RESUMO
Rhipicephalus sanguineus s.l. is an intra- and peridomiciliary tick of medical and veterinary importance, whose control is carried out through the application of various ixodicides, to which it can develop resistance. The objective of this work was to determine the discriminant doses (d.d.) to identify resistance against three ixodicides - fipronil, flumethrin and coumaphos - in R. sanguineus s.l. larvae originating from Mexico. Engorged ticks were collected from naturally infested dogs residing in rural communities in five Mexican states; the dogs had no history of recent treatment with ixodicides. All ticks were identified as R. sanguineus s.l. They were incubated for 25 days and their progeny was used in the larval package test (LPT) to be exposed to d.d. as determined in Rhipicephalus microplus, and those that were susceptible were analyzed using the LPT with six concentrations, for fipronil from 0.1 to 0.003125%, for flumethrin from 0.02 to 0.000625% and for coumaphos from 0.4 to 0.0125%. Mortality was analyzed with Probit methodology, to calculate the 50 and 99% lethal concentrations (LC50 and LC99). The d.d. was determined as a consensus value by multiplying the LC99 value × 2. Nine double susceptible samples (fipronil + flumethrin) and one triple susceptible sample (fipronil + flumethrin + coumaphos) were found; the d.d. determined were fipronil 0.05%, flumethrin 0.01% and coumaphos 0.43%. These doses can be used to rapidly and inexpensively identify resistant populations in samples collected in the field.
RESUMO
The brown dog tick, Rhipicephalus sanguineus s.l., is considered the most widely distributed three-host tick in the world and has medical and veterinary importance; the control of infestation is carried out with acaricides, towards which it can develop resistance. This study aimed to determine the discriminant dose (d.d) of amitraz to identify resistance in R. sanguineus s.l. larvae natives from Mexico and to evaluate its application in field-collected ticks. Engorged ticks were collected from naturally infested dogs residing in rural communities and were incubated for 25 days, and their progeny was used in a larval immersion test (LIT) to be exposed to the d.d. determined in Rhipicephalus microplus, and those that were susceptible were analyzed using the LIT in six concentrations. Mortality was analyzed through probit methodology to calculate the lethal concentration (LC) 50 and 99. The d.d. was determined as a consensus value by multiplying the LC99 × 2, and then, we proceeded to evaluate it in in-field samples by using the LIT technique. The d.d. calculated was 4 ppm. The in-field evaluation found 64% of the resistant samples to amitraz with mortality percentages between 98.3% and 0.35%. This dose can be used to rapidly and inexpensively identify resistant populations in samples collected in the field.
RESUMO
The objective of this investigation was to evaluate the influence of two carrier agents, Nopal and Aloe Vera mucilage on the physicochemical properties and stability of blackberry and raspberry powders obtained by spray drying. A pilot scale spray dryer with a feed flow of 20 L/h and an atomization speed of 28,000â rpm was used. The inlet and outlet air temperatures were from 180 to 80°C, respectively. Yield, moisture content, water activity, hygroscopicity index, solubility time, volumetric density, stability diagrams, micrographs, and particle temperature were evaluated. The highest yields for blackberry extract were 75% with a concentration of 2.5% (w/v) Nopal mucilage, while raspberry extract yielded 65% with a concentration of 5% (w/v) Nopal mucilage. The increase in the concentration of the carrier agent presented an increase in the values of humidity, water activity, volumetric density, and solubility when Nopal mucilage was used as a carrier agent in both blackberry and raspberry extracts. Furthermore, when Aloe Vera mucilage was used as a carrier agent, these same values decreased with increasing concentration. The storage conditions of the powders obtained should be stored at temperatures below 20°C and water activities below 0.4. In addition, the stability diagrams show the particle conditions that should not be exceeded during spray drying.
RESUMO
Resumen La industria alimentaria utiliza hasta el 15 % del total de la energía eléctrica que demanda el sector industrial, principalmente en procesos de secado. Esto suscita la búsqueda de nuevas alternativas de secado que reduzcan el uso de energía eléctrica. Una opción es el secado solar, principalmente, el de tipo indirecto, a través de captadores solares de placa plana (CSPP). El objetivo de este trabajo fue analizar los recientes desarrollos de los CSPP, características, ventajas, desventajas, eficiencia y diversas tecnologías utilizadas en conjunto, para aumentar la eficiencia térmica en el secado solar. Los CSPP han desarrollado, a través de la hibridación con la utilización de otras fuentes de energía (eléctrica, biomasa, solar), un incremento en su eficiencia que los vuelve cada vez más viables para ser utilizados en procesos comerciales de secado de alimentos.
Abstract The food industry uses up to 15 % of the total electrical energy demanded by the industrial sector, mainly in drying processes. This motivates the search for new drying alternatives that reduce the use of electrical energy. One option is solar drying; mainly indirect type solar drying, that uses flat plate solar collectors (FPSC). The objective of this work was to analyze the recent developments of the FPSC, their characteristics, advantages, disadvantages, efficiency, and the range of technologies used in conjunction with the FPSC to increase their thermal efficiency for solar drying. The FPSC have developed through hybridization with the use of other energy sources (electricity, biomass, solar), an increase in their efficiency, that increasingly turns them into viable options for food drying processes.
