Fusarium species can produce fumonisins (FBs), fusaric acid, beauvericin (BEA), fusaproliferin (FUS) and moniliformin. Data on the natural occurrence of FBs have been widely reported, but information on BEA and FUS in maize is limited. The aims of this study were to establish the occurrence of Fusarium species in different maize hybrids in Mexico, to determine the ability of Fusarium spp. isolates to produce BEA, FUS and FBs and their natural occurrence in maize. Twenty-eight samples corresponding to seven different maize hybrids were analyzed for mycobiota and natural mycotoxin contamination by LC. Fusarium verticillioides was the dominant species (44-80%) followed by F. subglutinans (13-37%) and F. proliferatum (2-16%). Beauvericin was detected in three different hybrids with levels ranging from 300 to 400 ng g(-1), while only one hybrid was contaminated with FUS (200 ng g(-1)). All samples were positive for FB1 and FB2 contamination showing levels up to 606 and 277 ng g(-1), respectively. All F. verticillioides isolates were able to produce FB1 (13.8-4,860 μg g(-1)) and some also produced FB2 and FUS. Beauvericin, FUS, FB1 and FB2 were produced by several isolates including F. proliferatum and F. subglutinans and co-production was observed. This is the first report on the co-occurrence of these toxins in maize samples from Mexico. The analysis of the presence of multiple mycotoxins in this substrate is necessary to understand the significance of these compounds in the human and animal food chains.

The susceptibility of the egg, pupa, and adult of Haematobia irritans (L.) (Diptera: Muscidae) to isolates of the fungi Metarhizium anisopliae (Metsch.) Sor., Beauveria bassiana (Bals.) Vuill., and Paecilomyces fumosoroseus (Wize) Brown and Smith, was evaluated under laboratory conditions. Groups of 20 eggs than 4 h old, pupae less than 48h old and adults were sprayed with a conidial suspension of each isolate. Eggs, pupae and adults of horn fly were susceptible to these entomopathogenic fungi. For treated eggs, the isolates Ma3, Ma 15, Ma25, Pfr1, and Pfr8 reduced adult emergence to 3.8% to 6.3% in comparison with the control (72%). The mortality of pupae infected by the isolates Ma2, Ma25, and Pfr10 ranged between 50% and 71.3%. Mortality of adults after treatment with the isolates Ma6, Ma 10, Ma 14, Ma 15, Pfr 1, Pfr 9, Pfr 10, Pfr 11, and Pfr12 were higher than 90%. The isolate Ma6 produced the lowest LC50 against adult horn flies (8.08 × 102conidia/ml). These findings supported the hypotheses that isolates of M. anisopliae, and P. fumosoroseus are pathogenic against the different biological stages of horn flies by reducing adult emergence when applied on groups of eggs and pupae, and producing mortality when applied to adults.

Fumonisins are mycotoxins responsible for equine leukoencephalomalacia (ELEM) and they are produced by Fusarium species of high incidence in corn crops. In Jalisco (Mexico), six cases were confirmed by histopathological and neurological findings and fumonisins analysis. This is the first report of fumonisins in corn stover associated to ELEM cases.

A partir de casos confirmados de leucoencefalomalacia equina en el municipio de Juchitlán (estado de Jalisco), esta investigación tuvo como objetivo determinar la presencia y niveles de fumonisinas en el alimento. El área de estudio incluyó a los principales municipios en donde se concentra la población equina de Jalisco, teniendo en común el uso de prácticas similares en el manejo de la alimentación y conservación del alimento. Las determinaciones analíticas se realizaron mediante inmunoensayo de tipo competitivo y cromatografía de líquidos de alta resolución. Se detectó contaminación con fumonisinas en el 100 % de muestras analizadas de todos los municipios, los niveles fueron de 0.23 a 19.18 mg/kg. Se observó diferencia entre municipios (P<0.001); la mayor concentración se observó en Ahualulco de Mercado (media: 12.83 mg/kg) y la menor en Concepción de Buenos Aires (media: 0.27 mg/kg). Del total de muestras analizadas, 62 % superaron el límite máximo recomendado para equinos.

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