T-2 toxin and diacetoxyscirpenol metabolism by Baccharis spp

Hybrids resulting from crosses between Baccharis sarothroides and B. pilularis (FS1), B. sarothroides (FS2) and B. megapotamica (FS3) were tested for their tolerance to trichothecenes as well as their ability to metabolize the toxins. B. sarothroides (desert broom) was placed in an aqueous solution containing 500 ppm of T-2 toxin and showed visible signs of toxicity on the twigs at 21 h after exposure but not at 6 h, indicating some resistance. Samples of the twigs harvested 6 and 21 h after treatment contained, respectively, T-2 (0.03 and 2.2 micrograms/g), HT-2 (0.09 and 7.6 micrograms/g), and T-2-tetraol (2.1 and 2.6 micrograms/g). The hybrid FS1 showed no signs of toxicity 6 h after treatment, and its twigs contained T-2 (0.8 micrograms/g), HT-2 (10.2 micrograms/g), and T-2-tetraol (10.8 micrograms/g). The leaves at 6 h contained 0.5 micrograms of T-2, 1.7 micrograms of HT-2, 0.01 microgram of 3'-hydroxy-HT-2, and 41 micrograms of T-2-tetraol per g. At 21 h, toxic signs were apparent and the twigs contained T-2 (39 micrograms/g), HT-2 (62 micrograms/g), 3'-hydroxy-HT-2 (0.8 microgram/g), and T-2-tetraol (22 micrograms/g).(ABSTRACT TRUNCATED AT 250 WORDS)     

Toxins of molds from decaying tomato fruit.

Among 27 mold isolates from decaying tomatoes, culture filtrates or ethyl acetate extracts of 8 isolates grown in yeast extract-sucrose medium were markedly toxic (mortality, greater than 50%) to brine shrimp larvae. The toxicity of six of these isolates could be attributed to the presence of citrinin, tenuazonic acid, or T-2 toxin. Ethyl acetate extracts of five Alternaria isolates and one Fusarium isolate were mutagenic for Salmonella typhimurium strains. In ripe tomatoes inoculated with toxin-producing isolates and incubated at 25 degrees C, one Alternaria alternata isolate produced tenuazonic acid in seven of seven tomatoes at levels of up to 106 micrograms/g and alternariol methyl ether in one of the seven tomatoes at 0.8 microgram/g. Another A. alternata isolate produced tenuazonic acid or alternariol methyl ether at much lower levels in only three of seven tomatoes. Patulin and citrinin were produced by a Penicillium expansum isolate at levels of up to 8.4 and 0.76 microgram/g, respectively. In tomatoes incubated at 15 degrees C, a Fusarium sulphureum isolate produced T-2 toxin, HT-2 toxin, and neosolaniol at levels of up to 37.5, 37.8 and 5.6 micrograms/g, respectively. If these mycotoxins are thermostable, they may occur at detectable levels in tomato products whenever partially moldy tomatoes are used as raw material.     

Toxins of molds from decaying tomato fruit.

Among 27 mold isolates from decaying tomatoes, culture filtrates or ethyl acetate extracts of 8 isolates grown in yeast extract-sucrose medium were markedly toxic (mortality, greater than 50%) to brine shrimp larvae. The toxicity of six of these isolates could be attributed to the presence of citrinin, tenuazonic acid, or T-2 toxin. Ethyl acetate extracts of five Alternaria isolates and one Fusarium isolate were mutagenic for Salmonella typhimurium strains. In ripe tomatoes inoculated with toxin-producing isolates and incubated at 25 degrees C, one Alternaria alternata isolate produced tenuazonic acid in seven of seven tomatoes at levels of up to 106 micrograms/g and alternariol methyl ether in one of the seven tomatoes at 0.8 microgram/g. Another A. alternata isolate produced tenuazonic acid or alternariol methyl ether at much lower levels in only three of seven tomatoes. Patulin and citrinin were produced by a Penicillium expansum isolate at levels of up to 8.4 and 0.76 microgram/g, respectively. In tomatoes incubated at 15 degrees C, a Fusarium sulphureum isolate produced T-2 toxin, HT-2 toxin, and neosolaniol at levels of up to 37.5, 37.8 and 5.6 micrograms/g, respectively. If these mycotoxins are thermostable, they may occur at detectable levels in tomato products whenever partially moldy tomatoes are used as raw material.     

Toxin production by Fusarium species from sugar beets and natural occurrence of zearalenone in beets and beet fibers.

Fifty-five Fusarium isolates belonging to nine species were collected from fungus-invaded tissue of stored sugar beets and identified as F. acuminatum (11 isolates), F. avenaceum (1 isolate), F. culmorum (1 isolate), F. equiseti (23 isolates), F. graminearum (4 isolates), F. oxysporum (1 isolate), F. solani (4 isolates), F. sporotrichioides (7 isolates), and F. subglutinans (2 isolates). All isolates were cultured on autoclaved rice grains and assayed for toxicity by feeding weanling female rats the ground-rice cultures of the isolates in a 50% mixture with a regular diet for 5 days. Fifty-eight percent of the isolates were acutely toxic to rats, 26% caused hematuria, 18% caused hemorrhages, and 29% caused uterine enlargement. In most cases, toxicity could not be accounted for by the known toxins found. The following mycotoxins were found in extracts of the rice cultures: zearalenone (22 to 6,282 micrograms/g), chlamydosporol (HM-8) (68 to 4,708 micrograms/g), moniliformin (45 to 400 micrograms/g), deoxynivalenol (10 to 34 micrograms/g), 15-acetyldeoxynivalenol (5 to 10 micrograms/g), diacetoxyscirpenol (22 to 63 micrograms/g), monoacetoxyscirpenol (21 to 26 micrograms/g), scirpenetriol (24 micrograms/g), T-2 toxin (4 to 425 micrograms/g), HT-2 toxin (2 to 284 micrograms/g), neosolaniol (2 to 250 micrograms/g), and T-2 tetraol (4 to 12 micrograms/g). F. equiseti was the predominant species found on visibly molded beets in the field. Six of 25 moldy sugar beet root samples collected in the field contained zearalenone in concentrations ranging between 12 and 391 ng/g, whereas 10 samples from commercial stockpiles were negative for zearalenone.(ABSTRACT TRUNCATED AT 250 WORDS)     

Toxin production by Fusarium species from sugar beets and natural occurrence of zearalenone in beets and beet fibers.

Fifty-five Fusarium isolates belonging to nine species were collected from fungus-invaded tissue of stored sugar beets and identified as F. acuminatum (11 isolates), F. avenaceum (1 isolate), F. culmorum (1 isolate), F. equiseti (23 isolates), F. graminearum (4 isolates), F. oxysporum (1 isolate), F. solani (4 isolates), F. sporotrichioides (7 isolates), and F. subglutinans (2 isolates). All isolates were cultured on autoclaved rice grains and assayed for toxicity by feeding weanling female rats the ground-rice cultures of the isolates in a 50% mixture with a regular diet for 5 days. Fifty-eight percent of the isolates were acutely toxic to rats, 26% caused hematuria, 18% caused hemorrhages, and 29% caused uterine enlargement. In most cases, toxicity could not be accounted for by the known toxins found. The following mycotoxins were found in extracts of the rice cultures: zearalenone (22 to 6,282 micrograms/g), chlamydosporol (HM-8) (68 to 4,708 micrograms/g), moniliformin (45 to 400 micrograms/g), deoxynivalenol (10 to 34 micrograms/g), 15-acetyldeoxynivalenol (5 to 10 micrograms/g), diacetoxyscirpenol (22 to 63 micrograms/g), monoacetoxyscirpenol (21 to 26 micrograms/g), scirpenetriol (24 micrograms/g), T-2 toxin (4 to 425 micrograms/g), HT-2 toxin (2 to 284 micrograms/g), neosolaniol (2 to 250 micrograms/g), and T-2 tetraol (4 to 12 micrograms/g). F. equiseti was the predominant species found on visibly molded beets in the field. Six of 25 moldy sugar beet root samples collected in the field contained zearalenone in concentrations ranging between 12 and 391 ng/g, whereas 10 samples from commercial stockpiles were negative for zearalenone.(ABSTRACT TRUNCATED AT 250 WORDS)     

T-2 toxin metabolism by ruminal bacteria and its effect on their growth

The effect of T-2 toxin on the growth rates of different bacteria was used as a measure of its toxicity. Toxin levels of 10 micrograms/ml did not decrease the growth rate of Selenomonas ruminantium and Anaerovibrio lipolytica, whereas the growth rate of Butyrivibrio fibrisolvens was uninhibited at toxin levels as high as 1 mg/ml. There was, however, a noticeable increase in the growth rate of B. fibrisolvens CE46 and CE51 and S. ruminantium in the presence of low concentrations (10 micrograms/ml) of T-2 toxin, which may indicate the assimilation of the toxin as an energy source by these bacteria. Three tributyrin-hydrolyzing bacterial isolates did not grow at all in the presence of T-2 toxin (10 micrograms/ml). The growth rate of a fourth tributyrin-hydrolyzing bacterial isolate was unaffected. B. fibrisolvens CE51 degraded T-2 toxin to HT-2 toxin (22%), T-2 triol (3%), and neosolaniol (10%), whereas A. lipolytica and S. ruminantium degraded the toxin to HT-2 toxin (22 and 18%, respectively) and T-2 triol (7 and 10%, respectively) only. These results have been explained in terms of the presence of two different toxin-hydrolyzing enzyme systems. Studies with B. fibrisolvens showed the presence of a T-2 toxin-degrading enzyme fraction in a bacterial membrane preparation. This fraction had an approximate molecular weight of 65,000 and showed esterase activity (395.6 mumol of p-nitrophenol formed per min per mg of protein with p-nitrophenylacetate as the substrate.     

T-2 toxin metabolism by ruminal bacteria and its effect on their growth.

The effect of T-2 toxin on the growth rates of different bacteria was used as a measure of its toxicity. Toxin levels of 10 micrograms/ml did not decrease the growth rate of Selenomonas ruminantium and Anaerovibrio lipolytica, whereas the growth rate of Butyrivibrio fibrisolvens was uninhibited at toxin levels as high as 1 mg/ml. There was, however, a noticeable increase in the growth rate of B. fibrisolvens CE46 and CE51 and S. ruminantium in the presence of low concentrations (10 micrograms/ml) of T-2 toxin, which may indicate the assimilation of the toxin as an energy source by these bacteria. Three tributyrin-hydrolyzing bacterial isolates did not grow at all in the presence of T-2 toxin (10 micrograms/ml). The growth rate of a fourth tributyrin-hydrolyzing bacterial isolate was unaffected. B. fibrisolvens CE51 degraded T-2 toxin to HT-2 toxin (22%), T-2 triol (3%), and neosolaniol (10%), whereas A. lipolytica and S. ruminantium degraded the toxin to HT-2 toxin (22 and 18%, respectively) and T-2 triol (7 and 10%, respectively) only. These results have been explained in terms of the presence of two different toxin-hydrolyzing enzyme systems. Studies with B. fibrisolvens showed the presence of a T-2 toxin-degrading enzyme fraction in a bacterial membrane preparation. This fraction had an approximate molecular weight of 65,000 and showed esterase activity (395.6 mumol of p-nitrophenol formed per min per mg of protein with p-nitrophenylacetate as the substrate.     

A colorimetric technique for detecting trichothecenes and assessing relative potencies

We tested a novel colorimetric toxicity test, based on inhibition of beta-galactosidase activity in the yeast Kluyveromyces marxianus, for sensitivity to a range of mycotoxins. A variety of trichothecene mycotoxins could be detected. The order of toxicity established with this bioassay was verrucarin A > roridin A > T-2 toxin > diacetoxyscirpenol > HT-2 toxin > acetyl T-2 toxin > neosolaniol > fusarenon X > T-2 triol > scirpentriol > nivalenol > deoxynivalenol > T-2 tetraol. The sensitivity of detection was high, with the most potent trichothecene tested, verrucarin A, having a 50% effective concentration (concentration of toxin causing 50% inhibition) of 2 ng/ml. Other mycotoxins (cyclopiazonic acid, fumonisin B1, ochratoxin A, patulin, sterigmatocystin, tenuazonic acid, and zearalenone) could not be detected at up to 10 micrograms/ml, nor could aflatoxins B1 and M1 be detected at concentrations up to 25 micrograms/ml. This test should be useful for trichothecene detection and for studies of relevant interactions-both between trichothecenes themselves and between trichothecenes and other food constituents.     

Natural occurrence of Fusarium mycotoxins in field samples from the 1992 Wisconsin corn crop.

Analysis of 98 moldy corn samples collected in Wisconsin between November 1992 and January 1993 for Fusarium toxins by various immunochemical assays revealed overall average mycotoxin concentrations of 305.6, 237.7, and 904.3 ng/g for type A trichothecenes (TCTCs), deoxynivalenol (DON)-related type B TCTCs (total DON), and zearalenone (ZE), respectively. A small portion (5.1%) of the samples was found to be contaminated with high levels ( > 1 microgram/g) of type A TCTCs and total DON during the whole survey. Over 40% of the samples had 100 to 1,000 ng of total DON per g, while 17% of the samples had the same levels of type A TCTCs. The analytical data were consistent with those from mycological examinations for the samples in which various toxic Fusarium spp., including F. sporotrichioides, F. poae, and F. graminearum, were found. The samples received in November 1992 had relatively low concentrations of toxin; the average levels of type A TCTCs and total DON were 9.9 and 79 ng/g, respectively. The toxin concentrations became progressively higher in the samples received in December. The average levels for the type A TCTCs and total DON increased to 920 and 335 ng/g, respectively. However, the levels of ZE were higher in the samples collected earlier. The average levels for samples collected in November and late December were 1,195 and 242 ng/g, respectively. Analysis of selected samples by high-performance liquid chromatography monitoring with an enzyme-linked immunosorbent assay revealed that T-2 toxin, HT-2 toxin, diacetoxyscirpenol, neosolaniol, and T-2 tetraol (T-2-4ol) were common in these samples. Statistical analysis revealed a weak correlation between the levels of total type A TCTCs and total DON in the samples (r = 0.18, P = 0.09), but a strong correlation between the levels of ZE and total type B TCTCs (r = 0.75, P < 0.0001) was found. The mycotoxin levels of total type A TCTCs, total DON-related type B TCTCs, and ZE in the cobs (5.2, 3.9, and 21 micrograms/g, respectively) were considerably higher than those in the kernels (1.0, 0.5, and 0.5 microgram/g, respectively). The type A toxin levels increased from a range of 14 to 35 ng/g to a range of 110 to 538 ng/g after the moldy corn samples were held at 5 degrees C for 8 days in the laboratory.     

T-2 metabolites in the excreta of broiler chickens administered 3H-labeled T-2 toxin.

A method for the detection of T-2 metabolites was developed and applied to analysis of metabolites in excreta of broiler chickens administered 3H-labeled T-2 toxin. The method used acetonitrile extraction and partitioning with petroleum ether followed by chromatography on Amberlite XAD-2, Florisil, and Sep-Pak C18. The recovery of T-2 toxin added to the chicken excreta was 73% at a concentration of 0.2 microgram/g. About 80% of orally administered 3H-labeled T-2 toxin was rapidly metabolized to more polar derivatives and eliminated in the excreta within 48 h. T-2 toxin, HT-2 toxin, neosolaniol, and T-2 tetraol were detected at 0.06 to 1.13% of the total dose, 48 h after administration. Eight unknown derivatives, named TB-1 to TB-8, were quantitatively more significant than the metabolites above. TB-3 and TB-9 represented about 12 and 25% of the total dose, respectively. One of the metabolites (TB-6), 1.5% of the total dose, was identified as 4-deacetylneosolaniol (15-acetyl-3 alpha, 4 beta, 8 alpha-trihydroxy-12, 13-epoxytrichothec-9-ene).     

Zearalenone, deoxynivalenol, and T-2 toxin associated with stalk rot in corn.

The mycotoxins zearalenone (2.8 micrograms/g), deoxynivalenol (1.5 microgram/g), and T-2 toxin (110 ng/g) have been found in the pith of corn stalks standing in the field. Such contaminated stalks may contribute to mycotoxicoses of farm animals.     

Zearalenone, deoxynivalenol, and T-2 toxin associated with stalk rot in corn.

The mycotoxins zearalenone (2.8 micrograms/g), deoxynivalenol (1.5 microgram/g), and T-2 toxin (110 ng/g) have been found in the pith of corn stalks standing in the field. Such contaminated stalks may contribute to mycotoxicoses of farm animals.     

Analysis of T-2 and HT-2 toxins in oats and other cereals by means of HPLC with fluorescence detection

Bearing in mind the high toxicity of T-2 and HT-2 toxins which occur in cereals (mainly in oats) EU plans legal limits for these mycotoxins. The occurrence data are insufficient because reliable and sensitive analysis methods are not available. A sensitive HPLC gradient method was developed which is applicable with common HPLC equipment (HPLC with fluorescence detection). After extraction of the toxins from sample matrix with methanol/water the diluted extracts were cleaned-up using immunoaffinity columns and then derivatized with 1-anthroylnitrile/DMAP. The T-2 and HT-2 toxins were separated from peaks of the cereal matrix and derivatization reagent by means of a relatively complex HPLC gradient method. The method was validated for oats, wheat, rye, barley, and maize. The recovery rates were in the range of 70–99%, the precision (RSD_R) of 3–8%. The limits of detection of T-2 and HT-2 toxins were 1 μg/kg. A total of 119 samples of cereals and cereal products was analyzed according to the optimized method. The analyses of 54 samples of dehulled oats and of 11 samples of processed oat products from food industry had a contamination frequency of 100%. The contents (sum of T-2 and HT-2 toxins) amounted to 3 to 174 μg/kg for the dehulled oats and to 4 to 48 μg/kg for the processed oat products. 29 samples of maize and maize products had a contamination frequency of 80% (2–106 μg/kg in the sum of T-2 and HT-2 toxins). In the samples of wheat and barley the toxins were detected only occasionally (contents: 1–10 μg/kg), in rye not at all.     

M&B 28,767: a potent anti-secretory and anti-ulcer PG analogue. A comparative study with 16, 16' dimethyl PGE2 methylester

M&B 28,767 [(+/-)11-deoxy-16-phenoxy-omega-tetranor PGE1] and 16, 16'-dimethyl PGE2 methylester (DMPG) were compared for their effects on gastric acid secretion (GAS) and gastric ulceration (GU), employing various laboratory models. In anaesthetised rats, GAS was stimulated by a continuous i.v. infusion of pentagastrin (30 micrograms/kg/h), and PG analogues were perfused through the stomach for 1 h. M&B 28,767 (3-15 micrograms/kg/h) and DMPG (3-60 micrograms/kg/h) reduced GAS in a dose-related manner, the ED50 values being 4 and 15 micrograms/kg/h respectively. In conscious rats possessing indwelling gastric cannulae, oral doses of M&B 28,767 (0.025-0.1 microgram/kg) and DMPG (0.50-1.0 microgram/kg) caused a prolonged inhibition of pentagastrin-stimulated GAS. M&B 28,767 was 17 times more potent than DMPG; the respective ED50 values were 0.036 and 0.6 microgram/kg. Indomethacin-induced ulceration in rats, was reduced by both M&B 28,767 and DMPG; the respective ED50 values being 3.0 and 0.8 micrograms/kg. Both compounds given orally increased gastrointestinal motility in mice; M&B 28,767 (1-3 mg/kg) and DMPG (0.1-0.3 mg/kg) caused diarrhoea, the former being about 0.1 times as potent as the latter. In another test, M&B 28,767 (0.5-5.0 mg/kg) and DMPG (10-40 micrograms/kg) overcame morphine-induced constipation in a dose-related manner, the respective ED50s being 0.9-1.4 mg/kg and 20-40 micrograms/kg. Thus, M&B 28,767 had a better profile of activity than DMPG as an antisecretory and antiulcer agent.     

Swine refusal factors elaborated by Fusarium strains and identified as trichothecenes.

Fusarium poae (Peck) Wollenw. NRRL 3287, F. nivale (Fr.) Ces. NRRL 3289, and F. moniliforme Sheldon NRRL 3197, each grown on cracked corn (13 days at 28 degrees C), produced refusal factors in pig bioassays. Substantial quantities of trichothecenes were detected in the refused corn: T-2 toxin (30 micrograms/g) was detected in corn fermented with the F. poae strain; the level of vomitoxin (1 microgram/g) in corn cultured with F. nivale did not account for the 48% refusal response in the pigs tested. The F. moniliforme concomitantly produced T-2 toxin (33 micrograms/g) and vomitoxin (1.5 micrograms/g). This strain's taxonomic position was reexamined, and it is shown to be a cultural variant of the species F. tricinctum (Cda.) Sacc.     

Trichothecenes and Mycoflora in Wheat Harvested in Nine Locations in Buenos Aires Province, Argentina

A total of 120 freshly harvested wheat samples from the 2004 season in nine locations from Northern Buenos Aires Province, Argentina, were analysed for trichothecene natural occurrence and associated mycoflora, and for determining the influence of commonly used fungicide field treatment and the cultivar type on trichothecene contamination. The trichothecenes T-2 tetraol, T-2 triol, HT-2 and T-2 toxin (HT-2, T-2), diacetoxyscirpenol (DAS), nivalenol (NIV), deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-ADON) and 15-acetyldeoxynivalenol (15-ADON) were analysed by gas chromatography and electron capture detection. Detection limits ranged from 4 to 20 μg/kg. The isolation frequencies of species were calculated. Alternaria alternata, Fusarium graminearum, Fusarium poae and Fusarium semitectum were the predominant fungal species identified as endogenous mycoflora. The type of cultivar and the fungicide field treatment did not affect significantly the trichothecene contamination. The trichothecenes type A detected were HT-2 and T-2 triol toxins and the type B were DON, NIV and 3-ADON. Based on 120 samples the incidences were 21.7% for 3-ADON, 22.5% for HT-2, 27.5% for T-2 triol and 85% for DON. NIV was confirmed in one sample. Mean levels of trichothecene positive samples were between 7 and 2788 μg/kg.     

The enzymes of the metabolism of exogenous compounds in the comparative assessment of the toxicity of trichothecene mycotoxins

Moderate clinical, biochemical and hematologic signs of intoxication were observed in mice after single administration of HT-2 toxin (deacetylated derivative of T-2 toxin) in LD50 of 12.75 mg/kg or in 1/5 of LD50 for 7 days. The toxin produced no toxic effect when 1/10 and 1/50 of LD50 were administered for 14 days. With the dose exceeding 1/50 of LD50 a reduction in cytochrome P-450 content, carboxylesterase activity and increased activity of UDP-glucuronosyltransferase and glutathione transferase were recorded. T-2 toxin produced a more pronounced toxic effect, inhibited UDP-glucuronosyltransferase and insignificantly stimulated glutathione transferase activity. Lower HT-2 toxin toxicity is believed to depend on its ability to activate conjugation reactions to a greater extent than T-2 toxin.     

Duckling toxicity and the production of fumonisin and moniliformin by isolates in the A and E mating populations of Gibberella fujikuroi (Fusarium moniliforme).

Two biological species of Gibberella fujikuroi (A and F mating populations) share the Fusarium moniliforme anamorph. Twenty strains of each of these biological species were tested for the ability to produce fumonisins B1, B2, and B3 and moniliformin and for toxicity to 1-day-old ducklings. Most of the members of the A mating population (19 of 20 strains) produced more than 60 micrograms of total fumonisins per g, whereas only 3 of 20 members of the F mating population produced more than trace levels of these toxins and none produced more than 40 micrograms of total fumonisins per g. In addition, only 3 of 20 members of the A mating population produced more than 1 microgram of moniliformin per g (and none produced more than 175 micrograms/g), while all 20 strains of the F mating population produced more than 85 micrograms of this toxin per g and 1 strain produced 10,345 micrograms/g. The duckling toxicity profiles of the strains of the two mating populations were similar, however, and the level of either toxin by itself was not strongly correlated with duckling toxicity. On the basis of our data we think that it is likely that the members of both of these mating populations produce additional toxins that have yet to be chemically identified. These toxins may act singly or synergistically with other compounds to induce the observed duckling toxicity.     

Occurrence of type A,B and D trichothecenes in barley and barley products from the Bavarian market

Fifty-nine samples of barley and barley products were analysed for 18 trichothecene mycotoxins by a sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method (detection limits 0.062-0.70 μg/kg) after sample extract clean-up on MycoSep®-226 columns. The samples were collected in 2009 from barley processing facilities (mills and malt houses) and at wholesale and retail stage from the Bavarian market. The predominant toxins were T-2 toxin (T-2), HT-2 toxin (HT-2) and deoxynivalenol (DON). For all samples, the mean levels of T-2 and HT-2 were 3.0 μg/kg and 6.8 μg/kg with rates of contamination of 63% and 71%, respectively. The maximum values were 40 μg/kg for T-2 and 47 μg/kg for HT-2. The rate of contamination with DON was high (95%) with a low mean level of 23 μg/kg. The DON levels ranged between 3.4 to 420 μg/kg. For T-2 tetraol, a mean level of 9.2 μg/kg and a maximum level of 51 μg/kg with a rate of contamination of 71% were determined. NIV was detected in 69% of the samples with a mean level of 11 μg/kg and a maximum level of 72 μg/kg. Other type A and B trichothecenes were detected only in traces. Type D trichothecenes, fusarenon-X, verrucarol and 4,15-diacetylverrucarol were not detected in any sample. Winter barley and malting barley were the most contaminated groups of all samples in this study. In malting barley, the highest levels of contamination with type A trichothecenes were found. In contrast, winter barley showed the highest contamination with type B trichothecenes. The lowest mycotoxin concentrations were found in de-hulled and naked barley and in pearl barley.     

Toxicity of several insecticide formulations against adult German cockroaches (Dictyoptera: Blattellidae)

Toxicity of bendiocarb, chlorpyrifos, cyfluthrin, cypermethrin, fenvalerate, hydramethylnon, malathion, propetamphos, propoxur, and pyrethrins against the adult German cockroaches, Blattella germanica (L.), was investigated. At LD50, cyfluthrin was the most toxic insecticide to adult males (0.53 microgram/g), adult females (1.2 micrograms/g), and gravid females (0.85 microgram/g). Malathion was the least toxic insecticide to adult males (464.83 micrograms/g), adult females (335.83 micrograms/g), and gravid females (275.90 micrograms/g). Males and gravid females were generally more sensitive than nongravid females to the insecticides that we tested. In tests with malathion, however, males were more tolerant. The order of toxicity of the insecticide classes varied among the stages of adult German cockroaches. The order of toxicity for males and nongravid females was pyrethroids greater than pyrethrins = organophosphates (except malathion) greater than carbamates = amidinohydrazone. The order of toxicity for gravid females was pyrethroids greater than pyrethrins = organophosphates (except malathion) greater than carbamates greater than amidinohydrazone. These differences in toxicity suggest that sex differences should be considered when determining insecticide toxicity for German cockroaches.