Trichomes of Lycopersicon spp. and their effect on Myzus persicae (Sulzer) (Hemiptera: Aphididae)

Abstract The green peach aphid ( Myzus persicae ) is becoming resistant to many of the pesticides used in the tomato ( Lycopersicon esculentum ) industry. A potential alternative method of control is host-plant resistance, which may be mediated by trichomes. Resistance to the green peach aphid was assessed for six accessions of L. hirsutum, three of L. pennellii and a L. esculentum control. Mortality, entrapment and number of aphids unaffected by trichomes were recorded 24, 48 and 72 h after placement. Using multiple regression against counts of glandular and non-glandular trichomes, the role of foliar pubescence in resistance to the aphid was established. Lycopersicon pennellii possessed the highest level of resistance after 72 h and type IV trichome density accounted for 26.5% of variance in mortality ( P  < 0.001). Low densities of type IV and high densities of type VII trichomes increased the number of aphids 'unaffected' by trichomes, a relationship accounting for 29% of variance ( P  < 0.001). Information on which types of trichomes most strongly affect resistance to insect pests will aid future breeding and L. pennellii shows potential for use in breeding programs to increase levels of host-plant resistance in L. esculentum.     

Efficacy of pymetrozine against Myzus persicae and in reducing potato virus Y transmission on tobacco plants

Forty‐four parthenogenetic lineages of Myzus persicae s.l. (Sulzer) from tobacco crops and peach orchards located in various regions of Greece were examined to determine their response to the insecticide pymetrozine using leaf‐dip bio‐assays. The results show that the aphid has not developed resistance, as all lineages exhibited resistance factors bellow 6.0. In transmission experiments of potato virus Y (PVY) using a lineage of the tobacco‐adapted subspecies M. persicae nicotianae Blackman on tobacco plants, one foliar application with pymetrozine provided adequate protection for 7 days. Pymetrozine significantly reduced both virus acquisition and inoculation compared with the untreated control and the reduction was comparable to a mineral oil application. These results are discussed in terms of the advantage of incorporating pymetrozine as a compound of pest management strategies against M. persicae s.l. and for control of non‐persistent viruses, especially in crops such as tobacco because of the high selection pressure from neonicotinoids resulting in potential of resistance developing in aphid populations.     

Effects of aluminum mulch on fecundity of apterous Myzus persicae on head lettuce in a field planting

Head lettuce field plantings were artificially infested with apterous adults of the green peach aphid, Myzus persicae (Sulzer). Significantly greater aphid fecundity was demonstrated on plants grown through aluminum-coated construction paper than on plants grown on bare soil. Higher temperatures and host-plant physiology were factors modified by the mulch, and could have resulted in larger aphid populations on plants grown over a reflective surface as the season progressed. Faster plant growth and a significantly larger yield per head of lettuce also resulted from the use of the aluminum mulch. The incidence of a leafhopper-borne plant disease, aster yellows, was significantly reduced on head lettuce in the aluminum mulch plots.

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Résumé Des cultures de laitue ont été artificiellement contaminées avec des adultes aptères de Myzus persicae. La fécondité a été significativement augmentée sur les plantes poussant sur un sol recouvert par un voile d'aluminium, comparées à celles poussant sur un sol nu. Cette augmentation pourrait entrainer des populations de pucerons de plus en plus importantes, au fur et à mesure de l'avancement de la saison, sur les plantes poussant au dessus d'une surface fortement réfléchissante. L'utilisation du voile d'aluminium a provoqué simultanément une accélération de la croissance et une augmentation des rendements de laitue. Ces résultats semblent dus à une augmentation de la température diurne, à une meilleure conservation de l'humidité et à une plus forte réflexion de la lumière lorsqu'il y a présence de voile d'aluminium. Par aulleurs, les dégâts provoqués sur feuilles par les germes pathogénes transmis par les Cicadelles delles sont significativement plus rares sur sol couvert de voile d'aluminium.

     

Relative consumption of three aphid species by the lacewing, Chrysoperla rufilabris, and effects on its development and survival

Relative consumption of three aphid species, Aphis gossypii Glover, Myzus persicae (Sulzer) and Lipaphis erysimi (Kaltenbach) (Homoptera: Aphididae), by larvae of the lacewing, Chrysoperla rufilabris (Burmeister) (Neuroptera: Chrysopidae), was determined in the laboratory, together with effects on lacewing development and survival. Percentages of survival of C. rufilabris from first instar to adult eclosion were significantly different among lacewing larvae fed different aphid species. When larvae were fed A. gossypii and M. persicae, all larvae developed to adulthood. All larvae died prematurely when they were fed L. erysimi. Developmental duration of C. rufilabris larvae was significantly shorter when larvae were fed A. gossypii (18.0 d) than when larvae were fed M. persicae (19.2 d). The number of fourth instar aphids consumed during development by C. rufilabris larvae differed significantly among individuals fed different aphid species. Chrysoperla rufilabris consumed an average of 168 M. persicae, followed by 141.6 A. gossypii, and only 26.6 L. erysimi. The percentage of these total number of aphids consumed by each larval stadium of C. rufilabris varied significantly among aphid species. The percentage of A. gossypii consumed by each larval stadium was similar to that for M. persicae, 12.1 and 11.4% by the first instar, 15.7 and 13.1% by the second instar, and 72.2 and 75.5% by the third instar, respectively; whereas in the case of L. erysimi, 23.3% of the total number of aphids were consumed by the first instar, 30.1% by the second instar, and 46.6% by the third instar.     

Variability of Lycopersicon hirsutum f. typicum and possible compounds involved in its resistance to Tuta absoluta

1 The resistance of Lycopersicon hirsutum f. typicum and L. esculentum to the leafminer Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) was investigated in two experiments. The first experiment assessed the resistance of L. hirsutum f. typicum (accession LA 1777) to T. absoluta, the second assessed the variability of the resistance among plants of this accession. 2 It was found that L. hirsutum f. typicum was resistant to the leafminer, which showed longer larval phase, higher larval mortality, smaller numbers of large mines and greater numbers of small mines/leaf than on L. esculentum. Seven plants of the accession LA 1777 showed lower number of small mines/leaf, but their results of larval mortality and length of larval and pupal phase were similar. Twenty-two peaks were observed in total ion chromatograms of L. hirsutum f. typicum hexane extracts of leaves subjected to a gas chromatographic-mass spectrometric analysis (CG-MS). However, the matches obtained between the peak spectra and the MS database were too low to justify even preliminary identification of the compounds.     

春季烟蚜有翅蚜空间分布及迁入量估计的初步研究

本文通过对春季烟田烟蚜有翅蚜的抽样调查,研究有翅蚜的空间分布并进行迁人量估计。采用频次分布方法进行有翅蚜空间分布型测定,拟合结果既符合泊松分布又符合负二项分布;通过计算有翅蚜在不同叶位上的概率分布,结果表明,有翅蚓适入后大部分集中于烟株上部;通过定期调查烟株有翅蚜数量,并采用定积分中的抛物线法近似计算有翅蚜迁入总量,结果表明,有翅蚜迁入量约为４７９头／百株。     

Effect of eggplant transformed with oryzacystatin gene on Myzus persicae and Macrosiphum euphorbiae

Abstract:  The effect of a genetically modified eggplant line expressing oryzacystatin on Myzus persicae (Sulzer) and Macrosiphum euphorbiae (Thomas) was examined. The transgenic eggplant reduced the net reproductive rate ( R ₀), the instantaneous rate of population increase ( r ), and the finite rate of population increase ( λ ) of both aphids species compared with a control eggplant line. The mean generation time ( T ) of the aphids was unaffected by the transgenic plants. Age-specific mortality rates of M. persicae and M. euphorbiae were higher on transgenic plants. These results indicate that expression of oryzacystatin in eggplant has a negative impact on population growth and mortality rates of M. persicae and M. euphorbiae and could be a source of plant resistance for pest management of these aphids.     

Response of insecticide-resistant and susceptible Colorado potato beetles, Leptinotarsa decemlineata to 2-tridecanone and resistant tomato foliage: the absence of cross resistance

Insecticide-resistant Colorado potato beetles (CPB), Leptinotarsa decemlineata, from Long Island, New York and susceptible beetles from North Carolina were tested for response to 2-tridecanone and foliage of the CPB resistant wild tomato, Lycopersicon hirsutum f. glabratum C. H. Mull, PI 134417. Populations did not differ in their response to 2-tridecanone or PI 134417 foliage. Exposure of beetles to sublethal doses of 2-tridecanone did not increase tolerance of either population to subsequent exposures to 2-tridecanone. It was also found that the New York beetles suffered higher mortality than North Carolina beetles on CPB susceptible L. esculentum foliage and PI 134417 foliage from which the glandular trichomes, which contain 2-tridecanone, were removed. Survival of North Carolina beetles was lower on PI 134417 foliage without trichomes than on L. esculentum foliage.

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Résumé La lutte contre Leptinotarsa decemlineata, sur la tomate et des autres récoltes, compte ordinairement sur les insecticides. Cette confiance a causé plusieurs populations de cette espèce à développer une résistance aux insecticides. Accession PI 134417 de la tomate sauvage, Lycopersicon hirsutum f. glabratum C. H. Mull, est résistant à L. decemlineata, en grande partie à cause de la presence de 2-tridécanone dans les éxtremités des poils glandulaires du feuillage. Notre étude entreprendait à rechercher la possibilité d'une résistance croisée aux insecticides et au 2-tridécanone.Les coléoptères de Long Island, New York, ceux qui sont résistants aux insecticides et ceux susceptibles de North Carolina, éprouvaient pour une réponse au 2-tridécanone et au feuillage résistant.Les deux populations de coléoptères ne diffèrent pas dans sa réponse au 2-tridécanone ou au feuillage résistant. Nous ne trouvons pas d'évidence d'une résistance croisée.Aussi, nous trouvons que les coléoptères de New York ne survivaient pas aussi bien que ceux de North Carolina au feuillage résistant sans les éxtremités des poils glandulaires et au feuillage susceptible. La survivance était plus basse sur le feuillage résistant sans les éxtremités des poils glandulaires que le feuillage susceptible seulement avec les coléoptères de North Carolina.

     

The effect of plant age and infection with virus yellows on the survival of Myzus persicae on sugar beet

Survival of Myzus persicae confined in clip-cages on mature leaves of sugar beet declined as the plants aged. Death of aphids was often preceded by the appearance of a black deposit in the aphids' stomachs, which may have been the cause of death. Both the rate of death and the proportion of aphids dying with black deposits was significantly less when plants were infected with beet yellows virus or beet mild yellowing virus, by comparison with healthy plants. The implication of these phenomena on the onset of mature plant resistance is discussed.     

Role of canopy height in the resistance of Lycopersicon hirsutum f. glabratum to Tuta absoluta (Lep., Gelechiidae)

The objective of this work was to study the effect of plant canopy height on the resistance of the tomato species Lycopersicon hirsutum to the tomato leafminer Tuta absoluta . Determination of the levels of tridecan-2-one (2-TD) and undecan-2-one (2-UD) in L. hirsutum , as well as the leaf area, density and types of trichomes present in L. hirsutum and L. esculentum were made on apical, medium and basal parts of plant canopy. Correlation of these data were made with the following biological characteristics of T. absoluta : rates of oviposition and egg hatching; length of egg, larval and pupal stages; mortality of the larval and pupal stages; pupal weight; and sex ratio. Levels of 2-TD on leaves of L. hirsutum increased from bottom to top of canopy. Tuta absoluta had higher oviposition and egg hatching, as well as lower mortalities and smaller larval and pupal periods in L. esculentum than in L. hirsutum . Longer pupal period and greater number of small and large mines of T. absoluta were verified in the apical and medium parts of L. hirsutum plants. On the other hand, higher pupal mortality and longer larval periods were obtained in the apical and basal parts of the L. hirsutum plants. Larval mortality was higher in the basal part of those plants. In L. esculentum , leaves from the apical part of the plant promoted lower mortality, longer larval period and greater number of large mines of T. absoluta . However, a shorter pupal period was verified on leaves of the basal part. It appears that an increase in glandular trichome density in L. hirsutum leads to an increase in the levels of 2-TD, which, in turn slows down larval development.     

An amino acid substitution on the second acetylcholinesterase in the pirimicarb-resistant strains of the peach potato aphid,Myzus persicae

cDNAs encoding two acetylcholinesterases (AChEs) were isolated from the peach potato aphid, Myzus persicae. MpAChE1 was orthologous and MpAChE2 was paralogous with the ace of Drosophila melanogaster. The deduced amino acid sequence of MpAChE1 cDNA was identical between the pirimicarb susceptible and resistant strains. However, a single amino acid substitution of Ser431Phe on MpAchE2 was found in the pirimicarb resistant strains. This substitution was located in the acyl pocket of the enzyme and was thought to alter the ligand specificity.     

Egg production by the coccinellid Hippodamia convergens fed on two morphs of the green peach aphid, Myzus persicae

Adults of the lady beetle Hippodamia convergens Guérin-Méneville requiring aphids for egg production, were fed suboptimal amounts of apteriform virginoparous larvae or alatiform gynoparous larvae of the green peach aphid, Myzus persicae (Sulz.), and artificial diet ad lib. The beetles initiated oviposition sooner and deposited significantly more eggs when supplied with the same weight of apterous virginoparous morph. The possible nutritional, hormonal, and ecological implications of the findings are discussed.

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Zusammenfassung Die Eiproduktion des Marienkäfers Hippodamia convergens, welcher hierzu Blattläuse als Nahrung benötigt, wurde bei Fütterung mit zwei verschiedenen Morphen der Blattlaus Myzus persicae untersucht. Der Verzehr derselben Menge flügelloser Virginoparen führte im Vergleich zu geflügelten Gynoparen zu früherer und signifikant erhöhter Eiabgabe. Der hormonale und ernährungsphysiologische Hintergrund und die ökologische Bedeutung dieser Ergebnisse werden diskutiert.

     

Toxicity of methyl ketones from tomato trichomes to Tetranychus urticae Koch

The two methyl ketones, 2-tridecanone and 2-undecanone, are constituents of type VI glandular trichomes of the wild tomato, Lycopersicon hirsutum f. glabratum (PI 134417). They are known to cause mortality in several herbivorous insect species. In this study we investigated the effects of these chemicals on two strains of the two-spotted spider mite, Tetranychus urticae Koch, collected from tomato and cucumber crops in Dutch greenhouses. The two ketones were tested separately, in combination in the ratio found in L. hirsutum f. glabratum and in several other ratios to detect any synergistic interaction between them. We measured both the direct contact and residual toxicity, as well as the viability of the eggs produced by ketone-treated females. The methyl ketones can be considered as quite toxic to spider mites because their LC50 values were comparable to that found for the formulated acaricide amitraz. 2-Tridecanone was slightly more toxic than 2-undecanone but only in the tomato strain. Synergistic effects were not detected. In the bio assays for the residual effects of the two methyl ketones no significant mortality occurred but the mites avoided feeding on the treated surface and the eggs were laid almost exclusively on the untreated area. Furthermore, there was no significant egg viability for most of the treatments and when some egg viability occurred, it was not correlated to the dose of the chemical. Based on published data on the levels of methyl ketones in the trichome tips of wild and cultivated tomato (L. hirsutum f. glabratum and Lycopersicon esculentum Mill, respectively) it was calculated how many contacts are required to reach the LD50 (ng a.i. per mite). It appeared that on wild tomato just a few contacts suffice, but many are needed on cultivated tomato. Nevertheless, it seems justified to conclude that even in cultivated tomato, 2-tridecanone represents a naturally occurring acaricide. The cucumber and tomato strains of the two-spotted spider mite did not differ in their response to the methyl ketones. Because this is surprising, given the selection pressures on their respective host plants, we formulated two hypotheses, one explaining the absence of a difference due to cross-resistance and another one proposing that bioaccumulation obscures the underlying differences between the strains. This revised version was published online in November 2006 with corrections to the Cover Date.     

The green peach aphid,Myzus persicae,acquires a LIPOXYGENASE5-derived oxylipin from Arabidopsis thaliana,which promotes colonization of the host plant

Oxylipins derived from lipoxygenase (LOX) activity play important roles in plant growth, development and stress response. In a recent study, we provided evidence that infestation of Arabidopsis thaliana foliage by the green peach aphid (GPA; Myzus persicae), a phloem sap-consuming insect, was promoted by plant LOX5-derived oxylipins. In comparison to the wild-type (WT) plant, GPA population was smaller on the Arabidopsis lox5 mutant. The insect spent less time feeding from the sieve element and xylem of the lox5 mutant compared with the WT plant. In addition, compared with insects feeding on the WT plant, when on the lox5 mutant, the GPA was unable to suppress an antibiotic activity that is present in Arabidopsis vascular sap. Roots are the critical source of a LOX5-derived oxylipin(s) that promotes colonization of the foliage by GPA. Here we show that the 9-hydoxy-10E, 12Z-octadecadienoic acid (9-HOD), a LOX5-derived oxylipin, accumulated in GPA that were reared on the WT, but not the lox5 mutant plant. However, 9-HOD accumulated in insects reared on lox5 mutant plants that were irrigated with 9-HOD, thus indicating that the insect ingests oxylipins from the host plant. We further demonstrate that the host plant requires LOX5 function to promote expression of the defense regulatory gene PHYTOALEXIN-DEFICIENT4 in the foliage. Taken together, our previous observations and results presented here indicate that while the host plant utilizes LOX5-dependent factors for promoting defense mechanisms, GPA has evolved to utilize plant 9-LOX-derived oxylipins as cues to facilitate infestation, thus suggesting a complex involvement of oxylipins in Arabidopsis interaction with GPA.     

Parasitism rate of Myzus persicae (Sulzer) by Diaeretiella rapae (McIntosh) in the presence of an alternative,resistant host

The aphids Lipaphis pseudobrassicae (Davis) and Myzus persicae (Sulzer) (Hemiptera: Aphididae) are important Brassicaceae pests, occurring worldwide and causing significant damage to crops. Interspecific variations in the resistance to natural enemies can potentially impact the interaction among aphid populations. Here we evaluated the hypothesis of associational resistance by determining if the presence of resistant aphids (L. pseudobrassicae) reduces the rate of parasitism by Diaeretiella rapae (McIntosh) on non-resistant aphids (M. persicae). The experiment was conducted using collard green plants infested with M. persicae and L. pseudobrassicae either resistant or susceptible to D. rapae. The percentage of parasitism by D. rapae was greater on L. pseudobrassicae in the susceptible than in the resistant treatment, but parasitism rates on M. persicae did not differ between the treatments. There was no difference in average growth rate between M. persicae and susceptible L. pseudobrassicae populations, but resistant L. pseudobrassicae had greater growth rate than M. persicae. These results suggest that over a short period of time the presence of resistant L. pseudobrassicae does not affect the rate of parasitism by D. rapae on M. persicae.     

2-Undecanone, a constituent of the glandular trichomes of Lycopersicon hirsutum f. glabratum: Effects on Heliothis zea and Manduca sexta growth and survival

The effects of 2-undecanone, a compound found in the glandular trichomes of the wild tomato, Lycopersicon hirsutum f. glabratum C. H. Mull, PI 134417, on the larvae of Heliothis zea (Boddie) and Manduca sexta (L.) were studied by rearing the larvae on artificial diets containing this chemical. 2-Undecanone increased larval mortality of H. zea in the first 48 h when combined with 2-tridecanone, but not alone, and caused deformity and mortality of H. zea pupae both alone and in combination with 2-tridecanone. 2-Undecanone had no effect on M. sexta larvae or pupae. Potential implications of these findings for insect pest management are discussed.

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Résumé Le 2-undécanone est une methyle cétone qui se trouve avec le 2-tridécanone dans les extrémités des poils glandulaires des feuilles de la tomate sauvage: Lycopersicon hirsutum f. glabratum C. H. Mull, PI 134417. Notre étude entreprendait à rechercher le rôle du 2-undécanone dans la resistance de cette plante à Heliothis zea et Manduca sexta.Les produits chimiques synthétiques s'étaient incorporés en diète artificièlle sur laquelle les insectes ont élevés. Le 2-undécanone a causé peu de mortalité des larves de H. zea sauf quand il soit combiné avec le 2-tridécanone, dans quel cas on trouve, dans les premiers 48 heures, une augmentation de mortalité, en comparaison au 2-tridécanone seul. Aussi le 2-undécanone a causé les difformités des nymphes de H. zea et la mortalité dans l'étage de nymphe, toutes les deux seul et en combinaison avec le 2-tridécanone. En contrast, le 2-undécanone n'a pas produit un effet sur les larves ou nymphes de M. sexta.L'élevage sélective des lignes de tomates de niveau plus élevé de 2-undécanone pourrait utile pour la lutte contre le H. zea. En combinaison avec des niveaux élevés du 2-tridécanone, c'est possible de reduire les populations nuisibles des larves. Il peut aussi réduire le nombre des lépidoptères adultes produit dans la récolte de tomate. Toutefois, il ne serait pas probablement de valeur dans la lutte contre le M. sexta.

     

Effect of floral and extrafloral resources on predation of Aphis spiraecola by Harmonia axyridis on Apple

Flowering companion plants and plants producing extrafloral nectar are being proposed to enhance biological control in apple (Malus domestica Borkh.) orchards. This experiment evaluated the impact of floral and extrafloral resources on predation of spirea aphid (Aphis spiraecola Patch) on apple by adult Harmonia axyridis (Pallas) under greenhouse conditions. Predation of spirea aphids was not affected by the presence of flowering buckwheat (Fagopyrum esculentum) as compared with either buckwheat with flowers removed or an uninfested apple shoot. However, there was a significant reduction in predation of spirea aphids on an apple shoot in the presence of a peach shoot with extrafloral nectar glands compared with either a peach shoot of the same cultivar without nectar glands or an uninfested apple shoot. These findings demonstrate that alternative food resources potentially could interfere with rates of biological control and, therefore, need to be carefully evaluated before incorporating in an orchard design. More studies are needed to adequately gauge the net effects of adding floral or extrafloral resources in orchards for conservation biological control.     

施钾马铃薯叶片对桃蚜的诱导抗性反应

本文研究了施钾条件下马铃薯两品种克新和费乌瑞它对桃蚜Myzus persicae Sulzer的抗性反应。结果表明,与对照相比,虫害、施钾与施钾+虫害处理均使两马铃薯品种中茉莉酸含量、脂氧合酶活性、蛋白酶抑制剂活性有所提高。其中虫害处理后克新中茉莉酸含量为对照的2.2倍,PI活性、脂氧合酶活性分别比对照增加了27.7%和37.3%;虫害费乌瑞它中上述生理指标的变化与克新一致,茉莉酸含量为对照的1.7倍,PI活性、脂氧合酶活性分别比对照增加了22.4%和29.1%。此外,施钾处理显著降低了克新和费乌瑞它2个品种的为害蚜量。表明施钾提高了马铃薯的诱导抗性,且克新的抗虫能力高于费乌瑞它。     

Co-localisation of host plant resistance QTLs affecting the performance and feeding behaviour of the aphid Myzus persicae in the peach tree

The architecture and action of quantitative trait loci (QTL) contributing to plant resistance mechanisms against aphids, the largest group of phloem-feeding insects, are not well understood. Comparative mapping of several components of resistance to the green peach aphid (Myzus persicae) was undertaken in Prunus davidiana, a wild species related to peach. An interspecific F(1) population of Prunus persica var. Summergrand × P. davidiana clone P1908 was scored for resistance (aphid colony development and foliar damage) and 17 aphid feeding behaviour traits monitored by means of the electrical penetration graph technique. Seven resistance QTLs were detected, individually explaining 6.1-43.1% of the phenotypic variation. Consistency was shown over several trials. Nine QTLs affecting aphid feeding behaviour were identified. All resistance QTLs except one co-located with QTLs underlying aphid feeding behaviour. A P. davidiana resistance allele at the major QTL was associated with drastic reductions in phloem sap ingestion by aphids, suggesting a phloem-based resistance mechanism. Resistance was also positively correlated with aphid salivation into sieve elements, suggesting an insect response to restore the appropriate conditions for ingestion after phloem occlusion. No significant QTL was found for traits characterising aphid mouthpart activity in plant tissues other than phloem vessels. Two QTLs with effects on aphid feeding behaviour but without effect on resistance were identified. SSR markers linked to the main QTLs involved in resistance are of potential use in marker-assisted selection for aphid resistance. Linking our results with the recent sequencing of the peach genome may help clarify the physiological resistance mechanisms.