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Some studies have reported the low genetic differentiation of Melanaphis sacchari/sorghi and its great phenotypic plasticity to quickly undergo adaptive changes that include change of host and rapid dispersion. In this experiment, damage and behavior of six commercial Sorghum bicolor (L.) Moench hybrids , against attack by the aphid were evaluated at Xalostoc, Morelos. The incidence of the sugarcane aphid from 21 after days sowing (ADS) was observed in all genotypes, despite insecticides coating the seed. The intensity of attack was light (25%) to 35 ADS. The intensity increased at the 49 ADS to (grade 2), with least severity in the Ambar hybrid (50.6%) and the greatest for Milenia (65%). The aphid was most abundant at 56 ADS, with P20 (85%) and Milena (83.7%) the most affected hybrids. At the end of the crop cycle, two groups were formed, the least infested (85 P15, Ambar, and DKS-46) and the most damaged one (Milenia, Cobalt, and 85 P20). Agronomic variables such as fresh weight of the plant, plant height, tang weight, and dry weight of the plant were not different. There were differences only in the brix degrees, with low values for Ambar (3.5°Bx) and P15 (4.2°Bx) hybrids, significantly different from 85 P20 (6.9) and Milena (6.5°Bx). Algunos estudios han informado la baja diferenciación genética de Melanaphis sacchari/sorghi y su gran plasticidad fenotípica, para someterse rápidamente a cambios adaptativos que incluyen el cambio de huésped y provocan la rápida dispersión de este insecto. En el ensayo se evaluó el nivel de daños y comportamiento de seis híbridos comerciales de Sorghum bicolor (L.) Moench, frente al ataque de este pulgón en Xalostoc, Morelos. Como resultado, se observó una incidencia del pulgón amarillo desde los 21 días de la siembra (DDS) en todos los genotipos, pese a los insecticidas presentes en la semilla. La intensidad del ataque fue ligera (25%) hasta los 35 DDS. Con un aumento de la intensidad a los 49 DDS (grado 2), con la menor severidad en el hibrido Ambar (50.6%) y el más elevado en Milenia (65%). A los 56 DDS se produjo el pico más elevado del ataque del pulgón, siendo los más afectados, 85P20 (85%) y Milena (83.7%). Al final del ciclo se formaron dos grupos, los menos infestados (P15, Ambar y DKS-46) y los más dañados (Milenia, Cobalto y 85 P20). Las variables agronómicas como: peso fresco de la planta, altura de la planta, peso de la panoja y peso seco de la planta no tuvieron diferencias. Solo hubo diferencias en los grados brix, con valores bajos para los híbridos Ambar (3.5°Bx) y 85 P15 (4.2°Bx), mismos que difieren de los que tuvieron valores más elevados, 85 P20 (6.9) y Milena (6.5°Bx), mientras éstos no se diferenciaron de DKS-46 y Cobalto con 4.7 y 5.2°Bx, respectivamente. [ABSTRACT FROM AUTHOR]

The effect of the Poncho®, Cruiser® 5 FS and Tools® TS insecticides applied in sorghum seed treatment (Sorghum bicolor L. Moench) on the germination, infestation of M. sacchari/sorghi and agronomic variables was evaluated. The hybrid genotype sorghum used was Ambar 752E443K (Asgrow®). The treatments consisted in the application of Poncho® at doses 4, 5, 6 and 8 mL kg-1 of seed; Cruiser® 5 FS at a dose of 2.5, 3.5, 5 and 7 mL kg-1 of seed; Tools® TS at doses 5, 6, 7 and 9 g kg-1 of seeds and an absolute control treatment. No negative effects of the treatments were observed on the germination, with germination exceeding 96% in all treatments. Doses of insecticides not exhibit a controlling effect on the populations of M. sacchari/sorghi. The effect of the insecticide treatments was not positive in the agronomic variables plant height, fresh leaf weight, fresh stem prisoner, fresh panicle weight, fresh grain weight, chlorophyll content and Brix degrees. [ABSTRACT FROM AUTHOR]

En México no existe un programa de fitomejoramiento específico que use progenitores con fuentes marcadas con genes dominantes que confieran resistencia o tolerancia del sorgo a Melanaphis sacchari/sorghi. Resultados preliminares indicaron que M. sacchari tiene una menor preferencia (antixesosis) por los híbridos Ámbar, P15, y Milenia. La menor tasa intrínseca de incremento poblacional (rm) se obtuvo en los genotipos Ámbar y 85 P 20, y se comprobó la tolerancia en Ámbar, Cobalto, y 85 P 20, manifestada con las variables, área foliar, peso seco y el índice clorofílico. Estos resultados, deben ser considerados como un avance importante en las futuras estrategias de manejo y programas de mejoramiento vegetal que se ejecuten para el combate de M. sacchari/sorghi en sorgo. To date, there is limited information on sources of resistance to Melanaphis sacchari/sorghi , in Sorghum bicolor (L.) Moench hybrids. These cultivars are sold by different seed companies in Mexico, basing their recommendations fundamentally on the potential yield of each genotype. So, there are no specific breeding programs that use sources marked from progenitors with dominant genes that confer resistance or tolerance to the insect. The objective of this study was to evaluate resistance mechanisms such as antixenosis, antibiosis, and tolerance in six commercial sorghum hybrids against M. sacchari at Morelos. Preliminary results indicated the aphid had less preference (antixenosis) for Ambar, P15, and Milenia hybrids. The antibiosis shown through the Lower Intrinsic Rate of Population Increment (rm), occurred in genotypes Ambar and 85 P 20, and there is evidence of tolerance based on the variables leaf area (AF), dry weight (PS), and chlorophyll index (Cl), with Ambar, Cobalt, and 85 P 20. These results should be considered an important advance in future management strategies and programs for the control of M. sacchari/sorghi in sorghum. [ABSTRACT FROM AUTHOR]