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1.
Arch Insect Biochem Physiol ; 108(3): e21840, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34569086

RESUMO

Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), the cotton bollworm, is a destructive pest which is famous for its resistance to a variety of insecticides. RNA interference is a posttranscriptional gene silencing mechanism that has become a popular tool to control insect pests, triggered by double-stranded RNAs (dsRNAs). The effect of ingestion and injection delivery methods of dsRNA related to some protease genes including Trypsin (Ha-TRY39 and Ha-TRY96), Chymotrypsin (Ha-CHY), and Cathepsin L (Ha-CAT) on growth and development of H. armigera was investigated in this study. All protease genes encoded full ORFs and were expressed in all H. armigera larvae stages and tissues. In both injection and feeding bioassays, Ha-RNAi CHY's performance outperformed that of other protease genes. CHY enzyme activity in the midgut of larvae was significantly reduced after treatment with ds-HaCHY. Oral administration of ds-CHY also resulted in significant mortality of H. armigera larvae. However, because of the high RNase activity in the midgut lumen of lepidoptera, a large amount of dsRNA was needed to effectively kill instars of H. armigera. To reduce dsRNA degradation, bacterial expression and dsRNA formulation were used. After oral administration, it was toxic to H. armigera larvae. Before oral administration, bacterial cells were sonicated to increase dsRNA release. The RNA interference efficiency of sonicated bacteria was significantly increased, resulting in higher larval mortality when administered orally. All of these findings point to Ha-CHY as a new candidate for developing an effective dsRNA-based pesticide for H. armigera control.


Assuntos
Mariposas , Peptídeo Hidrolases , RNA de Cadeia Dupla/farmacologia , Animais , Bactérias/genética , Catepsinas/efeitos dos fármacos , Catepsinas/genética , Quimotripsina/efeitos dos fármacos , Quimotripsina/genética , Proteínas de Insetos/genética , Larva/efeitos dos fármacos , Larva/genética , Larva/crescimento & desenvolvimento , Mortalidade , Mariposas/efeitos dos fármacos , Mariposas/genética , Mariposas/crescimento & desenvolvimento , Organismos Geneticamente Modificados , Peptídeo Hidrolases/efeitos dos fármacos , Peptídeo Hidrolases/genética , Controle de Pragas/métodos , Interferência de RNA , RNA de Cadeia Dupla/biossíntese , RNA de Cadeia Dupla/metabolismo , Tripsina/efeitos dos fármacos , Tripsina/genética
2.
J Chem Ecol ; 47(8-9): 732-739, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34347234

RESUMO

The pine brown tail moth, Euproctis terminalis (Walker 1855), is a periodic pest in pine plantations in South Africa. The larvae feed on pine needles and can cause severe defoliation when population densities are high. Population densities fluctuate temporally and spatially, complicating the prediction of potential growth loss and tree mortality. The aim of this study was to identify the sex pheromone of the pine brown tail moth to provide stakeholders with a tool for monitoring it. Gas chromatography-electroantennogram detection and gas chromatography/mass spectrometry analyses of female pheromone gland extracts identified the major component as (Z,Z,Z,Z)-7,13,16,19-docosatetraen-1-ol isobutyrate. Traps baited with (Z,Z,Z,Z)-7,13,16,19-docosatetraen-1-ol isobutyrate caught more males than unbaited traps. A delta trap was shown to be a superior design compared to a bucket funnel trap. This pheromone can now be used for monitoring E. terminalis in pine plantations.


Assuntos
Mariposas/fisiologia , Atrativos Sexuais/análise , Animais , DNA/química , Complexo IV da Cadeia de Transporte de Elétrons/genética , Feminino , Cromatografia Gasosa-Espectrometria de Massas , Isobutiratos/análise , Isobutiratos/farmacologia , Larva/crescimento & desenvolvimento , Masculino , Mariposas/química , Mariposas/crescimento & desenvolvimento , Pinus/parasitologia , Análise de Sequência de DNA , Atrativos Sexuais/farmacologia , Comportamento Sexual Animal/efeitos dos fármacos
3.
Molecules ; 26(15)2021 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-34361721

RESUMO

To improve the proinsecticidal activity and phloem mobility of amino acid-tralopyril conjugates further, nine conjugates were designed and synthesized by introducing glutamic acid to tralopyril, and the length of the linker between glutamic acid and tralopyril ranged from 2 atoms to 10 atoms. The results of insecticidal activity against the third-instar larvae of P. xylostella showed that conjugates 42, 43, 44,and 45 (straight-chain containing 2-5 atoms) exhibited good insecticidal activity, and their LC50 values were 0.2397 ± 0.0366, 0.4413 ± 0.0647, 0.4400 ± 0.0624, and 0.4602 ± 0.0655 mM, respectively. The concentrations of conjugates 43-45 were higher than that of conjugate 42 in the phloem sap at 2 h, and conjugate 43 showed the highest concentration. The introduction of glutamic acid can improve phloem mobility. The in vivo metabolism of conjugates 42 and 43 was investigated in P. xylostella, and the parent compound tralopyril was detected at concentrations of 0.5950 and 0.3172 nmol/kg, respectively. According to the above results, conjugates 42 and 43 were potential phloem mobile pro-insecticide candidates.


Assuntos
Ácido Glutâmico/química , Inseticidas/farmacologia , Larva/efeitos dos fármacos , Mariposas/efeitos dos fármacos , Pró-Fármacos/farmacologia , Pirróis/farmacologia , Animais , Transporte Biológico , Biotransformação , Concentração Inibidora 50 , Inseticidas/síntese química , Inseticidas/metabolismo , Larva/crescimento & desenvolvimento , Larva/metabolismo , Longevidade/efeitos dos fármacos , Mariposas/crescimento & desenvolvimento , Mariposas/metabolismo , Floema/metabolismo , Floema/parasitologia , Plantas/metabolismo , Plantas/parasitologia , Pró-Fármacos/síntese química , Pró-Fármacos/metabolismo , Piretrinas/metabolismo , Piretrinas/farmacologia , Pirróis/síntese química , Pirróis/metabolismo , Relação Estrutura-Atividade
4.
J Insect Physiol ; 133: 104276, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34245800

RESUMO

The insect taste system regulates insect feeding behavior and patterns of food consumption. In this study, we showed that the medial and lateral sensilla styloconica in the mouthparts of 5th-instar Asian corn borer larvae are sensitive to fructose and sucrose in a concentration-dependent way. The two sensilla produced significant electrophysiological responses (greater than100 spikes/s) by exposure to 10 mM fructose or sucrose. However, electrophysiological responses and feeding preferences to fructose or sucrose were inhibited by neuropeptide F double-stranded RNA (dsNPF). Additionally, the medial sensilla styloconica are sensitive to low concentrations of the deterrents caffeine and nicotine. However, starvation, followed by increases in larval npf expression plus feeding, led to increases in spike frequencies of related sensilla to fructose, sucrose, and deterrents. In contrast, these responses were reduced on the dsNPF treatment. Our results suggest that NPF plays an important role influencing caterpillar feeding behavior through regulating the taste neurons of the sensilla styloconica.


Assuntos
Frutose/metabolismo , Proteínas de Insetos/genética , Mariposas/fisiologia , Neuropeptídeos/genética , Sacarose/metabolismo , Animais , Relação Dose-Resposta a Droga , Comportamento Alimentar , Proteínas de Insetos/metabolismo , Larva/crescimento & desenvolvimento , Larva/fisiologia , Mariposas/crescimento & desenvolvimento , Neuropeptídeos/metabolismo , Sensilas/fisiologia , Percepção Gustatória
5.
Ecotoxicol Environ Saf ; 221: 112452, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34198186

RESUMO

Helicoverpa armigera (cotton bollworm) is one of the most destructive pests worldwide. Due to resistance to Bacillus thuringiensis and conventional insecticides, an effective management strategy to control this pest is urgently needed. Spinosad, a natural pesticide, is considered an alternative; however, the mechanism underlying the developmental effects of sublethal spinosad exposure remains elusive. In this study, the mechanism was examined using an insect model of H. armigera. Results confirmed that exposure to sublethal spinosad led to reduced larval wet weight, delayed larval developmental period, caused difficulty in molting, and deformed pupae. Further investigation demonstrated that exposure to sublethal spinosad caused a significant decrease in 20E titer and increase in JH titer, thereby leading to the discordance between 20E and JH titers, and consequently alteration in the expression levels of HR3 and Kr-h1. These results suggested that sublethal spinosad caused hormonal disorders in larvae, which directly affect insect development. Our study serves as a reference and basis for the toxicity evaluation of spinosad on molting and pupation in insect metamorphosis, which may contribute to identifying targets for effective control of cotton bollworm.


Assuntos
Inseticidas/toxicidade , Macrolídeos/toxicidade , Mariposas/efeitos dos fármacos , Animais , Combinação de Medicamentos , Larva/efeitos dos fármacos , Muda/efeitos dos fármacos , Mariposas/crescimento & desenvolvimento , Pupa/efeitos dos fármacos
6.
J Insect Sci ; 21(4)2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-34233003

RESUMO

Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae) is a pest of great economic importance which can feed on more than 300 plant species. As it is polyphagous, its host plants may have variable physical and chemical constitutions. This may influence larval development, as protein and carbohydrate levels are important factors for adequate biological development. The aim of this study was to evaluate insect developmental parameters as well as to compare the food consumption of S. frugiperda larvae reared using diets with different protein levels under laboratory conditions. Three artificial diet formulations were used: one typically used for routine laboratory rearing, based on bean, wheat germ and brewer's yeast (D1); one containing half the original amount of protein (D2), and the other with twice the original amount of protein (D3). The relative consumption rate (RCR), relative growth rate (RGR), and efficiency of conversion of ingested food (ECI) for S. frugiperda fourth instar larvae varied among diets. The protein present in the diet influenced the duration of larval and pupal periods and pupal weight, but did not affect larval survival, fecundity and longevity of adults. The different protein levels in the diets did not negatively influence population growth, so these three diet variations can be used for mass rearing in the laboratory. However, the influence of these diets on successive generations of the insect remains untested.


Assuntos
Ração Animal , Spodoptera/crescimento & desenvolvimento , Animais , Larva/crescimento & desenvolvimento , Mariposas/crescimento & desenvolvimento
7.
J Chem Ecol ; 47(7): 664-679, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34196857

RESUMO

Larval Diaphania indica (Saunders) (Lepidoptera: Crambidae) cause complete defoliation of Trichosanthes anguina L. and reduce crop yield in India. Females lay eggs on the leaf surface, and therefore leaf surface waxes are potentially involved in host selection. Alkanes and free fatty acids are the major constituents of leaf surface waxes, so a study was conducted to determine whether these wax constituents from three T. anguina cultivars (MNSR-1, Baruipur Long, and Polo No.1) could act as short-range attractants and oviposition stimulants in D. indica females. Twenty n-alkanes from n-C14 to n-C36 and 13 free fatty acids from C12:0 to C21:0 were detected in the leaf surface waxes of these cultivars. Heptadecane and stearic acid were predominant among n-alkanes and free fatty acids, respectively, in these cultivars. Females showed attraction towards one leaf equivalent surface wax of each of these cultivars against solvent controls (petroleum ether) in Y-tube olfactometer bioassays. A synthetic blend of heptadecane, eicosane, hexacosane, and stearic acid, a synthetic blend of hexacosane and stearic acid, and a synthetic blend of pentadecane and stearic acid comparable to amounts present in one leaf equivalent surface wax of MNSR-1, Baruipur Long, and Polo No.1, respectively, were short-range attractants and oviposition stimulants in D. indica. Female egg laying responses were similar to each of these blends, providing information that could be used to developing baited traps in integrated pest management (IPM) programs.


Assuntos
Cucurbitaceae/metabolismo , Mariposas/fisiologia , Oviposição/efeitos dos fármacos , Ceras/farmacologia , Alcanos/análise , Alcanos/isolamento & purificação , Alcanos/farmacologia , Animais , Análise Discriminante , Ácidos Graxos não Esterificados/análise , Ácidos Graxos não Esterificados/isolamento & purificação , Ácidos Graxos não Esterificados/farmacologia , Feminino , Cromatografia Gasosa-Espectrometria de Massas , Larva/efeitos dos fármacos , Larva/fisiologia , Mariposas/crescimento & desenvolvimento , Olfatometria , Folhas de Planta/metabolismo , Ceras/química , Ceras/isolamento & purificação
8.
Artigo em Inglês | MEDLINE | ID: mdl-34082360

RESUMO

Chemosensory proteins (CSPs) are important for insect chemoreception, which bind, solubilize and transport hydrophobic chemical molecules from external environment to dendrite membrane of chemosensory neurons. Moreover, CSPs are also involved in non-sensory physiological activities. The peach fruit borers Carposina sasakii Matsumura (Lepidoptera: Carposinidae) seriously damage fruit trees and their chemoreception mainly occurs in the adult stage. We identified 10 putative CSPs (CsasCSP1 ~ CsasCSP10) from head transcriptomes of C. sasakii adult males and females, all of which are classic CSPs that have 4 conserved cysteines with a spacing pattern C1-X6-C2-X17-18-C3-X2-C4. Their phylogenetic characteristics were also described. An analysis using fluorescence quantitative PCR showed CsasCSP2 has the highest level of expression in the heads, so it is more likely to be involved in C. sasakii chemoreception than the other C. sasakii CSPs. CsasCSP1, CsasCSP3, CsasCSP4, CsasCSP6, CsasCSP7 and CsasCSP8 are expressed dominantly in the wings; CsasCSP5 and CsasCSP10 have the highest expression level in the thoraxes; CsasCSP9 is dominantly and equally expressed in the thoraxes and abdomens. This study contributes to understanding physiological functions of C. sasakii CSPs and chemosensory mechanism at C. sasakii molecular level.


Assuntos
Regulação da Expressão Gênica , Proteínas de Insetos/metabolismo , Larva/metabolismo , Mariposas/metabolismo , Transcriptoma , Animais , Frutas/parasitologia , Proteínas de Insetos/genética , Larva/genética , Larva/crescimento & desenvolvimento , Mariposas/genética , Mariposas/crescimento & desenvolvimento , Filogenia , Prunus persica/parasitologia
9.
Artigo em Inglês | MEDLINE | ID: mdl-34171685

RESUMO

The diamondback moth, Plutella xylostella (Lepidoptera: Plutellidae) is a holometabolous insect that its cuticles must undergo the significant changes during the larval-pupal metamorphosis development. To elucidate these changes at molecular levels, RNA-seq analysis of cuticles from LLS (later fourth instar larval stage), PPS (prepupal stage) and PS (pupal stage) were performed in P. xylostella. In this paper, a total of 17,710 transcripts were obtained in the larval-pupal transition of P. xylostella, and out of which 2293 (881 up-regulated and 1412 down-regulated) and 2989 transcripts (2062 up-regulated and 927 down-regulated) were identified to be differentially expressed between LLS and PPS, as well as PPS and PS, respectively. The further GO and KEGG analysis of differentially expressed genes (DEGs) revealed that the 'structural constituent of cuticle', 'chitin metabolic process', 'chitin binding', 'tyrosine metabolism' and 'insect hormone biosynthesis' pathways were significantly enriched, indicating these pathways might be involved in the process of larval pupation in P. xylostella. Then, we found some genes that encoded cuticular proteins, chitinolytic enzymes, chitin synthesis enzymes, and cuticle tanning proteins changed their expression levels remarkably, indicating these genes might play important roles in the restruction (degradation and biosynthesis) of insect cuticles during the larval metamorphosis. Additionally, the significant changes in the mRNA levels of 20-hydroxyecdysone (20E) and juvenile hormone (JH) related genes suggested their crucial roles in regulating cuticle remodeling during the larval metamorphosis of P. xylostella. In conclusion, the present study provide us the comprehensive gene expression profiles to explore the molecular mechanisms of cuticle metamorphosis in P. xylostella, which laid a molecular basis to study roles of specific pathways and genes in insect development.


Assuntos
Regulação da Expressão Gênica no Desenvolvimento , Proteínas de Insetos/metabolismo , Larva/crescimento & desenvolvimento , Metamorfose Biológica , Mariposas/crescimento & desenvolvimento , Pupa/crescimento & desenvolvimento , RNA-Seq/métodos , Animais , Proteínas de Insetos/genética , Larva/genética , Larva/metabolismo , Mariposas/genética , Mariposas/metabolismo , Pupa/genética , Pupa/metabolismo , Transcriptoma
10.
Zootaxa ; 4991(1): 177-184, 2021 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-34186728

RESUMO

This work presents the first description of the morphology of the last larval instar and pupa of the clearwing moth species Synanthedon caucasica (Gorbunov, 1986). All diagnostic morphological characters are described in detail, compared with the closely related species Synanthedon loranthi (Králícek, 1966), and these diagnostic characters are illustrated with photographs and line drawings.


Assuntos
Mariposas , Animais , Larva , Mariposas/anatomia & histologia , Mariposas/classificação , Mariposas/crescimento & desenvolvimento , Pupa , Ulmus/parasitologia
11.
J Chem Ecol ; 47(7): 680-688, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34101117

RESUMO

Past work shows a significant negative correlation between foliar oregonin concentration and western tent caterpillar (Malacosoma californicum Packard) feeding on red alder (Alnus rubra Bong.). Above an oregonin threshold of 20% leaf dry weight, little feeding by caterpillars is observed. Concentrations of defensive chemicals are influenced by plant genotype, environmental conditions, insect feeding, and the interactions of these factors. Our objective was to measure the effects of nitrogen (N) availability and wounding on foliar oregonin and condensed tannin concentrations in red alder genotypes. One-year-old seedlings from 100 half-sib red alder families were treated with two levels of ammonium nitrate (NH4NO3) for two growing seasons in a common garden. In the second year, leaves from 50 families from the fertilization experiment were used in a bioassay feeding experiment to determine the effects of N fertilization and genotype on WTC damage, and to identify a subset of 20 families with a range of damage to analyze for phytochemical composition. In separate experiments, wound-induction treatments were conducted outdoors and, in a greenhouse using the N treated trees in their third and fourth year, respectively. Foliar condensed tannin, oregonin and N concentrations were measured and ranked among the plant genotypes, and between the two N treatments and two wounding treatments. Results showed that oregonin and condensed tannin concentrations varied among the alder genotypes. Leaf N concentration was negatively correlated with concentration of oregonin. Neither of the measured phenolic compounds responded to wounding. The results suggest that red alder foliar oregonin and condensed tannin are likely constitutive defenses that are largely determined by genotype, and that the negative correlation of defense compounds with plant internal N status holds in this N-fixing tree.


Assuntos
Alnus/química , Diarileptanoides/química , Mariposas/efeitos dos fármacos , Compostos Fitoquímicos/farmacologia , Taninos/análise , Alnus/genética , Alnus/crescimento & desenvolvimento , Animais , Cromatografia Líquida de Alta Pressão , Diarileptanoides/farmacologia , Fertilizantes/análise , Genótipo , Herbivoria/efeitos dos fármacos , Larva/efeitos dos fármacos , Larva/fisiologia , Mariposas/crescimento & desenvolvimento , Mariposas/fisiologia , Nitrogênio/química , Nitrogênio/metabolismo , Compostos Fitoquímicos/química , Folhas de Planta/química , Folhas de Planta/metabolismo , Plântula , Espectrofotometria Ultravioleta , Taninos/farmacologia
12.
PLoS One ; 16(5): e0251134, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33945577

RESUMO

The efficacy and non-target arthropod effects of transgenic DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 Bt cotton, expressing proteins Cry1Ac, Cry1F and Vip3Aa19, was examined through field trials in Brazil. Fifteen field efficacy experiments were conducted from 2014 through the 2020 growing season across six different states in Brazil to evaluate performance against key lepidopteran pests through artificial infestations of Chrysodeixis includens (Walker), Spodoptera frugiperda (J.E. Smith,1797), Spodoptera cosmioides (Walker, 1858) and Chloridea virescens (F., 1781), and natural infestations of Alabama argillacea (Hübner) and S. frugiperda. The impact of this Bt cotton technology on the non-target arthropod community in Brazilian cotton production systems was also assessed in a multi-site experiment. DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 cotton significantly reduced the feeding damage caused by S. frugiperda, S. cosmioides, C. includens, C. virescens and A. argillacea, causing high levels of mortality (greater than 99%) to all target lepidopteran pests evaluated during vegetative and/or reproductive stages of crop development. Non-target arthropod community-level analyses confirmed no unintended effects on the arthropod groups monitored. These results demonstrate the value of transgenic Bt cotton containing event DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 for consideration as part of an integrated approach for managing key lepidopteran pests in Brazilian cotton production systems.


Assuntos
Ácido 4-Acetamido-4'-isotiocianatostilbeno-2,2'-dissulfônico/análogos & derivados , Artrópodes/crescimento & desenvolvimento , Gossypium/metabolismo , Gossypium/parasitologia , Ácido 4-Acetamido-4'-isotiocianatostilbeno-2,2'-dissulfônico/metabolismo , Animais , Brasil , Controle de Insetos , Larva/crescimento & desenvolvimento , Mariposas/crescimento & desenvolvimento , Controle Biológico de Vetores/métodos , Folhas de Planta/parasitologia , Plantas Geneticamente Modificadas/parasitologia , Spodoptera/crescimento & desenvolvimento
13.
Bull Entomol Res ; 111(5): 595-604, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33998414

RESUMO

With further climate change still expected, it is predicted to increase the frequency with plants will be water stressed, which subsequently influences phytophagous insects, particularly Lepidoptera with limited mobility of larvae. Previous studies have indicated that oviposition preference and offspring performance of Lepidoptera insects are sensitive to drought separately. However, the integration of their two properties is not always seen. Here, we evaluated changes in oviposition selection and offspring fitness of a Lepidoptera insect under three water-stressed treatments using a model agroecosystem consisting of maize Zea mays, and Asian corn borer Ostrinia furnacalis. Results found that female O. furnacalis preferred to laying their eggs on well-watered maize, and then their offspring tended to survive better, attained bigger larvae mass, and developed more pupae and adults on the preferred maize. Oviposition selection of O. furnacalis positively correlated with height and leaf traits of maize, and offspring fitness positively related with water content and phytochemical traits of hosts. Overall, these results suggest that oviposition choice performed by O. furnacalis reflects the maximization of offspring fitness, supporting preference-performance hypothesis. This finding further highlights that the importance of simultaneous evaluation of performance and performance for water driving forces should be involved, in order to accurately predict population size of O. furnacalis under altered precipitation pattern.


Assuntos
Comportamento de Escolha , Mariposas/fisiologia , Oviposição , Zea mays/parasitologia , Animais , Desidratação , Herbivoria , Mariposas/crescimento & desenvolvimento , Zea mays/fisiologia
14.
Ecotoxicol Environ Saf ; 220: 112324, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34015630

RESUMO

Insecticides are extensively used worldwide to kill insect pests, yet organisms are most often exposed to insecticides at sublethal concentrations. Our understanding of sublethal effects on life histories is needed to predict the impact of insecticides on population dynamics and improve insecticide use and pest control. Sublethal concentrations can impact life histories directly and indirectly through changes in the intraspecific competition. Yet, few studies have evaluated the sublethal effects on intraspecific competition and these do not disentangle the insecticide effects on interference competition versus exploitative competition. As such, sublethal effects on the relative contribution of each pathways in shaping life histories are largely unknown, despite the fact that this can impact population dynamics. In this study, we focused on the neurotoxic insecticide spinosad and investigated its sublethal effects on interference among the aggressive larvae of the tortrix moth Adoxophyes honmai and the consequences for life histories. We conducted a set of paired experiments to disentangle the insecticide effects on interference from the ones on exploitation. Spinosad was found to amplify interference with most effects on mortality which lets us suggest that the insecticide likely increases the level of aggressive interactions resulting in more conspecific killings (e.g. cannibalism). Spinosad exposure was found to impair movement ability. Less movements may increase susceptibility to conspecific attacks and or increase aggresivity for better defence, two plausible mechanisms that could explain the increase in interference with insecticide. This study shows that insecticide at sublethal concentration can impact life histories by altering the strength of interference competition. Many organisms (pest and non-target species) compete through interference and theory predicts that a change in interference can substantially change dynamics. Our finding therefore reveals the importance of assessing the effect of insecticides on the mechanisms of competition when predicting their impact on populations.


Assuntos
Controle de Insetos , Inseticidas/farmacologia , Macrolídeos/farmacologia , Mariposas/efeitos dos fármacos , Agressão/efeitos dos fármacos , Animais , Relação Dose-Resposta a Droga , Combinação de Medicamentos , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Larva/fisiologia , Mariposas/crescimento & desenvolvimento , Mariposas/fisiologia , Movimento/efeitos dos fármacos , Dinâmica Populacional
15.
Bull Entomol Res ; 111(4): 385-393, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33988096

RESUMO

The oriental armyworm Mythimna separata (Walker) (Lepidoptera: Noctuidae) is a major migratory pest of cereal crops in East Asia, South Asia and Australia. To comprehensively understand the ecological tolerance of M. separata, we collected life table data of individuals from four consecutive generations reared under outdoor natural fluctuating temperatures from 15 April to 17 October 2018 in Yangling, Shaanxi, China. The results showed that the immature stage in early summer and summer were shorter than in spring and autumn. High mortality in late larval instar and pupal stages was observed in the summer generation. The adult pre-oviposition period in autumn was longer than the other seasons. The population in the earlier two seasons had heavier pupae and higher fecundity than the population in the latter two seasons. The intrinsic rate of increase and the finite rate of increase was the highest in early summer (r = 0.1292 day-1, λ = 1.1391 day-1), followed by spring (r = 0.1102 day-1, λ = 1.1165 day-1), and was the lowest in summer (r = 0.0281 day-1, λ = 1.0293 day-1). The results of this study would be useful to predict the population dynamics of M. separata and deepen our standing of the adaptiveness of this migratory pest in natural fluctuating ambient environments.


Assuntos
Mariposas/crescimento & desenvolvimento , Animais , Feminino , Tábuas de Vida , Masculino , Estações do Ano , Temperatura
16.
Elife ; 102021 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-33875133

RESUMO

Insect herbivores use different cues to locate host plants. The importance of CO2 in this context is not well understood. We manipulated CO2 perception in western corn rootworm (WCR) larvae through RNAi and studied how CO2 perception impacts their interaction with their host plant. The expression of a carbon dioxide receptor, DvvGr2, is specifically required for dose-dependent larval responses to CO2. Silencing CO2 perception or scrubbing plant-associated CO2 has no effect on the ability of WCR larvae to locate host plants at short distances (<9 cm), but impairs host location at greater distances. WCR larvae preferentially orient and prefer plants that grow in well-fertilized soils compared to plants that grow in nutrient-poor soils, a behaviour that has direct consequences for larval growth and depends on the ability of the larvae to perceive root-emitted CO2. This study unravels how CO2 can mediate plant-herbivore interactions by serving as a distance-dependent host location cue.


Assuntos
Dióxido de Carbono/metabolismo , Herbivoria , Mariposas/fisiologia , Zea mays/metabolismo , Animais , Cadeia Alimentar , Larva/crescimento & desenvolvimento , Larva/fisiologia , Mariposas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo
17.
Arch Insect Biochem Physiol ; 107(1): e21767, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33835527

RESUMO

Mythimna separata Walker (Lepidoptera: Noctuidae) is one of the major pests that can cause severe damage to grain crops. The development of low-toxicity and high-performance botanical insecticides is becoming the focus of new pesticide research to control M. separata. Tutin, a sesquiterpene lactone compound obtained from Coriaria sinica Maxim, a native Chinese poisonous plant, has antifeedant, absorption, and stomach poisoning against a variety of pests. To understand the toxic effect of tutin on M. separata larvae, we set out to determine their antifeedant, mortality, paralysis, weight change, and to examine the spreading of M. separata hemocytes under different concentrations of tutin treatment. Tissue distribution of the immune-associated gene growth-blocking peptide (GBP) and neuroglian peptide (Nrg) was detected by reverse transcription polymerase chain reaction (PCR). Furthermore, real-time quantitative PCR was carried out to determine the expression profiles of GBP and Nrg after different concentrations of tutin stimulation. Our results revealed that tutin exhibited significant antifeedant and insecticidal activities, paralysis, weight loss to M. separata. Besides, tutin significantly influenced on the morphology of hemocytes and enhanced the expression of GBP and Nrg in M. separata.


Assuntos
Inseticidas/farmacologia , Mariposas/efeitos dos fármacos , Picrotoxina/análogos & derivados , Sesquiterpenos/farmacologia , Animais , Citocinas/efeitos dos fármacos , Citocinas/metabolismo , Hemócitos/efeitos dos fármacos , Proteínas de Insetos/efeitos dos fármacos , Proteínas de Insetos/metabolismo , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Mariposas/crescimento & desenvolvimento , Neuropeptídeos/efeitos dos fármacos , Controle de Pragas , Picrotoxina/farmacologia
18.
Genes (Basel) ; 12(4)2021 03 24.
Artigo em Inglês | MEDLINE | ID: mdl-33805104

RESUMO

The rice leaf folder, Cnaphalocrocis medinalis is a major pest of rice and is difficult to control. UDP-N-acetylglucosamine pyrophosphorylase (UAP) is a key enzyme in the chitin synthesis pathway in insects. In this study, the UAP gene from C. medinalis (CmUAP) was cloned and characterized. The cDNA of CmUAP is 1788 bp in length, containing an open reading frame of 1464 nucleotides that encodes 487 amino acids. Homology and phylogenetic analyses of the predicted protein indicated that CmUAP shared 91.79%, 87.89%, and 82.75% identities with UAPs of Glyphodes pyloalis, Ostrinia furnacalis, and Heortia vitessoides, respectively. Expression pattern analyses by droplet digital PCR demonstrated that CmUAP was expressed at all developmental stages and in 12 tissues of C. medinalis adults. Silencing of CmUAP by injection of double-stranded RNA specific to CmUAP caused death, slow growth, reduced feeding and excretion, and weight loss in C. medinalis larvae; meanwhile, severe developmental disorders were observed. The findings suggest that CmUAP is essential for the growth and development of C. medinalis, and that targeting the CmUAP gene through RNAi technology can be used for biological control of this insect.


Assuntos
Clonagem Molecular/métodos , Mariposas/crescimento & desenvolvimento , Nucleotidiltransferases/genética , Nucleotidiltransferases/metabolismo , Animais , Regulação da Expressão Gênica no Desenvolvimento , Regulação Enzimológica da Expressão Gênica , Inativação Metabólica , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Mariposas/enzimologia , Mariposas/genética , Fases de Leitura Aberta , Oryza/parasitologia , Interferência de RNA , Distribuição Tecidual
19.
Bull Entomol Res ; 111(4): 476-484, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33814025

RESUMO

The small tomato borer, Neoleucinodes elegantalis (Guenée, 1854) is a multivoltine pest of tomato and other cultivated solanaceous plants. The knowledge on how N. elegantalis respond to temperature may help in the development of pest management strategies, and in the understanding of the effects of climate change on its voltinism. In this context, this study aimed to select models to describe the temperature-dependent development rate of N. elegantalis and apply the best models to evaluate the impacts of climate change on pest voltinism. Voltinism was estimated with the best fit non-linear model and the degree-day approach using future climate change scenarios representing intermediary and high greenhouse gas emission rates. Two out of the six models assessed showed a good fit to the observed data and accurately estimated the thermal thresholds of N. elegantalis. The degree-day and the non-linear model estimated more generations in the warmer regions and fewer generations in the colder areas, but differences of up to 41% between models were recorded mainly in the warmer regions. In general, both models predicted an increase in the voltinism of N. elegantalis in most of the study area, and this increase was more pronounced in the scenarios with high emission of greenhouse gases. The mathematical model (74.8%) and the location (9.8%) were the factors that mostly contributed to the observed variation in pest voltinism. Our findings highlight the impact of climate change on the voltinism of N. elegantalis and indicate that an increase in its population growth is expected in most regions of the study area.


Assuntos
Aquecimento Global , Modelos Biológicos , Mariposas/crescimento & desenvolvimento , Animais , Reprodução , Temperatura
20.
J Insect Sci ; 21(2)2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33844017

RESUMO

The codling moth Cydia pomonella (L.) (Lepidoptera: Tortricidae) is a destructive pest of apple (Malus domestica (Rosales: Rosaceae)), pear (Pyrus spp. (Rosales: Rosaceae)), and other pome tree fruits; outbreaks cause significant ecological and economic losses. In this study, we used CLIMEX model to predict and evaluate the global risk of C. pomonella based on historical climate data (1989-2018) and simulated future climate data (2071-2100) under the RCP4.5 scenarios. Cydia pomonella exhibited a wide distribution under both historical and future climate conditions. Climate change is predicted to expand the northern boundary of the potential distribution from approximately 60°N to 75°N. Temperature was the most dominant factor in climatic suitability for the pest. Combinations of multiple meteorological factors (relative humidity and precipitation) associated with a failure to break diapause in certain regions also affect suitability, particularly in northern South America and central Africa. Irrigation only had a slight impact on species favorability in some areas. The projections established in our study present insight into the global potential suitability of C. pomonella under climate change scenarios by the end of the 21st century. Farmers should be aware of the risk associated with the pest based on the results, which would provide guidance for quarantine agencies and trade negotiators worldwide.


Assuntos
Mudança Climática , Modelos Estatísticos , Mariposas , Dinâmica Populacional , Animais , Clima , Produtos Agrícolas/economia , Diapausa , Análise Fatorial , Frutas , Aquecimento Global , Malus , Mariposas/crescimento & desenvolvimento , Mariposas/fisiologia , Controle de Pragas , Pyrus , Temperatura , Árvores
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