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1.
Exp Appl Acarol ; 79(1): 47-68, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31388896

RESUMO

We compared the life cycles and diapause attributes among three closely related spider mites, Oligonychus castaneae on Castanea crenata, and O. gotohi and O. amiensis on Lithocarpus edulis. The lower thermal thresholds from egg to egg were 10.5, 8.5 and 8.9 °C, respectively, and the thermal constants were 177.8, 229.5 and 232.5 degree-days, respectively. The cumulative hatching rates of diapause eggs of O. castaneae and O. gotohi increased as the season progressed in and after early-to-mid January, which indicates diapause termination. In contrast, O. amiensis showed higher hatching rates in December and January, but hatchability gradually decreased in and after February because some of the eggs died from the cold. Oligonychus castaneae and O. gotohi females produced diapause eggs in response to the short photoperiod in late September to early October and in early-to-late October, respectively, which corresponded to the times predicted by the critical photoperiods (at 15 °C) of 12 h 15 min and 11 h 15 min for the respective species. Oligonychus castaneae showed at least a single population peak over the 3-year observation period, but the time of peak population varied from mid-July to mid-September. The population of O. gotohi was higher between November and May when diapause eggs were present on host plants in early winter and the first-generation females laid eggs on leaves in spring. The population of O. amiensis, which is a non-diapause species, was only high between September and December, because eggs were laid on leaves in autumn to winter and then gradually disappeared and/or died during winter. Natural enemies were observed as the number of spider mites declined, and the density suppression effect by natural enemies was confirmed in the field.


Assuntos
Diapausa , Cadeia Alimentar , Fotoperíodo , Tetranychidae/fisiologia , Animais , Fagaceae , Feminino , Larva/crescimento & desenvolvimento , Larva/fisiologia , Masculino , Ninfa/crescimento & desenvolvimento , Ninfa/fisiologia , Óvulo/crescimento & desenvolvimento , Dinâmica Populacional , Estações do Ano , Especificidade da Espécie , Tetranychidae/crescimento & desenvolvimento
2.
Exp Appl Acarol ; 78(4): 521-534, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31346835

RESUMO

The overwintering pattern of parasitic herbivorous arthropods is closely related to host phenology, because defoliation imposes strong selection pressures on various developmental stages. This relationship has been well studied in populations of spider mites (Acari: Tetranychidae) on deciduous hosts, but is little studied in populations on evergreen hosts, probably because their leaves are always available. However, spring defoliation may also influence the life cycle. We studied the overwintering pattern of Schizotetranychus brevisetosus (Acari: Tetranychidae), a specialist on evergreen oak, Quercus glauca, in Kochi, Japan. Only adult females and their eggs (winter eggs) survived the coldest months. We also observed a conspicuous seasonal change in egg colour and size: December winter eggs were 1.7× larger than September summer eggs, suggesting the winter eggs are diapausing. Adult females produced summer eggs until November and winter eggs from late November until they disappeared in March. The winter eggs hatched in early March. The immature stages developed in mid- to late March, when 39% of old leaves fell, some of which carried hundreds of immature individuals. Therefore, even in evergreen hosts, defoliation places potentially strong selection pressure on the immature stages. Despite this, S. brevisetosus appears not to change its egg hatching season to avoid the defoliation season, so it may have evolved a behavioural adaptation to escape falling leaves. The existence of several species with similar lifestyles suggests the importance of host phenology and predation pressure for evolution of the overwintering pattern.


Assuntos
Traços de História de Vida , Tetranychidae/fisiologia , Animais , Ecossistema , Feminino , Japão , Larva/crescimento & desenvolvimento , Larva/fisiologia , Ninfa/crescimento & desenvolvimento , Ninfa/fisiologia , Óvulo/crescimento & desenvolvimento , Óvulo/fisiologia , Densidade Demográfica , Quercus , Reprodução , Estações do Ano , Tetranychidae/crescimento & desenvolvimento
3.
Exp Appl Acarol ; 78(2): 295-314, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31154548

RESUMO

The peanut red spider mite, Tetranychus ogmophallos Ferreira and Flechtmann (Acari: Tetranychidae), is an important pest of peanut in Brazil and is considered a quarantine pest in other countries. This study investigates the development, reproduction, survival and life table parameters of T. ogmophallos on five peanut cultivars-three with high levels of oleic acid [high oleic] and recently released: Granoleico, IAC OL 3 and IAC 503; and two regular and previously used by farmers: Runner IAC 886, IAC Tatu ST 3-and two breeding lines (L. 8008 and L. 322) in the growth chamber. There were differences between the developmental times of all immature stages, the oviposition period, fecundity and adult longevity of T. ogmophallos reared on the peanut cultivars and breeding lines. The longest duration of the immature stage and lowest fecundity occurred on cultivars Granoleico and Runner IAC 886, and breeding line L. 322, which also displayed the lowest intrinsic rate of increase (r), finite rate of increase (λ) and net reproductive rate (R0) and the shortest mean generation time (T). The highest fitness occurred on the IAC Tatu ST, IAC OL 3, IAC 503 and L. 8008. Our study shows that peanut cultivars belonging to the group with high oleic trait and recently released (IAC OL 3 and IAC 503) are susceptible to T. ogmophallos, except Granoleico, which is resistant. The regular and previously used cultivar Runner IAC 886 and breeding line L. 322 are resistant to the peanut red spider mite.


Assuntos
Antibiose , Arachis/fisiologia , Tetranychidae/fisiologia , Animais , Arachis/genética , Brasil , Feminino , Fertilidade , Larva/crescimento & desenvolvimento , Larva/fisiologia , Tábuas de Vida , Longevidade , Masculino , Ninfa/crescimento & desenvolvimento , Ninfa/fisiologia , Oviposição , Tetranychidae/crescimento & desenvolvimento
4.
Exp Appl Acarol ; 78(2): 273-293, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31168751

RESUMO

Tetranychus urticae (Acari: Tetranychidae) is an extremely serious cassava (Manihot esculenta) pest. Building a genomic resource to investigate the molecular mechanisms of cassava responses to T. urticae is vital for characterizing cassava resistance to mites. Based on the tolerance of cassava varieties to mite infestation (focusing on mite development rate, fecundity and physiology), cassava variety SC8 was selected to analyze transcriptomic and proteomic changes after 5 days of T. urticae feeding. Transcriptomic analysis revealed 698 and 2140 genes with significant expression changes under low and high mite infestation, respectively. More defense-related genes were found in the enrichment pathways at high mite density than at low density. In addition, iTRAQ-labeled proteomic analysis revealed 191 proteins with significant expression changes under low mite infestation. Differentially expressed genes and proteins were mainly found in the following defense-related pathways: flavonoid biosynthesis, phenylpropanoid biosynthesis, and glutathione metabolism under low-density mite feeding and plant hormone signal transduction and plant-pathogen interaction pathways under high-density mite feeding. The plant hormone signal transduction network, involving ethylene, jasmonic acid, and salicylic acid transduction pathways, was explored in relation to the M. esculenta response to T. urticae. Correlation analysis of the transcriptome and proteome generated a Pearson correlation coefficients of R = 0.2953 (P < 0.01), which might have been due to post-transcriptional or post-translational regulation resulting in many genes being inconsistently expressed at both the transcript and protein levels. In summary, the M. esculenta transcriptome and proteome changed in response to T. urticae, providing insight into the general activation of plant defense pathways in response to mite infestation.


Assuntos
Cadeia Alimentar , Manihot/fisiologia , Proteínas de Plantas/análise , Proteoma , Tetranychidae/fisiologia , Transcriptoma , Animais , Antibiose , Manihot/genética , Transdução de Sinais
5.
Exp Appl Acarol ; 77(4): 555-570, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31055676

RESUMO

The tomato red spider mite, Tetranychus evansi Baker & Pritchard, is one of the main pests of the tomato crop in several countries, mainly in Africa, where it can reduce tomato yield by up to 90%. The biotic potential of this mite is high and its control is difficult because of low efficiency of chemicals used and the rapid development of resistance to acaricides. We used the two-sex life table to evaluate the effect of two wild tomato genotypes (PI134417 and PI134418) and five tomato varieties widely grown in Benin (Kekefo, Akikon, TLCV15, Tounvi, and TOML4) on demographic characteristics of T. evansi under laboratory conditions. Tetranychus evansi did not develop on the genotypes PI134417 and PI134418, indicating their resistance to this mite. Developmental time of immature stages and female longevity were significantly higher on TLCV15 and Kekefo. Fecundity, net reproductive rate (R0), intrinsic rate of increase (r), and finite rate of increase (λ) of T. evansi on the African varieties were not statistically different among varieties. Generation time (T) was shorter on TOML4 than on TLCV15 and Tounvi. Thus, efforts should be made to prospect varieties with resistance characteristics or to develop other control means, to reduce the use of pesticides to control T. evansi in Africa.


Assuntos
Lycopersicon esculentum/genética , Tetranychidae/fisiologia , Animais , Benin , Feminino , Fertilidade , Cadeia Alimentar , Genótipo , Larva/crescimento & desenvolvimento , Larva/fisiologia , Tábuas de Vida , Masculino , Ninfa/crescimento & desenvolvimento , Ninfa/fisiologia , Óvulo/fisiologia , Reprodução , Tetranychidae/crescimento & desenvolvimento
6.
Exp Appl Acarol ; 77(4): 545-554, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30997606

RESUMO

The acaricide bifenazate acts as complex III inhibitor whereas cyenopyrafen and SYP-9625 act as complex II inhibitors. All these acaricides are commonly used to control two-spotted spider mite (TSSM), Tetranychus urticae Koch. We examined field-evolved and laboratory-selected resistance of TSSM to these three acaricides and determined cross-resistance among them. Six field populations of TSSM showed low levels of resistance to bifenazate with resistance ratios ranging from 2.20 to 10.65 compared to a susceptible strain. SYP-9625, structurally similar to cyenopyrafen, showed slightly higher activity to TSSMs but significant cross-resistance in both field populations and a laboratory-selected strain by SYP-9625. However, low levels of resistance to these two chemicals were found in field populations even when used for short time periods. Cross-resistance was not found between bifenazate and Complex II inhibitors, cyenopyrafen and SYP-9625, in both field populations and the laboratory-selected strain. Field-evolved resistance of TSSM to the tested acaricides is still low and should be delayed by the implementation of resistance management practices. Cross-resistance between cyenopyrafen and SYP-9625 is obvious, so they should not be used together in resistance management strategies based on mode of action rotation.


Assuntos
Acaricidas/farmacologia , Evolução Biológica , Resistência a Medicamentos , Tetranychidae/efeitos dos fármacos , Acrilonitrila/análogos & derivados , Acrilonitrila/farmacologia , Animais , Carbamatos/farmacologia , China , Hidrazinas/farmacologia , Pirazóis/farmacologia , Tetranychidae/fisiologia
7.
Exp Appl Acarol ; 77(3): 359-373, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30919170

RESUMO

Enhancing the performance of predatory mites is often regarded as the best biological control approach towards the spider mite Tetranychus urticae, the main pest of strawberry plantations. Optimizing the colonization of plantations by predators from adjacent areas such as field margins is seen as an important component of conservation biocontrol. We have investigated the factors contributing to enhancing the numbers of predatory mites (Acari: Phytoseidae), such as management of the field margins, vegetation composition and the effect of the presence of woody species. We also tested the penetration of the phytoseiids from the field margins into the crop. In a study carried out in 14 open-field extensively managed strawberry plantations in Poland we found phytoseiids to be abundant in field margins; 14 taxa were discovered. However, only two species Amblyseius andersoni and Euseius finlandicus dispersed a modest distance into the crop. We found that the diversity and densities of the predatory mites were enhanced somewhat by the management type of the field margins; especially the spontaneous vegetation favoured the presence of phytoseiids. However, despite the predatory mites being rather retained in the field margins also significant reduction in numbers of their prey T. urticae was recorded over the course of the year. The low penetration of predatory mites into the main part of the field, indicates that conservation biological control measures in the field margin might not be sufficient on their own to enhance the impact of predatory mites within the main part of the fields.


Assuntos
Proteção de Cultivos/métodos , Fragaria , Ácaros/fisiologia , Controle Biológico de Vetores/métodos , Comportamento Predatório , Animais , Fragaria/crescimento & desenvolvimento , Polônia , Tetranychidae/fisiologia , Controle de Ácaros e Carrapatos/métodos
8.
Pest Manag Sci ; 75(10): 2634-2641, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30706630

RESUMO

BACKGROUD: The red spider mite Tetranychus urticae is known as a worldwide pest in cassava production which can caused serious economic losses. Because no threshold levels are established for T. urticae in cassava cropping, many growers in China are applying excessive chemical applications per cassava cropping period. This is not only expensive, but also results in lower yields because of severe leaf damage and development of resistance. This study aims to develop an immediate threshold level for T. urticae control which could be determined in the laboratory and fit the field application requirements. RESULTS: The mite density of 25 mites/leaf was the threshold which caused significant decrease of photosynthetic pigment contents and protective enzyme activities in cassava leaves in the laboratory. Moreover, 25 mites/leaf was also the threshold density which resulted in significantly lower leaf damage and higher yield levels compared with a higher level of mites/leaf where calendar sprays were used. CONCLUSION: The mite density threshold that brought about significant physiological and biochemical changes in the laboratory basically coincided with the threshold that resulted in significant yield loss in the field. It is therefore concluded that the optimum threshold acaricide spray for T. urticae on cassava is 25 mites/leaf. © 2019 Society of Chemical Industry.


Assuntos
Acaricidas , Manihot , Tetranychidae , Controle de Ácaros e Carrapatos , Animais , China , Manihot/crescimento & desenvolvimento , Densidade Demográfica , Tetranychidae/fisiologia
9.
Plant Physiol ; 179(4): 1298-1314, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30765478

RESUMO

Plant immunity depends on fast and specific transcriptional reprogramming triggered by the perception of biotic stresses. Numerous studies have been conducted to better understand the response of plants to the generalist herbivore two-spotted spider mite (Tetranychus urticae). However, how plants perceive mites and how this perception is translated into changes in gene expression are largely unknown. In this work, we identified a gene induced in Arabidopsis (Arabidopsis thaliana) upon spider mite attack that encodes a two-domain protein containing predicted lectin and Toll/Interleukin-1 receptor domains. The gene, previously named PP2-A5, belongs to the Phloem Protein2 family. Biotic assays showed that PP2-A5 confers tolerance to T. urticae Overexpression or knockout of PP2-A5 leads to transcriptional reprogramming that alters the balance of hormone accumulation and corresponding signaling pathways. The nucleocytoplasmic location of this protein supports a direct interaction with regulators of gene transcription, suggesting that the combination of two putative signaling domains in a single protein may provide a novel mechanism for regulating gene expression. Together, our results suggest that PP2-A5 improves the ability to defend against T. urticae by participating in the tight regulation of hormonal cross talk upon mite feeding. Further research is needed to determine the mechanism by which this two-domain protein functions and to clarify its molecular role in signaling following a spider mite attack.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/imunologia , Peptídeos e Proteínas de Sinalização Intracelular/genética , Tetranychidae/fisiologia , Animais , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Feminino , Glucosinolatos/metabolismo , Herbivoria , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo
10.
Proc Natl Acad Sci U S A ; 116(12): 5588-5596, 2019 03 19.
Artigo em Inglês | MEDLINE | ID: mdl-30782803

RESUMO

The thermal limit of ectotherms provides an estimate of vulnerability to climate change. It differs between contrasting microhabitats, consistent with thermal ecology predictions that a species' temperature sensitivity matches the microclimate it experiences. However, observed thermal limits may differ between ectotherms from the same environment, challenging this theory. We resolved this apparent paradox by showing that ectotherm activity generates microclimatic deviations large enough to account for differences in thermal limits between species from the same microhabitat. We studied upper lethal temperature, effect of feeding mode on plant gas exchange, and temperature of attacked leaves in a community of six arthropod species feeding on apple leaves. Thermal limits differed by up to 8 °C among the species. Species that caused an increase in leaf transpiration (+182%), thus cooling the leaf, had a lower thermal limit than those that decreased leaf transpiration (-75%), causing the leaf to warm up. Therefore, cryptic microclimatic variations at the scale of a single leaf determine the thermal limit in this community of herbivores. We investigated the consequences of these changes in plant transpiration induced by plant-insect feedbacks for species vulnerability to thermal extremes. Warming tolerance was similar between species, at ±2 °C, providing little margin for resisting increasingly frequent and intense heat waves. The thermal safety margin (the difference between thermal limit and temperature) was greatly overestimated when air temperature or intact leaf temperature was erroneously used. We conclude that feedback processes define the vulnerability of species in the phyllosphere, and beyond, to thermal extremes.


Assuntos
Aclimatação/fisiologia , Folhas de Planta/fisiologia , Termotolerância/fisiologia , Animais , Afídeos/fisiologia , Artrópodes/fisiologia , Mudança Climática , Temperatura Alta , Microclima , Transpiração Vegetal , Temperatura , Tetranychidae/fisiologia
11.
Plant Physiol ; 179(4): 1822-1833, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30700538

RESUMO

Jasmonic acid (JA) plays an important role in the induction of herbivore resistance in many plants. However, JA-independent herbivore resistance has been suggested. An herbivore-resistance-inducing substance was isolated from Tobacco mosaic virus-infected tobacco (Nicotiana tabacum) leaves in which a hypersensitive response (HR) was induced and identified as loliolide, which has been identified as a ß-carotene metabolite. When applied to tomato (Solanum lycopersicum) leaves, loliolide decreased the survival rate of the two-spotted spider mite, Tetranychus urticae, egg deposition by the same pest, and the survival rate of larvae of the common cutworm Spodoptera litura without exhibiting toxicity against these herbivores. Endogenous loliolide levels increased not only with an infestation by S litura larvae, but also with the exogenous application of their oral secretions in tomato. A microarray analysis identified cell-wall-associated defense genes as loliolide-responsive tomato genes, and exogenous JA application did not induce the expression of these genes. Suppressor of zeaxanthin-less (szl), an Arabidopsis (Arabidopsis thaliana) mutant with a point mutation in a key gene of the ß-carotene metabolic pathway, exhibited the decreased accumulation of endogenous loliolide and increased susceptibility to infestation by the western flower thrip (Frankliniella occidentalis). A pretreatment with loliolide decreased susceptibility to thrips in the JA-insensitive Arabidopsis mutant coronatine-insensitive1 Exogenous loliolide did not restore reduced electrolyte leakage in szl in response to a HR-inducing bacterial strain. These results suggest that loliolide functions as an endogenous signal that mediates defense responses to herbivores, possibly independently of JA, at least in tomato and Arabidopsis plants.


Assuntos
Benzofuranos/metabolismo , Herbivoria , Tabaco/química , Animais , Arabidopsis/efeitos dos fármacos , Benzofuranos/química , Benzofuranos/isolamento & purificação , Carotenoides/metabolismo , Morte Celular , Lycopersicon esculentum/efeitos dos fármacos , Lycopersicon esculentum/parasitologia , Spodoptera/fisiologia , Tetranychidae/fisiologia , Tabaco/virologia , Vírus do Mosaico do Tabaco
12.
Exp Appl Acarol ; 77(1): 1-10, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30604195

RESUMO

The two-spotted spider mite (TSSM), Tetranychus urticae, is a chelicerate herbivore with a wide host range and strong ability to develop pesticide resistance. Experimental TSSM populations are easy to maintain, and the recent publication of the complete TSSM genome sequence and development of RNA interference-based reverse genetics protocols make this species an ideal chelicerate model for the study of pesticide resistance and plant-herbivore interactions. In such studies, treated leaf discs are often used for oral delivery of test compounds. When preparing these leaf discs, the organosilicone surfactant Silwet L-77 is used to promote wetting of the leaf surface and distribution of the test compound across the entire leaf surface. Here, we examined the toxicity of Silwet L-77 and found it to be toxic to TSSMs. We then developed a novel means of preparing leaf discs in which a polypropylene sheet rather than Silwet L-77 was used to ensure distribution of a tracer dye across the entire leaf surface. These leaf discs were then successfully used to deliver the tracer dye into the midgut of TSSMs. No significant differences were observed in the survival, fecundity, or feeding activity of TSSMs fed on leaf discs treated with water via our novel method compared with those fed on untreated leaf discs. Thus, our novel method of preparing leaf discs eliminates concerns regarding the bioactivity of surfactants in TSSMs, and we anticipate that it will be useful for improving oral delivery-based bioassays that use TSSMs.


Assuntos
Herbivoria , Compostos de Organossilício/química , Folhas de Planta/fisiologia , Tensoativos/química , Tetranychidae/fisiologia , Animais , Bioensaio , Feminino
13.
Colloids Surf B Biointerfaces ; 173: 632-638, 2019 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-30368210

RESUMO

Synergistic combination of pesticides and nanomaterials has been rarely reported in pest management science at present. In this work, graphene oxide (GO) was synergistically used with three types of pesticides (pyridaben (Pyr), chlorpyrifos (Chl) and beta-cyfluthrin (Cyf) respectively as acaricide against two economically important spider mites Tetranychus truncatus and T. urticae Koch. The results demonstrated that GO can enhance the activity of three types of pesticides. Compared with pesticides, the GO-Cyf, GO-Pyr and GO-Chl mixtures exhibited 1.77-, 1.56- and 1.55-fold higher contact toxicity against T. truncatus, and 1.50-, 1.75-, and 1.78-fold higher contact toxicity against T. urticae. SEM results showed that pesticide can adsorbed on the surface of GO. The synergistic mechanism may be that GO can serve as a carrier of pesticides, which can be adsorbed on the surface of mites and thus improve efficacy and utilization efficiency of pesticides. This kind of GO-based nanoscale pesticide delivery system may find widespread application in the field of plant protection in the future.


Assuntos
Acaricidas/toxicidade , Clorpirifos/toxicidade , Grafite/toxicidade , Nitrilos/toxicidade , Piretrinas/toxicidade , Piridazinas/toxicidade , Tetranychidae/efeitos dos fármacos , Acaricidas/química , Adsorção , Animais , Clorpirifos/química , Grafite/química , Longevidade/efeitos dos fármacos , Nanocompostos/química , Nanocompostos/toxicidade , Nitrilos/química , Óxidos , Piretrinas/química , Piridazinas/química , Tetranychidae/anatomia & histologia , Tetranychidae/fisiologia
14.
Insect Sci ; 26(1): 108-118, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-28636085

RESUMO

It is well known that herbivore-induced plant defenses alter host plant quality and can affect the behavior and performance of later arriving herbivores. Effects of sequential attacks by herbivores that either suppress or induce plant defenses are less well studied. We sequentially infested leaves of tomato plants with a strain of the phytophagous spider mite Tetranychus urticae that induces plant defenses and the closely related Tetranychus evansi, which suppresses plant defenses. Plant quality was quantified through oviposition of both spider mite species and by measuring proteinase inhibitor activity using plant material that had been sequentially attacked by both herbivore species. Spider-mite oviposition data show that T. evansi could suppress an earlier induction of plant defenses by T. urticae, and T. urticae could induce defenses in plants previously attacked by T. evansi in 1 day. Longer attacks by the second species did not result in further changes in oviposition. Proteinase inhibitor activity levels showed that T. evansi suppressed the high activity levels induced by T. urticae to constitutive levels in 1 day, and further suppressed activity to levels similar to those in plants attacked by T. evansi alone. Attacks by T. urticae induced proteinase inhibitor activity in plants previously attacked by T. evansi, eventually to similar levels as induced by T. urticae alone. Hence, plant quality and plant defenses were significantly affected by sequential attacks and the order of attack does not affect subsequent performance, but does affect proteinase inhibitor activity levels. Based on our results, we discuss the evolution of suppression of plant defenses.


Assuntos
Herbivoria , Lycopersicon esculentum/metabolismo , Inibidores de Proteases/metabolismo , Tetranychidae/fisiologia , Animais , Feminino , Oviposição
15.
Pest Manag Sci ; 75(1): 252-261, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29877064

RESUMO

BACKGROUND: Carboxylesterases (CarEs) are important in pesticide resistance. Four overexpressed CarE genes with inducible character were screened out in fenpropathrin-resistant Tetranychus cinnabarinus, but their functional roles remained to be further analyzed by RNAi and protein expression. RESULTS: Feeding a single double-stranded (ds)RNA of each of four genes led to gene-specific downregulation of mRNA, decreased esterase activity and diminished resistance in T. cinnabarinus. More interestingly, feeding four dsRNAs simultaneously led to a more significant decrease in enzymatic activity and fold resistance than feeding a single dsRNA individually, suggesting that these CarE genes were involved in fenpropathrin-resistance and had cooperative roles. The gene CarE6 was regarded as the primary and representative candidate to be functionally expressed, because silencing of CarE6 led to the most significant decrease in resistance level. The activity of CarE6 protein was competitively inhibited by fenpropathrin. It could effectively decompose 41.7 ± 0.09% of fenpropathrin within 3 h, proving that CarE6 protein was capable of metabolizing fenpropathrin effectively in T. cinnabarinus. CONCLUSION: The results confirm that four CarE genes are cooperatively involved in fenpropathrin resistance and the metabolic enzymes encoded by these overexpressed genes do indeed metabolize acaricide in resistant T. cinnabarinus in the evolution of acaricide resistance. © 2018 Society of Chemical Industry.


Assuntos
Acaricidas/farmacologia , Proteínas de Artrópodes/genética , Hidrolases de Éster Carboxílico/genética , Resistência a Medicamentos , Piretrinas/farmacologia , Tetranychidae/genética , Sequência de Aminoácidos , Animais , Proteínas de Artrópodes/química , Proteínas de Artrópodes/metabolismo , Hidrolases de Éster Carboxílico/química , Hidrolases de Éster Carboxílico/metabolismo , Expressão Gênica , Interferência de RNA , RNA de Cadeia Dupla/farmacologia , Tetranychidae/efeitos dos fármacos , Tetranychidae/fisiologia , Regulação para Cima
16.
Pest Manag Sci ; 75(7): 1962-1970, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30578583

RESUMO

BACKGROUND: Zoophytophagous predators can trigger plant defenses affecting prey populations beyond predation. Euseius stipulatus is a presumed zoophytophagous phytoseiid common in citrus. The response of citrus to one of its potential prey, Tetranychus urticae, is genotype dependent, with Citrus reshni and C. aurantium exhibiting extreme susceptibility and resistance, respectively. Volatile blends produced upon infestation affected the behavior of these two mites. We wondered whether E. stipulatus could trigger similar responses. RESULTS: Euseius stipulatus triggered genotype-dependent defense responses in citrus. Whereas C. aurantium upregulated the Jasmonic Acid, Salicylic Acid and flavonoids defensive pathways, C. reshni upregulated JA only. Likewise, different volatile blends were induced. These blends were exploited by E. stipulatus to select less-defended plants (i.e., those in which higher pest densities are expected) and, interestingly, did not prevent T. urticae from choosing E. stipulatus-infested plants. To the best of our knowledge, this is the first time that this type of response has been described for a zoophytophagous phytoseiid. CONCLUSION: The observed responses could affect herbivore populations through plant-mediated effects. Although further research is needed to fully characterize them and include other arthropods in the system, these results open opportunities for more sustainable and effective pest control methods (i.e., combining semiochemicals and biological control). © 2018 Society of Chemical Industry.


Assuntos
Citrus/genética , Citrus/metabolismo , Ácaros/fisiologia , Tetranychidae/fisiologia , Animais , Ciclopentanos/metabolismo , Comportamento Alimentar/psicologia , Flavonoides/metabolismo , Herbivoria/fisiologia , Oxilipinas/metabolismo , Comportamento Predatório/fisiologia , Ácido Salicílico/metabolismo
17.
Exp Appl Acarol ; 76(2): 161-183, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30293177

RESUMO

Mulching of soil beds of strawberry fields is usually done with polyethylene film in southern Minas Gerais state, Brazil. This material is relatively expensive and difficult to discard after use. In some countries, mulching is done with the use of organic material that could have an advantage over the use of plastic for its easier degradation after use, and for favoring edaphic beneficial organisms. Predatory mites (especially Gamasina, Mesostigmata) may be abundant in the soil and could conceivably move to the soil surface and onto the short-growing strawberry plants at night, helping in the control or pest arthropods. The two-spotted spider mite, Tetranychus urticae Koch, is considered an important strawberry pest in that region, where the fungus Neozygites floridana (Weiser and Muma) has been found to infect it. Different mulching types could affect the incidence of this pathogen. Dehydrated coffee husk and pulp (DCHP) is a byproduct readily available in southern Minas Gerais, where could be used as organic mulching in strawberry beds. The temporary contact of that material with the soil of a patch of natural vegetation could facilitate its colonization by edaphic predatory mites helpful in the control of strawberry pests. The objective of this work was to study the effect of mulching type on the population dynamics of the two-spotted spider mite, associate mites and N. floridana, in a greenhouse and in the field. The use of DCHP increased the number of edaphic Gamasina on strawberry plants-Proctolaelaps pygmaeus (Müller) (Melicharidae) and Blattisocius dentriticus (Berlese) (Blattisociidae) were observed on strawberry leaflets, mainly in nocturnal samplings, indicating their possible daily migration from soil to plants. Lower levels of two-spotted spider mite occurred on plants from pots or soil beds mulched with DCHP instead of polyethylene film, possibly because of the slightly higher levels of mites of the family Phytoseiidae and infection by N. floridana. Adding DCHP onto the floor of natural vegetation did not result in higher diversity or levels of gamasine mites on DCHP. Complementary studies should be conducted to find ways to increase diversity and density of those organisms in strawberry beds, in an attempt to improve biological control of strawberry pests. The decision to use DCHP for mulching should also take into account other factors such as strawberry yield, costs and efficiency of weed management, to be evaluated in subsequent studies.


Assuntos
Coffea/química , Produção Agrícola/métodos , Entomophthorales/fisiologia , Fragaria/crescimento & desenvolvimento , Ácaros/fisiologia , Controle Biológico de Vetores/métodos , Animais , Cadeia Alimentar , Dinâmica Populacional , Comportamento Predatório , Tetranychidae/fisiologia
18.
G3 (Bethesda) ; 8(12): 3865-3879, 2018 12 10.
Artigo em Inglês | MEDLINE | ID: mdl-30333191

RESUMO

The two-spotted spider mite Tetranychus urticae is an important pest with an exceptionally broad host plant range. This generalist rapidly acclimatizes and adapts to a new host, hereby overcoming nutritional challenges and a novel pallet of constitutive and induced plant defenses. Although recent studies reveal that a broad transcriptomic response upon host plant transfer is associated with a generalist life style in arthropod herbivores, it remains uncertain to what extent these transcriptional changes are general stress responses or host-specific. In the present study, we analyzed and compared the transcriptomic changes that occur in a single T. urticae population upon long-term transfer from Phaseolus vulgaris to a similar, but chemically defended, host (cyanogenic Phaseolus lunatus) and to multiple economically important crops (Glycine max, Gossypium hirsutum, Solanum lycopersicum and Zea mays). These long-term host plant transfers were associated with distinct transcriptomic responses with only a limited overlap in both specificity and directionality, suggestive of a fine-tuned transcriptional plasticity. Nonetheless, analysis at the gene family level uncovered overlapping functional processes, recruiting genes from both well-known and newly discovered detoxification families. Of note, our analyses highlighted a possible detoxification role for Tetranychus-specific short-chain dehydrogenases and single PLAT domain proteins, and manual genome annotation showed that both families are expanded in T. urticae Our results shed new light on the molecular mechanisms underlying the remarkable adaptive potential for host plant use of generalist arthropods and set the stage for functional validation of important players in T. urticae detoxification of plant secondary metabolites.


Assuntos
Proteínas de Artrópodes/biossíntese , Produtos Agrícolas/parasitologia , Regulação da Expressão Gênica/fisiologia , Interações Hospedeiro-Parasita/fisiologia , Tetranychidae/fisiologia , Transcriptoma/fisiologia , Animais
19.
Exp Appl Acarol ; 76(3): 339-354, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30341475

RESUMO

Panonychus citri (McGregor) (Trombidiformes: Tetranychidae) is one of the main defoliator mites in citrus groves. In Brazil, P. citri was formerly considered a secondary pest, but in recent years, the population levels of this mite have increased in many groves, requiring additional acaricide applications for its control. The population growth of P. citri is associated with the increase in the number of applications of pyrethroid and neonicotinoid insecticides to control insect citrus pests. This study assessed the effects of pyrethroid (deltamethrin, esfenvalerate, λ-cyhalothrin) and neonicotinoid (imidacloprid and thiamethoxam) insecticides on biological, behavioral and demographic parameters of P. citri. None of the insecticides tested affected larval hatching, but deltamethrin, esfenvalerate, and λ-cyhalothrin reduced the survival of larvae and protonymphs. Deltamethrin, esfenvalerate, and λ-cyhalothrin induced a significant increase in the fecundity of surviving females. Pyrethroids also caused repellency and changed feeding and oviposition preferences. In contrast, imidacloprid and thiamethoxam did not affect the survival of immature stages, but imidacloprid significantly increased fecundity. Imidacloprid and thiamethoxam did not cause any repellent effect or changes in the feeding and oviposition preferences. Based on the demographic parameters, deltamethrin, λ-cyhalothrin, and imidacloprid increased Ro, r, and λ, whereas esfenvalerate and thiamethoxam were similar to the control. Therefore, the use of these insecticides (especially deltamethrin, λ-cyhalothrin, and imidacloprid) requires caution, such as avoiding repeated use of these compounds during the periods of P. citri incidence in citrus groves.


Assuntos
Controle de Insetos , Inseticidas , Neonicotinoides , Piretrinas , Tetranychidae/efeitos dos fármacos , Animais , Brasil , Citrus/crescimento & desenvolvimento , Feminino , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Larva/fisiologia , Masculino , Ninfa/efeitos dos fármacos , Ninfa/crescimento & desenvolvimento , Ninfa/fisiologia , Tetranychidae/crescimento & desenvolvimento , Tetranychidae/fisiologia
20.
Microb Pathog ; 125: 385-392, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30290267

RESUMO

Entomopathogenic fungi (EPF) have primarily been applied as an inundative approach to manage pests. However, in recent decade multifunctional role of EPF have been documented which provide multiple benefits to host plants when colonized as an endophyte. In this study five fungal isolates from the genus Beauveria (three), Isaria (one) and Lecanicillium (one) were evaluated for their ability to colonize common bean, Phaseolus vulgaris and to assess their effects in planta on plant growth promotion and possible negative effects on the two-spotted spider mites, Tetranychus urticae. All the tested isolates in this study were able to endophytically colonize root, stem and even leaves of inoculated plants examined at 7 and 14 days post inoculation, indicating the systemic colonization of EPF. Colonized plants showed increased plant heights, fresh shoot and root weights compared to plants without inoculation. Survivorship of T. urticae significantly differed among the treatments with higher survival probability in control plants. Significant reduction in larval development, adult longevity and female fecundity of spider mites were observed when fed on treated plants compared to control plants. The negative effects were found to be carried over the second generation fed on fresh plants. Overall, our results show (i) the positive effects of fungal endophytes on plant growth, (ii) reduction in population growth rate and (iii) negative effects of endophytes on growth and reproduction of spider mites in successive generations. The study presents reports on the endophytic management of plant-feeding mites and highlights the possibility of utilizing entomopathogenic fungal endophytes in the integrated pest management program.


Assuntos
Endófitos/crescimento & desenvolvimento , Hypocreales/crescimento & desenvolvimento , Interações Microbianas , Phaseolus/crescimento & desenvolvimento , Doenças das Plantas/parasitologia , Tetranychidae/fisiologia , Animais , Fertilidade , Larva/fisiologia , Controle Biológico de Vetores/métodos , Phaseolus/microbiologia , Phaseolus/parasitologia , Desenvolvimento Vegetal , Doenças das Plantas/prevenção & controle , Folhas de Planta/microbiologia , Raízes de Plantas/microbiologia , Caules de Planta/microbiologia , Análise de Sobrevida
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