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1.
Environ Sci Pollut Res Int ; 26(30): 30885-30892, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31446593

RESUMO

The western flower thrips (Frankliniella occidentalis Perg.) is one of the most economically important insect pests of greenhouse plants. Plant protection against this pest is based predominantly on synthetic insecticides; however, this form of protection poses problems in terms of thrip resistance to the active substances, along with health risks associated with insecticide residues on the treated plants. Therefore, new active substances need to be sought. Essential oils could be a new, appropriate, and safe alternative for greenhouse culture protection. As greenhouses are enclosed areas, fumigation application of EOs is possible. This paper presents acute toxicity results for 15 commercial EOs applied by fumigation, as well as the effect of sublethal concentrations on fertility of F. occidentalis females. The most efficient EOs were obtained from Mentha pulegium and Thymus mastichina, with LC50(90) estimated as 3.1(3.8) and 3.6 (4.6) mg L-1 air, respectively. As found for the very first time, sublethal concentrations of EOs could result in a significant reduction in the fertility of surviving T. occidentalis females. Among the tested EOs, the EO from Nepeta cataria provided the highest inhibition of fertility, with EC50(90) estimated as 0.18 (0.36) mg L-1 air. Chemical composition of the most efficient EOs and possible applications of the results in practice are discussed. In conclusion, in light of the newly determined facts, EOs can be recommended as active substances for botanical insecticides to be applied against Thysanopteran pests by fumigation.


Assuntos
Inseticidas/farmacologia , Óleos Voláteis/farmacologia , Tisanópteros/efeitos dos fármacos , Animais , Feminino , Fertilidade/efeitos dos fármacos , Fumigação , Mentha pulegium/química , Óleos Voláteis/química , Thymus (Planta)/química , Tisanópteros/fisiologia
2.
Pestic Biochem Physiol ; 158: 77-87, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31378364

RESUMO

Pyrethroid-resistance in onion thrips, Thrips tabaci, has been reported in many countries including Japan. Identifying factors of the resistance is important to correctly monitoring the resistance in field populations. To identify pyrethroid-resistance related genes in T. tabaci in Japan, we performed RNA-Seq analysis of seven T. tabaci strains including two pyrethroid-resistant and five pyrethroid-susceptible strains. We identified a pair of single point mutations, T929I and K1774N, introducing two amino acid mutations, in the voltage-gated sodium channel gene, a pyrethroid target gene, in the two resistant strains. The K1774N is a newly identified mutation located in the fourth repeat domain of the sodium channel. Genotyping analysis of field-collected populations showed that most of the T. tabaci individuals in resistant populations carried the mutation pair, indicating that the mutation pair is closely associated with pyrethroid-resistance in Japan. Another resistance-related mutation, M918L, was also identified in part of the resistant populations. Most of the individuals with the mutation pair were arrhenotokous while all individuals with the M918L single mutation were thelytokous. The result of differentially expressed gene analysis revealed a small number of up-regulated detoxification genes in each resistant strain which might be involved in resistance to pyrethroid. However, no up-regulated detoxification genes common to the two resistant strains were detected. Our results indicate that the mutation pair in the sodium channel gene is the most important target for monitoring pyrethroid-resistance in T. tabaci, and that pyrethroid-resistant arrhenotokous individuals with the mutation pair are likely to be widely distributed in Japan.


Assuntos
Piretrinas/farmacologia , Tisanópteros/efeitos dos fármacos , Tisanópteros/metabolismo , Canais de Sódio Disparados por Voltagem/metabolismo , Animais , Resistência a Inseticidas/genética , Inseticidas/farmacologia , Japão , Mutação/genética , Mutação Puntual/genética , Tisanópteros/genética , Canais de Sódio Disparados por Voltagem/genética
3.
J Chem Ecol ; 45(5-6): 490-501, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31175497

RESUMO

The development of pesticide resistance in insects and recent bans on pesticides call for the identification of natural sources of resistance in crops. Here, we used natural variation in pepper (Capsicum spp.) resistance combined with an untargeted metabolomics approach to detect secondary metabolites related to thrips (Frankliniella occidentalis) resistance. Using leaf disc choice assays, we tested 11 Capsicum accessions of C. annuum and C. chinense in both vegetative and flowering stages for thrips resistance. Metabolites in the leaves of these 11 accessions were analyzed using LC-MS based untargeted metabolomics. The choice assays showed significant differences among the accessions in thrips feeding damage. The level of resistance depended on plant developmental stage. Metabolomics analyses showed differences in metabolomes among the Capsicum species and plant developmental stages. Moreover, metabolomic profiles of resistant and susceptible accessions differed. Monomer and dimer acyclic diterpene glycosides (capsianosides) were pinpointed as metabolites that were related to thrips resistance. Sucrose and malonylated flavone glycosides were related to susceptibility. To our knowledge, this is the first time that dimer capsianosides of pepper have been linked to insect resistance. Our results show the potential of untargeted metabolomics as a tool for discovering metabolites that are important in plant - insect interactions.


Assuntos
Capsicum/química , Diterpenos/química , Glicosídeos/química , Metabolômica , Animais , Capsicum/metabolismo , Capsicum/parasitologia , Cromatografia Líquida de Alta Pressão , Análise por Conglomerados , Dimerização , Análise Discriminante , Glicosídeos/farmacologia , Interações Hospedeiro-Parasita , Metaboloma , Folhas de Planta/química , Folhas de Planta/metabolismo , Folhas de Planta/parasitologia , Análise de Componente Principal , Espectrometria de Massas em Tandem , Tisanópteros/efeitos dos fármacos , Tisanópteros/fisiologia
4.
J Chem Ecol ; 45(2): 116-127, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30221331

RESUMO

Plants produce an extremely diverse array of metabolites that mediate many aspects of plant-environment interactions. In the context of plant-herbivore interactions, it is as yet poorly understood how natural backgrounds shape the bioactivity of individual metabolites. We tested the effects of a methanol extract of Jacobaea plants and five fractions derived from this extract, on survival of western flower thrips (WFT). When added to an artificial diet, the five fractions all resulted in a higher WFT survival rate than the methanol extract. In addition, their expected combined effect on survival, assuming no interaction between them, was lower than that of the methanol extract. The bioactivity was restored when the fractions were combined again in their original proportion. These results strongly suggest synergistic interactions among the fractions on WFT survival rates. We then tested the effects of two pyrrolizidine alkaloids (PAs), free base retrorsine and retrorsine N-oxide, alone and in combination with the five shoot fractions on WFT survival. The magnitude of the effects of the two PAs depended on the fraction to which they were added. In general, free base retrorsine was more potent than retrorsine N-oxide, but this was contingent on the fraction to which these compounds were added. Our results support the commonly held, though seldom tested, notion that the efficacy of plant metabolites with respect to plant defence is dependent on their phytochemical background. It also shows that the assessment of bioactivity cannot be decoupled from the natural chemical background in which these metabolites occur.


Assuntos
Compostos Fitoquímicos/química , Alcaloides de Pirrolizidina/farmacologia , Tisanópteros/efeitos dos fármacos , Animais , Asteraceae/química , Asteraceae/metabolismo , Cromatografia Líquida de Alta Pressão , Flores/química , Flores/metabolismo , Compostos Fitoquímicos/farmacologia , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Brotos de Planta/química , Brotos de Planta/metabolismo , Alcaloides de Pirrolizidina/química , Espectrometria de Massas em Tandem , Tisanópteros/fisiologia
5.
Pest Manag Sci ; 75(2): 515-526, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30047237

RESUMO

BACKGROUND: Insecticide resistance management (IRM) practices that improve the sustainability of agricultural production systems are developed, but few studies address the challenges with their implementation and success rates of adoption. This study examined the effectiveness of a voluntary, extension-based program to increase grower adoption of IRM practices for onion thrips (Thrips tabaci) in onion. The program sought to increase the use of two important IRM practices: rotating classes of insecticides during the growing season and applying insecticides following an action threshold. RESULTS: Onion growers (n = 17) increased their adoption of both IRM practices over the 3-year study. Growers increased use of insecticide class rotation from 76% to 100% and use of the action threshold for determining whether to apply insecticides from 57% to 82%. Growers who always used action thresholds successfully controlled onion thrips infestations, applied significantly fewer insecticide applications (one to four fewer applications) and spent $148/ha less on insecticides compared with growers who rarely used the action threshold. Growers who regularly used action thresholds and rotated insecticide classes did so because they were primarily concerned about insecticide resistance development in thrips populations. CONCLUSION: Implementation of the IRM education program was successful, as adoption rates of both practices increased within 3 years. Growers were surprisingly most receptive to adopting these practices to mitigate insecticide resistance as opposed to saving money. Developing extension-based programs that involve regular and interactive meetings with growers may significantly increase the adoption of IRM and related integrated pest management tactics. © 2018 Society of Chemical Industry.


Assuntos
Proteção de Cultivos/métodos , Controle de Insetos/métodos , Resistência a Inseticidas , Inseticidas/farmacologia , Tisanópteros/efeitos dos fármacos , Animais , New York , Cebolas/crescimento & desenvolvimento
6.
Environ Entomol ; 47(6): 1560-1564, 2018 12 07.
Artigo em Inglês | MEDLINE | ID: mdl-30346518

RESUMO

The onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), is a polyphagous pest that causes serious damage to agricultural crops, vegetables, and ornamental plants worldwide. Farmers rely on the extensive usage of synthetic chemical insecticides to control T. tabaci. There is a dire need to develop alternative control strategies to overcome the problems posed by chemical insecticides. Efficient traps would allow sensitive monitoring and possibly mass trapping. A field experiment was conducted to evaluate the potential of three plant compounds with known release rates (ranging from 6-30 mg/d); eugenol (Eug), 1, 8-cineole (eucalyptol), and linalool in all possible combinations with a thrips attractant, ethyl iso-nicotinate (EI). A combination of EI with Eug increased the effect of EI by attracting 100% more thrips (effect size, 1.95) as compared to the control of EI alone. Catches in remaining treatments were lower and or not significantly different from EI alone. The results from our study could be used to develop improved volatile blends to be used for monitoring traps. Our data suggests that these traps could be effective even at very low populations.


Assuntos
Eugenol/farmacologia , Ácidos Isonicotínicos/farmacologia , Monoterpenos/farmacologia , Feromônios/farmacologia , Tisanópteros/efeitos dos fármacos , Animais , Sinergismo Farmacológico
7.
Plant Sci ; 276: 87-98, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30348331

RESUMO

Variation in the induction of plant defenses along the plant canopy can determine distribution and colonization of arthropod herbivores within the plant. In tomato, type VI glandular trichomes, which are epidermal defensive structures, and their derived volatiles are induced by the phytohormone jasmonic acid (JA). How JA-mediated induction of these trichome-associated chemical defenses depends on the leaf developmental stage and correlates with resistance against herbivory is unknown. We showed that application of JA reduced thrips-associated damage, however the amplitude of this response was reduced in the fully developed leaves compared to those still developing. Although JA increased type-VI trichome densities in all leaf developmental stages, as well as JA-inducible defensive proteins, these increases were stronger in developing leaves. Remarkably, the concentration of trichome-derived volatiles was induced by JA to a larger degree in developing leaves than in fully developed leaves. In fully developed leaves, the increase in trichome-derived volatiles was explained by an enhanced production per trichome, while in developing leaves this was mainly caused by increases in type-VI trichome densities. Together, we showed that JA-mediated induction of trichome density and chemistry depends on leaf development stage, and it might explain the degree of thrips-associated leaf damage in tomato.


Assuntos
Lycopersicon esculentum/química , Feromônios/metabolismo , Exsudatos de Plantas/química , Tisanópteros/efeitos dos fármacos , Tricomas/química , Animais , Ciclopentanos/metabolismo , Herbivoria , Lycopersicon esculentum/crescimento & desenvolvimento , Lycopersicon esculentum/imunologia , Oxilipinas/metabolismo , Reguladores de Crescimento de Planta/metabolismo , Folhas de Planta/química , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/imunologia , Tisanópteros/fisiologia , Tricomas/crescimento & desenvolvimento , Tricomas/imunologia , Compostos Orgânicos Voláteis/metabolismo
8.
Pestic Biochem Physiol ; 150: 33-39, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30195385

RESUMO

To understand the role of target site insensitivity in abamectin resistance in the western flower thrips (WFT), Frankliniella occidentalis (Pergande), cDNAs encoding gamma-aminobutyric acid receptor subunit (FoRdl) and glutamate-gated chloride channel (FoGluCl) were cloned from WFT, and both single nucleotide polymorphisms (SNPs) and mRNA expression levels of FoRdl and FoGluCl were detected in a susceptible strain (ABA-S) and a laboratory selected strain (ABA-R) displaying 45.5-fold resistance to abamectin. Multiple cDNA sequence alignment revealed three alternative splicing variants of FoRdl and two alternative splicing variants of FoGluCl generated by alternative splicing of exon 3. While sequence comparison of FoRdl and FoGluCl in ABA-S and ABA-R strains identified no resistance-associated mutations, the expression level of FoGluCl in ABA-R strain was 2.63-fold higher than that in ABA-S strain. Thus, our preliminary results provide the evidence that the increased mRNA expression of FoGluCl could be an important factor in FoGluCl-mediated target site insensitivity in WFT.


Assuntos
Canais de Cloreto/genética , Receptores de GABA/genética , Tisanópteros/genética , Processamento Alternativo , Sequência de Aminoácidos , Animais , Canais de Cloreto/química , Clonagem Molecular , Éxons , Resistência a Inseticidas/genética , Inseticidas/farmacologia , Ivermectina/análogos & derivados , Ivermectina/farmacologia , Polimorfismo de Nucleotídeo Único , RNA Mensageiro/genética , Receptores de GABA/química , Homologia de Sequência de Aminoácidos , Tisanópteros/efeitos dos fármacos
9.
J Econ Entomol ; 111(5): 2069-2075, 2018 09 26.
Artigo em Inglês | MEDLINE | ID: mdl-29992326

RESUMO

We attempted to develop an efficient management strategy against gall thrips (Gynaikothrips uzeli Zimmermann (Thysanoptera: Phlaeothripidae)) via the combined application of a systemic insecticide (imidacloprid) and an entomopathogenic fungus (Lecanicillium lecanii Zimmerman (Hypocreales: Clavicipitaceae)). The attraction of G. uzeli to Ficus microcarpa volatiles after imidacloprid treatment was weaker than for untreated plants, which could be due to modulation of volatile metabolite profiles by imidacloprid. The toxicity of L. lecanii against nymph and adult thrips was much higher for those that fed on plants treated with a 50% lethal concentration (LC50) of imidacloprid than for the controls. Phenoloxidase (PO) activity was significantly inhibited in treated G. uzeli, while hemocyte abundances were not different in treated and healthy individuals. Thus, imidacloprid impacted the PO-related humoral immunity of G. uzeli, but not their cellular immunity. Overall, F. microcarpa treated with imidacloprid at LC50 concentrations exhibited volatile profiles that decreased the attraction of G. uzeli and also indirectly increased the pathogenicity of L. lecanni by inhibiting the humoral immunity of gall thrips. The results reported here suggest that combined application of imidacloprid and L. lecanii could be used as a new integrated control strategy against gall thrips.


Assuntos
Interações Hospedeiro-Patógeno/efeitos dos fármacos , Hypocreales , Inseticidas , Neonicotinoides , Nitrocompostos , Tisanópteros/imunologia , Animais , Ficus , Controle de Insetos , Olfatometria , Tisanópteros/efeitos dos fármacos
10.
Pest Manag Sci ; 74(12): 2773-2782, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29737621

RESUMO

BACKGROUND: Elevated CO2 can alter the leaf damage caused by insect herbivores. Frankliniella occidentalis (Pergande) is highly destructive invasive pest of crop production worldwide. To investigate how elevated CO2 affects F. occidentalis fed with Phaseolus vulgaris and, in particular, the interaction between plant defense and thrips anti-defense, nutrient content and antioxidant enzyme activity of P. vulgaris were measured, as well as the detoxifying enzyme activity of adult thrips. RESULTS: Elevated CO2 increased the soluble sugar, soluble protein and free amino acid content in non thrip-infested plants, and decreased superoxide dismutase (SOD) and peroxidase (POD) activity in these plants. Feeding thrips reduced the nutrient content in plants, and increased their SOD, catalase and POD activity. Variations in nutrient content and antioxidant enzyme activity in plants showed an opposite tendency over thrip feeding time. After feeding, acetylcholinesterase, carboxylesterase, and mixed-function oxidase activity in thrips increased to counter the plant defenses. Greater thrip densities induced stronger plant defenses and, in turn, detoxifying enzyme levels in thrips increased over thrip numbers. CONCLUSION: Our study revealed that F. occidentalis can induce not only an antioxidant-associated plant defense, but also detoxifying enzymes in thrips. Elevated CO2 might both enhance plant defense against thrip attack, and increase thrip anti-defense against plant defenses. © 2018 Society of Chemical Industry.


Assuntos
Dióxido de Carbono/farmacologia , Espécies Introduzidas , Phaseolus/efeitos dos fármacos , Tisanópteros/efeitos dos fármacos , Tisanópteros/fisiologia , Animais , Antioxidantes/metabolismo , Relação Dose-Resposta a Droga , Phaseolus/enzimologia , Phaseolus/metabolismo , Solubilidade
11.
J Econ Entomol ; 111(3): 1030-1041, 2018 05 28.
Artigo em Inglês | MEDLINE | ID: mdl-29635299

RESUMO

Peanut growers use a combination of tactics to manage spotted wilt disease caused by thrips-transmitted Tomato spotted wilt virus (TSWV). They include planting TSWV-resistant cultivars, application of insecticides, and various cultural practices. Two commonly used insecticides against thrips are aldicarb and phorate. Both insecticides exhibit broad-spectrum toxicity. Recent research has led to the identification of potential alternatives to aldicarb and phorate. In this study, along with reduced-risk, alternative insecticides, we evaluated the effect of conventional versus strip tillage; single versus twin row seeding pattern; and 13 seed/m versus 20 seed/m on thips density, feeding injury, and spotted wilt incidence. Three field trials were conducted in Georgia in 2012 and 2013. Thrips counts, thrips feeding injuriy, and incidence of spotted wilt were less under strip tillage than under conventional tillage. Reduced feeding injury from thrips was observed on twin-row plots compared with single-row plots. Thrips counts, thrips feeding injury, and incidence of spotted wilt did not vary by seeding rate. Yield from twin-row plots was greater than yield from single-row plots only in 2012. Yield was not affected by other cultural practices. Alternative insecticides, including imidacloprid and spinetoram, were as effective as phorate in suppressing thrips and reducing incidence of spotted wilt in conjunction with cultural practices. Results suggest that cultural practices and reduced-risk insecticides (alternatives to aldicarb and phorate) can effectively suppress thrips and incidence of spotted wilt in peanut.


Assuntos
Arachis , Produção Agrícola/métodos , Controle de Insetos/métodos , Inseticidas/administração & dosagem , Tisanópteros/fisiologia , Tospovirus/fisiologia , Animais , Arachis/crescimento & desenvolvimento , Georgia , Macrolídeos/administração & dosagem , Neonicotinoides/administração & dosagem , Doenças das Plantas/prevenção & controle , Doenças das Plantas/virologia , Tisanópteros/efeitos dos fármacos
12.
J Econ Entomol ; 111(3): 1290-1297, 2018 05 28.
Artigo em Inglês | MEDLINE | ID: mdl-29590397

RESUMO

Experimental approaches to studying the consequences of pesticide use, including impacts on beneficial insects, are vital; however, they can be limited in scale and realism. We show that an ecoinformatics approach that leverages existing data on pesticides, pests, and beneficials across multiple fields can provide complementary insights. We do this using a multi-year dataset (2002-2013) on pesticide applications and density estimates of two pests, citrus thrips (Scirtothrips citri (Moulton [Thysanoptera: Thripidae])) and citrus red mites (Panonychus citri McGregor [Acari: Tetranychidae]), and a natural enemy (Euseius spp. predatory mites) collected from citrus groves in the San Joaquin Valley of California. Using correlative analyses, we investigated the long-term consequences of pesticide use on S. citri and P. citri population densities to evaluate the hypothesis that the pest status of these species is largely due to the disruption of natural biological control-i.e., these are induced pests. We also evaluated short-term pesticide efficacy (suppression of citrus thrips and citrus red mite populations immediately post-application) and asked if it was correlated with the suppression of Euseius predator populations. Although the short-term efficacy of different pesticides varied significantly, our dataset does not suggest that the use of citrus pesticides suppressed Euseius densities or worsened pest problems. We also find that there is no general trade-off between pesticide efficacy and pesticide risk to Eusieus, such that highly effective and minimally disruptive compounds were available to citrus growers during the studied time period.


Assuntos
Ácaros e Carrapatos/efeitos dos fármacos , Acaricidas/toxicidade , Cadeia Alimentar , Inseticidas/toxicidade , Controle Biológico de Vetores , Comportamento Predatório/efeitos dos fármacos , Ácaros e Carrapatos/fisiologia , Animais , California , Citrus/crescimento & desenvolvimento , Controle de Insetos , Densidade Demográfica , Tetranychidae/efeitos dos fármacos , Tetranychidae/fisiologia , Tisanópteros/efeitos dos fármacos , Tisanópteros/fisiologia , Controle de Ácaros e Carrapatos
13.
Pest Manag Sci ; 74(7): 1564-1574, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29427375

RESUMO

BACKGROUND: Spinetoram, a new type of spinosyn with novel modes of action, has been used in effective thrips control programs, but resistance remains a threat. In the present study, a laboratory Thrips hawaiiensis population was subjected to spinetoram for resistance selection to investigate resistance development, stability, cross-resistance potential, biological fitness and underlying biochemical mechanisms. RESULTS: Resistance to spinetoram in T. hawaiiensis rapidly increased 103.56-fold (for 20 generations of selection with spinetoram) compared with a laboratory susceptible population, and the average realized heritability (h2 ) of resistance was calculated as 0.1317. Maintaining the resistant population for five generations without any further selection pressure resulted in a decline in the resistance ratio from 19.42- to 9.50-fold, suggesting that spinetoram resistance in T. hawaiiensis is unstable. Moreover, the spinetoram-resistant population exhibited a lack of cross-resistance to other classes of insecticides, and showed biological fitness costs. The results of synergism experiments using enzyme inhibitors and biochemical analyses revealed that metabolic mechanisms might not be responsible for the development of spinetoram resistance in T. hawaiiensis. CONCLUSION: The current study expands understanding of spinosyn resistance in thrips species, providing a basis for proposing better integrated pest management strageties for thrips control programs and defining the most appropriate tools for such resistance management. © 2018 Society of Chemical Industry.


Assuntos
Resistência a Inseticidas , Inseticidas/farmacologia , Macrolídeos/farmacologia , Tisanópteros/efeitos dos fármacos , Animais , Feminino , Aptidão Genética , Resistência a Inseticidas/genética , Masculino , Ninfa/efeitos dos fármacos , Ninfa/genética , Ninfa/crescimento & desenvolvimento , Tisanópteros/genética , Tisanópteros/crescimento & desenvolvimento
14.
J Econ Entomol ; 110(4): 1755-1763, 2017 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-28444324

RESUMO

Frankliniella occidentalis (Pergande) is an economically important pest of agricultural crops. High resistance has been detected in field populations of F. occidentalis against the insecticide spinosad. In this study, we compared life history traits, body sizes, and feeding behaviors (recorded via an electrical penetration graph) of spinosad-susceptible (Ivf03) and spinosad-resistant (NIL-R) near-isogenic lines of F. occidentalis. Life table analysis showed that NIL-R had reduced female longevity and reduced fecundity. The relative fitness of NIL-R (0.43) was less than half that of Ivf03. NIL-R individuals were smaller than Ivf03 individuals, both in body length and body width at every stage. The number and duration of feeding activities were significantly reduced in NIL-R, with the exception of total duration of long-ingestion probes. These results suggest that there is a fitness trade-off associated with spinosad resistance in F. occidentalis, and that the development of resistance in this pest species may be reduced by rotating spinosad with other pesticides lacking cross-resistance.


Assuntos
Aptidão Genética , Resistência a Inseticidas , Inseticidas/farmacologia , Macrolídeos/farmacologia , Tisanópteros/efeitos dos fármacos , Animais , Combinação de Medicamentos , Comportamento Alimentar/efeitos dos fármacos , Feminino , Masculino , Ninfa/efeitos dos fármacos , Ninfa/genética , Ninfa/crescimento & desenvolvimento , Ninfa/fisiologia , Pupa/efeitos dos fármacos , Pupa/genética , Pupa/crescimento & desenvolvimento , Pupa/fisiologia , Tisanópteros/genética , Tisanópteros/crescimento & desenvolvimento , Tisanópteros/fisiologia
15.
Phytochemistry ; 138: 93-103, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28267991

RESUMO

Plant specialised metabolites (SMs) are very diverse in terms of both their number and chemical structures with more than 200,000 estimated compounds. This chemical diversity occurs not only among different groups of compounds but also within the groups themselves. In the context of plant-insect interactions, the chemical diversity within a class of structurally related metabolites is generally also related to their bioactivity. In this study, we tested firstly whether individual SMs within the group of pyrrolizidine alkaloids (PAs) differ in their effects on insect herbivores (western flower thrips, Frankliniella occidentalis). Secondly, we tested combinations of PA N-oxides to determine whether they are more active than their individual components. We also evaluated the bioactivity of six PA free bases and their corresponding N-oxides. At concentrations similar to that in plants, several PAs reduced thrip's survival but the effect also differed strongly among PAs. In general, PA free bases caused a lower survival than their corresponding N-oxides. Among the tested PA free bases, we found jacobine and retrorsine to be the most active against second instar larvae of thrips, followed by erucifoline and seneciphylline, while senecionine and monocrotaline did not exhibit significant dose-dependent effects on thrip's survival. In the case of PA N-oxides, we found that only senecionine N-oxide and jacobine N-oxide reduced thrip's survival, although the effect of senecionine N-oxide was weak. Combinations of PA N-oxides showed no synergistic effects. These findings indicate the differences observed in the effect of structurally related SMs on insect herbivores. It is of limited value to study the bioactivity of combined groups, such as PAs, without taking their composition into account.


Assuntos
Herbivoria , Alcaloides de Pirrolizidina/química , Tisanópteros/efeitos dos fármacos , Animais , Larva , Estrutura Molecular
16.
J Nat Prod ; 79(6): 1698-701, 2016 06 24.
Artigo em Inglês | MEDLINE | ID: mdl-27227966

RESUMO

Two new and seven known sesquiterpene compounds were isolated from an agar plate culture of Granulobasidium vellereum, isolated from a log of Ulmus sp. The two new structures were elucidated with spectroscopic methods as an illudalane derivative, granulolactone (1), and a 15-norilludane, granulodione (9). The acaricidal and insecticidal activities of the isolated compounds were examined in vitro against two major horticultural pests, the two-spotted spider mite Tetranychus urticae and the glasshouse thrips Heliothrips haemorrhoidalis, respectively.


Assuntos
Basidiomycota/química , Inseticidas/isolamento & purificação , Sesquiterpenos/isolamento & purificação , Animais , Inseticidas/química , Inseticidas/farmacologia , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , Sesquiterpenos/química , Sesquiterpenos/farmacologia , Tetranychidae/efeitos dos fármacos , Tisanópteros/efeitos dos fármacos , Ulmus/microbiologia
17.
J Chem Ecol ; 42(4): 294-9, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-27008648

RESUMO

Two dibasic esters, the dimethyl ester of hexanedioic acid (dimethyl adipate, DBE-6) and the dimethyl ester of pentanedioic acid (dimethyl glutarate, DBE-5) were found in head-thorax extracts of male Echinothrips americanus. DBE-5 induced abdomen wagging and raising in males and females, which is typically exhibited when encountering a male. DBE-6 was avoided by males and was detected on mated, but not on virgin, females. Both substances applied to virgin females lead to females being ignored by males. The role of both substances is discussed with regard to the male mating system.


Assuntos
Atrativos Sexuais/farmacologia , Comportamento Sexual Animal/efeitos dos fármacos , Tisanópteros/efeitos dos fármacos , Adipatos/química , Adipatos/farmacologia , Animais , Bioensaio , Feminino , Masculino , Atrativos Sexuais/química
18.
Pestic Biochem Physiol ; 129: 28-35, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-27017878

RESUMO

Onion thrips, Thrips tabaci Lindeman, is the main pest of onion-growing fields in Isfahan and is mainly controlled by frequently spraying several insecticides. To investigate the resistance status and mechanisms, the susceptibility of ten field populations collected from Isfahan onion-growing regions were tested to several currently used pesticides. Resistance to the tested insecticides was observed in most populations when compared with the susceptible reference population. Enhanced detoxification, implicated by the use of inhibitors of major metabolic detoxification enzymes, was observed in the populations resistant to profenofos and chlorpyrifos. In the deltamethrin resistant populations, the amino acid substitution T929I was detected in the voltage gated sodium channel, which is known to confer pyrethroid resistance. These data are a first step towards more efficient resistance management tactics through early detection of resistant onion thrips in Iran.


Assuntos
Agricultura , Resistência a Inseticidas , Compostos Organofosforados/farmacologia , Piretrinas/farmacologia , Tisanópteros/efeitos dos fármacos , Animais , Irã (Geográfico)
19.
J Econ Entomol ; 109(1): 62-9, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26377766

RESUMO

Tomato spotted wilt virus (TSWV) is transmitted by Frankliniella occidentalis (Pergande) in a persistent-propagative manner. We previously observed significant results in terms of feeding behavior of spinosad-susceptible (Ivf03) and -resistant (Spin-R) strains of F. occidentalis using electrical penetration graph. TSWV transmission by the two strains was compared in the present study. The results showed that the titer of TSWV-N RNA (a part of S RNA of TSWV and encoding the nucleocapsid protein) in Ivf03 and Spin-R strains was not significantly different after a 48-h inoculation access period. The TSWV transmission rate did not significantly differ between the two strains and was 51.0% for Ivf03 and 44.4% for Spin-R. The virus transmission rate was significantly higher for males than females of both strains. The virus transmission rate for males and females of Ivf03 was 68.1 and 33.8%, respectively; however, in case of Spin-R, it was 60 and 28.8% for males and females, respectively. Additionally, number of probes and duration of probes were generally greater for viruliferous females of Ivf03 than for viruliferous females of Spin-R but the total number and duration of noningestion probes did not significantly differ between males of the two strains. The latter finding behavior may help explain the similar transmission rates for the susceptible and resistant strains.


Assuntos
Inseticidas/farmacologia , Lycopersicon esculentum/virologia , Macrolídeos/farmacologia , Doenças das Plantas/virologia , Tisanópteros/efeitos dos fármacos , Tisanópteros/virologia , Animais , Combinação de Medicamentos , Feminino , Resistência a Inseticidas , Masculino , Ninfa/efeitos dos fármacos , Ninfa/crescimento & desenvolvimento , Ninfa/virologia , Tisanópteros/crescimento & desenvolvimento , Tospovirus/fisiologia
20.
J Econ Entomol ; 108(2): 559-65, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26470166

RESUMO

Determination of sublethal and transgenerational effects of pesticides on natural enemies is necessary for successful implementation of biocontrol in integrated pest management programs. In this study, these effects of abamectin on the predatory thrips Scolothrips longicornis Priesner fed on Tetranychus urticae Koch were estimated under laboratory conditions in which adult predators were exposed to pesticide residues on bean leaves. The estimated values of LC50 for female and male predators were 0.091 and 0.067 µg a.i./ml, respectively. Low-lethal concentrations (LC10, LC20 and LC30) of abamectin severely affected fecundity and longevity of treated females of S. longicornis. In addition, transgenerational effects on reproductive and life table parameters of the subsequent generation were observed. The results from this research can be used to develop guidelines for the use of abamectin to minimize the impact on S. longicornis.


Assuntos
Inseticidas/toxicidade , Ivermectina/análogos & derivados , Controle Biológico de Vetores , Comportamento Predatório/efeitos dos fármacos , Tetranychidae , Tisanópteros/efeitos dos fármacos , Animais , Feminino , Ivermectina/toxicidade , Masculino
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