|
|
- Physalis floridana suppresses the expression of trehalase gene HvTREs in
Henosepilachna vigintioctopunctata (Coleoptera: Coccinellidae) for defense
against herbivorous insects-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Abstract Plants use various secondary chemicals in their chemical defense against herbivores. While botanical insecticides are crucial for reducing the reliance on chemical pesticides, the development of plant-derived insecticides remains limited. In this study, we fed Henosepilachna vigintioctopunctata with three different host plants (Solanum nigrum, Solanum tuberosum, and Physalis floridana) and observed that feeding on P. floridana led to changes in the body size and a significantly high mortality rate. Through transcriptome analysis, it was found that the trehalose metabolism pathway of H. vigintioctopunctata changed significantly under different host feeding conditions, especially since the expression level of the trehalase gene was extremely different. We subsequently identified eight transcripts of HvTREs and analyzed their evolution and structure. Among them, significant differences are observed in the relative expression levels of HvTRE1-5 in H. vigintioctopunctata after the fourth instar and were affected by different plant diets. Compared with the natural host S. nigrum, the larvae that fed on P. floridana significantly reduced the contents of trehalose, glucose and glycogen and significantly affected the trehalase activity. Knockdown of HvTRE1-5 by RNAi increased mortality at the H. vigintioctopunctata prepupation stage, suggesting that HvTRE1-5 is important for H. vigintioctopunctata pupation. This study provides new insights into developing of green control methods for H. vigintioctopunctata and offers a valuable example for understanding the interaction between host plants and herbivorous insects.
PubDate: 2024-08-10
- Potential of blue light-emitting diodes (LEDs) to disturb whiteflies on
the crop: a new push–pull strategy'-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Abstract Mass trapping can be a crucial component of a push–pull strategy, which involves deterrence of pests from a crop (push), while luring them toward an attractive source e.g., a trap (pull). In this study, we explored the effect of blue and blue + UV LEDs on the dispersal of greenhouse whiteflies settled on tomato plants (“push” factor) and the contribution of a yellow sticky trap (YST) and a green LED-enhanced YST (green LED trap) on their recapture after take-off (“pull” factor), in controlled conditions. In following scaling-up experiments in the greenhouse, we tested the effect of different blue spotlight arrangements and intensities on whitefly dispersal, in the presence of a green LED trap. Number of dispersed and trapped whiteflies was counted and the results revealed that blue and blue + UV LEDs increased the dispersed whiteflies by twofold compared to the control without deterrent LEDs and 87–90% of them were captured on a green LED trap. In the greenhouse, high-intensity blue spotlights (186 μmol/m2/s) deterred nearly 50% of whiteflies from the plants and more than half of them were recaptured, regardless the different arrangement of the blue spotlights. The green LED trap was at least twice as attractive as the YST, and in the greenhouse, it captured nearly 12 times more whiteflies in the presence of high-intensity deterrent blue spotlights, compared to the control. These findings provide significant implications for improving targeted whitefly control techniques and can lead to the development of new push–pull strategies.
PubDate: 2024-08-09
- Unbiased sequence analysis of vgsc gene reveals circulation of novel and
known knock-down resistance mutations in Culex pipiens, challenging vector
control measures-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Abstract Pyrethroids, targeting the voltage gated sodium channel (VGSC), are fundamental for the control of arboviral disease circulation. The spread of pyrethroid resistance among vector species represents thus a major public health concern. Culex pipiens is one of the most abundant European mosquito species and main vector of West Nile virus, leading cause of arboviral encephalitis worldwide. Despite this, monitoring of its resistance status and the understanding of underlying mechanisms are widely neglected. Herein, we performed an oligo-hybridization capture approach on 82 Cx. pipiens specimens from Italy and Greece to investigate the whole coding sequence of the vgsc gene for the presence of known and potential knock-down resistance (kdr) mutations associated with target-site resistance to pyrethroids in insects. Among the 26 non-synonymous substitutions revealed by the analysis, the super-kdr haplotype—i.e. the association of kdr-alleles 918T and 1014F, known for conferring a strongly enhanced resistance phenotype in Musca domestica – was revealed for the first time in mosquitoes. Three more potential kdr alleles were detected for the first time in Cx. pipiens and multiple kdr variants were observed for locus 1014, with allele 1014F, reaching frequencies > 80%. Overall, results depict a worrisome situation that could affect the ability to control West Nile virus outbreaks in southern Europe. To avoid this, resistance monitoring needs to be intensified and an enhancement of the diagnostic tool box for the easy detection of different kdr-variants (including in particular the super-kdr haplotype) and for subsequent functional studies on the resistance phenotype of detected variants, is required.
PubDate: 2024-08-09
- Susceptibility of Dalbulus maidis to insect-pathogenic fungi: unveiling
the protective role of brochosomes and self-cleaning behavior-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Abstract The corn leafhopper, Dalbulus maidis (Hemiptera, Cicadellidae), is an important pest of maize in Latin America, transmitting plant pathogens that impact grain production. Recently, mycopesticides have been considered as an alternative for the biological control of D. maidis populations, but there is controversy surrounding the efficacy of these products. We assessed the susceptibility of D. maidis to invertebrate-pathogenic fungi and, for the first time, investigated the protective role of the protein-lipid coat of brochosomes on the insect integument as a barrier against infections. Adult mortality was lower than 35% seven days after exposure to maize plants sprayed with water + surfactant-based conidia suspensions of 31 fungal strains from three different genera (Beauveria, Cordyceps and Metarhizium). Direct application of conidia suspensions on adults did not increase significantly the mortality rates when compared to adults exposed to contaminated surfaces. Conidia in water + surfactant readily adhered and germinated on detached forewings of D. maidis from which brochosomes were removed, but wings coated with this protein-lipid layer repelled droplets. Dry conidia easily adhered to brochosome-coated wings and their germination was not affected, although the methodical self-cleaning behavior of the adults effectively dislodged most conidia (either in suspensions or as a dry powder) from insect’s body after treatment. In conclusion, brochosomes and self-cleaning together efficiently prevent adhesion of conidia to D. maidis cuticle, serving as important barriers against fungal invasion and decreasing insect mortality. Our study highlights the importance of combining mycopesticides with effective adjuvants in spray applications to enhance infection rates and successfully control D. maidis populations.
PubDate: 2024-08-05
- Differential induction of JA/SA determines plant defense against
successive leaf-chewing and phloem-feeding insects-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Abstract Plants face an array of insect herbivores and have evolved complex defense approaches against various insect feeding strategies. However, little is known about how plants respond to successive attacks by herbivores with different feeding modes and coordinate their diverse defense mechanisms. In this study, we unveil that inducible jasmonic acid (JA) accumulation in response to leaf-chewing insects augments plant resistance and repellence to sequential leaf-chewing insect (caterpillar) and phloem-feeding insect (whitefly) infestations. Conversely, constitutive and whitefly inducible salicylic acid (SA) accumulation exclusively bolsters defense against later-stage whitefly invasion. Through assessments of herbivore performance and preferences on wild-type, JA-deficient, and SA-deficient plants, we show that JA/SA levels regulate plant resistance to both initial and sequential herbivores. Notably, JA or SA accumulation due to caterpillar or whitefly attacks does not substantially affect constitutive levels of the other compound, despite their antagonistic crosstalk. Furthermore, exogenous JA application in tobacco elicits efficient defense against successive caterpillar and whitefly assaults, surpassing SA's efficacy, albeit with associated growth penalties. Our discoveries demonstrate that plants can tailor their defense strategies against initial and sequential insects with different feeding modes. This customized defense is facilitated by JA/SA responses and their intricate cross-talk while taking account of the growth-defense trade-off.
PubDate: 2024-08-01
- Interspecific predation of a native herbivore facilitates colonization by
fall armyworms, Spodoptera frugiperda-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Abstract Spodoptera frugiperda is a newly invasive pest in China, often sharing the same feeding niche with native S. exigua. To clarify the competitive displacement, colonization and potential threat to crops by S. frugiperda, the cannibalism and predation behavior, feeding preferences, development and reproduction of both species under laboratory conditions, as well as the population dynamics and damage to maize plants in the field, were studied. Results found that food scarcity intensified interspecific predation between S. frugiperda and S. exigua, but the survival rate of 4th instar S. frugiperda was not significantly influenced (> 93%; P > 0.05). Although S. frugiperda exhibited less aggressive behaviors, its cannibalism coefficient and attack intensity were significantly higher than those of S. exigua (P < 0.05). Moreover, S. frugiperda showed a higher feeding preference for mechanically lethal insects when the maize leaf supply was insufficient. Additionally, a combined diet of maize leaves and lethal insects significantly increased their pupal weight and fecundity (P < 0.05). Field trials showed that when S. frugiperda and S. exigua co-occurred, the population of S. frugiperda at mature stage was similar to that after the intraspecific treatment, and seriously damaged maize plants. These results suggested that interspecific predation by S. frugiperda on S. exigua not only conferred an obvious advantage, but may also promote its development and reproduction, and facilitated its colonization in the invaded area. Our results provide an understanding of the rapid colonization mechanisms of S. frugiperda and will assist development of integrated management strategies.
PubDate: 2024-07-31
- A potential acaricide of Moutan Cortex essential oil encapsulated in
nanoemulsion and mesoporous silica nanoparticles against the house dust
mite Dermatophagoides farinae-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Abstract Moutan Cortex essential oil (MCEO) is considered to be a promising botanical insecticide. However, like most oils, MECO has several limitations, including instability and poor solubility. Nanoencapsulation technology is an excellent strategy for stabilizing essential oils because of its controlled release, enhanced efficacy, and strengthened biological activity. The present study investigated the acaricidal efficacy of pure MCEO and its encapsulated nanoemulsion (NE) and mesoporous silica nanoparticles (MSNs) against the house dust mite Dermatophagoides farinae using contact bioassays, fumigant bioassays, repellent bioassays, and the observation of toxic symptoms. MCEO-MSNs obtained in the study successfully encapsulated MCEO with an encapsulation efficiency of 63.83%. The acaricidal mortality experiments revealed that MCEO-NE and MCEO-MSN showed more significant toxicity against D. farinae than did pure MCEO. The nanomaterials showed better larvicidal and nymphicidal activities than pure MCEO at a high concentration (12-h LC90). Notably, the repellent effect experiment showed that MCEO-NE and MCEO-MSN had long-term and stable repellent effects on D. farinae, indicating the sustained release and persistence of the nanomaterials. More toxicity symptoms were observed in the IM-type group than in the KD-type group, suggesting that the MCEO nanoparticles have adverse effects on the respiratory system. Nanomaterials and MCEO promoted superoxide dismutase (SOD) activity and inhibited acetylcholinesterase (AChE) activity in D. farinae. In addition, the binding sites of paeonol to SOD and AChE were found through molecular docking. These findings demonstrate the potential of MCEO as a biological acaricide, which merits further investigation.
PubDate: 2024-07-31
- Dual effects of tomato chlorosis virus on its whitefly vector and its host
plant to facilitate viral spread-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Abstract Tomato chlorosis virus (ToCV) causes widespread infections in tomatoes globally, rapidly spreading in China is closely associated with the dominant whitefly, Bemisia tabaci (Gennadius) Mediterranean (MED). Viruliferous whiteflies have been reported to have shown preference for healthy tomato plants and thus greatly facilitate the spread of this virus. However, the mechanism underlying the change in the host selection behavior is yet unknown. We studied the effects of ToCV infection on the volatile emissions of tomato plants to determine the main volatiles associated with host selectivity by B. tabaci MED. Gas chromatography mass spectrometry (GC-MS) analyses revealed that ToCV infection significantly altered concentrations of 11 volatile compounds. Notably, the attractive p-ethylacetophenone, decreased, while the repellent butylated hydroxytoluene increased. RT-qPCR showed significant expression changes in 10 odorant binding protein (OBP) genes and 11 chemosensory protein (CSP) genes in viruliferous whiteflies compared to non-viruliferous whiteflies. RNA interference indicated that silencing OBP-17 or CSP-1 triggered a strong repellent response from B. tabaci toward tomatoes. Furthermore, OBP-17 expression rose notably with p-ethylacetophenone exposure, with both OBP-17 and CSP-1 exhibiting strong binding affinity for this compound, having dissociation constants of KD OBP-17 = 17.24 µmol/L and KD CSP-1 = 15.02 µmol/L, respectively. In conclusion, our study revealed dual effects of ToCV on its vectoring whitefly as well as its host plant, which together facilitate the spread of the virus. This novel insight into the epidemiological mechanisms of insect-vectored plant viruses may help to develop new strategies to control these exceedingly important agricultural pests.
PubDate: 2024-07-30
- Effects of classical biocontrol agents on indigenous natural enemies:
reproduction in pomegranate butterfly Deudorix livia eggs by native and
imported parasitoids-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Abstract Exotic natural enemies that are imported to control a target pest may attack non-target species or disrupt the performance of other natural enemies of the target that are already present. We evaluate possible interactions between three parasitoid species, the native Telenomus nizwaensis and the imported Trichogramma brassicae and Trichogramma evanescens, when presented with Deudorix livia host eggs under high-density laboratory conditions. Deudorix livia is a butterfly which is an economically damaging pest in the Omani pomegranate agro-ecosystem. Most (73.5% overall) of the observed parasitism was by T. nizwaensis. It performed best when presented with host eggs in the absence of either of the Trichogramma species. These imported species thus have some potential to disrupt suppression of the pest by the indigenous natural enemy under lower-density conditions in the field, and neither of them achieved high parasitism rates themselves (laboratory conditions: T. brassicae = 12.5%; T. evanescens = 18.5%; with no evidence for any parasitism of field-collected eggs). Future efforts in this agro-ecosystem would best be directed towards encouraging T. nizwaensis, rather than towards importation of Trichogramma. Screening for negative effects of natural enemies on the pest suppression provided by other natural enemies is recommended.
PubDate: 2024-07-27
- The use of the juvenoid pyriproxyfen accelerates sexual maturity in
mass-reared Anastrepha ludens tephritid males but reduces their tolerance
to chilling and to starvation-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Abstract The Sterile Insect Technique (SIT) is a system based on the release of millions of sterile insects to prevent the reproduction of specific pest populations. However, to improve the efficacy of the SIT, sterile males must reach sexual maturity before being released to increase their probability of mating with wild females. Treatments with juvenile hormone (JH) analogs, such as pyriproxyfen (PPF), accelerate sexual maturity in sterile Anastrepha ludens (Loew) (Diptera: Tephritidae) males. We hypothesized that speeding up this life-history trait can affect male resistance to stressors such as chilling and starvation. In this study, we compared some quality control parameters of flies of two different strains, selected to resist desiccation (DR) and non-selected flies (NS), treated with PPF, and subsequently exposed to starvation and pre-release chilling periods. We used males that were treated with PPF after emergence. The results showed that, from 4 to 6 days of age, DR PPF-fed males mated less than NS PPF-fed males. DR and NS males obtained a similar number of copulations at 7 days of age. After chilling, survival was higher in DR than in NS males. In addition, NS males showed a slight advantage in number of copulations when they reached 5 days of age but not at 6 and 7 days of age. Chill-coma recovery time was longer in PPF-fed flies than in control flies. Moreover, PPF-fed flies obtained less copulations after exposure to chilling at 5 days of age compared to non-chilled flies. These results indicate that sexual maturity is accelerated in PPF-fed males, especially in NS flies. However, using PPF as a pre-release treatment for A. ludens results in a reduction in male quality, regardless of whether they are DR or NS.
PubDate: 2024-07-27
- Reversal of practical resistance in fall armyworm to Cry1F maize: a case
report on the resistance to susceptibility in Bt crops from the
southeastern USA-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Abstract The fall armyworm, Spodoptera frugiperda, is a polyphagous pest in the Americas and a target of Bt crops. A study from 2011-2013 demonstrated practical resistance of S. frugiperda to Cry1F maize in the southeastern coastal region of the U.S. In this study, diet-overlay and leaf tissue bioassays were conducted to determine the susceptibility to four common Bt proteins in maize (Cry1F, Cry1A.105, Cry2Ab2, and Vip3Aa) in 23 S. frugiperda populations collected during 2021-2022 from seven southern U.S. states, including nine populations from the southeastern coastal region. In the diet-overlay bioassays with Cry1F, 22 populations were equally or more susceptible than a susceptible reference, with a single population showing an increased susceptibility ratio (LC50 of field population/LC50 of the susceptible strain) of 1.97. Susceptibility ratios of the 23 populations ranged from <0.15 to 4.67 for Cry1A.105 and <0.12 to 5.04 for Vip3Aa. Three populations exhibited an LC50 >tenfold greater than the susceptible strain to Cry2Ab2. Altogether, the study did not provide evidence of practical resistance in S. frugiperda to the four Bt proteins. Instead, the results show that the recently collected populations were susceptible to Cry1F, Cry1A.105, and Vip3Aa. The Bt susceptibility was consistent across geographical locations and host plants. Results from the leaf tissue assays confirmed the findings of the diet-overlay bioassays. The reversed Cry1F susceptibility in S. frugiperda identified in this study represents the first case of documented practical resistance reverting to susceptible status in Bt crop-insect systems and thus has important implications for resistance management.
PubDate: 2024-07-27
- Enhancing the durability of mosquito repellent textiles through
microencapsulation of lavender oil-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Abstract In this study, the objective was to develop a long-lasting mosquito repellent textile by synthesizing silk-based lavender oil microcapsules and applying them to cotton fabric. Lavender oil, derived from Lavandula angustifolia, was chosen as the plant-based material. The microcapsules’ morphology and the fabric’s surface were examined using optical and scanning electron microscopes. Dynamic light scattering was utilized to measure the capsule size and zeta potential. The mosquito repellent efficacy was evaluated through cage tests before and after multiple wash cycles and after exposure to different environments. A cytotoxicity assay was conducted on functionalized fabrics in order to assess their biocompatibility. Additionally, comfort properties such as breathability and water absorbency were assessed and compared to a control fabric. The results indicated that a higher concentration of lavender oil microcapsules (15 wt%) on the fabric exhibited excellent mosquito repellent efficacy (95.7%) prior to washing, which remained effective as 84.5% even after 40 washes. Furthermore, the functionalized fabric maintained its repellent properties following exposure to temperatures of 25 °C and 37 °C for 4 weeks. The cytotoxicity results indicated that the functionalized fabric exhibited non-toxic properties toward L929 cells, thereby confirming its favorable biocompatibility. This study successfully demonstrated the synthesis and application of silk-based lavender oil microcapsules on textiles, resulting in highly durable mosquito repellent fabrics effective against Aedes aegypti mosquitoes. These findings highlight the potential of this eco-friendly approach for developing effective and long-lasting mosquito repellent textiles.
PubDate: 2024-07-23
- Arsenophonus and Wolbachia-mediated insecticide protection in Nilaparvata
lugens-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Abstract While symbiont infections in invertebrates are widespread, their role in protecting hosts against natural enemies and chemical insecticides remains incompletely understood. Our study investigates the protective effects of Arsenophonus and Wolbachia, either individually or in co-infection, on Nilaparvata lugens against chemical insecticides. Our findings reveal that both Arsenophonus and Wolbachia confer protection against chemical insecticides, including triflumezopyrim, nitenpyram, and dinotefuran. However, these symbionts do not show protective effects against pymetrozine. Wolbachia infection leads to the up-regulation of the glutathione S-transferase (GST) gene GSTm2 and the P450 gene CYP6AY1. Uniquely, co-infection results in the up-regulation of the P450 gene CYP18A1. Furthermore, the stability of the co-infection is not constant, with its frequency decreasing from 93.3 to 73.1% over a nine-generation passage, while single infections remain consistently high (> 95%). Our study suggests that Wolbachia and Arsenophonus, both individually and in co-infection, provide protection against two commonly used chemical insecticides in N. lugens.
PubDate: 2024-07-20
- Guardians within: entomopathogenic fungi-driven antibiosis and
compensatory growth combines to reduce the damage of herbivores to melon
plants-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Abstract Endophytic and rhizosphere-competent entomopathogenic fungi (EF) are important plant bodyguards, although the mechanisms underlying this phenomenon are poorly understood. Therefore, we aimed to elucidate the roles of antibiosis (lethal and sublethal effects), and potential growth compensation (in response to leaf injury) in melon plants exposed to cotton leafworm. Plants were inoculated with one of three EF strains (EAMa 0158-Su Metarhizium brunneum strain or EABb 04/01-Tip and EABb 01/33-Su Beauveria bassiana strains) by either foliar spray, seed dressing or soil drenching and then challenged with either multiple short-term, or single long-term Spodoptera littoralis larval infestation. Endophytic colonization and relative expression of plant defense genes were tracked using molecular techniques alongside evaluation of antibiosis effects on S. littoralis and plant tolerance to larval-induced leaf injuries. Inoculated plants exhibited antibiosis and potential growth compensation in responses to various S. littoralis challenges, which resulted in increased fresh and dry weight, chlorophyll content, number of secondary branches and stem diameter. Furthermore, up-regulation in the relative expression of ethylene (ACO1, ACO3, EIN2, EIN3) and jasmonic acid (LOX2)-related genes were observed, with the endophytic B. bassiana- induction of ethylene and jasmonic acid production being higher in S. littoralis infested plants. Our findings strongly confirm the EF multifunctionality and the involvement of the Endophytic EF triggered melon defensive system induction in the antibiosis and compensatory growth to protect melon plants from pest damage.
PubDate: 2024-07-20
- Genome-wide exploration of metabolic-based pyrethroid resistance mechanism
in Helicoverpa armigera-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Abstract To elucidate the deltamethrin resistance mechanism in Helicoverpa armigera, we explored mutations at the deltamethrin target site, genomic level variations between insecticide-susceptible and -resistant strains, and differences in gene expression patterns between the strains. Known pyrethroid resistance-associated point mutations within the voltage-gated sodium channel were undetected in the cDNA and gDNA of resistant strains or field populations. The whole-genome de novo assembly of a Korean-resistant strain was performed (GCA_026262555.1), and 13 genomes of susceptible and resistant individuals were re-sequenced using field populations. Approximately 3,369,837 variants (SNPs and indels) were compared with our reference H. armigera genome, and 1,032,689 variants were identified from open reading frames. A resistance-specific CYP3 subfamily gene with five variants (CYP321A1v1–v5) was identified in the resistant strains, indicating the potential role of these variants in resistance. RNA-seq analysis identified 36,720 transcripts from 45 Illumina RNA-seq datasets of the fatbody, gut, and the rest of the body. Differential gene expression analysis revealed some differently overexpressed detoxification enzyme genes in the resistant strains, particularly cytochrome P450 genes. This finding was consistent with the results of bioassay tests using PBO-based synergists that inhibit enzymes belong to cytochrome P450 family, further supporting the role of detoxification enzymes in resistance. Therefore, H. armigera may acquire deltamethrin resistance through a combination of actions, including the overexpression of various detoxification enzymes, such as CYP321A5 identified in this study may serve as a basis for understanding insecticide resistance at the molecular level and can be applied as diagnostic markers for resistance.
PubDate: 2024-07-19
- Sex-biased juvenile hormone and gene expression underlie sex difference of
stress resistance in the American cockroach-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Abstract Sexually dimorphic traits are prevalent throughout the animal kingdom, extending to insects. In addition to sex-biased gene expression networks, these traits often involve variations in hormone levels. Juvenile hormone (JH), which is synthesized by corpora allata (CA), regulates development and reproduction in insects. However, there is limited understanding regarding sex-biased gene expression in CA and the sexually dimorphic functions of JH. We discovered sexual dimorphism in JH levels in cockroaches. To explore the underlying mechanism, we analyzed RNA-sequencing data from CA tissues in the adult females and males of the American cockroach, Periplaneta americana. Our investigation revealed significant variation in sex-biased gene expression, with female-biased genes primarily involved in cytochrome P450, glutathione S-transferase and peroxidase pathways, associating with resistance to environmental stress. Notably, exposure to the insecticide imidacloprid, injection of Escherichia coli and H2O2 led to a higher mortality rate in males, whereas females exhibited resistance. Importantly, the application of the JH analog methoprene following the injection of E. coli and H2O2 rescued survival and the expression of stress response-related genes in males. Furthermore, these stressors resulted in reduced JH biosynthesis in males, while females remained unaffected. In summary, our results reveal that sexually dimorphic JH levels and gene expression modulate stress responses in P. americana. These findings shed light on sex-specific responses to environmental stress, offering tailored strategies for pest control based on gender.
PubDate: 2024-07-17
- Leveraging air-borne VOC-mediated plant defense priming to optimize
Integrated Pest Management-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Abstract Plant defense priming involves the release of air-borne volatile organic compounds (VOCs) by plants, serving to prepare defense-related mechanisms against herbivores and pathogens in adjacent receiver plants. While the concept of VOC-mediated plant defense priming for enhancing plant resistance has garnered considerable attention in the last two decades, it has yet to be fully realized and applied in practical crop protection. This review summarizes current research, examining the spectrum of VOC-mediated plant defense priming in terms of anti-herbivore or anti-pathogen properties, the cost–benefit implications for plants, and the influence of abiotic factors on the priming. Additionally, we explore two promising approaches within the framework of Integrated Pest Management (IPM): the implementation of companion sentinel intercropping and the application of synthetic VOCs. In conclusion, we propose future research directions for this promising area, anticipating that this review will stimulate efforts aimed at harnessing the effects of plant defense priming for the development of innovative pest management strategies and optimized IPM programs in crop protection.
PubDate: 2024-07-10
- Detection of Paecilomyces formosus in wood-boring beetles associated with
oak dieback and decline in the Zagros forests of Iran-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Abstract Oak dieback disease caused by the fungus Paecilomyces formosus threatens oak trees in the Zagros forests in western Iran. Various insects, such as wood-infesting beetles (Coleoptera), may play a role in dissemination of P. formosus. We collected larvae and adult insects from branch wood of oak trees with dieback symptoms in the Zagros forests. For larval identification, the mitochondrial gene cytochrome c oxidase I (COXI) was amplified by polymerase chain reaction (PCR). Fungal isolates from wood and insects collected from the sampled oaks were identified by morphology, acid production on creatine sucrose agar (CREA) medium, phylogeny of DNA sequence data for the β-tubulin gene and the internal transcribed spacer (ITS) rDNA. To detect P. formosus in larvae and adult insects, we used a nested PCR assay with the species-specific primer pairs PaMF and PaMR. The insects that most often tested positive for P. formosus were larvae of the buprestids Acmaeodera sp. and Chrysobothris affinis, and larvae of the cerambycid Trichoferus campestris. Adults of C. affinis and Calchaenesthes diversicolis (Cerambycidae), which were collected from within their galleries, also tested positive. Beetle larvae of Anthaxia sp. (Buprestidae), Latipalpis plana (Buprestidae), Monochamus sp. (Cerambycidae) and Crypticus gibbulus (Tenebrionidae) also tested positive. Larvae that tested negative for P. formosus were species of Cossidae (Lepidoptera), Elateridae (Coleoptera), Gasteruptiidae (Hymenoptera) and Syrphidae (Diptera). Future research is needed to determine whether any of these insects can serve as vectors of P. formosus. These results can be used to target-specific insects for monitoring.
PubDate: 2024-07-10
- Exogenous systemin peptide treatment in olive alters Bactrocera oleae
oviposition preference-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Abstract The olive fruit fly, Bactrocera oleae (Rossi), is a key pest of the olive crop, whose control relies mostly on the use of insecticides. Plant peptides may represent a more environmentally-friendly tool to manage olive fly, due to their recognized role to activate and/or prime plant defence responses against pests. In this work, behavioural experiments (no-choice and two-choice) and analysis of volatile compounds were carried out to evaluate the impact of the exogenous application of the peptide systemin to olive tree on olive fly infestation, and to elucidate its mode of action to prime plant defence. The treatment of olive branches with 10 nM systemin showed to confer protection against olive fly, by reducing significantly the ovipositions (up to 3.0-fold) and the number of infested fruits (up to 2.9-fold) when compared to non-treated branches. This protective effect was even detected in neighbouring non-treated branches, suggesting the ability of systemin to trigger plant-to-plant communication. The deterrent activity of the primed olives was associated with the emission of the volatiles 2-ethyl-1-hexanol, 4-tert-butylcyclohexyl acetate and 1, 2, 3-trimethyl-benzene, which were negatively correlated with oviposition and fly infestation. Systemin has also showed to trigger the biosynthesis of specific volatiles (esters) in olives in response to fly attacks. Overall, the observed protection conferred by systemin against olive fly is likely due to the emission of specific volatiles that can act as a defence and/or as signalling molecules to upregulate the plant defence response. Thus, systemin represents a novel and useful tool to manage olive fruit fly.
PubDate: 2024-07-08
- A predatory mite as potential biological control agent of Bemisia tabaci
on tomato plants-
Free pre-print version: Loading...
Rate this result:
What is this?
Please help us test our new pre-print finding feature by giving the pre-print link a rating.
A 5 star rating indicates the linked pre-print has the exact same content as the published article.
Abstract: Abstract Several natural enemies are known as predators of the whitefly Bemisia tabaci, which is one of the most invasive pests worldwide and has developed high resistance to pesticides. However, biological control of this pest on tomato is often difficult because the plant’s glandular trichomes release substances that are toxic to arthropods and hinder the foraging of natural enemies. Therefore, adaptation of natural enemies to this crop is one of the selection criteria for potential biocontrol agents. We collected predatory mites from wild and feral tomato plants and found the species Amblyseius herbicolus and A. tamatavensis. Whereas the latter is known to feed on B. tabaci eggs, we investigated the ability of A. herbicolus to develop and reproduce when feeding on this prey stage, and assessed whether both species can feed and develop on B. tabaci crawlers. To verify the adaptation of these predators to tomato, we assessed their ability to disperse on tomato plants and their establishment on clean tomato plants with pollen as an alternative food. Finally, we evaluated whether the predators were effective in controlling B. tabaci on tomato plants with different pollen dosages as alternative food. We show that both predators fed and reproduced on B. tabaci immatures. A. herbicolus established and dispersed better on tomato plants supplemented with cattail pollen than A. tamatavensis and only A. herbicolus was able to control B. tabaci in two population dynamics experiments. Our results suggest that A. herbicolus is better adapted to tomato than A. tamatavensis and may therefore be a promising biocontrol agent on tomato.
PubDate: 2024-07-06
|
Hybrid journal (It can contain Open Access articles)
