Fungal Infestation Research Articles

The chemistry of the postpharyngeal gland of female European beewolves.

Females of the European beewolf, Philanthus triangulum, possess a large glove-shaped gland in the head, the postpharyngeal gland (PPG). They apply the content of the PPG to their prey, paralyzed honeybees, where it delays fungal infestation. Here, we describe the chemical composition of the gland by using combined GC-MS, GC-FTIR, and derivatization. The PPG of beewolves contains mainly long-chain unsaturated hydrocarbons (C23–C33), lower amounts of saturated hydrocarbons (C14–C33), and minor amounts of methyl-branched hydrocarbons (C17–C31). Additionally, the hexane-soluble gland content is comprised of small amounts of an unsaturated C25 alcohol, an unknown sesquiterpene, an octadecenylmethylester, and several long-chain saturated (C25, C27) and unsaturated (C23–C27) ketones, some of which have not yet been reported as natural products. Surprisingly, we found a dimorphism with regard to the major component of the PPG with some females having (Z)-9-pentacosene, whereas others have (Z)-9-heptacosene as their predominant component. The biological relevance of the compounds for the prevention of fungal growth on the prey and the significance of the chemical dimorphism are discussed.

Food wrapping by females of the European Beewolf, Philanthus triangulum, retards water loss of larval provisions

Abstract Females of the European beewolf, Philanthus triangulum F. (Hymenoptera, Crabronidae), embalm the provisions of their larvae, paralyzed honeybees, with a secretion from a postpharyngeal gland prior to oviposition. This food wrapping is known to delay fungus infestation of the prey. In the present study, the hypothesis that the food wrapping has an additional function, namely the prevention of prey desiccation, is tested. Water loss of paralyzed but unembalmed honeybees and embalmed honeybees is measured and the composition and quantity of their cuticular hydrocarbons analyzed by coupled gas chromatography–mass spectrometry. Water loss is significantly lower in embalmed compared with unembalmed bees. This might have important advantages for the larvae under the warm and dry conditions that prevail in some brood cells. The embalming by beewolf females increases the total amount of hydrocarbons on the surface of the bees by almost ten‐fold. Moreover, the proportion of unsaturated and short‐chained hydrocarbons is significantly increased. Unsaturated and short‐chain hydrocarbons are usually less effective against water loss, so the increased protection against water loss appears to be mediated mainly by the thickness of the hydrocarbon layer.

Effect of Fungal Infection and the Application of the Biological Agent EM 1<sup>™</sup> on the Rate of Photosynthesis and Transpiration in Pea (<i>Pisum Sativum</i> L.) Leaves

Field experiments conducted during the years 2003-2005 showed that the rate of photosynthesis and transpiration decreased as a result of pea infection by Peronospora viciae. Foliar application of effective microorganisms (EM) combined with chemical control increased the rate of photosynthesis in pea, while other methods of EM application reduced net photosynthesis values (An). Chemical control and seed dressing with the tested biological agent caused a significant decrease in molar transpiration (E) values, compared to the control treatment. Soil application of EM contributed to inhibiting fungal pathogen infestation on pea plants.

Assessment of Thymus vulgaris L. essential oil as a safe botanical preservative against post harvest fungal infestation of food commodities

Abstract A total of 14 odoriferous angiospermic essential oils were tested against the toxigenic strain of Aspergillus flavus. The essential oil of Thymus vulgaris L. showed highest antifungal efficacy. The thyme oil absolutely inhibited the mycelial growth of A. flavus at 0.7 μl ml− 1 and exhibited a broad fungitoxic spectrum against eight different food contaminating fungi viz. Fusarium oxysporum, Cladosporium herbarum, Curvularia lunata, Aspergillus terreus, Aspergillus niger, Aspergillus fumigatus, Alternaria alternata and Botryodiploidia theobromae. The oil also showed significant antiaflatoxigenic efficacy as it completely arrested the aflatoxin B1 production at 0.6 μl ml− 1. Thyme oil as fungitoxicant was also found superior over most of the prevalent synthetic fungicides. The LC50 of thyme oil against mice was recorded as 7142.85 μl kg− 1 body weight indicating its non-mammalian toxicity and strengthening its safe exploitation as preservative for stored food commodities. The findings recommend the thyme oil as potential botanical preservative in eco-friendly control of biodeterioration of food commodities during storage. Industrial relevance The thyme essential oil may be recommended for large scale application as a plant based preservative for stored food items because of its strong antifungal as well as antiaflatoxigenic efficacy. Because of broad antimicrobial spectrum, more efficacy over prevalent synthetic preservatives as well as non-mammalian toxicity, the thyme essential oil may be formulated as a safe and economical plant based preservative against post harvest fungal infestation and aflatoxin contamination of food commodities.

Some Fungi and Water Molds in Waters of Lake Michigan with Emphasis on Those Associated with the Benthic Amphipod Diporeia spp.

To determine types of fungi in the water and associated with the benthic amphipod Diporeia spp., samples were collected at various depths in Lake Michigan in an area where the Diporeia population was in a severe state of decline. No fungi were found associated with living, freshly-dead, or dried Diporeia cultured separately from Lake Michigan water. When dead Diporeia and other organic substrates (snake skin and hemp seeds) were used to grow fungi in Lake Michigan water, a rich and diverse fungal and water mold community was revealed. A total of 31 species were found, with the most common genera being Achlya, Aphanomyces, Myzocytium, and Pythium. In general, species were homogeneously distributed in the water; that is, few differences were found in species richness between nearshore (10–15 m) and offshore (60–80 m) waters, and between near-surface (1 m) and near-bottom waters (1 m off bottom). Sampling occurred during the unstratified period (April and October) to maximize the number of species collected, which may have contributed to the uniform spatial pattern observed. While conclusions must be placed in context with our methods of detection, we found no evidence that a fungal infestation was associated with Diporeia in this region of the lake.

Are green islands red herrings? Significance of green islands in plant interactions with pathogens and pests

The term green island was first used to describe an area of living, green tissue surrounding a site of infection by an obligately biotrophic fungal pathogen, differentiated from neighbouring yellowing, senescent tissue. However, it has now been used to describe symptoms formed in response to necrotrophic fungal pathogens, virus infection and infestation by certain insects. In leaves infected by obligate biotrophs such as rust and powdery mildew pathogens, green islands are areas where senescence is retarded, photosynthetic activity is maintained and polyamines accumulate. We propose such areas, in which both host and pathogen cells are alive, be termed green bionissia. By contrast, we propose that green areas associated with leaf damage caused by toxins produced by necrotrophic fungal pathogens be termed green necronissia. A range of biotrophic/hemibiotrophic fungi and leaf-mining insects produce cytokinins and it has been suggested that this cytokinin secretion may be responsible for the green island formation. Indeed, localised cytokinin accumulation may be a common mechanism responsible for green island formation in interactions of plants with biotrophic fungi, viruses and insects. Models have been developed to study if green island formation is pathogen-mediated or host-mediated. They suggest that green bionissia on leaves infected by biotrophic fungal pathogens represent zones of host tissue, altered physiologically to allow the pathogen maximum access to nutrients early in the interaction, thus supporting early sporulation and increasing pathogen fitness. They lead to the suggestion that green islands are 'red herrings', representing no more than the consequence of the infection process and discrete changes in leaf senescence.

Mycoflora and natural occurrence of aflatoxins and fumonisin B 1 in cassava and yam chips from Benin, West Africa

The presence of fungi, aflatoxins and fumonisin B 1 in cassava and yam chips (during 28 processing and storage) were evaluated during two consecutive seasons in two agroecological zones of Benin (Northern Guinea Savannah, NGS and Sudan Savannah, SS). The Benin samples were assessed for moisture content, fungal infestation and total aflatoxin and fumonisin B 1 contamination. During the two seasons, samples collected from the NGS, had moisture contents ranging from 10.0 to 14.7% in cassava chips and from 11.4 to 15.3% in yam chips. In samples from the SS, moisture content ranged from 10.1 to 14.5% and 11.1 to 14.5% in cassava and yam chips, respectively. A. flavus was the predominant fungal species. The maximum cfu/g in cassava and yam chips was 8950 and 6030, respectively. Other fungal species isolated included P. chrysogenum, M. piriformis, Phoma sorghina, F. verticillioides, R. oryzae and Nigrospora oryzae. High performance liquid chromatography analysis of both cassava and yam chips showed no contamination by either aflatoxins or fumonisin B 1.

Pilze im forensischen Obduktionswesen

Fungal infestations normally represent additional findings in forensic autopsies, but also may appear as a cause of death. Moreover different kinds of fungi occur during late postmortem decay. In this paper, particular emphasis is put on the context of immunodeficiency and finally, lethal septic states.

Methods for preventing, decontaminating and minimizing the toxicity of mycotoxins in feeds

Moulds and associated mycotoxins are important factors adversely affecting foods produced using contaminated plant products or animal products derived from animals fed on contaminated feeds. Mycotoxins are toxic to humans and animals, which explains the major concern of food and feed industries in preventing them from entering the food chain. Prevention is essential since there are few ways to completely overcome problems once mycotoxins are present. Toxin-producing moulds may invade plant material in the field before harvest, during post-harvest handling and storage and during processing into food and feed products. Thus, toxigenic fungi have been roughly classified into two groups (i) field fungi; (ii) storage fungi. The Fusarium genus, e.g. F. verticillioides (formerly F. moniliforme), F. roseus, F. tricinctum and F. nivale, are ubiquitous soil organisms, which may infect cereals directly in the field thereby, increasing fumonisins, trichothecene, and zearalenone levels (depending on the species) during growth, ripening of grain and at harvesting. Fusarium sp. can have deleterious effect on plants and decrease plant productivity. Many species can infect heads of wheat and other small grain cereals in fields causing head scab or blight (FHB). Ear rot also can be caused by Fusarium sp. growing on maize. Furthermore, fungi can grow on the non-grain part of plants producing large amounts of mycelium towards the stem where it colonizes the vascular bundles, which inhibits the transfer of nutrients in the upper part of the plant. On the contrary, Fusarium sp. does not significantly contribute to the storage fungi or to the fungal contaminants found only on damaged grains. Due to the multiple possible origins of fungal infection, any prevention strategy for fungal and mycotoxin contamination must be carried out at an integrative level all along the food production chain. Three steps of intervention have been identified. The first step in prevention should occur before any fungal infestation; the second step is during the period of fungal invasion of plant material and mycotoxin production; the third step is initiated when the agricultural products have been identified as heavily contaminated. Such hazard analysis has some similarity with the HACCP management system of food safety [Degirmencioglu N., Esecali H., Cokal Y., Bilgic M., 2005. From safety feed to safety food: the application of HACCP in mycotoxin control. Arch. Zootech. 8, 19–32], mainly with the principles 2 (Determination of critical control points) and 3 (Establish critical limits). Most of the efforts must be concentrated on the two first steps since, once mycotoxins are present, it is difficult to eliminate them in a practical way.

Effects of the Harvest Method on the Infestation of Chestnuts (Castanea sativa) by Insects and Moulds

AbstractChestnuts were collected either every 7 days from suspended nets used to intercept the fruits, every 2 days from the ground or every 7 days from the ground. Nuts were visually inspected after collection for the presence of exit holes of the chestnut weevil (Curculio elephas) and the chestnut moth (Cydia splendana), and 20 nuts per sampling and tree were bisected to assess fungal colonization. Apparently healthy nuts were incubated at 24°C and 70–80% relative humidity for 21 days. All nuts were bisected after incubation and examined for the presence of insects and moulds. The harvest method did not have a statistically significant effect on either moulding or insect infestation except onAmphiporthe castanea. This vertically transmitted fungal endophyte was less frequently isolated from fruits collected after 7 days from the ground. The black rot fungusCiboria batschianadid not occur in chestnuts intercepted in nets, but the difference to chestnuts collected from the ground was statistically not significant. The frequency of nuts colonized byC. batschianawas low in general probably due to the hot and dry summer in 2003. Big, marketable fruits appeared to be less frequently colonized by insects and moulds right after collection. This difference disappeared after incubation except for the chestnut moth. The mother tree had the greatest effect on fungal and insect infestation, indicating the importance of the genetic disposition and/or the phytosanitary situation of each tree. The chestnut weevil preferred chestnuts of the variety ‘Lüina’ to those of the variety ‘Torcion’, whereas the fungiA. castanea,Trichothecium roseum,Clonostachys roseaandPenicilliumspp. preferentially colonized chestnuts of the variety ‘Torcion’.

Evaluation of some essential oils as botanical fungitoxicants for the protection of stored food commodities from fungal infestation

AbstractEssential oils from different parts of 18 plants belonging to 11 families were extracted and tested against two toxigenic strains of Aspergillus flavus Link through the poisoned food technique. The oil of Mentha arvensis was found to be effective against both strains of A. flavus and completely stopped the radial mycelial growth of A. flavus at 0.10 mg mL−1. It was found to be superior over the synthetic fungicides tested and showed a broad fungitoxic spectrum against A. niger, A. fumigatus, Botryodiplodia theobromae, Cladosporium cladosporioides, Fusarium oxysporum, Helminthosporium oryzae, Macrophomina phaseolina and Sclerotium rolfsii at 0.10 mg mL−1. The oil completely inhibited the aflatoxin B1 production by the toxigenic strain of A. flavus at 0.05 mg mL−1. Moreover, the Mentha oil also exhibited potent antioxidant activity in 2,2′‐azino‐bis‐3‐ethylbenzothiazoline‐6‐sulphuric acid (ABTS) bioassay. Keeping in mind the side effects of synthetic pesticides and the global interest in botanical pesticides for plant protection due to their biodegradable nature, M. arvensis oil may be used as a botanical fungitoxicant against fungal attack to stored food commodities. The antiaflatoxigenic and antioxidant nature of the oil suggest the possibility of its exploitation for enhancing the shelf life of stored food commodities. Copyright © 2007 Society of Chemical Industry

Life within insect antennae: Symbiotic bacteria protect wasp larvae against fungal infestation

Life within insect antennae: Symbiotic bacteria protect wasp larvae against fungal infestation

Life within insect antennae: Symbiotic bacteria protect wasp larvae against fungal infestation

Life within insect antennae: Symbiotic bacteria protect wasp larvae against fungal infestation

Preservative property of Aframomum danielli fractions in stored grains

The use of petroleum ether and ethanol fractions of Aframomoum danielli was explored in the preservation of stored grains; soybean, cowpea and maize. Preservation property of A. danielli increased with increase in concentration of fractions used. The ethanolic fractions showed higher activity in reducing fungal infestation than petroleum ether fractions.

Influence of harvest date and geographical location on kernel symptoms, fungal infestation and embryo viability of malting barley

This study focused on the influence of harvest timing and geographical location on spring malting barley (potential malting variety) in terms of fungal infestation and seedling viability in symptomatic and asymptomatic kernels. The study was conducted over two consecutive crop years (2003–2004) at four locations in Slovakia. The following categories of the barley kernels were used for the assessment: kernels with black point symptoms (BPK), kernels with black cover on their surface (BCK), pink-colored kernels (PCK) and asymptomatic kernels (AK). The occurrence of various fungi was detected in all kernel categories ranging from 60 to 100%. The most frequent fungal contaminants were members of the genus Alternaria, recovered from BPK in the range of 52.6–69.85%, BCK (62.36–73.28%) and AK (55.35–69.58%). The prevalence of Alternaria spp. was recorded for each harvest time. Other dematiaceous fungi, Epicoccum nigrum and Cochliobolus sativus were found with medium frequency in the same three categories. However, C. sativus was recovered with a higher frequency in BPK (2.6–25.3%). In PCK, the most commonly recovered fungi were species of Fusarium with F. avenaceum (59.2–93.2%) as the most prevalent. The infestation of kernels by fungi from other genera showed only low frequency within all the kernel categories investigated. There was no significant influence of the year and location on the proportion of the symptomatic kernel categories. Kernel germination was inhibited to a greater degree in the wetter and colder year. The strongest inhibition of germination ranging from 2.35 to 22.45% was recorded in PCK in all locations and both years. Germination declined from PCK to BCK (43.2–90.32%), and BPK (45.6–91.61%), while it was highest in AK at all harvest times (63–93.6%). This study found that the black covering symptoms (BCK) caused greater damage to viability of the kernels than black point symptoms (BPK). The delayed harvest time resulted not only in increasing numbers of discolored kernels and undesirable symptomatic kernel fractions but also in lower germination of the kernels tested.

Frequency of Alternaria brassicicola in commercial cabbage seeds in Japan

Plug seedlings, widely used in cabbage cultivation in Japan, are often infected by seed-borne pathogens, especially the serious pathogen Alternaria brassicicola. Because information on seed infestation is scant in Japan, we investigated fungal infestation in commercial batches of cabbage seeds produced between 1984 and 2001. A total of 123 lots were divided into six groups by production period (1984–1989, 1994–1998, and 2001) and by use or nonuse of fungicide. One hundred seeds from each lot were incubated separately on agar at 25°C to isolate the predominant fungus. Alternaria brassicicola was isolated most frequently, 0%–94% of the seeds depending on seed lot or 6%–21% of the seeds grouped by production period and fungicide treatment. Thus, the pathogen was isolated even from seeds refrigerated for 17 years. Alternaria brassicicola accounted for 57%–95% of all isolated fungi by the group and was higher on older or fungicide-treated seeds. Seeds that were not treated with fungicide in lots grouped by production districts in western Japan were infested with A. brassicicola at a rate of over 12%, higher than that in the eastern region (<4%). Infestation was higher in the warmer areas of Japan. Eighty-five isolates, other than A. brassicicola, produced spots on cabbage cotyledons, although they were not isolated as frequently: less than 5% of seeds by group separated by production period and fungicide treatment. Most of these isolates were Alternaria alternata. This is the first report on the frequency of fungal infestation of commercial cabbage seeds in Japan.

Effect of bacterium Pseudomonas fluorescens and low fungicide dose seed treatments on parasite fungus Aphanomyces cochlioides and sugar beet yield and quality

Effect of sugar beet seed inoculation with a bacterium Pseudomonas fluorescens and treatment by fungicides Thiram&amp;nbsp;42-S and Dithane S-60 with and without seed inoculation aiming to control Aphanomyces cochlioides &amp;ndash; root decay agent was studied. The trial lasted for three years on two soil types (Mollic Gleysols and Eutric Cambisols). The following parameters of sugar beet yield and quality were investigated: root yield, sugar content, sugar in molasses, sugar yield as well as percentage of the infected and decayed plants as a consequence of parasite fungus infestation. The highest average sugar beet root yield was obtained in the variant of the seed treated with fungicide Thiram 42-S and inoculated with bacterium P. fluorescens (85.15 t/ha). However, there were no statistically significant differences (P &amp;lt; 0.05) between the above-mentioned variant and the one with seed inoculated only with bacterium P. fluorescens (84.63 t/ha). The highest mean sugar content of 16.39% was also accomplished during the three-year investigation in the variant of the inoculated seed treated by fungicide Thiram 42-S. All other variants accomplished statistically very significantly lower values of this parameter. The same variant was characterized by the highest mean sugar yield value (12.79 t/ha) on both soil types. Namely, an average sugar yield of the variants inoculated with bacteria was 11.22 t/ha and by 44.22% higher compared to an average yield of non-inoculated variants. The highest percent of the infected and decayed plants (average value on both soil types in the three year investigation) was reported in the control variant (28.92% infected and 25.00% decayed plants) whereas the lowest one was detected in the variant of the seed inoculated with bacterium P. fluorescens in combination with low dose of fungicide Thiram 42-S (4.70% infected plants and 2.88% decayed plants). An average percent of the infected plants inoculated with bacterium P.&amp;nbsp;fluorescens was 9.13% whereas the aforesaid value of the plants infected with parasitic fungus A. cochlioides in non-inoculated variants was by 146.00% higher being 22.42%.

Interaction of Fusarium solani f. sp. glycines and Heterodera glycines in Sudden Death Syndrome of Soybean

ABSTRACT Sudden death syndrome (SDS) of soybean is caused by the soilborne Fusarium solani f. sp. glycines (synonym F. virguliforme). In a sequential approach, two multifactor factorial-design microplot experiments were conducted to investigate the effects of fungal infestation levels and soil moisture on both root necrosis and foliar SDS severity, and the interaction between F. solani f. sp. glycines and Heterodera glycines in fumigated versus nonfumigated soil. In 2003, soybean cv. Spencer was grown in nonfumigated or methyl bromide-fumigated soil and infested with increasing levels of F. solani f. sp. glycines, either under rainfall or irrigated after growth stage V6/R1. In 2004, interactions between F. solani f. sp. glycines and H. glycines were explored in a factorial inoculation design in fumigated or nonfumigated soil, planted to Williams 82 or Cyst-X20-18. In both years, higher levels of foliar SDS severity and root necrosis were found in F. solani f. sp. glycines-infested soils with H. glycines than in soils without the nematode on the soybean cultivars susceptible to both pathogens. Both natural infestations of H. glycines in 2003 and artificially amended populations of H. glycines in 2004 contributed to higher foliar SDS severity. More severe foliar SDS symptoms always were associated with more root necrosis, but elevated levels of root necrosis did not predict severe leaf symptoms. In contrast to the critical role of H. glycines, increasing fungal infestation levels had no significant effects on increasing either foliar SDS symptoms or root necrosis. Effects of moisture regime and fungal infestation levels also were examined in factorial greenhouse and growth chamber experiments. High soil moisture resulted in higher levels of SDS root necrosis. In the greenhouse, root necrosis increased at a higher rate in low soil moisture than the rate in high soil moisture. The two pathogens acted as a complex and the disease development was strongly dependent on high soil moisture.

Assessment of blue-stain resistance according to the EN 152 and a reverse test method using visual and computer-aided techniques

A computer technique for assessing blue-stained coated wood has been implemented for evaluating the discoloration of coatings and analysing the interior wood staining of samples subjected to testing according to European Standard EN 152. The comparison of visual assessment and computer-evaluated percentages of blue staining is based on a combination of correlation measures, principal components and cluster analysis. It appears difficult to imitate human evaluation with image processing, since computer ratings represent exact percentages, while subjective evaluations do not. Additionally, more specific techniques for exploring fungal growth in coated wood have been described. As EN 152 was specifically developed for testing efficacy of wood preservatives, a modified test methodology was elaborated for testing the efficacy of wood coatings, called here as the EN 152-reverse method. Furthermore three-dimensional (3D) reconstruction is validated as a tool for in-depth analysis of blue-stain disfigurement. This 3D visualisation indicates important differences in fungal infestation and proves its suitability for blue-stain resistance testing.

Phytotoxic effects of fumonisin B1 on cowpea seed

The cultivation of cowpea (Vigna unguiculata) plays a vital role in the livelihood of many subsistence farmers and rural communities in tropical and subtropical countries. The seeds are prone to fungal infestation and mycotoxin contamination during sub-optimal storage conditions. Fumonisin B1 (FB1), produced byFusarium proliferatum, has been detected in cowpea seeds. Surface-disinfected seeds were imbibed in sterile distilled water amended with FB1 at various concentrations. Percentage germination was determined according to the International Seed Testing Association rules. All the toxin concentrations significantly decreased seed germination and the two highest concentrations — 50 and 100µg ml−1 FB1 — inhibited root and shoot elongation. FB1-treated embryonic tissues evinced compaction of the protoplasm and separation of the plasmalemma from the cell wall. Lipid bodies accumulated, which seemed to be lining the cell wall. This is the first study to demonstrate the phytotoxic effects of FB1 on cowpea seeds.