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1.
Sci Rep ; 14(1): 15122, 2024 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-38956289

RESUMO

Natalisin (NTL) is a conserved neuropeptide, only present in insects, that has been reported to regulate their sexual activity. In this study, we investigated the involvement of NTL in the reproductive behaviors of a major invasive pest, Spodoptera frugiperda. We identified NTL precursor-encoded transcripts, and evaluated their transcript levels in different stages and tissues of S. frugiperda. The results showed that the NTL transcript level was expressed in both male and female pupae and both male and female adults in the later stage. It was highly expressed in male pupae, 3-day-old male and female adults, and 5-day-old male adults. In different tissues, the expression level is higher in the male and female adult brain and male testis. Immunohistochemical staining of the brain of S. frugiperda female and male adults revealed that three pairs of brain neurons of S. frugiperda adults of both sexes secreted and expressed NTL. To study the role of NTL in reproductive behaviors, NTL was silenced in S. frugiperda male and female adults by RNA interference (RNAi) technology, the results showed that silencing NTL could significantly affect the sexual activity behavior of the adults, reducing the calling rate of females, the courtship rate of males, and the mating rate. In summary, this study emphasizes the important role of NTL in regulating the mating behavior and sexual activity of S. frugiperda in both male and female adults, potentially laying a foundation to employ NTL as a new insect-specific target to control populations of pest insects.


Assuntos
Neuropeptídeos , Comportamento Sexual Animal , Spodoptera , Animais , Spodoptera/genética , Spodoptera/fisiologia , Masculino , Feminino , Neuropeptídeos/metabolismo , Neuropeptídeos/genética , Comportamento Sexual Animal/fisiologia , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Encéfalo/metabolismo , Interferência de RNA , Reprodução
2.
Sci Rep ; 14(1): 12649, 2024 06 02.
Artigo em Inglês | MEDLINE | ID: mdl-38825611

RESUMO

Economic losses from insect herbivory in agroecosystems has driven the development of integrated pest management strategies that reduce pest incidence and damage; however, traditional chemicals-based control is either being complemented or substituted with sustainable and integrated methods. Major sustainable pest management strategies revolve around improving host plant resistance, and one of these traits of interest is Brown midrib (BMR). Originally developed to increase nutritional value and ease of digestion for animal agriculture, BMR is a recessive plant gene usually found in annual grasses, including sorghum and sorghum-sudangrass hybrids. In sorghum-sudangrass, BMR expressed plants have lower amounts of lignin, which produces a less fibrous, more digestible crop, with possible implications for plant defense against herbivores- an area currently unexplored. Fall Armyworm (FAW; Spodoptera frugiperda) is a ruinous pest posing immense threat for sorghum producers by severely defoliating crops and being present in every plant stage. Using FAW, we tested the effect of seed treatment, BMR, and plant age on FAW growth, development, and plant defense responses in sorghum-sudangrass. Our results show that seed treatment did not affect growth or development, or herbivory. However, presence of BMR significantly reduced pupal mass relative to its non-BMR counterpart, alongside a significant reduction in adult mass. We also found that plant age was a major factor as FAW gained significantly less mass, had longer pupation times, and had lower pupal mass on the oldest plant stage explored, 60-days, compared to younger plants. These findings collectively show that pest management strategies should consider plant age, and that the effects of BMR on plant defenses should also be studied.


Assuntos
Herbivoria , Sorghum , Spodoptera , Animais , Spodoptera/fisiologia , Spodoptera/crescimento & desenvolvimento , Sorghum/parasitologia , Sorghum/crescimento & desenvolvimento , Larva
3.
Sci Rep ; 14(1): 13721, 2024 06 14.
Artigo em Inglês | MEDLINE | ID: mdl-38877078

RESUMO

The beet armyworm, Spodoptera exigua (Hubner) (Lepidoptera: Noctuidae), has become a significant pest of chickpea in recent years. The polyphagous nature allows it to survive on various hosts during the off-season, creating a great menace to the crop in the following season. To assess the incidence and document the alternate hosts of S. exigua, a rapid roving survey was conducted in 11 chickpea-growing areas of Prakasam district, Andhra Pradesh, India. Additionally, the life history traits of S. exigua were studied on major alternate host plants under laboratory conditions (27 ± 1 °C and 70 ± 2% RH) to understand the survival, life expectancy and potential contribution to future populations. The results show that, among the different crops surveyed, the maximum larval incidence was noticed in maize (1.93 larvae/plant), cowpea (1.73 larvae/plant), and sunflower (1.68 larvae/plant) during the off-season. Life history studies of S. exigua showed that highest larval survival percentage was observed on chickpea (83.6%), while the lowest was on maize (44.5%). The mean developmental time for larvae was longest on maize (27.1 days) and shortest on chickpea (14.9 days). Larvae did not develop beyond the third instar when fed with chilli. The growth index statistics showed chickpea (9.2) was the most suitable host plant, whereas maize (0.9) was the least suitable host. The age-stage-specific survival rate (Sxj) varied across developmental stages, and the survival curves overlapped, indicating different growth rates among individuals. The life expectancy (exj) at age zero was highest on groundnut (37.06 days). The intrinsic rate of increase (r) of S. exigua was lowest on maize (0.10 ± 0.0013) and highest on chickpea (0.22 ± 0.0010). Similarly, the net reproductive rate (R0) was highest on chickpea (846.39 ± 18.22) and lowest on maize (59.50 ± 2.06). The population doubled every 3.08 ± 0.011 days on chickpea compared to 7.22 ± 0.80 days on maize. The study conclusively indicates that chickpea and sunflower, primarily cultivated during the rabi season in India, are the most preferred hosts for S. exigua. In contrast, maize and cotton, mainly grown during the kharif season, are less preferred and merely support the pest's survival. Consequently, S. exigua switches hosts between different crops growing seasons, so effective management of S. exigua during the kharif season can help prevent pest outbreaks during the rabi season.


Assuntos
Cicer , Larva , Estações do Ano , Spodoptera , Animais , Spodoptera/crescimento & desenvolvimento , Spodoptera/fisiologia , Larva/crescimento & desenvolvimento , Cicer/parasitologia , Produtos Agrícolas/parasitologia , Índia , Zea mays/parasitologia , Vigna/parasitologia , Vigna/crescimento & desenvolvimento
4.
J Econ Entomol ; 117(3): 673-682, 2024 06 10.
Artigo em Inglês | MEDLINE | ID: mdl-38700485

RESUMO

Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) and Spodoptera litura (Fabricius) are the main pests on corn (Poaceae: Gramineae). The performance of the larval wasp, Microplitis pallidipes Szépligeti (Hymenoptera: Braconidae), was reported on S. frugiperda and S. litura. In this study, we evaluated host selectivity, constructed an age-stage, 2-sex life table, and assessed the pest control potential of M. pallidipes against these 2 pests under laboratory conditions. In a 2-choice host preference experiment, M. pallidipes exhibited a stronger preference for S. frugiperda over S. litura and a distinct preference for second instars. We also investigated the parasitism of females that were either unfed or fed with 10% honey-water solution under different host densities and found that the highest parasitism rate was observed when M. pallidipes were fed with honey-water solution on the first day after mating and a presented female wasp:host ratio of 1:90. In a nonselective assay, M. pallidipes successfully completed a full generation on both hosts. However, the parasitoids exhibited higher fitness and population growth potential when reared on S. frugiperda, with a net reproductive rate (R0) of 24.24, an intrinsic rate of increase (r) of 0.20 per day, a finite rate of increase (λ) of 1.23 per day, and a mean generation time (T) of 15.69 days. This study elucidates the performance of M. pallidipes on 2 Spodoptera host species and offers insights into its biological control potential on lepidopteran pests.


Assuntos
Interações Hospedeiro-Parasita , Larva , Controle Biológico de Vetores , Spodoptera , Vespas , Animais , Spodoptera/parasitologia , Spodoptera/crescimento & desenvolvimento , Spodoptera/fisiologia , Vespas/fisiologia , Larva/crescimento & desenvolvimento , Larva/fisiologia , Larva/parasitologia , Feminino , Masculino
5.
J Agric Food Chem ; 72(21): 12003-12013, 2024 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-38748811

RESUMO

Insect gustatory receptors (GRs) aid in the precise identification of deterrent or stimulant compounds associated with food, mating, and egg-laying. Thus, they are promising targets for developing efficient insecticides. Here, 61 GRs in the chemosensory organs of Spodoptera litura larvae and adults were identified. Among them, SlitGR206 exhibited larval labium (LL)-specific expression characteristics. To explore the role of SlitGR206, a bacterial expression system was established to produce high-quality double-stranded RNA (dsRNA) and suppress SlitGR206 expression in LL. Subsequent behavioral assessments revealed that SlitGR206 silencing influenced larval feeding preferences and absorption. Moreover, it was found to reduce the ability of larvae to forage the five crucial host odorants. These findings demonstrate that SlitGR206 likely plays an indirect regulatory role in host recognition, consequently affecting foraging behavior. This provides a crucial foundation for the analysis of functional diversity among insect GRs and the precise development of nucleic acid pesticides in the future.


Assuntos
Comportamento Alimentar , Proteínas de Insetos , Larva , Spodoptera , Animais , Spodoptera/metabolismo , Spodoptera/fisiologia , Spodoptera/genética , Spodoptera/crescimento & desenvolvimento , Larva/metabolismo , Larva/crescimento & desenvolvimento , Larva/fisiologia , Proteínas de Insetos/metabolismo , Proteínas de Insetos/genética , Receptores de Superfície Celular/metabolismo , Receptores de Superfície Celular/genética
6.
PLoS One ; 19(5): e0299154, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38709802

RESUMO

The fall armyworm (FAW), Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae), an invasive agricultural pest, has significantly impacted crop yields across Africa. This study investigated the relationship between temperature and FAW life history traits, employing life cycle modeling at temperatures of 20, 25, 28, 30, and 32°C. The development time for eggs, larvae, and pupae varied from 0-3 days, 10-18 days, and 7-16 days, respectively. The optimal temperature range for immature stage survival and female fecundity was identified as 21-25°C, with the intrinsic rate of increase (rm) and gross reproductive rate (GRR) peaking at 25-28°C. Model validation confirmed the accuracy of these findings. The research further projected the Establishment Risk Index (ERI), Activity Index (AI), and Generation Index (GI) for FAW under current and future climates (2050 and 2070) using RCP 2.6 and RCP 8.5 scenarios. Results indicate that RCP 2.6 leads to a reduction in high-risk FAW areas, particularly in central Africa. Conversely, RCP 8.5 suggests an increase in areas conducive to FAW activity. These findings highlight the impact of climate policy on pest dynamics and the importance of incorporating climatic factors into pest management strategies. The study predicts a potential decrease in FAW prevalence in West Africa by 2070 under aggressive climate mitigation, providing a basis for future FAW management approaches.


Assuntos
Estágios do Ciclo de Vida , Spodoptera , Temperatura , Zea mays , Animais , Spodoptera/fisiologia , Spodoptera/crescimento & desenvolvimento , África , Zea mays/parasitologia , Zea mays/crescimento & desenvolvimento , Tábuas de Vida , Feminino , Larva/fisiologia , Larva/crescimento & desenvolvimento
7.
Plant Cell Environ ; 47(8): 3227-3240, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38738504

RESUMO

Plants synthesise a vast array of volatile organic compounds (VOCs), which serve as chemical defence and communication agents in their interactions with insect herbivores. Although nitrogen (N) is a critical resource in the production of plant metabolites, its regulatory effects on defensive VOCs remain largely unknown. Here, we investigated the effect of N content in tomato (Solanum lycopersicum) on the tobacco cutworm (Spodoptera litura), a notorious agricultural pest, using biochemical and molecular experiments in combination with insect behavioural and performance analyses. We observed that on tomato leaves with different N contents, S. litura showed distinct feeding preference and growth and developmental performance. Particularly, metabolomics profiling revealed that limited N availability conferred resistance upon tomato plants to S. litura is likely associated with the biosynthesis and emission of the volatile metabolite α-humulene as a repellent. Moreover, exogenous application of α-humulene on tomato leaves elicited a significant repellent response against herbivores. Thus, our findings unravel the key factors involved in N-mediated plant defence against insect herbivores and pave the way for innovation of N management to improve the plant defence responses to facilitate pest control strategies within agroecosystems.


Assuntos
Herbivoria , Nitrogênio , Folhas de Planta , Solanum lycopersicum , Spodoptera , Compostos Orgânicos Voláteis , Solanum lycopersicum/metabolismo , Solanum lycopersicum/fisiologia , Solanum lycopersicum/parasitologia , Animais , Nitrogênio/metabolismo , Spodoptera/fisiologia , Compostos Orgânicos Voláteis/metabolismo , Folhas de Planta/metabolismo , Folhas de Planta/fisiologia , Defesa das Plantas contra Herbivoria , Volatilização , Larva/fisiologia
8.
J Econ Entomol ; 117(3): 899-906, 2024 06 10.
Artigo em Inglês | MEDLINE | ID: mdl-38665059

RESUMO

The fall armyworm, Spodoptera frugiperda (J.E. Smith), is a polyphagous pest native to the Americas. It first invaded Japan in July 2019, and the most damaged crop in this region to date has been maize. To determine pest control strategies, the range of crops potentially damaged by S. frugiperda in Japan should be identified. In this study, the effects of 8 major crops in Japan-forage maize Zea mays subsp. mays, sugarcane Saccharum officinarum, forage and edible rice Oryza sativa subsp. japonica, soybean Glycine max, eggplant Solanum melongena, green bell pepper Capsicum annuum var. grossum, sweet potato Ipomoea batatas, and taro Colocasia esculenta-on the development of S. frugiperda were analyzed by feeding leaves of domestic cultivars during larval stage. Spodoptera frugiperda developed from hatching to adulthood and laid eggs in all 7 treatments, except for taro. However, among them, only soybean showed comparable developmental suitability to maize. Therefore, its oviposition preference for maize and soybean was examined using further nonchoice and choice tests. In the nonchoice test, the number of egg masses oviposited for 3 days on soybean plants was significantly less than that on test containers, while that on maize was comparable to that on containers. These findings can explain partly why major damage has been limited to maize in Japan.


Assuntos
Glycine max , Oviposição , Spodoptera , Zea mays , Animais , Spodoptera/crescimento & desenvolvimento , Spodoptera/fisiologia , Japão , Zea mays/crescimento & desenvolvimento , Glycine max/crescimento & desenvolvimento , Larva/crescimento & desenvolvimento , Larva/fisiologia , Produtos Agrícolas/crescimento & desenvolvimento , Feminino , Herbivoria
9.
Sci Total Environ ; 930: 172807, 2024 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-38679092

RESUMO

Biodiversity loss, as driven by anthropogenic global change, imperils biosphere intactness and integrity. Ecosystem services such as top-down regulation (or biological control; BC) are susceptible to loss of extinction-prone taxa at upper trophic levels and secondary 'support' species e.g., herbivores. Here, drawing upon curated open-access interaction data, we structurally analyze trophic networks centered on the fall armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae) and assess their robustness to species loss. Tri-partite networks link 80 BC organisms (invertebrate or microbial), 512 lepidopteran hosts and 1194 plants (including 147 cultivated crops) in the Neotropics. These comprise threatened herbaceous or woody plants and conservation flagships such as saturniid moths. Treating all interaction partners functionally equivalent, random herbivore loss exerts a respective 26 % or 108 % higher impact on top-down regulation in crop and non-crop settings than that of BC organisms (at 50 % loss). Equally, random loss of BC organisms affects herbivore regulation to a greater extent (13.8 % at 50 % loss) than herbivore loss mediates their preservation (11.4 %). Yet, under moderate biodiversity loss, (non-pest) herbivores prove highly susceptible to loss of BC organisms. Our topological approach spotlights how agriculturally-subsidized BC agents benefit vegetation restoration, while non-pest herbivores uphold biological control in on- and off-farm settings alike. Our work underlines how the on-farm usage of endemic biological control organisms can advance conservation, restoration, and agricultural sustainability imperatives. We discuss how integrative approaches and close interdisciplinary cooperation can spawn desirable outcomes for science, policy and practice.


Assuntos
Biodiversidade , Herbivoria , Animais , Ecossistema , Spodoptera/fisiologia , Cadeia Alimentar , Conservação dos Recursos Naturais/métodos
10.
J Agric Food Chem ; 72(18): 10304-10313, 2024 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-38657164

RESUMO

Neuropeptides are involved in many biological processes in insects. However, it is unclear what role neuropeptides play in Spodoptera litura adaptation to phytochemical flavone. In this study, 63 neuropeptide precursors from 48 gene families were identified in S. litura, including two neuropeptide F genes (NPFs). NPFs played a positive role in feeding regulation in S. litura because knockdown of NPFs decreased larval diet intake. S. litura larvae reduced flavone intake by downregulating NPFs. Conversely, the flavone intake was increased if the larvae were treated with NPF mature peptides. The NPF receptor (NPFR) was susceptible to the fluctuation of NPFs. NPFR mediated NPF signaling by interacting with NPFs to regulate the larval diet intake. In conclusion, this study suggested that NPF signaling regulated diet intake to promote S. litura adaptation to flavone, which contributed to understanding insect adaptation mechanisms to host plants and provide more potential pesticidal targets for pest control.


Assuntos
Proteínas de Insetos , Larva , Neuropeptídeos , Spodoptera , Animais , Spodoptera/fisiologia , Spodoptera/metabolismo , Neuropeptídeos/metabolismo , Neuropeptídeos/genética , Neuropeptídeos/química , Larva/crescimento & desenvolvimento , Larva/metabolismo , Larva/química , Proteínas de Insetos/metabolismo , Proteínas de Insetos/genética , Proteínas de Insetos/química , Flavonas/metabolismo , Flavonas/química , Comportamento Alimentar , Sequência de Aminoácidos
11.
Chemosphere ; 356: 141888, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38582169

RESUMO

Climate change complicates ecotoxicology studies because species responses to pesticides depend on temperature. Classically illustrated by the effect of constant laboratory temperatures, a recent review revealed that the toxicity of pesticides is also often increased by daily temperature fluctuations. Here, we investigated the combined effects of daily temperature fluctuation and mean temperature on the toxicity of two insecticides in the moth Spodoptera littoralis. Our study tested the toxicity of chlorpyrifos and deltamethrin on larvae of six experimental groups that crossed three treatments of daily temperature fluctuations (0, 5 or 10 °C) and two treatments of mean temperatures (25 or 33 °C). We showed that daily temperature fluctuation increased larval mortality induced by chlorpyrifos and deltamethrin. However, the response differed between the organophosphorus insecticide chlorpyrifos and the pyrethroid insecticide deltamethrin. The increase in chlorpyrifos toxicity by daily temperature fluctuation did not differ between mean temperatures of 25 and 33 °C. Remarkably, the increase in deltamethrin toxicity by daily temperature fluctuation was dependent on the crossed effects of the amplitude of daily fluctuation and mean temperature. This increase in deltamethrin toxicity occurred with a daily fluctuation of only 5 °C for larvae reared at 25 °C and a daily fluctuation of 10 °C in larvae reared at 33 °C. To confidently quantify the responses of insecticide toxicity to temperature, future ecotoxicology studies will have to evaluate the generality of the interaction between the effects of daily temperature fluctuation and mean temperature.


Assuntos
Clorpirifos , Inseticidas , Larva , Nitrilas , Piretrinas , Temperatura , Animais , Inseticidas/toxicidade , Piretrinas/toxicidade , Larva/efeitos dos fármacos , Nitrilas/toxicidade , Clorpirifos/toxicidade , Mudança Climática , Spodoptera/efeitos dos fármacos , Spodoptera/fisiologia , Spodoptera/crescimento & desenvolvimento , Mariposas/efeitos dos fármacos , Mariposas/fisiologia , Mariposas/crescimento & desenvolvimento
12.
Transgenic Res ; 33(3): 75-88, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38578501

RESUMO

Genetically engineered (GE) cotton event MON 88702, producing Mpp51Aa2 (previously mCry51Aa2) from Bacillus thuringiensis (Bt), controls sucking pests, such as Lygus spp. (Hemiptera: Miridae) and thrips (Thysanoptera). Ingesting high doses of the insecticidal protein resulted in adverse effects on life table parameters of beneficial, predatory Orius spp. (Hemiptera: Anthocoridae). This triggered laboratory studies with more realistic food treatments, including different combinations of prey types with and without Bt protein to further characterize risks to this important group of non-target organisms. In this work, exclusive feeding of frozen spider mites (Tetranychus urticae, Acari: Tetranychidae) from Bt cotton confirmed adverse effects on longevity and fecundity of O. majusculus adults. Alternate feeding of Bt protein-containing spider mites and Bt-free Ephestia kuehniella (Lepidoptera: Pyralidae) eggs mitigated effects on longevity, but not on fecundity. When living larvae of Spodoptera littoralis (Lepidoptera: Noctuidae) from Bt cotton were fed to the predators, however, no effects on longevity and reproduction of female O. majusculus were observed, despite the fact that Bt protein concentrations in larvae were almost as high as concentrations in spider mites. When a diverse mix of prey species with various Bt protein concentrations is consumed in the field, it is unlikely that exposure of Orius spp. to Mpp51Aa2 is high enough to exert adverse effects on predator populations. MON 88702 cotton may thus be a valuable tool for integrated management of sucking pests.


Assuntos
Bacillus thuringiensis , Gossypium , Longevidade , Controle Biológico de Vetores , Plantas Geneticamente Modificadas , Reprodução , Animais , Gossypium/genética , Gossypium/parasitologia , Gossypium/crescimento & desenvolvimento , Gossypium/metabolismo , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/crescimento & desenvolvimento , Plantas Geneticamente Modificadas/parasitologia , Bacillus thuringiensis/genética , Reprodução/genética , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Comportamento Predatório , Fertilidade/genética , Spodoptera/crescimento & desenvolvimento , Spodoptera/fisiologia , Spodoptera/genética , Larva/crescimento & desenvolvimento , Larva/genética , Toxinas de Bacillus thuringiensis/genética , Endotoxinas/genética , Endotoxinas/metabolismo , Heterópteros/genética , Heterópteros/fisiologia , Heterópteros/crescimento & desenvolvimento , Proteínas Hemolisinas/genética , Proteínas Hemolisinas/metabolismo , Tetranychidae/genética , Feminino
13.
Physiol Plant ; 176(2): e14243, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38467539

RESUMO

Seed priming with beneficial endophytic fungi is an emerging sustainable strategy for enhancing plant resistance against insect pests. This study examined the effects of Beauvaria bassiana Bb20091317 and Metarhizium rileyi MrCDTLJ1 fungal colonization on maize growth, defence signalling, benzoxazinoid levels and gene expression. The colonization did not adversely affect plant growth but reduced larval weights of Spodoptera frugiperda. Maize leaves treated with M. rileyi exhibited higher levels of jasmonic acid, jasmonoyl-Isoleucine, salicylic acid, and indole acetic acid compared to control. B. bassiana and M. rileyi accelerated phytohormone increase upon S. frugiperda herbivory. Gene expression analysis revealed modulation of benzoxazinoid biosynthesis genes. We further elucidated the immune regulatory role of the transcription factor zmWRKY36 using virus-induced gene silencing (VIGS) in maize. zmWRKY36 positively regulates maize immunity against S. frugiperda, likely by interacting with defense-related proteins. Transient overexpression of zmWRKY36 in tobacco-induced cell death, while silencing in maize reduced chitin-triggered reactive oxygen species burst, confirming its immune function. Overall, B. bassiana and M. rileyi successfully colonized maize, impacting larval growth, defense signalling, and zmWRKY36-mediated resistance. This sheds light on maize-endophyte-insect interactions for sustainable plant protection.


Assuntos
Benzoxazinas , Zea mays , Animais , Spodoptera/fisiologia , Zea mays/genética , Zea mays/metabolismo , Benzoxazinas/metabolismo , Benzoxazinas/farmacologia , Herbivoria , Larva/fisiologia , Fungos
14.
Sci Rep ; 14(1): 6029, 2024 03 12.
Artigo em Inglês | MEDLINE | ID: mdl-38472262

RESUMO

Fall armyworm, Spodoptera frugiperda (FAW) is a cosmopolitan crop pest species that has recently become established in sub-Saharan Africa and Southeast Asia. Current FAW control is almost entirely dependent on synthetic pesticides. Biopesticides offer a more sustainable alternative but have limitations. For example, pyrethrum is an effective botanical insecticide with low mammalian toxicity but is highly UV labile, resulting in a rapid loss of efficacy in the field. Beauveria bassiana is an entomopathogenic fungus that is more persistent, but there is a time lag of several days before it causes insect mortality and leads to effective control. The combination of these biopesticides could mitigate their drawbacks for FAW control. Here we evaluated the efficacy of pyrethrum and B. bassiana as individual treatments and in combination against 3rd instar FAW. Four different combinations of these two biopesticides were tested, resulting in an antagonistic relationship at the lowest concentrations of B. bassiana and pyrethrum (1 × 104 conidia mL-1 with 25 ppm) and an additive effect for the other 3 combined treatments (1 × 104 conidia mL-1 with 100 ppm and 1 × 105 conidia mL-1 with 25 ppm and 100 ppm pyrethrum). Additionally, a delay in efficacy from B. bassiana was observed when combined with pyrethrum as well as a general inhibition of growth on agar plates. These results appear to show that this particular combination of biopesticides is not universally beneficial or detrimental to pest control strategies and is dependent on the doses of each biopesticide applied. However, the additive effect shown here at specific concentrations does indicate that combining biopesticides could help overcome the challenges of persistence seen in botanical pesticides and the slow establishment of EPF, with the potential to improve effectiveness of biopesticides for IPM.


Assuntos
Praguicidas , Piretrinas , Animais , Agentes de Controle Biológico , Larva , Controle de Pragas , Spodoptera/fisiologia
15.
Bull Entomol Res ; 114(2): 244-253, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38444240

RESUMO

Since metabolism, survival, and reproduction in hexapods are closely related to temperatures; changes in the mean and variance of temperature are major aspects of global climate change. In the typical context of biological control, understanding how predator-prey systems are impacted under thermal conditions can make pest control more effective and resilient. With this view, this study investigated temperature-mediated development and predation parameters of the predator Harmonia axyridis against the potential prey Spodoptera litura. The age-stage, two-sex life table of the predator was constructed at four temperatures (i.e. 15, 20, 25, and 30°C) by feeding on the first instar larvae of S. litura. Our results showed that the mean generation time (T) decreased but the intrinsic rate of increase (r) and the finite rate of increase (λ) increased with increased temperature. The mean duration of the total preadult stage decreased with higher temperatures. The T and r were 70.47 d and 0.0769 d-1 at 15°C; 58.41 d and 0.0958 d-1 at 20°C; 38.71 d and 0.1526 d-1 at 25°C; and 29.59 d and 0.1822 d-1 at 30°C, respectively. The highest net reproductive rate (R0) and fecundity were obtained at 25°C. The highest λ (1.1998 d-1) and lowest T (29.59 d) were obtained at 30°C, whereas the maximum net predation rate (C0) was at 25°C. Total population and predation rates projections were the highest at 30°C. Based on these findings, we anticipate that biological control strategies for this predator release against S. litura should be attuned to warming scenarios to achieve better biocontrol functions.


Assuntos
Besouros , Larva , Controle Biológico de Vetores , Comportamento Predatório , Reprodução , Spodoptera , Temperatura , Animais , Spodoptera/fisiologia , Spodoptera/crescimento & desenvolvimento , Larva/crescimento & desenvolvimento , Larva/fisiologia , Besouros/fisiologia , Besouros/crescimento & desenvolvimento , Feminino , Masculino
16.
J Econ Entomol ; 117(3): 1041-1046, 2024 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-38482558

RESUMO

Climate change involves changes in the pattern of temperature fluctuations and the frequency and magnitude of thermal extremes. It is essential to investigate how insects respond to increased temperature variations, especially for species that usually experience diel temperature variations extending to thermal performance limits. To explicitly elucidate the effects of sizes of amplitudes of temperature variations, we used daily alternating temperatures with an equivalent mean of 28 °C to investigate the impact of different fluctuation amplitudes (±â€…0 °C,  ±â€…2 °C,  ±â€…4 °C, and  ±â€…6 °C) across permissive temperature regimes on the performance of Spodoptera lituraFabricius, a highly destructive polyphagous pest of crops and vegetables in tropical and temperate climates. Amplitudes of temperature fluctuations significantly affected developmental durations, adult life spans, pupal weights, fecundity, and fertility of S. litura. The survival rates from the egg stage to the adult eclosion did not differ significantly across different temperature treatments. The developmental durations of individual life cycles significantly increased with larger amplitudes in 3 fluctuating temperature treatments. The pupal weight was significantly lower and the adult life span was significantly shorter in the ±â€…6 °C treatment in all treatments. Fecundity and fertility were significantly reduced in the ±â€…6 °C treatment, making the continuation of generations nearly impossible. The results should provide critical information for understanding the ecology of this widespread pest under diel, seasonal, and global climate changes.


Assuntos
Pupa , Spodoptera , Animais , Spodoptera/fisiologia , Spodoptera/crescimento & desenvolvimento , Pupa/crescimento & desenvolvimento , Pupa/fisiologia , Feminino , Fertilidade , Larva/crescimento & desenvolvimento , Larva/fisiologia , Mudança Climática , Masculino , Temperatura Alta , Longevidade , Temperatura
17.
Dev Comp Immunol ; 154: 105142, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38309673

RESUMO

The fall armyworm, Spodoptera frugiperda, poses a significant threat as a highly destructive agricultural pest in many countries. Understanding the complex interplay between the insect immune system and entomopathogens is critical for optimizing biopesticide efficacy. In this study, we identified a novel microbial binding protein, SfMBP, in S. frugiperda. However, the specific role of SfMBP in the immune response of S. frugiperda remains elusive. Encoded by the LOC118269163 gene, SfMBP shows significant induction in S. frugiperda larvae infected with the entomopathogen Beauveria bassiana. Consisting of 115 amino acids with a signal peptide, an N-terminal flexible region and a C-terminal ß-sheet, SfMBP lacks any known functional domains. It is expressed predominantly during early larval stages and in the larval epidermis. Notably, SfMBP is significantly induced in larvae infected with bacteria and fungi and in SF9 cells stimulated by peptidoglycan. While recombinant SfMBP (rSfMBP) does not inhibit bacterial growth, it demonstrates binding capabilities to bacteria, fungal spores, peptidoglycan, lipopolysaccharides, and polysaccharides. This binding is inhibited by monosaccharides and EDTA. Molecular docking reveals potential Zn2+-interacting residues and three cavities. Furthermore, rSfMBP induces bacterial agglutination in the presence of Zn2+. It also binds to insect hemocytes and SF9 cells, enhancing phagocytosis and agglutination responses. Injection of rSfMBP increased the survival of S. frugiperda larvae infected with B. bassiana, whereas blocking SfMBP with the antibody decreased survival. These results suggest that SfMBP acts as a pattern recognition receptor that enhances pathogen recognition and cellular immune responses. Consequently, this study provides valuable insights for the development of pest control measures.


Assuntos
Proteínas de Transporte , Mariposas , Animais , Spodoptera/fisiologia , Proteínas de Transporte/metabolismo , Simulação de Acoplamento Molecular , Peptidoglicano/metabolismo , Mariposas/metabolismo , Larva/metabolismo , Insetos/metabolismo , Receptores de Reconhecimento de Padrão/genética , Receptores de Reconhecimento de Padrão/metabolismo
18.
J Plant Physiol ; 292: 154164, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38141481

RESUMO

Exposure to herbivore-induced plant volatiles (HIPVs) is known to enhance the defense responses in plants. This so-called priming effect has only been marginally studied in intercropping systems. We tested whether HIPVs from cowpea, which often serves as an intercrop alongside maize, can prime herbivore-induced volatile emissions in maize. Conventional volatile collection assays and real-time mass spectrometry revealed that maize plants that were exposed to HIPVs from cowpea infested with Spodoptera exigua caterpillars emitted more than control plants when they themselves were subsequently damaged by the same pest. The enhanced emission was only evident on the first day after infestation. Maize plants that were exposed to HIPVs from cowpea infested by S. frugiperda larvae showed no priming effect and released considerably less upon S. frugiperda infestation than upon S. exigua infestation. The latter may be explained by the fact that S. frugiperda is particularly well adapted to feed on maize and is known to suppress maize HIPV emissions. Our results imply that HIPVs from cowpea, depending on the inducing insect herbivore, may strongly prime maize plants. This deserves further investigation, also in other intercropping systems, as it can have important consequences for tritrophic interactions and crop protection.


Assuntos
Beta vulgaris , Vigna , Compostos Orgânicos Voláteis , Animais , Spodoptera/fisiologia , Zea mays , Larva , Herbivoria
19.
J Agric Food Chem ; 71(51): 20602-20612, 2023 Dec 27.
Artigo em Inglês | MEDLINE | ID: mdl-38088835

RESUMO

Ionotropic receptors (IRs) play an important role in olfaction, but little is known in nondrosophila insects. Here, we report in vitro and in vivo functional characterization of IR75q.2 in the invasive moth pest Spodoptera frugiperda. First, 13 IRs (including four coreceptor IRs) were found specifically or highly expressed in adult antennae. Second, these IRs were tested for responding profiles to 59 odorants using the Xenopus oocyte expression system, showing that only SfruIR75q.2 responded to 8-10C fatty acids and their corresponding aldehydes, with SfruIR8a as the only coreceptor. Third, the three acids (especially nonanoic acid) showed repellent effects on moth's behavior and oviposition, but the repellence significantly reduced to the insects with IR75q.2 knockout by CRISPR/Cas9. Taken together, our study reveals the function of SfruIR75q.2 in perception of acid and aldehyde odorants and provides the first in vivo evidence for olfactory function of an odor-specific IR in Lepidoptera.


Assuntos
Mariposas , Animais , Feminino , Spodoptera/fisiologia , Mariposas/genética , Insetos , Ácidos Graxos/metabolismo , Larva
20.
Int J Mol Sci ; 24(23)2023 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-38069011

RESUMO

Cruciferous plants manufacture glucosinolates (GSLs) as special and important defense compounds against insects. However, how insect feeding induces glucosinolates in Brassica to mediate insect resistance, and how plants regulate the strength of anti-insect defense response during insect feeding, remains unclear. Here, mustard (Brassica juncea), a widely cultivated Brassica plant, and beet armyworm (Spodoptera exigua), an economically important polyphagous pest of many crops, were used to analyze the changes in GSLs and transcriptome of Brassica during insect feeding, thereby revealing the plant-insect interaction in Brassica plants. The results showed that the content of GSLs began to significantly increase after 48 h of herbivory by S. exigua, with sinigrin as the main component. Transcriptome analysis showed that a total of 8940 DEGs were identified in mustard challenged with beet armyworm larvae. The functional enrichment results revealed that the pathways related to the biosynthesis of glucosinolate and jasmonic acid were significantly enriched by upregulated DEGs, suggesting that mustard might provide a defense against herbivory by inducing JA biosynthesis and then promoting GSL accumulation. Surprisingly, genes regulating JA catabolism and inactivation were also activated, and both JA signaling repressors (JAZs and JAMs) and activators (MYCs and NACs) were upregulated during herbivory. Taken together, our results indicate that the accumulation of GSLs regulated by JA signaling, and the regulation of active and inactive JA compound conversion, as well as the activation of JA signaling repressors and activators, collectively control the anti-insect defense response and avoid over-stunted growth in mustard during insect feeding.


Assuntos
Beta vulgaris , Mostardeira , Animais , Mostardeira/genética , Mostardeira/metabolismo , Transcriptoma , Spodoptera/fisiologia , Glucosinolatos/metabolismo , Beta vulgaris/genética , Beta vulgaris/metabolismo , Herbivoria/genética , Insetos/metabolismo
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