Pezothrips kellyanus (Thysanoptera: Thripidae) nymphs on orange fruit: importance of the second generation for its management
Keywords:
citrus, IPM, chlorpyriphos, spinosad, spirotetramat, side effect, predatory miteAbstract
Kelly’s citrus thrips Pezothrips kellyanus (Bagnall) (Thysanoptera: Thripidae) is a new pest of oranges in New Zealand, southern Australia, and the Mediterranean Basin. The nymphs of this thrips can damage the fruit from petal fall up to 6 wk later. Because there is a lack of information on its management, the aims of this study were to determine the number of generations occurring on the fruit and the efficacy of 3 insecticides (chlorpyrifos, spinosad, and spirotetramat) to control this pest. Chlorpyrifos and spinosad displayed a high efficacy against nymphs and reduced significantly the percentage of damaged fruit when a single generation of P. kellyanus attacked the fruit. However, these insecticides did not prevent development of a subsequent generation of P. kellyanus. The percentage of damaged fruit was higher when the 2nd generation was present. Spirotetramat did not display a knockdown effect, and its efficacy was less than that of chlorpyrifos and spinosad. Similar to these insecticides, spirotetramat did not prevent the attack of a 2nd generation when it occurred. Additionally, we analyzed the side effects of these treatments on predatory mites. Spinosad and spirotetramat negatively affected these beneficial species.
Resumen
Pezothrips kellyanus (Bagnall) (Thysanoptera: Thripidae) es una nueva plaga de cítricos en Nueva Zelanda, el sur de Australia y la Cuenca del Mediterráneo. Las ninfas de estos trips pueden dañar los frutos desde la caída de pétalos hasta sesi semanas después. A pesar de los estudios realizados sobre esta plaga y que hasta ahora sólo es posible su control mediante insecticidas, la información para realizar un adecuado manejo integrado es insuficiente. Por ello, el objetivo de este estudio fue determinar el número de generaciones que pueden encontrarse sobre el fruto y la eficacia de tres insecticidas (clorpirifos, spinosad y spirotetramat) con diferente modo de acción en el control de esta plaga y los efectos secundarios sobre fitoseidos en cítricos. Clorpirifos y spionsad tuvieron una elevada eficacia contra ninfas y redujeron significativamente el porcentaje de frutos dañados cuando fueron atacados por una sola generación. Sin embargo, su actividad no pudo prevenir el ataque de una siguiente generación de P. kellyanus. Además, el pordentaje de frutos dañados aumentó cuando se detectó esta segunda generación. Spirotetramat no tuvo un efecto de choque y su eficacia fue menor que la de clorpirifos y spinosad. Al igual que estos insecticidas, spirotetramat no pudo evitar un segundo ataque cuando se produjo. Los efectos secundarios evaluados de estos tratamientos sobre fitoseidos mostraron que spinosad y spirotetramat les afectaron negativamente.
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