Chilli Thrips (Thysanoptera: Thripidae) to Capsicum Cultivars in Choice Tests in the Greenhouse and Laboratory and Relative Benefits of Protecting these Cultivars with Spinetoram

Cliff G. Martin, Dakshina R. Seal

Abstract


Since the chilli thrips, Scirtothrips dorsalis Hood (Thysanoptera: Thripidae) poses a considerable threat to production of peppers in the Western Hemisphere, it is important to determine the relative vulnerability of different cultivars of Capsicum annuum L. and C. chinense Jacquin. In addition it is important to determine the relative benefits to the productivity of these cultivars of controlling the chilli thrips with insecticides. Therefore the effects of the chilli thrips on 11 pepper cultivars (Capsicum spp.; Solanales: Solanaceae) were tested in greenhouse and laboratory environments. When data for spinetoram-treated and untreated plants of each cultivar were pooled, the number of pedicels, number of flowers, and total (pedicels + flowers + fruit) differed between cultivars, and ‘Astry’ and ‘Cheyenne’ had the highest counts of these organs, while ‘Hot Habanero Orange’ and ‘Hot Fatalli’ had the least. When cultivars were pooled for spinetoram-treated separately from untreated plants, spinetoram was found to have increased the numbers of pedicels and total counted plant organs. For spinetoram-treated plants, ‘Hot San Ardo’ had the greatest canopy volume and ‘Hot Fatalli’ the smallest, whereas ‘Fresno 6022’ had the most fruits and ‘Hot Fatalli’ had the least. Based on comparing canopy volume and number of fruits of spinetoram-treated and untreated plants, ‘Numex Big Jim’ was found to have been benefitted the least by spinetoram application, whereas ‘Fresno 6022’, ‘Hot Tormenta’, ‘Cheyenne’, ‘Astry’, and ‘Jamaican Yellow’ were benefitted the most. A greenhouse choice test indicated ‘Fresno 6022’, ‘Hot Tormenta’, ‘Hot Fatalli’, ‘Hot San Ardo’, ‘Hot Habanero Orange’, ‘Numex Big Jim’, and ‘Jamaican Yellow’ each had fewer larvae per plant than ‘Astry’. In a choice of cultivars in laboratory Petri dishes, larvae per leaf disk were most abundant on ‘Agriset 4108’, ‘Red Devil Cayenne’, ‘Numex Big Jim’, ‘Astry’, and ‘Jamaican Yellow’ and least abundant on ‘Hot Fatalli’. ‘Hot Fatalli’ attracted the fewest thrips and seemed to be the least susceptible cultivar in the 3 experiments, though it had the smallest plant size and lowest yields. Spinetoram improved yields of productive cultivars like ‘Fresno 6022’, which may be more feasible to grow than ‘Hot Fatalli’.

 

Porque los trips de pimienta, Scirtothrips dorsalis Hood (Thysanoptera: Thripidae) esta amenazanda la producción de pimientas en el Hemispherio Occidental, es importante determinar las vulnerabilidades relativos de cultivares diferentes de Capsicum annuum L. y C. chinense Jacquin. Tambien es importante determinar los beneficios relativos a las productividades de estos cultivares quando los trips de pimienta estan contolada para las insecticidas. Por lo tanto, se evaluaron los efectos de trips de pimienta en 11 cultivares de pimienta (Capsicum spp.; Solanales: Solanaceae) en el Centro Tropical de Recherche y Educación del Universitario de Florida, Homestead, en invernaderos y el laboratorio. Quando plantas tratados y no tratados fueron combinados para cada cultivar, fuéron differencias entre cultivares por los tallos de flores cortados, flores, y totales (tallos cortados + flores + frutas) y ‘Astry’ y ‘Cheyenne’ fueron mas altas y ‘Hot Habanero Orange’ y ‘Hot Fatalli’ mas bajas. Quando cultivares fueron combinados para las plantas tratados y por los no tratados, spinetoram aumentó las quantidades de tallos de flores cortados, y totales de órganos contados de las plantas. ‘Hot San Ardo’ fué mas alta y ‘Hot Fatalli’ mas baja por volumen del follaje tratado, y ‘Fresno 6022’ fué mas alta y ‘Hot Fatalli’ mas baja por frutas tratadas. Basado en la comparación del volumen de follaje y numero de frutas para plantas tratadas y no tratadas, ‘Numex Big Jim’ fué menos ayudado y ‘Fresno 6022’, ‘Hot Tormenta’, ‘Cheyenne’, ‘Astry’, y ‘Jamaican Yellow’ mas ayudados para aplicación de spinetoram. Una prueba de preferencia en invernadero indicó que ‘Fresno 6022’, ‘Hot Tormenta’, ‘Hot Fatalli’, ‘Hot San Ardo’, ‘Hot Habanero Orange’, ‘Numex Big Jim’, y ‘Jamaican Yellow’ tuvieron menos larvas por cada planta que ‘Astry’. Una prueba de preferencia para las cultivares de pimienta en placas Petri en una cámara de crecimiento del laboratorio muestro que ‘Agriset 4108’, ‘Red Devil Cayenne’, ‘Numex Big Jim’, ‘Astry’, y ‘Jamaican Yellow’ obtuvieron las mas larvas por disco de hoja y ‘Hot Fatalli’ obtuvo los menos. ‘Hot Fatalli’ atrajo los menos trips de todo las cultivares y pareció a ser la menos susceptible en todo los tres experimentos, aunque tuvo las tamaños de plantas y rendimientos mas pequeños. Spinetoram mejoró los rendimientos de cultivares productivos como ‘Fresno 6022’, lo qual puede ser mas practico a criar que ‘Hot Fatalli’.


Keywords


Scirtothrips dorsalis; Capsicum annuum; Capsicum chinense; spinetoram

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