Plutella Xylostella Research Articles

Whole-genome sequence of Enterobacter hormaechei, isolate jjbc recovered from the gut of Plutella xylostella feeding on cabbage.

We present the whole-genome sequence of Enterobacter hormaechei (previously Enterobacter cloacae) obtained from long and short reads. It is a dominant gut symbiont of the notorious crop pest Plutella xylostella, highly prevalent in lepidopteran midguts and a useful model for the evolution of resistance to antimicrobials.

Efficacy of microbial biopesticides to manage Pieris brassicae (Linnaeus) and Plutella xylostella (Linnaeus) in cauliflower

Efficacy of microbial biopesticides to manage Pieris brassicae (Linnaeus) and Plutella xylostella (Linnaeus) in cauliflower

Plasticity in moth mating behavior and ejaculate proteomic diversity induced by male competition

In male competition, large and costly ejaculates are advantageous. Prior research on male accessory gland secretions in Plutella xylostella left open questions about how males modulate their mating behaviors and ejaculate composition allocation in response to varying levels of competition. The current study aimed to delve deeper into these unexplored facets. A totally of 928 ejaculate proteins were identified across males exposed to different competition conditions. Notably, males courting under non–, low-, and high-competition scenarios exhibited 867, 635, and 858 ejaculate proteins, respectively. Approximately 10% of these ejaculate proteins displayed variations that aligned with changes in competition intensity. Subsequent analyses focused on the proteins transferred to females, revealing that 44% of ejaculate proteins were transferred, with 37 proteins exhibiting differential expression. Functional analyses uncovered their crucial roles in sperm maturation, motility, and capacitation. Our findings reveal adaptive adjustments in ejaculate protein abundance and transmission in P. xylostella as a response to varying competition levels. Moreover, fluorescent sperm labeling indicated higher sperm transfer during low competition correlated with shorter sperm length. Furthermore, evidence suggests that males shorten their courtship duration and extend their mating duration when faced with competition. These results illustrate how competition drives ejaculate investment and behavioral plasticity, offering valuable insights for advancements in assisted reproductive technologies and pest management strategies.

An Orphan Gene Enhances Male Reproductive Success in Plutella xylostella.

Plutella xylostella exhibits exceptional reproduction ability, yet the genetic basis underlying the high reproductive capacity remains unknown. Here, we demonstrate that an orphan gene, lushu, which encodes a sperm protein, plays a crucial role in male reproductive success. Lushu is located on the Z chromosome and is prevalent across different P. xylostella populations worldwide. We subsequently generated lushu mutants using transgenic CRISPR/Cas9 system. Knockout of Lushu results in reduced male mating efficiency and accelerated death in adult males. Furthermore, our findings highlight that the deficiency of lushu reduced the transfer of sperms from males to females, potentially resulting in hindered sperm competition. Additionally, the knockout of Lushu results in disrupted gene expression in energy-related pathways and elevated insulin levels in adult males. Our findings reveal that male reproductive performance has evolved through the birth of a newly evolved, lineage-specific gene with enormous potentiality in fecundity success. These insights hold valuable implications for identifying the target for genetic control, particularly in relation to species-specific traits that are pivotal in determining high levels of fecundity.

Silence of Aminopeptidase N 2gene reveals the trade-offs for acquiring Cry1Ac resistance in Plutella xylostella.

Bacillus thuringiensis (Bt) is widely used as a biopesticide worldwide. To date, at least eight pest species have been found to be resistant to Bt in the field. As the first pest that was reported having resistance to Bt in the field, considerable research has been done on the mechanisms of Bt resistance in Plutella xylostella. However, whether the acquisition of Bt resistance by P. xylostella comes at a fitness cost is also a valuable question. In this study, Aminopeptidase-N 2 (APN2), a Cry toxin receptor gene of P. xylostella, was knocked down by RNA interference, resulting in improved resistance to Cry1Ac. It was also found that larval mortality of APN2 knockdown P. xylostella was significantly higher than that of the control, while the pupation rate, pupal weight, eclosion rate, fecundity (egg/female), hatchability, and female adult longevity were significantly lower in APN2 knockdown P. xylostella than in the control. These results illustrate that if Cry1Ac resistance was obtained only through the reduction of APN2 expression, P. xylostella would need to incur some fitness costs for it.

Design, Synthesis, and Acaricidal/Insecticidal Activities of New Phenylpyrazole Derivatives Comprising an Imide Moiety.

Using nicofluprole as the lead compound, we designed and synthesized a series of new phenylpyrazole analogues through substituting the methyl group on the nitrogen atom of the amide with an acyl group. Bioassay results showed that compounds A12-A17 with a 1-cyanocyclopropimide group exhibited outstanding insecticidal activity. The LC50 values for compounds A12-A17 against Tetranychus cinnabarinus ranged from 0.58 to 0.91 mg/L. Compound A15 showed an LC50 value of 0.29 and 3.10 mg/L against Plutella xylostella and Myzus persicae, respectively. Molecular docking indicated the potential binding interactions of compound A15 with a gamma-aminobutyric acid receptor. Additionally, density functional theory calculations implied that the 1-cyanocyclopropimide structure might be essential for its biological activity. Phenylpyrazole derivatives, containing a 1-cyanocyclopropimide fragment, have the potential for further development as potential insecticides.

Percentage Attacks of Plutella xylostella and Parasitization of the Parasitoid Diadegma semiclausum on Cabbage in Kintamani District

Cabbage plants are one of the horticultural commodities that many farmers cultivate in Indonesia because they have economic value, because apart from being able to meet domestic needs, cabbage also has the opportunity to become an export commodity. This study aims to determine the percentage of attacks by the cabbage leaf caterpillar Plutella xylostella and the level of parasitization of the parasitoid Diadegma semiclausum in Kintamani District. This research was carried out in Sekaan Village and Kedisan Village. The research method uses a survey method. Sampling of cabbage plants in the field was carried out diagonally so that 5 sample points were obtained, 10 plants were observed at each sample point. The research results showed that the percentage of P. xylostella pest attacks in Sekaan Village and Kedisan Village ranged from 12% to 28%. The average population of P. xylostella larvae in Sekaan Village ranges from 0.98 individuals/plant to 1.82 individuals/plant and the highest average population of P. xylostella larvae in Kedisan Village ranges from 0.7 individuals/plant to 1.66 individuals/plant. The level of parasitization of the parasitoid D. semiclausum in Sekaan Village ranges from 32% to 56% and the level of parasitization of the parasitoid D. semiclausum in Kedisan Village ranges from 24% to 48%. The highest peak of parasitization was found in the fourth observation (4 WAP).

Insecticide resistance and characteristics of mutations related to target site insensitivity of diamondback moths in Taiwan

Diamondback moth (DBM, Plutella xylostella) is the most significant pest of cruciferous vegetables as they rapidly develop high-level resistance to many insecticides. Monitoring DBM susceptibility and target-site mutation frequency is essential for pest control. In this study, 10 insecticides were tested on 11 field populations. Frequencies of target-site mutations (including para, ace1, Rdl1, RyR1, and nAChRα6 genes) were estimated by pyrosequencing. Insecticides registered after 2007 for DBM control in Taiwan, i.e., spinetoram, chlorantraniliprole, chlorfenapyr, metaflumizone, and flubendiamide, showed >80% mortality toward several populations; Bacillus thurigiensis, emamectin benzoate, and chlorfluazuron showed medium to low efficacy in all populations; and tolfenpyrad and mevinphos were highly ineffective. Susceptibility to insecticides varied substantially among populations: eight out of nine populations were highly susceptible to spinetoram, but only one was susceptible to flubendiamide. Target-site mutations related to organophosphates, pyrethroids, fipronil, and diamides were detected in all populations, but there were few spinosad and spinetoram mutations. Our three-year field study demonstrated rapid efficacy loss for all insecticides tested, particularly for more toxic insecticides. Skipped-generation selection of a field DBM strain to emamectin benzoate, metaflumizone, chlorantraniliprole, and flubendiamide revealed that mortality rates dropped from 60 to 80% to <10% after 6 generations. Next-generation sequencing was performed to identify possible target gene mutations. A resistance management program that considers the instability of resistance to some chemicals and pertinent data on resistance mechanisms should be established. Identifying compounds to overcome high-frequency field DBM point mutations could be beneficial for pest control.

Comparative Efficacy and Economics of Biopesticides with Emamectin Benzoate against Diamondback Moth, Plutella xylostella (L.) in Cabbage, Brassica oleracea var. Capitata (L.)

A field trial was conducted during rabi season 2023-2024 at Central Research Farm (CRF), Sam Higginbottom University of Agriculture, Technology and Sciences, Naini, Prayagraj, Uttar Pradesh. The experiment was laid out in Randomised Block Design (RBD) with eight treatments each replicated thrice using a variety Green Soccer (546). The treatments viz., Emamectin benzoate 5% SG, Bacillus thuringiensis 5.0% WP, Spinosad 02.50 % SC, Verticillium lecanii 5.0% SC, Neem seed kernel extract 5%, Beauveria basssiana 1x 108CFU/ml, Azadirechtin 00.03 % WSP and along with an untreated control against plutella xylostella in cabbage.The data on larval population of Diamond back moth over control on first and second spray overall mean revealed that all treatments were significantly superior over control.Amomg all the treatments minimum larval population was recorded in in T3 Spinosad 02.50 %SC (1.045) followed by T1 Emamectin benzoate5%SG (1.212), T2Bacillus thuringiensis 5.0% WP (1.345),T6 Beauveria bassiana 1x 108 CFU/ml (1.512),T4 Verticillium lecanii 5.0 % SC (1.667),T5 Neem seed kernel extract 5 % (1.934),T7 Azadirechtin 00.03 % WSP (2.133).While, the highest yield (298q/ha) was obtained from the treatment T3 spinosad 02.50%SC as well as B:C ratio (1:5.76) was obtained high from this treatment. It followed by T1 Emamectin benzoate 5%SG (276q/ha) (1:5.53),T2 Bacillus thuringiensis 5.0% WP (269q/ha)(1:5.42),T6 Beauveria bassiana 1x 108CFU/ml (259q/ha) (1:5.24), T4 Verticillium lecanii 5.0% SC(249q/ha)(1:5.04), T5 Neem seed kernel extract 5% (233q/ha) (1:4.65), T7 Azadirechtin 00.03% WSP(215q/ha)(1:4.42) and the lowest yield and B:C ratio is recorded in T0 Control (186q/ha) (1:4.05).

In-Depth Structural Simplification of Celangulin V: Design, Synthesis, and Biological Activity.

Celangulin V is a novel botanical insecticide with significant bioactivity and a unique molecular target, but its complex polyol ester structure hinders its broader application in agriculture. To discover new analogues of celangulin V with a simpler structure and enhanced biological activities, we initiated a research project aimed at simplifying its structure and assessing insecticidal efficacy. In this study, a series of novel 1-tetralone derivatives were designed via a structure-based rational design approach and synthesized by a facile method. The biological activities of the target compounds were determined against Mythimna separata (M. separata), Plutella xylostella, and Rhopalosiphum padi. The results revealed that most of the synthesized compounds exhibited superior activities compared to celangulin V. Remarkably, the insecticidal activity of compound 6.16 demonstrated 102-fold greater stomach toxicity than celangulin V against M. separata. In addition, certain compounds showed significant contact toxicity against M. separata, a finding not reported previously in the structural optimization studies of celangulin V. Molecular docking analysis illustrated that the binding pocket of compound 6.16 with the H subunit of V-ATPase was the same as celangulin V. This study presents novel insights into the structural optimization of botanical pesticides.

MicroRNA-8514-5p regulates adipokinetic hormone/corazonin-related peptide receptor to affect development and reproduction of Plutella xylostella.

Dicer1 plays a crucial role in regulating the development and reproduction of insects. Knockout of Dicer1 causes pupal deformity, low eclosion and low fecundity in Plutella xylostella, but the mechanism behind this phenomenon is not clear. This study aims to identify differentially-expressed genes and miRNAs in the Dicer1-knockout strain (ΔPxDcr-1) and assess their impact on the reproduction and development of P. xylostella. The knockout of Dicer1 affected the expression of genes including the adipokinetic hormone/corazonin-related peptide receptor (PxACPR). The expression of PxACPR was upregulated, and the expression of miR-8514-5p was downregulated in ΔPxDcr-1 of P. xylostella. The dual luciferase reporter assay and pull-down assay showed that miR-8514-5p bound to PxACPR in vitro and in vivo. The expression profiles demonstrated a negative correlation between PxACPR mRNA and miR-8514-5p in different developmental stages of the wild-type strain. Both the miR-8514-5p agomir and double-stranded RNA of ACPR (dsPxACPR) injected into the pre-pupae inhibited the mRNA level of PxACPR, causing high mortality and deformity of pupae, and low fecundity and hatching rate, which were consistent with the phenotype of ΔPxDcr-1. The injection of miR-8514-5p antagomir caused a similar phenotype to the injection of miR-8514-5p agomir. Additionally, the injection of miR-8514-5p antagomir significantly rescued the phenotype caused by dsPxACPR. These results indicate that miR-8514-5p affects the development and reproduction of P. xylostella by regulating PxACPR, and the homeostasis of PxACPR expression is essential for the development and reproduction of P. xylostella. © 2024 Society of Chemical Industry.

Oriented synthesis and insecticidal activities of novel meta‐diamide scaffolds incorporating with 1,2,4‐triazole moiety

AbstractIn an effort to discover a new insecticide, we designed and synthesized a series of novel meta‐diamide compounds containing 1,2,4‐triazole with cyproflanilide as a lead compound. All the compounds were characterized by 1H NMR, 13C NMR, and HR‐MS. Both Plutella xylostella and Mythimna separata were tested for their insecticidal activity at 200 mg/L (P. xylostella: 0%–100%; M. separata: 0%–100%), 20 mg/L (P. xylostella: 0%–97%; M. separata: 0%–100%), and 2 mg/L (P. xylostella: 0%–97%; M. separata: 0%–100%), while Aphis craccivora was tested for its insecticidal activity at 400 mg/L (A. craccivora: 0%–36%). Further studies are needed to investigate the insecticidal activity of A. craccivora. Preliminary bioactivity results showed that most of the compounds had good insecticidal activity at 200 mg/L against P. xylostella and M. separata. Especially, the compound 7p, N‐(cyclopropylmethyl)‐N‐(5‐((2,6‐dibromo‐4‐(perfluoropropan‐2‐yl)phenyl) carbamoyl)‐2‐(1H‐1,2,4‐triazol‐1‐yl)phenyl)‐6‐(trifluoromethyl)nicotinamide (7p), showed good insecticidal activity at even lower doses of 2 mg/L (P. xylostella: 97%; M. separata: 100%), which was equivalent to that of the lead compound cyproflanilide (P. xylostella: 100%; M. separata: 100%), as well as significantly better than the two known compounds Ia (P. xylostella: 97%; M. separata: 0%) and Ib (P. xylostella: 60%; M. separata: 0%). Preliminary structure–activity relationship was also discussed based on insecticidal tests. The results indicate that meta‐diamide compounds containing 1,2,4‐triazole can be developed as novel insecticides.

Efficacy of Selected Insecticides against Diamond Back Moth (Plutella xylostella L.) on Cabbage (Brassica oleracea L.)

The research trial was undertaken at Central Research Field, Sam Higginbottom University of Agriculture, Technology and Sciences, Prayagraj. Experiment was laid in RBD with three replication consists of eight treatments viz, Emamectin benzoate 5% SG (0.4 gm/lit), Chlorantraniliprole 18.5% SC (0.5 ml/lit), Novaluron 10% EC (2 ml/lit), Spinosad 45% SC (0.5 ml/lit), Beauveria bassiana 1.15% WP (1 gm/lit), Neem oil 1% (10 ml/lit), Karanj oil 2% (20 ml/lit) and untreated control. The mean larval population of diamondback moth (Plutella xylostella) on cabbage at 3rd, 7th, and 14th days after two sprays revealed that the treatment Chlorantraniliprole 18.5% SC (2.63) observed the lowest population of diamond back moth followed by Spinosad 45%SC (2.96), Emamectin benzoate 5% SG (3.02), Novaluron 10% EC (3.32), Beauveria bassiana 1.15% WP (3.54), Neem oil 1% (3.70) and Karanj oil2% (3.85) as compared to control (5.45). Among the treatments studied, the best and most economical treatment was Chlorantraniliprole 18.5 %SC with 245.52 q/ha yield and cost benefit ratio (1:6.53), followed by Spinosad 45% SC 230.15 q/ha with (1:6.04) C:B ratio, Emamectin benzoate 5% SG 190.30 q/ha with (1:5.54) C:B ratio, Novaluron 10% EC 170.20 q/ha with (1:4.67) C:B ratio, Beauveria bassiana 1.15%WP 150.35 q/ha with (1:4.40) C:B ratio, Neem oil 1% 142 q/ha with (1:3.85) C:B ratio and Karanj oil 2% 135.45 q/ha with (1:3.68) C:B ratio and Control 65.20 q/ha (1: 1.97) C:B ratio.

Discovery of Novel (+)-Nootkatone-Based Amine Derivatives as Potential Insecticide Candidates.

To discover novel natural product-based insecticides, a series of (+)-nootkatone-based amine derivatives 3a-t were prepared and evaluated for their insecticidal activities against Mythimna separata Walker, Myzus persicae Sulzer, and Plutella xylostella Linnaeus. Insecticidal assays showed that most of the title (+)-nootkatone derivatives exhibited stronger insecticidal activities against three insect pests than the precursor (+)-nootkatone after the introduction of amine groups on the parent (+)-nootkatone. Compounds 3a, 3d, 3h, 3m, 3n, 3p, and 3r displayed more promising growth inhibitory (GI) effect against M. separata than the commercially available botanical insecticide toosendanin. Compound 3o exhibited the most potent aphicidal activity with an LD50 value of 0.011 μg/larvae, which was 2.09-fold higher than the positive control rotenone. Additionally, compounds 3g and 3n showed more promising larvicidal activity against P. xylostella with LC50 values of 260 and 230 mg/L, respectively, superior to that of rotenone (460 mg/L). Moreover, derivatives 3g and 3n exhibited better control efficacy toward P. xylostella than rotenone under greenhouse conditions. Preliminary mechanistic studies revealed that derivative 3n could inhibit the activity of glutathione S-transferase (GST) in P. xylostella and thus exerted larvicidal activity, and molecular docking further demonstrated that 3n could interact well with some amino acid residues of GST. Finally, the toxicity assay suggested that derivatives 3g and 3n were relatively less toxic to nontarget organisms. These findings will provide insights into the development of (+)-nootkatone derivatives as green pesticides.

Evaluating the Efficacy of Selected Insecticides on Diamondback Moth (Plutella xylostella) Damaging Cabbage (Brassica oleracea)

A field investigation was carried out in Rabi season of 2022-2023 at the Central Research Farm (CRF), Sam Higginbottom University of Agriculture, Technology and Sciences, Prayagraj, Uttar Pradesh, India to evaluate the efficacy of some selected pesticides on controlling diamondback moth that causes yield loss of cabbage. The experiment was laid in Randomized Block Design (RBD) with eight treatments each replicated thrice using a single variety Green Soccer. The treatments viz. NSKE 5% @50 ml/L, Spinosad 45% SC @0.35 ml/L, Emamectin Benzoate 5% SG @0.5 g/L, Neem oil 5% @50 ml/L, Dimethoate 30% EC @1 ml/L, Indoxacarb 14.5% SC @ 0.5 g/L, Cartap Hydrochloride 50% SP @0.5ml/L, and along with an untreated control was used against Plutella xylostella in Cabbage. The overall mean data on larval population of diamond back moth over control on first and second spray revealed that all treatments were significantly superior over control. Among all the treatments Spinosad 45% SC showed the lowest mean larval population (2.04%), (0.93%) followed by Emamectin benzoate 5% SG (2.22%) (1.06%), Indoxacarb 14.5% SC (2.66%) (1.37%), Cartap Hydrochloride 50% SP (3.20%) (1.86%), Dimethoate 30% EC (3.48%) (2.02 %), and NSKE 5% (4.08 %) (2.33 %), Neem oil 5% (3.82 %), (2.37 %) and highest population was recorded in control (8.13%), (7.73%). The highest yield and cost benefit ratio recorded in Spinosad 45% SC (296 q/ha) (1:5.7) followed by Emamectin benzoate 5% SG (264 q/ha) (1:6.2), Indoxacarb 14.5% SC (249 q/ha) (1:5.0), Cartap Hydrochloride 50% SP (215 q/ha) (1:4.8) followed by Dimethoate 30% EC (194 q/ha) (1:4.4), Neem oil 5% (178 q/ha), (1:3.9) and NSKE 5% (170 q/ha) (1:3.8) and control (102 q/ha) (1:2.5). The information obtained in this study has the potential application for controlling diamondback moth and will be useful to the farmers and researchers.

Identification and detection of the V1848I indoxacarb resistance mutation in the beet armyworm, Spodoptera exigua

Indoxacarb is a pivotal insecticide used worldwide to manage Spodoptera exigua, a devastating agricultural pest. This active compound plays a crucial role in resistance management strategies due to its distinctive mode of action. A field population of S. exigua (SH23) from Shanghai, China, exhibited significantly reduced susceptibility to indoxacarb, with a resistance ratio of 113.84-fold in biological assays. Following two rounds of laboratory screening with indoxacarb, the resistance of the new strain (SH23-S2) escalated steeply to 876.15-fold. Genetic analyses of both the SH23 and SH23-S2 strains demonstrated autosomal inheritance and incompletely dominant resistance patterns. Synergist assays indicated a minor role of detoxification enzymes (glutathione s-transferases and cytochrome P450) of SH23-S2 strain in this resistance, implicating target-site resistance as the primary mechanism. To explore the impact of target-site resistance, segment 1–6 of domain IV (IVS1–6) of the sodium channel in S. exigua was cloned, and the sequences from susceptible and indoxacarb-resistant S. exigua were compared. The V1848I mutation, linked to indoxacarb resistance in Plutella xylostella, Tuta absoluta and Liriomyza trifolii, was identified and strongly associated with the indoxacarb-resistant phenotype in the S. exigua SH23-S2 strain, whereas the F1845Y mutation was not detected. Furthermore, a molecular test for the V1848I mutation in field populations was created using an allele-specific PCR (AS-PCR). The discovery of indoxacarb resistance mutation and the creation of diagnostic tool will enable the early detection of indoxacarb resistance, which will facilitate the implementation of targeted resistance management strategies, ultimately delaying the proliferation of resistance.

Glycine-doped metal–organic frameworks as intelligent nanocarriers to enhance pesticide delivery and provide micronutrient in plants

The development of multifunctional pesticide-delivery system is of practical significance for realizing efficient utilization of pesticides and minimizing environmental risks. In this work, methoxyfenozide (Met)-loaded glycine-doped zeolitic imidazolate framework-8 composites (Met@Gly@ZIF-8) for intelligent-release of Met and effective pest management were facilely constructed. The physical properties of Met@Gly@ZIF-8, including ultraviolet (UV) resistance, deposition and release profiles were evaluated. Compared with Met, the residual content after UV irradiation and retention content on cabbage leaves of Met@Gly@ZIF-8 increased by 121.2% and 98.2%, respectively, and the contact angle on foliar decreased by 26.5% compared with Met suspension concentrate (SC), demonstrating better photolysis resistance, deposition and wetting ability. Release experiments indicated that Met@Gly@ZIF-8 possessed significant stimuli-responsive release characteristics which were negatively correlated with pH, due to the acidic degradation of ZIF-8. The biological activity experiments showed that Met@Gly@ZIF-8 possessed elevated control efficacy on Plutella xylostella compared with Met and reduced the LC50 value by 53.2%. The application performance experiments indicated that the penetration amount of Met@Gly@ZIF-8 in cabbage leaves increased by 194.7% and the translocation factor (TFleaf) increased by 63.3%, respectively, as compared with those of Met. Compared with the blank control, Gly@ZIF-8 and Met@Gly@ZIF-8 increased the total biomass of cabbage by 37.8% and 25.7%, respectively, exhibiting nutritional functions for plants. Toxicity test showed that Met@Gly@ZIF-8 was relatively safe for zebrafish compared with Met. The present approach could be strategically promising for constructing functional and environmentally friendly smart-nanopesticide.

Potential of secondary metabolites from soil-derived actinomycetes as juvenile hormone disruptor and insecticides

Actinomycetes represent sources of potential alternatives to chemicals as biological pest control agents, and several actinomycetes are known to produce metabolites with insecticidal activities against insect pests. Although these metabolites are eco-friendly and effective, it is necessary to identify a novel insect-specific insecticidal agents that can minimize the occurrence of resistance. Thus, in this study, we screened the juvenile hormone disruptor (JHD) and insecticidal activities of crude acetone extracts derived from various actinomycetes as novel biopesticide candidates. A total of 300 soil-derived actinomycetes were isolated from various sites in Korea, and were screened for their JHD and insecticidal activities against a range of important medical and agricultural pests. Among them, eight extracts showed high levels of JHD activity. The AN120590 strain showed a broad insecticidal spectrum with stably maintained JHD properties. Additionally, the dead larvae of Aedes albopictus and Plutella xylostella treated with acetone extracts of the AN120590 strain displayed morphological deformities similar to those of insects treated with juvenile hormone-based insect growth regulators (IGRs). These findings indicate that actinomycetes represent promising sources of novel IGRs that can be effectively applied as insecticides with a broad insecticidal spectrum.

Transfection of entomopathogenic Metarhizium species with a mycovirus confers hypervirulence against two lepidopteran pests

Although most known viruses infecting fungi pathogenic to higher eukaryotes are asymptomatic or reduce the virulence of their host fungi, those that confer hypervirulence to entomopathogenic fungus still need to be explored. Here, we identified and studied a novel mycovirus in Metarhizium flavoviride, isolated from small brown planthopper (Laodelphax striatellus). Based on molecular analysis, we tentatively designated the mycovirus as Metarhizium flavoviride partitivirus 1 (MfPV1), a species in genus Gammapartitivirus, family Partitiviridae. MfPV1 has two double-stranded RNAs as its genome, 1,775 and 1,575 bp in size respectively, encapsidated in isometric particles. When we transfected commercial strains of Metarhizium anisopliae and Metarhizium pingshaense with MfPV1, conidiation was significantly enhanced (t test; P-value < 0. 01), and the significantly higher mortality rates of the larvae of diamondback moth (Plutella xylostella) and fall armyworm (Spodoptera frugiperda), two important lepidopteran pests were found in virus-transfected strains (ANOVA; P-value < 0.05). Transcriptomic analysis showed that transcript levels of pathogenesis-related genes in MfPV1-infected M. anisopliae were obviously altered, suggesting increased production of metarhizium adhesin-like protein, hydrolyzed protein, and destruxin synthetase. Further studies are required to elucidate the mechanism whereby MfPV1 enhances the expression of pathogenesis-related genes and virulence of Metarhizium to lepidopteran pests. This study presents experimental evidence that the transfection of other entomopathogenic fungal species with a mycovirus can confer significant hypervirulence and provides a good example that mycoviruses could be used as a synergistic agent to enhance the biocontrol activity of entomopathogenic fungi.

Evaluation of kale genotypes on the nutritional indices and oviposition decisions against Plutella Xylostella (Lepidoptera: Plutellidae)

Evaluation of kale genotypes on the nutritional indices and oviposition decisions against Plutella Xylostella (Lepidoptera: Plutellidae)