Fungal contamination and selected mycotoxins in pre- and post-harvest maize in Honduras

Sixty nine samples of maize were collected from pre-harvest standing crops and on-farm storage facilities from 52 smallholder farms located within 4 regions of Honduras during October 1992 and November 1993. Samples were visually assessed for insect damage and fungal spoilage, and the mycoflora quantified on artificial media. The major components of the ear rot complex were:Fusarium moniliforme, F. moniliforme var.subglutinans, Penicillium species,Stenocarpella maydis, S. macrospora andAcremonium spp. Representative samples were also assayed for mycotoxin content. Fumonisin B₁ was detected in all 24 samples tested at levels of between 68–6,555 (µg/kg), and aflatoxin was detected in 2 samples heavily contaminated withAspergillus flavus. Moniliformin and tenuazonic acid were not detected in the samples tested. The implications of these findings for human and livestock health risk are discussed, together with possible strategies for controlling these pathogens.     

Cutaneous leishmaniasis caused by members of Leishmania braziliensis complex in Nayarit, State of Mexico

An epidemiological study was carried out in the northern Mexican state, Nayarit. Fourteen patients with possible cutaneous leishmaniasis skin lesions gave positive Montenegro skin tests. Biopsies were taken from the skin ulcer and analyzed by polymerase chain reaction (PCR) with specific primers for the Leishmania mexicana complex; however all biopsies were not amplified. PCR carried out with specific primers for the L. braziliensis complex resulted in the amplification of all patient DNA. DNA from 12 out of 14 biopsies gave positive amplification with primers species specific for L. (Viannia) braziliensis and hybridized with a species specific L. (V.) braziliensis probe. These results demonstrate the presence in Nayarit of at least two members of the L. braziliensis complex. Most of the cutaneous lesions were caused by L. (V.) braziliensis and two by another species belonging to the L. braziliensis complex. As far as we are aware, this is the first report of L. (V.) braziliensis in Nayarit. The main risk factor associated with the contraction of this disease in Nayarit is attributed to working on coffee plantations.     

Occurrence of fungi and mycotoxins in corn silage, Jalisco State, Mexico

The aim of this study was to evaluate the chemical composition, mold count and mycotoxin contamination of corn silage collected during a six month-period. The results indicated that the chemical composition and the physicochemical parameters evaluated did not show significant variation during the sampling time. Fungal count on RBC ranged from 1.7 x 10(3) to 9 x 10e8 CFU/g. Mucor, Penicillium and Aspergillus spp. were the most frequent fungal species in the corn silage. Fusarium count ranged from 1.6 x 10(3) to 1.6 x 10e8 CFU/g in Nash Snyder culture media. Aflatoxin B, fumonisins, ochratoxin A, ochratoxin B, deoxynivalenol, and zearalenone were detected throughout the period of corn silage maintenance (100% positive samples). However, only deoxynivalenol levels were higher than the maximum limit recommended by the FDA.     

Brevipalpus mites associated with coffee plants (Coffea arabica and C. canephora) in Chiapas,Mexico

Experimental and Applied Acarology - Tenuipalpid mites of the genus Brevipalpus are of significant economic and quarantine importance in agriculture. They can damage and vector phytopathogenic...     

Immunochemical assessment of mycotoxins in 1989 grain foods: evidence for deoxynivalenol (vomitoxin) contamination.

To assess the potential for mycotoxin contamination of the human food supply following the 1988 U.S. drought, 92 grain food samples were purchased from retail outlets in the summer of 1989 and surveyed for aflatoxin B1, zearalenone, and deoxynivalenol (DON [vomitoxin]) by monoclonal antibody-based competitive enzyme-linked immunosorbent assay (ELISA). Only one sample (buckwheat flour) was found to contain aflatoxin B1 (12 ng/g), whereas zearalenone was found in 26% of the samples at a mean concentration of 19 ng/g. In contrast, the DON ELISA was positive in 50% of the samples at a detection level of 1.0 micrograms/g. Between 63 and 88% of corn cereals, wheat flour/muffin mixes, rice cereals, and corn meal/muffin mixes yielded positive results for DON, whereas 25 to 50% of oat cereals, wheat- and oat-based cookies/crackers, corn chips, popcorn, and mixed-grain cereals were positive for DON. The mean DON content of the positive samples was 4.0 micrograms/g, and the minimum and maximum levels were 1.2 and 19 micrograms/g, respectively. When positive ELISA samples were also analyzed by high-performance liquid chromatography, a strong correlation between the two methods was found. The presence of DON in the two highest samples, corn meal and mixed-grain cereal, which contained 19 and 16 micrograms/g, respectively, was quantitatively confirmed by gas chromatography-mass spectrometry. The results indicated that DON was present in 1989 retail food products at concentrations that exceeded those found in previous market surveys and that have been experimentally associated with impaired animal health.     

3-Methylbutanoyl and 3-methylbut-2-enoyl disaccharides from green coffee beans (Coffea arabica)

The aerial parts of Teucrium oliverianum yielded two neo-clerodane diterpenoids, teucrolin F and G, together with the known teucrolin E. The previously proposed structure for teucrolin E was revised so that it contains a tetrahydrofuran ring instead of an oxetane ring. This was based on analysis of the NMR spectroscopic data of its diacetate, including its NOE spectra. In addition, the structural assignments of the new diterpenoids were based on 1H and 13C NMR spectroscopic studies, mainly 2D NMR experiments, including homonuclear and heteronuclear correlations.     

Agricultural development and maize diversity in Mexico

Mexico is within the center of origin of Zea mays and has among the highest levels of maize genetic diversity in the world. This diversity is traced to factors at the regional and farm levels. Loss of crop genetic diversity has been related to economic and agricultural development, although opposed views of this exist for the Mexican case. Agricultural development appears to be affecting virtually all types of farms in Mexico. A case study in Chiapas suggests that the adoption of some improved varieties has enhanced genetic diversity in maize, but one improved type competes with landraces in the most favorable land. The adoption of this improved type is associated with greater access to capital and with lower risk.The research for this project was carried out with the support of the UC/MEXUS program of the University of California and CONACYT. We wish to acknowledge the advice and assistance provided by Esteban Betanzos of the Chiapas office of the Instituto Nacional de Investigaciones Forestales y Agropecuarios, Efraim Hernandez of the Colegio de Postgraduados at Chapingo, Robert Tripp of the Centro Internacional de Mejoramiento de Maiz y Trigo, and to Manuel Parra of the Centro de Investigaciones Ecologicas del Sureste in San Cristobal de las Casas. The authors wish to thank J. Edward Taylor, Andraes Buerkert, Aaron Zazueta, and Daniel Mountjoy for their useful comments on an earlier draft.     

Fusarium species complex and mycotoxins in grain maize from maize hybrid trials and from grower's fields

Aims: To quantify and to compare the occurrence of Fusarium species in maize kernels and stalk pieces, to analyse mycotoxins in kernels and maize crop residues, to evaluate two approaches to obtain kernel samples and to compare two methods for mycotoxin analyses. Methods and Results: The occurrence of Fusarium species in maize kernels and stalk pieces from a three‐year maize hybrid trial and 12 kernel samples from grower’s fields was assessed. Nine to 16 different Fusarium species were detected in maize kernels and stalks. In kernels, F. graminearum, F. verticillioides and F. proliferatum were the most prevalent species whereas in stalks, they were F. equiseti, F. proliferatum and F. verticillioides. In 2006, 68% of the kernel samples exceeded the recommended limit for pig feed for deoxynivalenol (DON) and 42% for zearalenone (ZON), respectively. Similarly, 75% of the samples from grower’s fields exceeded the limits for DON and 50% for ZON. In maize crop residues, toxin concentrations ranged from 2·6 to 15·3 mg kg^?1 for DON and from 0·7 to 7·4 mg kg^?1 for ZON. Both approaches to obtain maize kernel samples were valid, and a strong correlation between mycotoxin analysis using ELISA and LC‐MS/MS was found. Conclusions: The contamination of maize kernels, stalk pieces and remaining crop residues with various mycotoxins could pose a risk not only to animal health but also to the environment. With the hand‐picked sample, the entire Fusarium complex can be estimated, whereas combine harvested samples are more representative for the mycotoxin contents in harvested goods. Significance and Impact of the Study: This is the first multi‐year study investigating mycotoxin contamination in maize kernels as well as in crop residues. The results indicate a high need to identify cropping factors influencing the infection of maize by Fusarium species to establish recommendations for growers.     

Fungi and mycotoxins in south african maize of the 1993 crop

The most dominant fungi in South African maize for the 1993 crop wereFusarium moniliforme andFusarium subglutinans. The mycotoxins occurring with the most frequency were the fumonisins, deoxynivalenol and nivalenol. Levels of fungal infection and mycotoxins varied between white maize and yellow maize, and between the respective grades.     

Mycotoxigenic fungi and mycotoxins associated with stored maize from different regions of Lesotho

Samples of stored maize from villages located in five different agroecological zones (southern lowlands, northern lowlands, Senqu river valley, foothills and mountains) of Lesotho were collected in 2009/10 and 2010/11 and assessed for contamination with toxigenic fungi. The water activity of all samples collected during the two seasons was <0.70. The total fungal populations of the maize from different regions in the two seasons was not significantly different (p?>?0.05). Fusarium verticillioides, F. proliferatum and F. subglutinans predominated in different regions in both seasons based on molecular analyses. In the 2009/10 season, the isolates of these species all produced FB₁, while in the 2010/11 season, very few produced FB₁. A. flavus isolates (2009/10) were recovered from mountains and Senqu river valley samples while the 2010/11 isolates were predominantly from the foothills and northern lowlands. The mountain isolates of Aspergillus section Flavi produced the highest levels of AFB₁ (20 mg kg^?1). Aspergillus parasiticus was only isolated from the foothills, Senqu river valley and southern lowlands samples, and the AFB₁ levels produced ranged from ‘none detected’ to 3.5 mg kg^?1. The Aspergillus ochraceous isolates were least frequently encountered in both seasons. In the 2009/10 season, the isolates from the northern lowlands produced ochratoxin A (OTA) in culture. No isolates of A. niger from different regions in both seasons produced any OTA. Multi-mycotoxin analyses of the maize samples were done for a range of mycotoxins. At least one sample from each region in both seasons was FB₁-positive. FB₁ levels for 2010/11 samples (7–936 μg kg^?1) were higher than in the 2009/10 season (2–3 μg kg^?1). In both seasons, the mountains registered the highest levels of FB₁. Deoxynivalenol (DON) was recovered from all the samples analysed, with the highest mean contamination of 1,469 μg kg^?1 in samples from the northern lowlands. Moniliformin (MON) was detected from all agroecological zones in the two seasons (5–320 μg kg^?1 in 2009/10; 15–1,205 μg kg^?1 in 2010/11). Emerging toxins such as fusaproliferin (FUS) and beauvericin (BEA) were also detected. OTA was not detected in any of the samples analysed. Only one 2009/10 sample in the Senqu river valley was positive for AFB₁. This is the first report on toxigenic fungi and multi-mycotoxin contamination of maize samples from subsistence farmers’ stores in different agroecological zones of Lesotho.     

Necrophilous coleoptera (Scarabaeidae, Silphidae y Trogidae) of Malinalco, State of Mexico, Mexico

Collections were made during one year, between August 2005 and July 2006, in Malinalco, State of Mexico, in three sites of tropical deciduous forest, a pasture and a induced forest of pine-oak, established in a altitudinal gradient ranging from 1,253 m to 2,300 m. The total of 7,680 specimens Scarabaeidae, Silphidae and Trogidae were captured through NTP-80, representing 18 genera and 38 species. Onthophagus and Canthon contained 46% of the richness of Scarabaeidae. The more distant sites were complementary in their species composition. The lowest complementarity occurred between sites with tropical deciduous forest. It revises the material collected through pitffal traps and light traps funnel type, increasing the list of 38 to 50 species in the study area. Between 40% and 50% of the species in Malinalco are distributed in localities of the province of the basin Balsas and localities of the province of the Sierra Madre del Sur, and 30% in the localities of the province of Pacifica coast. For the first time 17 species of Scarabaeidae and three Trogidae were reported for the State of Mexico.     

Diurnal variation in ciliate protozoa in the rumen of black buck (Antilope cervicapra) fed green forage

The protozoa in the rumen of a black buck were a B-type population with numbers varying between 0·31 and 0·61 times 10⁶cells/ml rumen liquor, when the animal was fed either vegetative green oat or third cut berseem. The total protozoa, total holotrichs, Dasytricha, total spirotrichs and small spirotrichs were significantly higher ( P < 0·01) on berseem feeding than those on oat feeding, while the numbers of Isotricha and large spirotrichs were unaffected by change of diet. Numerically the most important group of protozoa was small spirotrichs (74·4–75·6% of total population) which accounted for only 9·85–13·61% of protozoal cell mass in the rumen.     

Natural occurrence of toxigenic fungi and mycotoxins in rice bran

Thirty four samples of rice bran, of which 9 were from raw (untreated) rice (RR) and 25 from parboiled rice (PbR) were collected from commercial rice mills in and around Madras and analysed for storage mycoflora and mycotoxins. Fungi of the Aspergillus flavus group were present in 29 of the 34 samples (8 from RR and 21 from PbR) in quantities ranging from <1–432 thousand propagules/g, though not always as the dominant mycoflora. Fungal numbers were usually higher in RR than in PbR samples.Five of the 9 RR samples and 6 of the 25 PbR samples were positive for aflatoxins. Among 29 isolates of A. flavus obtained from the bran samples, 16 isolates –6 from RR bran and 10 from PbR bran — were found to be toxigenic in vitro. Some isolates of A. candidus also seemed to produce aflatoxin and other fluorescent substances.     

Effects of the botanical composition and weather conditions on mycotoxins in winter forage from grassland

The paper focuses on possible effects of the botanical composition and weather conditions on the extend of zearalenone and ochratoxin A concentrations in various grass swards in winter pasture systems. Zearalenone is only detectable in pure stands ofLolium perenne or inLolio-Cynosuretum plant communities, respectively. The occurrence of ochratoxin A is more frequent and less specific concerning the botanical composition. This mycotoxin was found in both,Lolium perenne andFestuca arundinacea in varying years. The incidence of ochratoxin A depends on year and is apparently related to the weather conditions in autumn and winter. There was no evidence that particular locatio8/22/2008 12:57PMns have a higher or a lower risk for high ochratoxin A or zearalenone concentrations than others. Peak values in individual swards are not intermittent over the years. Presented at the 25th Mykotoxin-Workshop in Giessen, Germany, May 19–21, 2003     

Abundance responses of frugivorous bats (Stenodermatinae) to coffee cultivation and selective logging practices in mountainous central Veracruz,Mexico

Shifting and permanent cultivation, selective logging, cattle production and coffee plantations are among the most important factors in montane cloud forest conversion and disturbance. Although shaded-coffee plantations can contribute to the preservation of local species richness, abundance of organisms could be determined by habitat resource availability in agricultural landscapes. We compared abundance of Sturnira and Artibeus bats (Phyllostomidae, Stenodermatinae), in shade coffee plantations and disturbed cloud forest fragments, which represent habitats with different chiropterochorous plant density. We also investigated the relationship between bat species abundance and food plant richness, abundance and diversity. We captured 956 bats, 76% in cloud forest fragments and 24% in shaded coffee plantations. Abundance of Sturnira spp. (small bats) was greater in cloud forest than in coffee plantations, but Artibeus spp. (large bats) abundance was similar in both habitats. Chiropterochorous plant abundance was positively related with bat abundance for Sturnira spp., while chiropterochorous plant richness and diversity were negatively related for Artibeus spp. This suggests that frugivorous bats with different morphological and ecological characteristics respond differentially to anthropogenic activities. For landscape management purposes, the maintenance and augmentation of diverse food resources, for frugivorous bats with different foraging requirements in coffee plantations, will benefit the resilience of bats to modification of their natural habitat.     

Natural occurrence of Beauveria bassiana in Hypothenemus hampei (Coleoptera: Curculionidae) populations in unsprayed coffee fields

Three unsprayed coffee farms (farm 1, 2 and 3) were studied for the natural occurrence of the insect pathogenic fungus Beauveria bassiana in Hypothenemus hampei populations throughout the rainy season of 2004 (July-November) and 2005 (July-December). B. bassiana infections were found during most sampling dates in both years, on all three farms. The B. bassiana infection levels were higher in 2005 than in 2004 with mean prevalence of 12.1% and 2.7%, respectively. No consistent significant differences in infection level between farms were found in any of the years. B. bassiana infection levels fluctuated widely throughout the season, and peaked at 13.5% on farm 3 in 2004 and at 44.0% on farm 1 in 2005. The H. hampei population was significantly higher in 2004 than in 2005, with 6.9% of the berries infested in 2004 and only 0.7% in 2005. In both years, the H. hampei infestation level was significantly higher on farm 2. No consistent significant differences in H. hampei infestation levels were found between sampling dates on any of the farms. H. hampei infestation levels fluctuated throughout both seasons, and peaked at 15.3% on farm 2 in 2004 and 2.2% on farm 2 in 2005. No consistent density dependent correlation between H. hampei infestation level and B. bassiana infection level was found. Correlations between climatic conditions and B. bassiana or H. hampei were not found.     

Measurement and prediction of digestibility of forage maize in The Netherlands

Results of digestibility trials on fresh and ensiled maize (aerial parts) were analysed and compared with laboratory data.

Digestibility of the organic matter of ears was almost constant at 84–85%. Digestibility of organic matter of stover showed great variation. Variation between animals in apparent digestibility of organic matter was greater for maize diets than for diets based on grass products. Most of the differences between animals were caused by differences in the digestion of cell walls. When the true digestibility of cell contents was assumed to be complete, endogenous excretion was, on average, only 7% with respect to organic matter intake, and seemed dependent on digestibility of organic matter.

Prediction of apparent digestibility was more accurate with digestibility in vitro than with crude fibre, although for maize silage, significant relationships were found between crude fibre content and digestibility of organic matter. Standard deviation of organic matter digestibility between lots of fresh and ensiled maize grown on commercial farms amounted to only about 1.2 –2%. As this was only twice the accuracy of digestibility in vivo with four animals, fixed values will be presented to farmers, possibly corrected for year, hybrid selection and cropping practice.     

PCR-based strategy to detect contamination with mycotoxigenic Fusarium species in maize

Contamination of cereals with mycotoxigenic species of Fusarium is an important source of trichothecenes, fumonisins and other mycotoxins which cause serious diseases in human and animals. In addition, these species are phytopathogenic and produce severe losses in cereal yield. Methods for early detection of these Fusarium species are crucial to prevent toxins entering the food chain and are a useful tool in disease management practices. We have developed an integrated protocol for diagnosis of mycotoxigenic Fusarium contamination in maize which can also be used for other cereals. The protocol consisted in an easy and rapid DNA extraction from maize samples (grain and germ), and subsequent group-specific polymerase chain reaction (PCR) assays for genus Fusarium, Gibberella fujikuroi complex, and trichothecene-producing species of Fusarium, that orientate the search of the critical species. We have additionally developed a PCR assay for the identification of F. proliferatum. The primers were designed on the basis of IGS sequence (Intergenic Spacer of rDNA), a multi-copy region in the genome that permits to enhance the sensitivity of the assay in comparison with PCR assays based on single-copy sequences. The suitability of the protocol and the relative efficacy of single and multi-copy sequence-based PCR assays have been tested in a wide range of fumonisin-contaminated maize samples.