RESUMEN
The levels of resistance in the wild species of cassava, Manihot tristis Muell-Arg. (Malpighiales: Euphorbiaceae), to the whitefly, Aleurotrachelus socialis Bondar (Hemiptera: Alelyrodidae), the most important economic pest in cassava, Manihot esculenta Crantz (Malpighiales: Euphorbiaceae) crops in South America, were estimated under glasshouse conditions. The parameters of the life history of A. socialis were studied on TST-26 and TST-18 accessions of the wild parent and compared with the susceptible (CMC-40) and resistant (MEcu-72) cultivars. The average longevity on the wild accessions (TST-26, 4.1; TST-18, 4.6 days) and oviposition rates (TST-26, 2.0; TST-18, 1.6 eggs/female/2 days) of the A. socialis females were not significantly different from those of MEcu-72 (5.1 days and 3.4 eggs/female/2 days). The longevity and oviposition rates on CMC-40 were highest (11 days and 8.6 eggs/female/2 days). Analyses of the demographic parameters (Ro, r(m); DT) showed a significant impact of the M. tristis accessions on the potential growth of A. socialis. The average survival time of adults that fed on TST-26, TST-18, and MEcu-72 were significantly different from those recorded on the susceptible genotype. Results from this study revealed important levels of resistance to the whitefly A. socialis on the TST-26 and TST-18 accessions due to the marked differences found for longevity and reproduction, which influenced and were consistent with the differences found in the net reproduction rate (Ro), intrinsic growth rate (r(m)) and population doubling time (DT). The combined effect of these parameters indicated that M. tristis accessions were inappropriate hosts for A. socialis.
Asunto(s)
Dípteros/crecimiento & desarrollo , Interacciones Huésped-Parásitos/fisiología , Longevidad/fisiología , Manihot/genética , Manihot/parasitología , Oviposición/fisiología , Análisis de Varianza , Animales , Colombia , Femenino , Tablas de Vida , Masculino , Reproducción/fisiología , Razón de Masculinidad , Especificidad de la EspecieRESUMEN
Two encyrtid species, Acerophagus coccois and Aenasius vexans, parasitoids of the cassava mealybug Phenacoccus herreni use a contact kairomone from the body surface of their host as a host-location stimulant. The kairomone was synthesized and identified as O-caffeoylserine based on a combination of chromatographic methods. The synthetic compound was determined to be active.
Asunto(s)
Ácidos Cafeicos/química , Ácidos Cafeicos/síntesis química , Himenópteros/química , Insectos/química , Feromonas/química , Feromonas/síntesis química , Serina/química , Serina/síntesis química , Animales , Conducta Animal , Himenópteros/parasitología , Insectos/parasitología , Movimiento , Serina/análogos & derivados , OlfatoRESUMEN
Cassava (Manihot esculenta) occupies a uniquely important position as a food security crop for smallholder farmers in ares of the tropics where climate, soils, or societal stresses constrain production. Given its reliability and productivity, cassava is the most important locally produced food in a third of the world's low-income, food-deficit countries. It is the fourth most important source of carbohydrates for human consumption in the tropics, after rice, sugar, and maize. World production of cassava from 1994-1996 averaged 166 million tons/year grown on 16.6 million hectares (ha), for an average yield of 9.9 tons/ha. Approximately 57% is used for human consumption, 32% for animal feed and industrial purposes, and 11% is waste. Africa accounts for 51.3% of the production; Asia, 29.4%; and Latin America, 19.3%. The area planted to cassava in Africa, Asia, and Latin America is 10.3, 3.7, and 2.6 million ha, respectively.