Insect Resistance Research Articles

CsAFS2 Gene from the Tea Plant Intercropped with Chinese Chestnut Plays an Important Role in Insect Resistance and Cold Resistance

α-Farnesene, a crucial secondary metabolite in sesquiterpenes, is crucial for plant biotic and abiotic stress resistance. In this study, we screened an AFS gene from transcriptome data of tea plants (Camellia sinensis) intercropped with Chinese chestnut (Castanea mollissima), resulting in the cloning of CsAFS2. CsAFS2 expression increased following treatment with MJ (Methyl jasmonate), SA (Salicylic acid), GA3 (Gibberellin A3), and various plant growth regulators, as well as under high-salt, drought, and low-temperature conditions. The heterologous genetic transformation of tobacco with CsAFS2 led to an enhanced resistance to low-temperature stress and aphid feeding, evident from elevated levels of osmotic regulatory substances, increased protective enzyme activity, and the upregulation of cold and insect resistance-related genes. Trichomes, crucial in cold and insect resistance, exhibited significantly greater length and density in transgenic tobacco as compared to control plants. These results confirm the vital role of CsAFS2 in enhancing cold and insect resistance, providing comprehensive insights into stress regulation mechanisms in tea plants and advancing stress-resistant tea plant breeding.

Toxicity of Ethyl Formate to Tribolium castaneum (Herbst) Exhibiting Different Levels of Phosphine Resistance and Its Influence on Metabolite Profiles

Ethyl formate (EF), a naturally occurring fumigant, has attracted widespread attention owing to its low toxicity in mammals. Here, Direct Immersion Solid-Phase Microextraction (DI-SPME) was employed for sample preparation in mass spectrometry-based untargeted metabolomics to evaluate the effects on Tribolium castaneum (Herbst) strains with different levels of PH3 resistance (sensitive, TC-S; moderately resistant, TC-M; strongly resistant, TC-SR) when exposed to a sub-lethal concentration (LC30) of EF. The bioassay indicated that T. castaneum strains with varying PH3 resistance levels did not confer cross-resistance to EF. A metabolomic analysis revealed that exposure to sublethal doses of EF significantly altered 23 metabolites in T. castaneum, including 2 that are unique to the species which remained unaffected by external conditions, while 11 compounds showed a strong response. A pathway topology analysis indicated that EF caused changes to several metabolic pathways, mainly involving fatty acids and their related metabolic pathways. This study showed that EF can induce highly similar metabolic responses in insects across varying levels of PH3 resistance, suggesting that the mechanisms driving the toxicity of EF and PH3 are distinct. These insights significantly extend our knowledge of the toxic mechanisms of EF and provide direct evidence for the efficacy of EF treatment for managing PH3 resistance in insects.

Safe Farming: Ultrafine Bubble Water Reduces Insect Infestation and Improves Melon Yield and Quality.

Melon pest management relies on the excessive application of pesticides. Reducing pesticide spraying has become a global issue for environmental sustainability and human health. Therefore, developing a new cropping system that is sustainable and eco-friendly is important. This study found that melon seedlings irrigated with ultrafine water containing H2 and O2 (UFW) produced more root hairs, increased shoot height, and produced more flowers than the control irrigated with reverse osmosis (RO) water. Surprisingly, we also discovered that UFW irrigation significantly reduced aphid infestation in melons. Based on cryo-scanning electron microscope (cryo-SEM) observations, UFW treatment enhanced trichome development and prevented aphid infestation. To investigate whether it was H2 or O2 that helped to deter insect infestation, we prepared UF water enrichment of H2 (UF+H2) and O2 (UF+O2) separately and irrigated melons. Cryo-SEM results indicated that both UF+H2 and UF+O2 can increase the density of trichomes in melon leaves and petioles. RT-qPCR showed that UF+H2 significantly increased the gene expression level of the trichome-related gene GLABRA2 (GL2). We planted melons in a plastic greenhouse and irrigated them with ultrafine water enrichment of hydrogen (UF+H2) and oxygen (UF+O2). The SPAD value, photosynthetic parameters, root weight, fruit weight, and fruit sweetness were all better than the control without ultrafine water irrigation. UFW significantly increased trichome development, enhanced insect resistance, and improved fruit traits. This system thus provides useful water management for pest control and sustainable agricultural production.

Olax zeylanica Leaf Extract-assisted Eco-Benevolent Synthesis of Sulfur Nanoparticles and the Determination of their Insecticidal Potential against Sitophilus oryzae (L.) (Coleoptera: Curculionidae)


 
 
 Stored-product insects are serious pests of dried, stored, durable agricultural goods and value-added foods worldwide. In spite of the commonest way of controlling pestiferous insects associated with cereal grains and their milled products via conventional insecticides, their usage on stored grains are not recommended due to expensiveness, inefficacy due to insect resistance, and potential health hazards to humans. These deleterious consequences thus have been encouraging to merit investigation on the plant extract-assisted eco-benevolent synthesis of nanoparticles, owing to their sustainable, non-noxious, convenient, and environmental friendly nature. In view of this background, the present study was aimed at evaluating the insecticidal effectiveness of green synthesized sulfur nanoparticles (SNPs) against Sitophilus oryzae adults. SNPs have been successfully prepared from sodium thiosulfate (Na2S2O3.5H2O) in the presence of Olax zeylanica leaf extract at room temperature. The resulting SNPs were then characterized by UV-Vis spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The toxicity of Sitophilus oryzae was bio-assayed by exposing the test insects to SNPs-treated rice grains at six different dosages at 1.5, 1.0, 0.5, 0.25, 0.125 and 0.0625 g/kg, whereby mortality counts were taken after every 24 hours for seven days. The UV- Vis spectroscopy showed a peak in the range of 260-280 nm, which showed the successful formation of SNPs, while being in accordance with the previous studies reported in the literature. According to the Debye-Scherrer formula of XRD data, the average crystalline size of the SNPs counted to be 72.7 nm. The particle size of SNPs is also confirmed by SEM images. FTIR results showed peak positions corresponding to S8 with slight differences due to the presence of biomolecules from the O. zeylanica leaf extract being bound onto the surface of SNPs. Bioassay results show that the mortality of insects increased with the increase of dosage and exposure time period, reporting 100% S. oryzae mortalities at 1.5 and 1.0 g/kg dosages within 7 days. Accordingly, the results of the present study thus suggest that the bio-transformed sulfur nanoparticles could be utilized not only as biocontrol agents, but also as ecofriendly candidates for the sustained-protection storage grain ecosystems from insect pest infestations.
 Keywords: Green-synthesized Sulfur nanoparticles, Olax zeylanica, Insecticidal, Sitophilus oryzae
 
 

Insecticide mixtures-uses, benefits and considerations.

Insecticides remain an important tool for the control of many insect pests. There has long been an interest in insecticide mixtures (in-can and tank-mix) as a means to provide the needed efficacy and/or spectrum to control many insect public health, crop pests or crop pest complexes. This aspect has become more important since insecticides developed in the last 30 years tend to be narrower in spectrum with many primarily focused on either sap-feeding or chewing insect pests. Insecticide mixtures are also seen as an important approach to insect resistance management (IRM) with certain requirements for optimal implementation. Additionally, insecticide mixtures can also address certain agronomic, commercial and intellectual property needs and opportunities. This perspective will review some of the drivers and considerations for insecticide mixtures and their potential uses. © 2024 Society of Chemical Industry.

Integrated environmental and genomic analysis reveals the drivers of fine‐scale divergence and local adaptation in northern populations of two wild rice species in China

Societal Impact StatementCrop wild relatives represent precious genetic resources for crop improvement. Investigating their local adaptation to marginal environments is important for the utilization of wild genetic resources. Oryza officinalis and Oryza granulata are wild relatives of cultivated rice and possess genes that convey resistance to insects, disease, and tolerance to shade and drought. The northern edge for the distribution of these two lies in China where populations are facing habitat destruction. This study found that the northern marginal populations of both species have adapted to local conditions, with specific implications for the conservation and utilization of wild rice.Summary O. officinalis and O. granulata, wild relatives of cultivated rice, represent important gene reservoirs with the potential to improve rice with respect to insect resistance and stress tolerance. However, the northern marginal populations of these two species in China are facing habitat destruction. Here, we investigated the genetic diversity and divergence of northern marginal populations of O. officinalis and O. granulata. The genomic variation of two species was examined by whole‐genome sequencing on 357 individuals. Generalized dissimilarity modeling was applied to investigate the effects of geographic and environmental isolation on population differentiation. Genetic‐environment association analysis and genome‐wide FST outlier scans were used to identify environmentally driven signals of selection. The marginal populations of both species exhibited low genetic diversity and obvious genetic differentiation stemmed from the joint effects of isolation by geographic distance and the environment. Both genomes exhibited specific signals of adaptation to cold environments in the north. Investigation of the divergence and adaptation of marginal populations of O. officinalis and O. granulata will help us to determine how wild rice can adapt to local environments, thus allowing for the development of scientific conservation policies and the identification of new genetic resources for rice with improved resistance.

Assessing the potential impact of retaining native off‐site tree species in woodland restoration

Reestablishing appropriate tree species is an important step in converting off‐site monocultures into woodlands. Species conversion is often necessary, as off‐site exotic species rarely function like woodland species. However, when off‐site tree species are native, and functionally redundant to woodland species, conversion may be unnecessary. To explore this possibility in the southeastern United States, we reviewed the literature on trait differences among the primary southern pines and qualitatively assessed the effect of their identity at the species and stand‐levels. In this region, woodland restoration focuses on removing loblolly (Pinus taeda) and slash pine (P. elliottii) to reestablish longleaf (P. palustris) or shortleaf pine (P. echinata). Our review found minimal variation among species in understory flammability, fire resistance at maturity, and Red‐cockaded Woodpecker (Leuconotopicus borealis) habitat at the stand‐level. Longleaf and shortleaf pine were generally more resistant to abiotic and pest disturbance at the tree‐level; however, stand‐level differences in wind, drought, and boring insect resistance among southern pines growing in open forests were considered minimal. Retaining loblolly and slash pine will improve stand‐level productivity in the short term, but creates regeneration problems due to low juvenile fire resistance and resilience. Ice resistance and long‐term carbon sequestration will also likely be reduced by retaining loblolly and slash pine. Collectively, these results suggest that southern pine species are generally interchangeable at the stand‐level in woodlands; although woodlands featuring loblolly and slash pine may be less stable in the face of disturbance than those dominated by shortleaf and longleaf pine.

An Overview of Natural Inert Dust Utilization Against Stored-Product Pests as Part of Integrated Pest Management

Natural inert dust has been used as a grain protectant since the ancient Aztecs of Mexico to this modern era. Natural inert dust is divided into three groups: the first group includes sand, kaolin, paddy husk ash, wood ash, and clay; the second group includes mineral dust; and the third group includes natural silicas such as diatomaceous earth and zeolite. Natural inert dust has a unique mechanism for killing insect pests. Inert dust particles penetrate the insects’ exoskeleton, causing dehydration through the cuticle. Relative humidity is a crucial factor affecting the efficacy of inert dust application. Inert dust has been traditionally used by farmers, which impacts the insects, such as decreasing population, no insect resistance, and being environmentally friendly. Problems of using inert dust include visible residues on grain, airborne dust, reduced flowability, bulk density reduction, and adverse effects on downstream processing machinery. Moreover, inert dust is a very light product, thus it may cause human respiratory illness. The inert dust can be applied to the smaller or larger storage containers. Natural silica can be readily integrated into modern agriculture as a pest management solution.

Functional characterization of novel RbTI gene from ricebean and validation of its insecticidal properties in transgenic tobacco.

Plant protease inhibitors (PI's) inhibit the activity of gut proteases and thus provide resistance against insect attack. Previously we have published first report on cloning and characterization of a novel Bowman-Birk protease inhibitor gene (RbTI) from ricebean (Vigna umbellata). In this study, the RbTI gene was further characterized and validated as a potential candidate for transferring insect resistance in economically important crops. We have successfully generated transgenic tobacco plants expressing RbTI gene constitutively under CaMV35S promoter using Agrobacterium transformation. Genomic PCR and GUS analysis confirmed the successful integration of RbTI gene into tobacco plant genome. qRT-PCR analysis revealed highest RbTI gene expression in transformed tobacco leaves nearing maturity. Feeding of transformed tobacco leaf tissue showed prominent effect on larval mortality throughout the larval growth stages mainly during first three days of feeding. For functional analysis of RbTI gene, we estimated the inhibitory activity of protein extracts from normal and transformed tobacco plants against gut proteases of Spodoptera litura and H. armigera larval instars. Maximum inhibition of trypsin (82.42% and 73.25%) and chymotrypsin (69.50% and 60.64%) enzymes was recorded at early larval stages of both insects. The results of this study validated the future use of RbTI gene from ricebean legume as a potential candidate for transferring insect resistance in economically important crops. Insight, innovation, integration: Present study was conducted with the aim to utilize the state of art biotechnological techniques for transferring key pest resistant genes from underutilized promising crop ricebean. The tobacco plant has been utilized as modern plant for proof of concept where a protease inhibitor gene from Ricebean has been transferred to tobacco plant which induced larval mortality within first three days of feeding at all larval developmental stages. The biochemical assays on mid-gut total protein extract showed that the transgenic tobacco leaves have inhibiting effect on trypsin and chymotrypsin enzymes of insect which is otherwise required for digestion of food by them. Hence, we provide a novel gene that could be utilized for pest resistance in other crops different developmental stages.

Two Point Mutations in CYP4CE1 Promoter Contributed to the Differential Regulation of CYP4CE1 Expression by FoxO between Susceptible and Nitenpyram-Resistant Nilaparvata lugens.

Four P450s were reported to be important for imidacloprid resistance in Nilaparvata lugens, a major insect pest on rice, which was confirmed in this study in an imidacloprid-resistant strain (ImiR). Here we found that only two (CYP4CE1 and CYP6ER1) from these four P450 genes were overexpressed in a nitenpyram-resistant strain (NitR) when compared to a susceptible strain (SUS). CYP4CE1 RNAi reduced nitenpyram and imidacloprid resistance in NitR and ImiR strains, with a greater reduction in nitenpyram resistance. The transcription factor FoxO mediated nitenpyram resistance in NitR and ImiR strains, but it was not differentially expressed among strains. The potential reason for the differential regulation of FoxO on CYP4CE1 expression was mainly from sequence differences in the CYP4CE1 promoter between susceptible and resistant insects. In six FoxO response elements predicted in the CYP4CE1 promoter, the single-nucleotide polymorphisms were frequently detected in over 50% of NitR and ImiR individuals. The luciferase reporter assays showed that two mutations, -650T/G and -2205T/A in two response elements at the positions of -648 and -2200 bp, mainly contributed to the enhanced regulation on CYP4CE1 expression by FoxO in resistant insects. The frequency was over 69% for both -650T/G and -2205T/A detected in NitR and ImiR individuals but less than 20% in SUS insects. In conclusion, CYP4CE1 overexpression importantly contributed to nitenpyram resistance in N. lugens, and two mutations in the CYP4CE1 promoter of resistant insects led to an enhanced regulation on CYP4CE1 expression by FoxO.

Biological Characteristics and Thermal Requirements of Telenomus podisi and Trissolcus basalis (Hymenoptera: Scelionidae) in Fresh and Cryopreserved Eggs of Euschistus heros and Nezara viridula (Hemiptera: Pentatomidae)

Brazil is one of the largest producers of pulses globally, and soybean ranks highly in terms of production. However, pests increase crop production costs and affect oilseed production and quality. Pests are primarily controlled by chemicals, leading to changes in insect pest populations. For example, secondary pests can become primary pests because of the selection of resistant insects and the elimination of natural enemies. Farmers have widely accepted biological control because of its high control efficacy and low environmental contamination risk. Two successful biological control programs in soybean used Telenomus podisi Ashmead (Hymenoptera: Platygastridae) to manage the Neotropical brown stink bug, Euschistus heros (Fabricius) (Hemiptera: Pentatomidae), and Trissolcus basalis (Wollaston, 1858) (Hymenoptera: Scelionidae) to manage the southern green stink bug, Nezara viridula (Linnaeus) (Hemiptera: Pentatomidae), when these pests were the most abundant in soybean-producing regions. To release parasitoids, rearing protocols must be developed in order to optimize production. This study evaluated the effect of temperature on the biological characteristics of T. podisi and T. basalis when fresh or frozen E. heros eggs were provided. Fifty fresh or previously frozen eggs were placed with parasitoids for 24 h in a climate chamber (25 ± 1 °C, 70 ± 10% RH, and 14-h photophase). At the end of this period, the eggs were transferred to other chambers and maintained at different temperatures (19, 22, 25, 28, 31, and 34 ± 1 °C, 70 ± 10% RH, with a 14-h photoperiod). The number of emerging adults from eggs parasitized by T. basalis was lower than that from eggs parasitized by T. podisi. Differences in T. basalis and T. podisi parasitism were observed depending on whether the E. heros eggs were frozen or fresh, but neither development nor emergence were affected. The duration of egg–adult development and the longevity of the two parasitoids were inversely proportional to the temperature increase. The sex ratio of T. basalis and T. podisi progeny was not affected by different temperatures or by the use of frozen or fresh eggs. The estimated number of both parasitoids’ generations corresponded with temperature, reaching 14–15 generations/cycle of soybean for Rio Verde, GO, and 12–14 generations/cycle for Barreiras, BA. Given these characteristics, we conclude that a biological control program using T. podisi can benefit large areas of soybean production by controlling the eggs of phytophagous bugs in soybean crops.

Evaluation of resistance and susceptibility level of single and double gene Bt cotton against Armyworm and American bollworm

Bt cotton was developed against lepidopteran insects and got a significant attraction by the Pakistani farmers to control target pests. The experiment was conducted to determine the resistance and susceptibility level of lepidopteran insects against double gene (Cry1Ac + Cry2A) and single genes Cry1Ac and Cry2A. Six Bt cotton genotypes G1 and G2 with Cry1Ac, G5 and G6 with Cry2A, and G3 and G4 with double gene (Cry1Ac + Cry2A) were studied. G7 was non-Bt which was used as a control. A qualitative test of Bt genes was done with immune-blot strips, and quantification was done by the ELISA technique. In the Armyworm bioassay, G1 and G2 showed 1.187 mg g-1 and 0.927 mg g-1 concentrations of Cry1Ac and 41.66% and 33.33% larval mortality, respectively. The Cry2A genotypes, G5 and G6, showed 7.60 mg g-1 and 7.79 mg g-1 concentrations of Cry2A, respectively, and larval mortality as 83.33% on both genotypes. The double gene genotypes, G3 and G4, showed Cry1Ac concentrations as 0.803 mg g-1 and 0.730 mg g-1, those of Cry2A 7.459 mg g-1 and 7.407 mg g-1, whereas the larval mortality of the two genotypes had been 91.67% and 100%, respectively. In the American bollworm bioassay, G1 and G2 showed concentration of Cry1Ac as 1.049 mg g-1 and 1.052 mg g-1 and larval mortality 33.33% and 41.66%, respectively. G5 and G6 showed Cry2A concentrations as 6.520 mg g-1 and 6.464 mg g-1 and the larval mortality levels as 66.67% and 58.33%, respectively. G3 and G4 showed concentrations of Cry1Ac and Cry2A as 1.460 mg g-1 and 0.968 mg g-1, and 6.025 mg g-1 and 6.651 mg g-1 and the larval mortality as 100% and 91.66%, respectively. Low weight gain was observed on those genotypes which contained double gene rather than any of the single genes. Strong positive correlations existed between insect’s mortality and double gene concentration. A lethal concentration (LC) of the double gene of Armyworm and American bollworm was 7.513 mg g-1 and 7.684 mg g-1, respectively, required to kill 99% of the insect’s population. Double gene Bt cotton genotypes had resistance against target pests, while single-gene Bt cotton genotypes lost their efficacy against the target pests.

Insights into the role of non-coding RNAs in the development of insecticide resistance in insects.

Pest control heavily relies on chemical pesticides has been going on for decades. However, the indiscriminate use of chemical pesticides often results in the development of resistance in pests. Almost all pests have developed some degree of resistance to pesticides. Research showed that the mechanisms of insecticide resistance in insects encompass metabolic resistance, behavioral resistance, penetration resistance and target-site resistance. Research on the these mechanisms has been mainly focused on the cis-regulatory or trans-regulatory for the insecticide resistance-related genes, with less attention paid to non-coding RNAs (ncRNAs), such as microRNA (miRNA), long non-coding RNA (lncRNA), and circular RNA (circRNA). There has been increased studies focus on understanding how these ncRNAs are involved in post-transcriptional regulation of insecticide resistance-related genes. Besides, the formatted endogenous RNA (ceRNA) regulatory networks (lncRNA/circRNA-miRNA-mRNA) has been identified as a key player in governing insect resistance formation. This review delves into the functions and underlying mechanisms of miRNA, lncRNA, and circRNA in regulating insect resistance. ncRNAs orchestrate insect resistance by modulating the expression of detoxification enzyme genes, insecticide target genes, as well as receptor genes, effectively regulating both target-site, metabolic and penetration resistance in insects. It also explores the regulatory mechanisms of ceRNA networks in the development of resistance. By enhancing our understanding of the mechanisms of ncRNAs in insecticide resistance, it will not only provide valuable insights into the new mechanisms of insecticide resistance but also help to enrich new directions in ncRNAs gene regulation research.

The role of the Bemisia tabaci and Trialeurodes vaporariorum cytochrome-P450 clade CYP6DPx in resistance to nicotine and neonicotinoids

The alkaloid, nicotine, produced by tobacco and other Solanaceae as an anti-herbivore defence chemical is one of the most toxic natural insecticides in nature. However, some insects, such as the whitefly species, Trialeurodes vaporariorum and Bemisia tabaci show strong tolerance to this allelochemical and can utilise tobacco as a host. Here, we used biological, molecular and functional approaches to investigate the role of cytochrome P450 enzymes in nicotine tolerance in T. vaporariorum and B. tabaci. Insecticide bioassays revealed that feeding on tobacco resulted in strong induced tolerance to nicotine in both species. Transcriptome profiling of both species reared on tobacco and bean hosts revealed profound differences in the transcriptional response these host plants. Interrogation of the expression of P450 genes in the host-adapted lines revealed that P450 genes belonging to the CYP6DP subfamily are strongly upregulated in lines reared on tobacco. Functional characterisation of these P450s revealed that CYP6DP1 and CYP6DP2 of T. vaporariorum and CYP6DP3 of B. tabaci confer resistance to nicotine in vivo. These three genes, in addition to the B. tabaci P450 CYP6DP5, were also found to confer resistance to the neonicotinoid imidacloprid. Our data provide new insight into the molecular basis of nicotine resistance in insects and illustrates how divergence in the evolution of P450 genes in this subfamily in whiteflies may have impacted the extent to which different species can tolerate a potent natural insecticide.

Grower perceptions and adoption of IPM and non-Bt refuge in field corn: a survey in North and South Carolina

Abstract Production of field corn in the southeastern United States is often impacted by a number of insect pests. However, surveys to assess stakeholder perception of the relative importance of insect pests and adopted management decisions for these pests have not been extensively reported in the region. A survey was conducted in North and South Carolina to address deficiencies in our knowledge about how corn producers perceive insect pests, implement management and insect resistance strategies, and understand and implement integrated pest management (IPM). The survey indicated that stink bugs (Hemiptera: Pentatomidae) and corn earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), were the most commonly managed insect pests in field corn. For transgenic corn expressing insecticidal toxins from Bacillus thuringiensis (Bt) (Berliner), the rate of resistance management (i.e., planting of non-Bt corn refuge) implemented (59%) by growers was higher than previously reported. The majority of grower respondents identified ear development as the most critical corn growth stage for managing stink bugs (52%), with the most commonly reported management strategy being applications of insecticide at the economic threshold. Growers also reported understanding the concepts of IPM and implementing it in field corn. Assessing the adoption of preventative approaches, such as Bt corn and insecticide seed treatments, and strategies to manage insect resistance, in the case of Bt corn in particular, is critical for tailoring research and Extension efforts to protect the durability of these management tactics.

Effectiveness of bagasse and rice straw ashes against postharvest pest, Sitophilus zeamais on maize seed

Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae) is the main pest on maize seed in the storage. In general, postharvest pest control uses synthetic insecticides. However, the use of these synthetic insecticides causes insect resistance and negative impact on human health. This study aimed to determine the effectiveness of rice straw and bagasse ashes as inert dust in postharvest pest management of S. zeamais. This study was conducted at the Laboratory of Entomology, Faculty of Agriculture, Universitas Hasanuddin. This study used two treatments with four different doses i.e., 2, 4, 6, 8 g, and untreated (control). The results showed that complete (100%) of adult mortality at highest dose (8 g/kg seed) of bagasse ash in three days after infestation, while in the higher doses (6 and 8 g/kg seed) of rice straw ash killed 99.15%. The use of inert dust also causes typical symptoms in mortality in the form of wings coming out of the elytra, which is different from adult mortality without treatment.

Attractant potential of Enterobacter cloacae and its metabolites to Bactrocera dorsalis (Hendel).

Bactrocera dorsalis (Hendel) has a wide host range. It has been the most important quarantine pest in many countries or regions. Currently, chemical control and bait trapping are mainly used in the monitoring, prevention, and control of B. dorsalis. However, chemical control will cause pollution of the environment and drug resistance of insects. Methyl eugenol, the main attractant currently used, can only attract males of B. dorsalis. This study focused on the attractant function and active substances of one key intestinal bacterium, Enterobacter cloacae, which was isolated from B. dorsalis. First, the attraction of the E. cloacae autoclaved supernatant to male and female adults of 0, 6, and15days post-emergence was confirmed using a Y-type olfactometer. Subsequently, through metabolome sequencing and bioassays, L-prolinamide was identified and confirmed as the most effective attractant for B. dorsalis. Finally, the synergistic effect of L-prolinamide with the sex attractant ME was validated through field experiments. This study confirmed the attraction effect of E. cloacae on B. dorsalis and also proved the attraction effect of L-prolinamide, the metabolite of E. cloacae, on B. dorsalis. This laid a theoretical foundation for the development of a new attractant and safe, green, and efficient prevention and control technology of B. dorsalis.

Safe Farming: Ultra-Fine Sparkling Water can Reduce Insect Pests and Increase Melon Yield and Quality

Melon pest control relies on over-application of pesticides. Reducing pesticide spraying has become a global issue for environmental sustainability and human health. Therefore, it is important to develop a new growing system that is sustainable and environmentally friendly. This study found that melon seedlings irrigated with ultrafine water containing H2 and O2 (UFW) produced more root hairs, increased branch height, and produced more flowers than the control irrigated with reverse osmosis (RO) water. Surprisingly, we also found that UFW irrigation significantly reduced aphid infestations in melons. Based on cryoscanning electron microscopy (cryo-SEM) observations, UFW treatment enhanced trichome development and prevented aphid infestation. To investigate whether it was H2 or O2 to prevent insect damage, we prepared UF enriched water with H2 (UF+H2 ) and O2 (UF+O2 ) alone and irrigated the melons. Cryo-SEM results show that UF+H2 and UF+O2 can increase the density of trichomes in melon leaves and petioles. RT-qPCR showed that UF+H2 significantly increased the gene expression level of the trichome-related gene GLABRA2 (GL2). We grow muskmelons in plastic greenhouses and use ultrafine water-rich hydrogen (UF+H2 ) and oxygen (UF+O2 ). The SPAD value, photosynthetic parameters, root weight, fruit weight, and fruit sweetness are all better than those without ultrafine water irrigation of comparison. UFW significantly promoted the development of trichomes, enhanced insect resistance, and improved fruit traits. The system therefore provides useful water management for pest control and sustainable agricultural production.

Genome wide association study reveals new genes for resistance to striped stem borer in rice (Oryza sativa L.).

Rice is one of the most important food crops in the world and is important for global food security. However, damage caused by striped stem borer (SSB) seriously threatens rice production and can cause significant yield losses. The development and use of resistant rice varieties or genes is currently the most effective strategy for controlling SSB. We genotyped 201 rice samples using 2849855 high-confidence single nucleotide polymorphisms (SNPs). We conducted a genome-wide association study (GWAS) based on observed variation data of 201 rice cultivars resistant to SSB. We obtained a quantitative trait locus (QTL)-qRSSB4 that confers resistance to SSB. Through annotation and analysis of genes within the qRSSB4 locus, as well as qRT-PCR detection in resistant rice cultivars, we ultimately selected the candidate gene LOC_Os04g34140 (named OsRSSB4) for further analysis. Next, we overexpressed the candidate gene OsRSSB4 in Nipponbare through transgenic methods, resulting in OsRSSB4 overexpressing lines (OsRSSB4OE). In addition, we evaluated the insect resistance of OsRSSB4OE lines using wild type (Nipponbare) as a control. The bioassay experiment results of live plants showed that after 20 days of inoculation with SSB, the withering heart rate of OsRSSB4OE-34 and OsRSSB4OE-39 lines was only 8.3% and 0%, with resistance levels of 1 and 0, respectively; however, the withering heart rate of the wild-type reached 100%, with a resistance level of 9. The results of the in vitro stem bioassay showed that, compared with the wild-type, the average corrected mortality rate of the SSB fed on the OsRSSB4OE line reached 94.3%, and the resistance reached a high level. In summary, we preliminarily confirmed that OsRSSB4 positively regulates the defense of rice against SSB. This research findings reveal new SSB resistance gene resources, providing an important genetic basis for SSB resistance breeding in rice crops.

Advances in Biotechnological Approaches to Enhance Insect Resistance in Sugarcane

Advances in Biotechnological Approaches to Enhance Insect Resistance in Sugarcane