Abstract
ABSTRACT This study was performed to evaluate the effect of exogenous application of salicylic acid as a resistance inducer to two-spotted spider mite and tomato pinworm on tomato genotypes. Bioassays were carried out in three commercial genotypes (‘Redenção’, ‘Giuliana’, and ‘Alambra’) and one wild genotype (Solanum habrochaites var. hirsutum, accession PI-127826). Average distance travelled by the two-spotted spider mite and number of eggs deposited over the leaflets of the genotypes were investigated. Concerning pinworm bioassay, number of eggs, leafminers on leaflet surface and percentage of leaf area consumed by leafminers were evaluated using a scanner. Furthermore, severity of attack to plants was evaluated by score scale for damages, types of lesions and attacked leaflets. Salicylic acid application induced resistance in the commercial genotypes against both pests, reducing the two-spotted spider mite and pinworm oviposition. The spider mites travelled shorter distance on leaflets of genotypes treated with salicylic acid at intermediate concentrations, indicating a positive effect of substance as inducing resistance. Attack severity by pinworm was also reduced when intermediate doses of salicylic acid were applied. Also, higher resistance was observed on accession PI-127826 as compared to other genotypes. The obtained results indicate that the resistance of PI-127826 was due to constitutive defense, whereas on commercial genotypes defense was dependent on responses mediated by salicylic acid. Hence, salicylic acid treatment, as resistance inducer, seems to be efficient against two-spotted spider mite and pinworm, being a promising tool within an integrated pest management on tomato plants.
Highlights
Ácido salicílico induz resistência à Tuta absoluta e Tetranychus urticae em tomateiro Objetivou-se avaliar os efeitos da aplicação exógena de ácido salicílico como indutor de resistência ao ácaro-rajado e à traça em genótipos de tomateiro
Pinworm (Tuta absoluta), a chewing herbivore that causes large damages due to galleries created on the leaf mesophyll by its leafminers on the leaf mesophyll, which affects petioles, stems, and fruits, causing high production losses (Dias et al, 2019)
Another arthropod pest that causes large losses in tomato plants is the two-spotted spider mite [Tetranychus urticae, (Acari: Tetranychidae)], a generalist sucking pest that feeds by punching leaf mesophyll cells with its stylets (Zanin et al, 2018)
Summary
Ácido salicílico induz resistência à Tuta absoluta e Tetranychus urticae em tomateiro Objetivou-se avaliar os efeitos da aplicação exógena de ácido salicílico como indutor de resistência ao ácaro-rajado e à traça em genótipos de tomateiro. A aplicação de ácido salicílico induziu resistência nos genótipos comerciais para ambas as pragas, diminuindo a oviposição do ácaro e da traça do tomateiro. Os ácaros percorreram menor distância nos folíolos dos genótipos que receberam tratamento com ácido salicílico nas concentrações intermediarias, indicando efeito benéfico da substância na indução de resistência. Control of arthropod-pests on crop plants is performed mainly with agrochemical applications, which have resulted in problems such as high production costs, the development of genetic resistance and residual damages to the environment (Ilias et al, 2017) In this sense, the elucidation of defense mechanisms of tomato plants can be a way to assist the pest control and, to reduce the use of pesticide applications. The salicylates (SA), jasmonates (JA) and ethylene (Et) are known to modulate plant defense responses (Brodersen et al, 2006; Aljbory & Chen, 2017)
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