Application of Foliar Synthetic Elicitors for the Management of Diaphorina citri (Hemiptera: Liviidae) Populations in Tahiti Lime (Citrus latifolia Tanaka)

Abstract

<jats:p>The Asian citrus psyllid (ACP), <jats:italic>Diaphorina citri</jats:italic> Kuwayama, is the most serious threat to the global citrus industry, and its management has depended mainly on the application of chemical insecticides. The application of plant elicitors can contribute to the insect management and also enhance plant physiology. A set of three different experiments was carried out to evaluate the efficacy of foliar applications of synthetic elicitors [salicylic acid (SA), brassinosteroids (Br), chitosan, or thiamine] on the population dynamics of <jats:italic>D. citri</jats:italic> and their effects on the physiology of Tahiti lime trees. The treatments were as follows: trees were sprayed separately with thiamine, SA, or chitosan at a dose of 100 ppm, respectively; trees were treated with foliar brassinosteroid applications at a dose of 1 ppm; and untreated trees (control). By the end of the experiment, the elicitors reduced (75%) the number of adult psyllids compared with the control, where trees treated with chitosan had ≈0.5 adult individuals accumulated per flush shoot, whereas the control showed around two individuals. Salicylic acid and thiamine also reduced the number of nymphs compared with the control in the 4 weeks after treatment (WAT) (5.5 vs. 10.08 nymphs, respectively). Treatment with synthetic elicitors also caused a 30% reduction in oviposition by <jats:italic>D. citri</jats:italic>. The foliar applications with Br promoted a greater relative growth rate (RGR) (44 mm·cm<jats:sup>−1</jats:sup>·d<jats:sup>−1</jats:sup>) compared with the control treatment and chitosan (24 and 26 mm·cm<jats:sup>−1</jats:sup>·d<jats:sup>−1</jats:sup>, respectively). Chitosan sprays favored proline synthesis in both flush shoots and leaves. These results suggest that the use of synthetic elicitors can be considered as a tool to reduce the number of applications of chemical insecticides and decrease the development of resistances by <jats:italic>D. citri</jats:italic> because these synthetic elicitors showed an efficacy between 40% and 60% in all its stages in field conditions.</jats:p>

Candidatus Liberibacter asiaticus: virulence traits and control strategies

“…The use of particle film barriers Particle films reduce insect damage by covering organs, such as leaves. Foliar spray of kaolin clay-and calcium carbonate-based particle films significantly reduced the population levels of psyllid adults, nymphs, and eggs on citrus trees compared to the untreated control in field trials in Colombia (Ramírez-Godoy et al 2018). In this study, foliar applications of kaolin clay showed similar effectiveness as the imidacloprid insecticide in reducing populations of psyllid eggs (Ramírez-Godoy et al 2018).…”

“…Foliar spray of kaolin clay-and calcium carbonate-based particle films significantly reduced the population levels of psyllid adults, nymphs, and eggs on citrus trees compared to the untreated control in field trials in Colombia (Ramírez-Godoy et al 2018). In this study, foliar applications of kaolin clay showed similar effectiveness as the imidacloprid insecticide in reducing populations of psyllid eggs (Ramírez-Godoy et al 2018). Studies performed under laboratory and field conditions revealed that processed kaolin interferes negatively with different aspects of the ACP's ability to find the host plant, resulting in a reduced adult population on treated citrus plants (Miranda et al 2018).…”

“…Moreover, trunk injection of salicylic acid, oxalic acid, acibenzolar-S-methyl, and potassium phosphate provided significant control of HLB by suppressing CLas titer and disease progression, with significantly induced expression of plant defense genes (e.g., PR-1 and PR-2) in the field (Hu et al 2018). Interestingly, foliar application of the synthetic elicitors, salicylic acid (SA), brassinosteroids, chitosan, or thiamine reduced the number of adult psyllids on Tahiti lime trees by 75% compared with the control in the field (Ramírez-Godoy et al 2018). These results suggest that synthetic elicitors could be considered an alternative tool for ACP control while reducing the use of chemical insecticides.…”

Mitigation of the Impact of Vascular Wilt and Soil Hypoxia on Cape Gooseberry Plants by Foliar Application of Synthetic Elicitors

“…The use of synthetic elicitors can be considered an effective tool to mitigate the negative effects generated by abiotic and biotic stresses in plants (Llorens et al, 2017;Naik and Al-Khayri, 2016). Elicitors are chemical compounds that can be sprayed on leaves, causing a stimulus on plant defense mechanisms and secondary metabolite synthesis under abiotic and biotic stress conditions (Llorens et al, 2017;Ramírez-Godoy et al, 2018;Thakur and Sohal, 2013). SA, BR, and plant BEs have been studied and characterized as compounds that activate plant defense mechanisms against stress conditions (abiotic and biotic) (Bektas and Eulgem, 2015;Singh et al, 2017;Vardhini and Anjum, 2015;Xue et al, 2013;Zhang et al, 2015).…”

Physiological Responses to the Foliar Application of Synthetic Resistance Elicitors in Cape Gooseberry Seedlings Infected with Fusarium oxysporum f. sp. physali

“…Plant resistance induction under abiotic and biotic stress conditions can be regulated by physiological, biochemical and molecular mechanisms [13,58]. Similarly, these plant resistance responses can be stimulated by exogenous synthetic elicitors application [59,60]. The present study showed that the foliar application of synthetic elicitors, mainly BR (1 mL L −1 ), SA (100 mg L −1 ) or BE (2.5 mL L −1 ), helped to mitigate the negative effects caused by Foph by favoring physiological and biochemical responses in cape gooseberry plants.…”