and lead to a shift in the balance between different co-occurring aphid species. In this study, we compared the performance of the English grain aphid (Sitobion avenae) and the bird cherry-oat aphid (Rhopalosiphum padi) simultaneously infesting leaves or ears of wheat (Triticum aestivum) plants, which had been either previously infested by S. avenae or kept uninfested. Colonies of S. avenae were larger on ears than on leaves, while the opposite pattern was found for R. padi. Pre-infestation of ears, but not of leaves, by S. avenae led to a higher total aphid number and colony size of S. avenae at some time points. The balance between the two species was only slightly affected by previous infestation at some time points. The findings of this study contribute to the understanding of plant-aphid as well as aphid-aphid interactions in agricultural fields.

Use of ResNets for HLB Disease Detection on Orange Leaves Using Terrestrial Multispectral Images

Abstract. Huanglongbing (HLB) is a bacterial disease transmitted by different vectors of sap-sucking insects. It affects all crops of citrus trees, decreasing the values of those fruits in the market and eventually the decay of orchards. In Brazil, the world's leading orange producer, citriculture faces severe issues with HLB and substantial economic loss. Technical means of scanning the orchards with high-throughput becomes essential for the sustainability of this industry. In this study, we propose to investigate an operational strategy consisting of scanning large portions of foliage (the canopy of one tree or more) in which there can few early foliage symptoms. It is proposed to investigate deep learning tools to solve this complex binary classification problem. The study is based on a dataset comprising 1,297 terrestrial multispectral (14 channels) images captured at high spatial resolution in a commercial orange orchard in Brazil. It is proposed to adapt and retrain standard neural network architectures, namely ResNets18 and ResNets34, to process such images. Our analysis reveals promising results, with both models demonstrating convergence and achieving stable performance. Notably, ResNet18 outperformed ResNet34, achieving an accuracy of 76.45% compared to 66.79% from ResNet34. These findings suggest that deep neural network methods can effectively manage non-radiometrically calibrated data and accurately distinguish images with HLB symptoms from healthy plants . However, with reduced datasets and limited possibilities for transfer learning and fine-tuning, it seems that only reasonable sized networks can be trained. Thus, more advanced state-of-the-art tools of the are still challenging to deploy for agricultural multi- or hyperspectral data.

Influence of Prey Consumption on the Predatory Potential and Biological Parameters of Exochomus nigripennis (Erichson) Against Phenacoccus solenopsis Tinsley and Icerya seychellarum (Westwood)

Phenacoccus solenopsis Tinsley and Icerya seychellarum (Westwood) are recent invasive sap-sucking insects in Egypt. Exochomus nigripennis (Erichson) being a viable option for conventional biological control. In the laboratory of the Plant Protection Research Institute, Agricultural Research Centre, Egypt, the biological parameters and predatory potential of E. nigripennis were assessed using P. solenopsis and I. seychellarum as preys. Fourth instar E. nigripennis larvae was recorded the highest average total consumption of 455 individuals, with a feeding capacity of 43.10 when reared on P. solenopsis. While the third larval instar of E. nigripennis consumed the maximum number of I. Seychellarum 43.11 with a feeding capacity of 45.18 compared to other instars. E. nigripennis females had a lifespan of 30.9 ± 1.21 days, and consuming 3255 preys on P. solenopsis, while males had a feeding capacity of 2198.64. The immature stages of E. nigripennis varied significantly based on the prey species. Larvae developed faster on I. Seychellarum, while pupal periods were shortest on I. Seychellarum and longest on P. solenopsis. The shortest development time was on I. Seychellarum (22.8 days), while the longest was on P. solenopsis (30.37 days). The longevity and reproduction of E. nigripennis were significantly influenced by the preys they were reared on. Males and females fed on P. solenopsis exhibited longer survival and females had an extended oviposition period. The fecundity was highest when females were fed P. solenopsis supplemented with sugar solution. The study suggests that an integrated pest management program can effectively manage P. solenopsis and I. seychellarum, by utilizing E. nigripennis as a biological control agent, making it suitable for mass rearing in agricultural ecosystems.

Side effects of semi-synthetic insecticide spinetoram on the whitefly parasitoid Encarsia formosa.

Insecticide risk assessment for biological control agents is essential for implementing integrated pest management (IPM) programs. Spinetoram is a naturally derived insecticide used to control a variety of agricultural sap-sucking insect pests, and Encarsia formosa Gahan (Hymenoptera: Aphelinidae) plays a key role in the biocontrol of greenhouse whiteflies. Despite its presumed safe ecotoxicological profile, the side effects of spinetoram on E. formosa are partially unknown, especially at sublethal doses. In the laboratory, we estimated the lethal concentrations (LC) of spinetoram on E. formosa by topical exposure of pupae and 48 h residual contact exposure of emerged adults. Afterwards, we assessed the impact of spinetoram LCs on the life history traits (juvenile development, adult longevity, parasitism, adult emergence) and population growth parameter (the instantaneous rate of increase, ri) of the parasitoid. Probit analysis allowed the estimation of LC10 = 0.10 mg/L, LC50 = 0.56 mg/L, and LC90 = 3.28 mg/L. Spinetoram at LC10 had no impact on the observed parameters of E. formosa. Conversely, spinetoram at LC50 and LC90 significantly reduced adult longevity by 19.2% and 40.6%, total parasitism by 33.4% and 38.7%, and total adult emergence by 29.6% and 39.1%, respectively. Also, the ri of E. formosa was significantly affected by spinetoram LC50 and LC90 with a reduction of 8.17 and 29.83%, respectively. Our results suggested that spinetoram significantly threatens the effectiveness of E. formosa when applied at the field recommended rate. However, further validation of spinetoram under greenhouse conditions is required for a comprehensive risk assessment for E. formosa in IPM programs. © 2024 Society of Chemical Industry.

Enhancing yield and economic benefits through sustainable pest management in Okra cultivation.

Okra (Abelmoschus esculentus) is a prominent vegetable crop in Asia, confronting persistent threats from pests such as leafhoppers, whiteflies, and shoot and fruit borers. Conventional chemical control methods, despite their adverse ecological effects, remain the primary approach for pest management. Indiscriminate chemical use has led to reduced biodiversity among natural predators and the disruption of food webs in ecosystems. To address these challenges, this study assessed the efficacy of integrated (IM) and biointensive (BM) pest management modules in comparison to conventional chemical methods (CM) for mitigating insect damage to okra leaves and fruits, and subsequently, their impact on okra yield. Our result revealed that the BM exhibited the least effectiveness but outperformed untreated control plots significantly. In contrast, both IM and CM significantly reduced damage from sap-sucking insects and borer pests. Notably, plots treated with the chemical module found decreased populations of natural enemies. The IM demonstrated the lowest fruit infestation rate (5.06%), yielding the highest crop production (8.97 t ha-1), along with the maximum net return (Indian Rupees: 44,245) and incremental cost-benefit ratio (3.31). Thus, the study suggested that the implementation of integrated pest management practices can result in higher okra yields and greater economic benefits. These findings shed light on the potential of sustainable agricultural practices as a safer and more economically viable alternative to chemical-intensive pest control in okra cultivation.

Unravelling the Molecular Identity of Bulgarian Jumping Plant Lice of the Family Aphalaridae (Hemiptera: Psylloidea).

Psyllids (Hemiptera: Psylloidea) are plant sap-sucking insects whose identification is often difficult for non-experts. Despite the rapid development of DNA barcoding techniques and their widespread use, only a limited number of sequences of psyllids are available in the public databases, and those that are available are often misidentified. Here, we provide 80 sequences of two mitochondrial genes, cytochrome c oxidase I (COI) and cytochrome b (Cytb), for 25 species of Aphalaridae, mainly from Bulgaria. The DNA barcodes for 15 of these species are published for the first time. In cases where standard primers failed to amplify the target gene fragment, we designed new primers that can be used in future studies. The distance-based thresholds for the analysed species were between 0.0015 and 0.3415 for COI and 0.0771 and 0.4721 for Cytb, indicating that the Cytb gene has a higher interspecific divergence, compared to COI, and therefore allows for more accurate species identification. The species delimitation based on DNA barcodes is largely consistent with the differences resulting from morphological and host plant data, demonstrating that the use of DNA barcodes is suitable for successful identification of most aphalarid species studied. The phylogenetic reconstruction based on maximum likelihood and Bayesian inference analyses, while showing similar results at high taxonomic levels to previously published phylogenies, provides additional information on the placement of aphalarids at the species level. The following five species represent new records for Bulgaria: Agonoscena targionii, Aphalara affinis, Colposcenia aliena, Co. bidentata, and Craspedolepta malachitica. Craspedolepta conspersa is reported for the first time from the Czech Republic, while Agonoscena cisti is reported for the first time from Albania.

Relative contribution of biotic and abiotic factors to population fluctuations of Auchenorrhyncha community that could play a role in the Cape Saint Paul Wilt Disease (CSPWD) (lethal yellowing) pathosystem in Ghana.

As a major setback to the global coconut industry, lethal yellowing disease (LYD), caused by phytoplasmas, continues to threaten coconut palms in the Americas, the Caribbean, Africa, and Oceania. Despite its economic impacts, limited information exists on LYD vectors, which impedes the prevention and management of the disease. Using double-sided yellow sticky traps, we investigate the factors that influence the seasonal abundance and population dynamics of three sap-sucking insects of LYD, i.e., Diostrombus (Hemiptera: Derbidae) sp. and Patara sp. (Hemiptera: Derbidae), and Nedoptepa curta Dmitriev (Hemiptera: Cicadellidae), on five coconut genotypes (Sri Lanka Green Dwarf (SGD), Vanuatu Tall (VTT), SGD × VTT, Malayan Yellow Dwarf (MYD) × VTT, and West African Tall (WAT)) in the Western Region, and one (SGD) in the Central Region of Ghana from April 2019 to May 2021. The results showed that N. curta and Patara sp. were the most abundant species in the Western and Central Regions, respectively. There was a significant difference between the coconut cultivars and sap-sucking insects. The peak population development of the sap-sucking insects was recorded during the dry season on all the coconut genotypes at all sampling locations. A significant positive correlation was detected between temperature and the population of N. curta and Patara sp. In the Agona Nkwanta, VTT had the highest population of N. curta, whereas WAT had the highest population of Patara sp. and Diostrombus sp. These findings provide useful information for assessing the role of factors that could affect the Cape Saint Paul Wilt disease pathosystem.

New Invasive and Potential Pests in Sugarcane Agrosystems in Africa: How to Apprehend Them for Better Preparedness and Management?

Abstract Africa is a key sugarcane-producing continent, particularly in the eastern and southern regions with South Africa being the first producer of this commodity. However, sugarcane is attacked by insect pests of economic importance such as the stem borers, white grubs, armyworms, and sap-sucking insects and arthropods (e.g., aphids, thrips, scale insects, froghoppers, mites), some of which are vectors of important diseases. The African continent is particularly exposed to insect incursions due to the lack of biosecurity plans, phytosanitary control at the border and awareness. The actions taken by South Africa in terms of biosecurity represent a good example to follow and are comparable to what has been implemented in Australia, a country that is constantly threatened by outside pests and diseases. Several examples are given here to explain how an invasive pest can dramatically threaten small-scale farmers, particularly in resource-poor countries and how it is important to have an efficient biosecurity strategy for emergency response for pest and disease control. Information © The Author 2024

Record of aphidophagous syrphids with their prey and host plants in India: A review

The article deals with the association of aphidophagous syrphids with their prey species and their host plants for programming the biocontrol approach against aphid pests. Aphids are tiny sap-sucking bugs and they are important phytophagous pests due to their polymorphism and rapid increase of their numbers by parthenogenetic development. Larvae of syrphids are the most important natural enemies of several sap-sucking insects and are useful bioagents in biological control programmes. After reviewing many articles 48 species of syrphids are recognised as predators of 72 aphid species infesting more than 141 plants of different families. Among these syrphids, Episyrphus balteatus was reported as a predator on maximum number of aphid species (43 species) followed by Ischiodon scutellaris (34 species), Eupeodes confrater (20 species), Betasyrphus serarius (18 species), Paragus serratus (17 species), and Allograpta javana (12 species).

Screening of reference genes for gene expression study in different tissues from the transcriptome data of the vector leafhopper Psammotettix striatus

Selecting appropriate reference genes is crucial for ensuring the accuracy and reliability of gene expression study using reverse transcription-quantitative PCR (RT-qPCR). To screen the optimal reference genes for analyzing gene expression in different tissues of the vector leafhopper Psammotettix striatus which causes extensive damage to a wide range of crops by vectoring multiple plant pathogenic microorganisms, the transcriptome data from Malpighian tubules (MTs) of P. striatus were mined. Twenty alternative candidate reference genes were initially selected for screening, among which seven genes with diverse Gene Ontology (GO) annotations were choosed as candidate reference genes, i.e., ribosomal protein L7A (RPL7A), ribosomal protein S28 (RPS28), ribosomal protein L22 (RPL22), ribosomal protein LP2 (RPLP2), H3 histone family 3A (H3F3A), elongation factor 1γ (EF-1γ), and elongation factor 1α (EF-1α). Gene expression levels in different tissues of P. striatus adults were examined using RT-qPCR, and their expression stability was analyzed using multiple reference gene screening software. This study revealed EF-1α as the most abundantly expressed gene, while RPL22 exhibited the lowest expression levels. EF-1α showed the most stable expression, whereas RPS28 showed the least stability. Various software tools confirmed EF-1α as the most stable single reference gene, and EF-1α and RPLP2 an optimal combination. This study provides a foundation for future investigation of the transmission of pathogenic microorganisms mediated by the vector leafhoppers, the function of the MTs, the biosynthesis of brochosomes, the coevolutionary processes and nutritional interactions of symbionts and host insects, and the gene expression study of other sap-sucking insects.

Citrus-mediated gene silencing of cytochrome P450 suppresses insecticide resistance and increases mortality in Diaphorina citri.

Asian citrus psyllid, Diaphorina citri, is a hemipteran that vectors the causal pathogen of citrus greening disease, or huanglongbing (HLB). HLB is a tree killing disease that has severely limited citrus production globally. Unfortunately, there is no cure for this disease, and mitigation depends on multiple insecticide applications to reduce vector populations. Silencing of cytochrome P450 expression associated with detoxification enzymes by RNA interference is known to increase susceptibility of D. citri to insecticides. However, dsRNA was previously introduced into psyllids by topical applications. The possible application of this technology for pest management will require effective field delivery of the dsRNA. Therefore, we evaluated a virus vector (Citrus tristeza virus; 'mild strain' T36) to deliver gene silencing directly to this sap-sucking insect via plant phloem. Citrus macrophylla plants inoculated with CTV expressing a truncated consensus sequence of CYP450 (CTV-tCYP450) constantly produced small interfering RNA in the plant phloem that targeted five cytochrome p540 (CYP450) genes in D. citri. Insecticide susceptible D. citri reared on citrus infected with CTV-tCYP450 were subsequently more susceptible to imidacloprid, fenpropathrin, carbaryl, and chlorpyrifos than those reared on citrus infected with wildtype CTV or non-infected negative controls. Additionally, nymph survival and adult lifespan were significantly reduced when psyllids were reared on CTV-tCYP450 citrus plants compared with controls. Interestingly, similar results were obtained after one and two generations of rearing. Finally, field-collected psyllids from areas with known broad-spectrum insecticide resistance were rendered more susceptible to imidacloprid and fenpropathrin after feeding on CTV-tCYP450 citrus trees as compared with those reared on controls. The integration of citrus-mediated RNA inference targeting psyllid detoxification enzymes could function as a resistance management tool and reduce insecticide input in an integrated pest management program for HLB. © 2024 Society of Chemical Industry.

Discovery of Two Novel Viruses of the Willow-Carrot Aphid, Cavariella aegopodii

The advancement of bioinformatics and sequencing technology has resulted in the identification of an increasing number of new RNA viruses. This study systematically identified the RNA virome of the willow-carrot aphid, Cavariella aegopodii (Hemiptera: Aphididae), using metagenomic sequencing and rapid amplification of cDNA ends (RACE) approaches. C. aegopodii is a sap-sucking insect widely distributed in Europe, Asia, North America, and Australia. The deleterious effects of C. aegopodii on crop growth primarily stem from its feeding activities and its role as a vector for transmitting plant viruses. The virome includes Cavariella aegopodii virga-like virus 1 (CAVLV1) and Cavariella aegopodii iflavirus 1 (CAIV1). Furthermore, the complete genome sequence of CAVLV1 was obtained. Phylogenetically, CAVLV1 is associated with an unclassified branch of the Virgaviridae family and is susceptible to host antiviral RNA interference (RNAi), resulting in the accumulation of a significant number of 22nt virus-derived small interfering RNAs (vsiRNAs). CAIV1, on the other hand, belongs to the Iflaviridae family, with vsiRNAs ranging from 18 to 22 nt. Our findings present a comprehensive analysis of the RNA virome of C. aegopodii for the first time, offering insights that could potentially aid in the future control of the willow-carrot aphid.

Impact of Plant Extracts on the Pollination Activity of <i>Apis mellifera</i> Linnaeus, 1758 (Hymenoptera: Apidae) on Flowers of Cowpea Variety Feekem, in Dang (Adamaoua, Cameroon)

Synthetic pesticides present worldwide risks of contamination of humans, livestock and the environment due to the strong persistence and the toxic residues in fruits and vegetables. Natural biopesticides of local plant origin present low persistence and are the best alternative for the control of crop pests. In the Adamaoua region (Northern Cameroon), few studies exist concerning effects of botanical pesticides on the behavior of beneficial insects. Studies aimed to draw up a list of pollinating insects on flowers of <i>Vigna unguiculata </i>(L.) Walp., 1843 (Fabales: Fabaceae), in situations of treatment with botanical pesticides compared to the situation of the use of synthetic insecticide and to determine the effect of the biopesticides on the behavior of the main floricultural insects. Field investigations were carried out during two cowpea cultivation campaigns (June to September 2021 and June to October 2022) in Dang (suburb of Ngaoundere) on the effect of leaves extracts of local plant origin on the foraging behavior of <i>Apis mellifera</i> Linnaeus, 1758 (Hymenoptera: Apidae) and the main sap-sucking insect <i>Aphis craccivora </i>Koch, 1854 (Hemiptera: Aphididae). Forty-four cowpea plots of 4x3.5 m each distributed according to the randomized complete block model (four untreated plots as negative control, four plots treated with the synthetic insecticide Parastar (40EC 535/ 10/IN, 20 g/l of imidacloprid and 20 g/l of lamda-cyhalothrin) as positive control, and 36 experimental plots treated with three concentrations (10%, 20% and 30%) of aqueous leaves extract of <i>Calotropis procera</i> (Gentianales: Apocynaceae), <i>Eucalyptus camaldulensis </i>(Myrtales: Myrtaceae), and <i>Tithonia diversifolia</i> (Asterales: Asteraceae) respectively, made it possible to conduct four treatments: (1) flowers left to freely pollination, (2) flowers protected against pollinators, (3) flowers visited exclusively by <i>Ap. mellifera</i> and (4) flowers protected against insects. Among eight species (four orders, four families and seven genera) recorded on the flowers of <i>V. unguiculata</i>, the domestic bee <i>Ap. mellifera</i> was the most common and collected nectar and pollen. The control plots and those treated with 10% or 20% aqueous leaves extracts allowed the bee to carry out its activity. Plots treated with 30% extract of each plant and those treated with the synthetic insecticide Parastar, drastically altered the rhythm and speed of activity in <i>Ap. mellifera</i> foragers. This behavior became less coordinated and slow on treated plants. It would be wise to use 10% or 20% aqueous extracts as botanical insecticides and an alternative to the synthetic insecticide Parastar.

Amphiphilic layered double hydroxides enhance plant-mediated delivery of dsRNAs to phloem‑feeding planthoppers

RNA interference (RNAi) is an emerging tool in crop protection by exogenous applications of double-stranded RNAs (dsRNAs) to silence the expression of essential pest genes. Nevertheless, topical delivery of dsRNAs to sap-sucking insects is a major challenge due to the insufficient infiltration and translocation to plant vascular. Foliar sprayed layered double hydroxide (LDH) showed insufficient translocation in plant vascular and the supplement of surfactants caused phytotoxicity to plant. Thus, in the present study, LDH was transformed from hydrophilic to amphiphilic by fatty acids modification to obtain a surfactant-like LDH (LDHS) with good leaf adhesion, translocation and excellent biocompatibility. LDHS was synthesized via a mild hydrothermal method using MgCl2, FeCl3 and palm oil as the precursors, resulting in LDH coated with long-chained carboxylates as hydrophobic tails. LDHS showed good binding affinity with dsRNA and high affinity to rice leaves. Once loaded with dsRNA, LDHS were shown to enhance the uptake of dsRNA to rice brown planthoppers (Nilaparvata lugens) through a direct spray. Moreover, in planta, dsRNA-LDHS exhibited translocation from rice leaves to vascular bundles and finally into the planthoppers, delivered 2.5-fold higher dsRNA and caused higher mortalities of planthoppers than hydrophilic LDH with adjuvants. Herein we generate and validate a platform that can deliver dsRNA through either direct sprays or sprayed living plant to brown planthoppers with high efficiency, low toxicity and adjuvant-free. Consequently, it is a green potential selection using amphiphilic LDHS agents instead of the conventional gene carriers to prepare biopesticide nanoparticles.

Plant-derived artificial miRNA effectively reduced the proliferation of aphid (Aphidoidea) through spray-induced gene silencing.

Aphids (Hemiptera: Aphididae) are notorious sap-sucking insects that rampantly threaten agricultural production worldwide. Current management against aphids in the field heavily relies on chemical pesticides, which makes economical and eco-friendly methods urgently needed. Spray-induced gene silencing (SIGS) offers a powerful and precise approach to pest management. However, the high costs and instability of double-stranded RNA (dsRNA) regulators applied for downstream RNA interference (RNAi) still limit this strategy. It remains uncertain if RNAi regulators applied in SIGS could extend to small RNA (sRNA), especially miRNA. We chose two sRNA sequences, miR-9b and miR-VgR, whose corresponding targets ABCG4 and VgR are both essential for aphid growth and development. The efficacy of these sequences was initially verified by chemically synthetic single-stranded RNA (syn-ssRNA). Through spray treatment, we observed a significantly decreased survival number and increased abnormality rate of green peach aphids fed on the host under laboratory conditions. Based on our previous study, we generated transgenic plants expressing artificial miR-9b (amiR-9b) and miR-VgR (amiR-VgR). Remarkably, plant-derived amiRNA exerted potent and long-lasting inhibitory efficacy with merely one percent concentration of chemical synthetics. Notably, the simultaneous application of amiR-9b and amiR-VgR exhibited superior inhibitory efficacy. We explored the potential use of sRNA-based biopesticide through SIGS while investigating the dosage requirements. To optimize this strategy, the utilization of plant-derived amiRNA was proposed. The results suggested that attributed to stability and durability, deploying amiRNA in pest management is a potential and promising solution for the field application. © 2024 Society of Chemical Industry.

Defense strategies and associated phytohormonal regulation in Brassica plants in response to chewing and sap-sucking insects.

Plants have evolved distinct defense strategies in response to a diverse range of chewing and sucking insect herbivory. While chewing insect herbivores, exemplified by caterpillars and beetles, cause visible tissue damage and induce jasmonic acid (JA)-mediated defense responses, sucking insects, such as aphids and whiteflies, delicately tap into the phloem sap and elicit salicylic acid (SA)-mediated defense responses. This review aims to highlight the specificity of defense strategies in Brassica plants and associated underlying molecular mechanisms when challenged by herbivorous insects from different feeding guilds (i.e., chewing and sucking insects). To establish such an understanding in Brassica plants, the typical defense responses were categorized into physical, chemical, and metabolic adjustments. Further, the impact of contrasting feeding patterns on Brassica is discussed in context to unique biochemical and molecular modus operandi that governs the resistance against chewing and sucking insect pests. Grasping these interactions is crucial to developing innovative and targeted pest management approaches to ensure ecosystem sustainability and Brassica productivity.

Thiamethoxam-Induced Intergenerational Sublethal Effects on the Life History and Feeding Behavior of Rhopalosiphum padi

Thiamethoxam, a second-generation neonicotinoid insecticide is widely used for controlling sap-sucking insect pests including Rhopalosiphum padi. The current study aimed to investigate the life-history parameters and feeding behavior of R. padi following treatments with sublethal concentrations of thiamethoxam. The lethal concentration 50 (LC50) value of thiamethoxam against adult R. padi was 11.458 mg L−1 after 48 h exposure. The sublethal concentrations of thiamethoxam (LC5 and LC10) significantly decreased the adult longevity, fecundity, and reproductive days in the directly exposed aphids (F0 generation). In the progeny R. padi (F1), the developmental durations and total prereproductive period (TPRP) were decreased while the adult longevity, fecundity, and reproductive days (RPd) were increased at both thiamethoxam concentrations. The demographic parameters including the net reproductive rate (R0), intrinsic rate of increase (r), and finite rate of increase (λ) were prolonged only at the LC5 of thiamethoxam. The EPG results indicated that the sublethal concentrations of thiamethoxam increases the total duration of non-probing (Np) while reducing the total duration of E2 in directly exposed aphids (F0). Interestingly, the E2 were significantly increased in the progeny generation (F1) descending from previously exposed parental aphids (F0). Overall, this study showed that thiamethoxam exhibited high toxicity against directly exposed individuals (F0), while inducing intergenerational hormetic effects on the progeny generation (F1) of R. padi. These findings provided crucial details about thiamethoxam-induced hormetic effects that might be useful in managing resurgences of this key pest.

Highly Reduced Complementary Genomes of Dual Bacterial Symbionts in the Mulberry Psyllid Anomoneura mori.

The genomes of obligately host-restricted bacteria suffer from accumulating mildly deleterious mutations, resulting in marked size reductions. Psyllids (Hemiptera) are phloem sap-sucking insects with a specialized organ called the bacteriome, which typically harbors two vertically transmitted bacterial symbionts: the primary symbiont "Candidatus Carsonella ruddii" (Gammaproteobacteria) and a secondary symbiont that is phylogenetically diverse among psyllid lineages. The genomes of several Carsonella lineages were revealed to be markedly reduced (158-174‍ ‍kb), AT-rich (14.0-17.9% GC), and structurally conserved with similar gene inventories devoted to synthesizing essential amino acids that are scarce in the phloem sap. However, limited genomic information is currently available on secondary symbionts. Therefore, the present study investigated the genomes of the bacteriome-associated dual symbionts, Secondary_AM (Gammaproteobacteria) and Carsonella_AM, in the mulberry psyllid Anomoneura mori (Psyllidae). The results obtained revealed that the Secondary_AM genome is as small and AT-rich (229,822 bp, 17.3% GC) as those of Carsonella lineages, including Carsonella_AM (169,120 bp, 16.2% GC), implying that Secondary_AM is an evolutionarily ancient obligate mutualist, as is Carsonella. Phylogenomic ana-lyses showed that Secondary_AM is sister to "Candidatus Psyllophila symbiotica" of Cacopsylla spp. (Psyllidae), the genomes of which were recently reported (221-237‍ ‍kb, 17.3-18.6% GC). The Secondary_AM and Psyllophila genomes showed highly conserved synteny, sharing all genes for complementing the incomplete tryptophan biosynthetic pathway of Carsonella and those for synthesizing B vitamins. However, sulfur assimilation and carotenoid-synthesizing genes were only retained in Secondary_AM and Psyllophila, respectively, indicating ongoing gene silencing. Average nucleotide identity, gene ortholog similarity, genome-wide synteny, and substitution rates suggest that the Secondary_AM/Psyllophila genomes are more labile than Carsonella genomes.

Evaluation of Toxicity Effect of different Insecticides against Camponotus Compressus.

Carpenter ant species play a significant ecological role and are widely prevalent. Ants contribute to safeguarding plants from sap-sucking pest insects through natural biological control mechanisms. The current study was conducted to collect ants from Block B farms at Muhammad Nawaz Sharif University of Agriculture, Multan (MNSUAM), Pakistan. In current study, various insecticides (such as Imidacloprid, Fipronil, Methoxyfenozide, Emamectin benzoate, and Flubendiamide) were formulated at different concentrations (including 160, 80, 40, 20, 10, 5, and 0 ppm) for evaluation against carpenter ants. Notably, Fipronil and emamectin benzoate exhibited heightened toxicity, even at lower doses of 5 ppm and 10 ppm, resulting in the mortality of nearly all worker ants within 24 hours. In contrast, Imidacloprid displayed no distinct preference, as most worker ants remained alive even after 72 hours. These findings indicate that Fipronil and emamectin benzoate may serve as effective active ingredients for controlling carpenter ants. The data was meticulously recorded and subjected to rigorous statistical analysis using specialized software.

Effects of repeated afidopyropen treatment on the structure and function of the soil microbial community

Chemical insecticides are the most effective pest control agents. Afidopyropen is a novel insecticide used against sap-sucking insects, such as aphids. However, the effects of repeated afidopyropen application on the structure and function of soil microorganisms remain unknown. In this study, the changes in the enzyme activities, community structure and function, and relative abundance of antibiotic resistance ontology (ARO) of soil microorganisms were investigated during three repeated afidopyropen applications under laboratory conditions at the maximum recommended dosage (M1) and 10 times the M1 (M10). The neutral phosphatase (NPA) and catalase (CAT) activities in the soil were significantly suppressed after afidopyropen treatment. The Simpson diversity index (1/D) and Shannon–Wiener diversity index (H) also decreased in both the M1 and M10 afidopyropen-treated soils, indicating a remarkable decrease in soil microorganism diversity. The average well color development (AWCD) first increased and subsequently recovered to normal levels after the third application of the insecticide, suggesting that afidopyropen application could increase the metabolic activity of soil microorganisms. Metagenomic analysis showed that repeated afidopyropen application in both the M1 and M10 treatment groups altered the community structure of soil microorganisms, albeit in different ways. Furthermore, repeated afidopyropen application significantly increased the relative ARO abundance, especially in the M10 treatment, with the most dominant AROs being adeF, baeS, and IND-6. These findings reveal the effects of excessive afidopyropen application on soil microorganisms and lay an important foundation for the comprehensive evaluation of the impact of this insecticide on the environment.