Impact of storage conditions on the shelf life of aflatoxin biocontrol products containing atoxigenic isolates of Aspergillus flavus as active ingredient applied in various countries in Africa

Aflatoxin contamination significantly threatens food safety and security, particularly in tropical and sub-tropical regions where staple crops such as maize, groundnut, and sorghum become frequently affected. This contamination is primarily caused by the fungus Aspergillus flavus. The contamination causes adverse health effects, reduced income, and trade restrictions. In response to this challenge, various technologies have been developed to mitigate the impacts of aflatoxin. Among these, biocontrol products containing atoxigenic isolates of A. flavus as the active ingredient can effectively reduce aflatoxin levels both at pre- and post-harvest. A notable example of such products is Aflasafe, which contains four atoxigenic isolates native to specific target regions. These products have undergone rigorous testing, have received regulatory approval, and are commercially available in multiple African countries. However, their manufacturing processes have evolved, and comprehensive shelf life studies for current formulations are lacking. Evaluations of the spore production ability of atoxigenic A. flavus isolates in Aflasafe products over 4 years, under various storage conditions, revealed a significant linear decrease in sporulation with storage months (P < 0.001; R 2  = 0.203), with no significant differences observed between treatments. However, this marginal decline (P = 0.398) is unlikely to be sufficient to prevent the effectiveness in limiting aflatoxin. In addition, storing the products for 2 weeks at 54 °C did not affect (P > 0.05) the ability of the coated fungi to produce spores compared to when the products were stored at 24 °C. The findings contribute valuable insights for manufacturers and users of atoxigenic-based aflatoxin biocontrol products, informing best practices for product storage and utilization to ensure prolonged effectivenes in aflatoxin mitigation efforts.

Leaffooted Bugs: Insect Pest Species of Growing Concern for Agriculture

Leptoglossus (Hemiptera: Coreidae) are a diverse genus of phytophagous insects. Literature regarding Leptoglossus has increased as species are identified as emerging agricultural pests or reported outside of their native range. Within Leptoglossus, five species dominate the literature and are known pests and vectors of plant pathogenic microbes in several major crops. Despite the increasing profile of Leptoglossus, current monitoring and management methods rely primarily on visual inspection, and semiochemical tools have yet to be developed. This Perspective identifies and discusses gaps in the Leptoglossus literature as well as areas of research needed for the development of effective tools for monitoring insect populations and enabling informed pest-management practices.

The Effects of Insect Infestation on Stored Agricultural Products and the Quality of Food

In this review article, we focus on the effects of insect pests on the quality of stored cereals and legume grains. The changes in the amino-acid content, the quality of proteins, carbohydrates, and lipids, and the technological characteristics of the raw materials when infested by specific insects are presented. The differences reported concerning the rate and kind of infestation effects are related to the trophic habits of the infesting insect species, the variation of the component distribution in the different species of grains, and the length of the storage period. For example, wheat germ and brans feeders such as Trogoderma granarium may cause a higher reduction in proteins than endosperm feeders such as Rhyzopertha dominica, since the germ and brans contain higher concentrations of proteins. Trogoderma granarium may also cause higher reduction in lipids than R. dominica in wheat, maize and sorghum, in which most of the lipids exist in the germ. Furthermore, infestation with insects such as Tribolium castaneum may downgrade the overall quality of wheat flour, by increasing the moisture content, the number of insect fragments, the color change, the concentration of uric acid, the microbial growth, and the prevalence of aflatoxins. Whenever possible, the significance of the insect infestation and the concomitant compositional alterations on human health are presented. It should be highlighted that understanding the impact of insect infestation on stored agricultural products and the quality of food will be crucial for the required food security in the future.

Plain set and stirred yogurt with different additives: implementation of food safety system as quality checkpoints

Hazard Analysis Critical Control Point (HACCP) is a risk management protocol developed to ensure food safety through a precautionary approach that is believed to offer assurances in producing safe food for customers. Yogurt is made in a number of phases, commencing with the collection of raw milk and ending with consumer consumption. While this is happening, major economic and health issues might arise from exposing the manufacturing line to biological, chemical, and/or physical contaminations. As a result, the decision tree approach was used to determine the CCPs during the production of yogurt. Additionally, biological dangers are incorporated as a by-product of the system's implementation performance. In particular, the plain set and nut puree-honey-fortified stirred yogurt manufacturing techniques are highlighted for the first time in this study. The potential manufacturing risks are described for the first time, together with information on how HACCP plans may guard against major risks that could result in the production of yogurt that is not in compliance with established standards.

The Effect of Monitoring System on Risk Assessment of Aflatoxins in Iran's Pistachio Nuts Exported to the E.U. During 2012 - 2018

Pistachio has high nutritional value and popularity. The susceptibility of pistachio to aflatoxin contamination caused establishing a monitoring system introduced and implemented by the Ministry of Health in Iran to ensure consumers' access to safe and hygienic pistachios. In this research, aflatoxin contamination level in all consignments (7298) exporting to E.U. was examined using HPLC with fluorescence detection after immunoaffinity column clean up from Nov 2012 to Oct 2018. The average recoveries ranged 78.6% - 97.6%, with a relative standard deviation for reproducibility below 8.5% and expanded uncertainty of aflatoxin B1 (AFB1) at spiked levels 1, 4, and 8 ng/g were 0.17, 0.57, 0.89 ng/g, respectively. The results showed that aflatoxin B1 and total (AFT) were detected in 1921 (23.4%) and 1927 cases (23.5%), with the mean values ranging from 2.18 - 4.6 ng/g and 2.8 - 5.1 ng/g during six consecutive years, respectively. Implementing an effective monitoring system for pistachio nuts could determine consignments contaminated with aflatoxins. Concerning AFB1, risk assessments recorded for dietary exposure dose, margin of exposure (MOE), Hazard Index (HI), estimated liver cancer risk, and cancer incidence attributable to dietary ranged 0.0132 - 0.1180 ng/kg.bw/day, 1441 - 12843, 0.21 - 1.84, 0.00071 - 0.00633 cases/10⁵ population/year, 0.02 - 0.2%, respectively. Identification and rejection of contaminated cargos lead to an increase in MOE (> 10000), and it also guarantees that pistachio consumption is safe from a toxicology point of view. Due to the monitoring system, the estimation of liver cancer incidence attributable to dietary AFB1 was reduced (≤ 0.02%). It indicates that the consumption of pistachio poses no health risk for Europeans and Iranians.

Effect of biological treatment used before harvesting and storage methods on the quality, health and microbial characteristics of unripe hazelnut in the husk (Corylus avellana L.)

BACKGROUND

The hazelnut (Corylus avellana) is still one of the most profitable nut crop species. In recent years, however, there has been growing interest in this species in the form of "fresh nuts" that are picked before falling out of the fruit cover. The aim of this study was to evaluate the effect of storage conditions for hazelnuts protected with biological preparations on selected morphological features of the fruits, their health status and the count of bacteria and fungi colonizing the fruits.

RESULTS

The hazelnuts harvested from the trees protected with a preparation containing Pythium oligandrum and stored for 2 months under the controlled atmosphere conditions and in Xtend® bags (MAP) had the greatest weight and the highest percentage of the kernel. After 3 months of storage, the hazelnuts had reduced commercial value. Only a few hazelnuts displayed symptoms of infectious diseases caused by species of Botrytis and Monilia. The protection applied before the hazelnut harvesting contributed to a multiple increase in the bacterial and yeasts count on the husks and shells of the hazelnuts stored for 3 months. The bacterial count on the nuts stored under the controlled atmosphere (CA, 3%O₂:3%CO₂, a temperature of 0-1 °C, humidity of 85-95%) and under the controlled atmosphere conditions and in Xtend® bags (MAP) increased significantly. An analysis of the ITS region sequence revealed the presence of bacteria Arthrobacter luteolus and Pantoea agglomerans. A Koch test proved that both non-pathogenic bacteria and pathogenic fungi can cause the browning of the C. avellana leaf under conditions of high humidity. The application of a controlled atmosphere is recommended for a short-term storage of hazelnuts in the husk.

CONCLUSION

This research showed that 2 months' storage of hazelnuts under controlled atmosphere conditions and Xtend® bags (MAP) prevented a reduction in the weight of hazelnuts in the husk, without the husk, and of the kernel and prevented the nut separation from the husk. In general, the application of biopreparations for the protection of the hazelnut had a positive effect on the kernel weight and size.

Antifungal Efficacy of Redox-Active Natamycin against Some Foodborne Fungi-Comparison with Aspergillus fumigatus

The fungal antioxidant system is one of the targets of the redox-active polyene antifungal drugs, including amphotericin B (AMB), nystatin (NYS), and natamycin (NAT). Besides medical applications, NAT has been used in industry for preserving foods and crops. In this study, we investigated two parameters (pH and food ingredients) affecting NAT efficacy. In the human pathogen, Aspergillus fumigatus, NAT (2 to 16 μg mL⁻¹) exerted higher activity at pH 5.6 than at pH 3.5 on a defined medium. In contrast, NAT exhibited higher activity at pH 3.5 than at pH 5.6 against foodborne fungal contaminants, Aspergillus flavus, Aspergillus parasiticus, and Penicillium expansum, with P. expansum being the most sensitive. In commercial food matrices (10 organic fruit juices), food ingredients differentially affected NAT antifungal efficacy. Noteworthily, NAT overcame tolerance of the A. fumigatus signaling mutants to the fungicide fludioxonil and exerted antifungal synergism with the secondary metabolite, kojic acid (KA). Altogether, NAT exhibited better antifungal activity at acidic pH against foodborne fungi; however, the ingredients from commercial food matrices presented greater impact on NAT efficacy compared to pH values. Comprehensive determination of parameters affecting NAT efficacy and improved food formulation will promote sustainable food/crop production, food safety, and public health.

Quantification of the Aflatoxin Biocontrol Strain Aspergillus flavus AF36 in Soil and in Nuts and Leaves of Pistachio by Real-Time PCR

The species Aspergillus flavus and A. parasiticus are commonly found in the soils of nut-growing areas in California. Several isolates can produce aflatoxins that occasionally contaminate nut kernels, conditioning their sale. Strain AF36 of A. flavus, which does not produce aflatoxins, is registered as a biocontrol agent for use in almond, pistachio, and fig crops in California. After application in orchards, AF36 displaces aflatoxin-producing Aspergillus spp. and thus reduces aflatoxin contamination. Vegetative compatibility assays (VCAs) have traditionally been used to track AF36 in soils and crops where it has been applied. However, VCAs are labor intensive and time consuming. Here, we developed a quantitative real-time PCR (qPCR) protocol to quantify proportions of AF36 accurately and efficiently in different substrates. Specific primers to target AF36 and toxigenic strains of A. flavus and A. parasiticus were designed based on the sequence of aflC, a gene essential for aflatoxin biosynthesis. Standard curves were generated to calculate proportions of AF36 based on threshold cycle values. Verification assays using pure DNA and conidial suspension mixtures demonstrated a significant relationship by regression analysis between known and qPCR-measured AF36 proportions in DNA (R² = 0.974; P < 0.001) and conidia mixtures (R² = 0.950; P < 0.001). Tests conducted by qPCR in pistachio leaves, nuts, and soil samples demonstrated the usefulness of the qPCR method to precisely quantify proportions of AF36 in diverse substrates, ensuring important time and cost savings. The outputs of this study will serve to design better aflatoxin management strategies for pistachio and other crops.

Impact of granite irradiation on aflatoxin reduction in pistachio

In this research with the effect of radioactive granite gamma radiation, the reduction of aflatoxin B1 in pistachios was examined in three steps. In the first step, the aflatoxin reduction in small packets by granite bed was tested. In this step, the aflatoxin level of 300 g pistachios packets was reduced up to 81.3 ± 1.5 percent by 4 kg granite bed after 4 days. After observation of aflatoxin reduction by granite bed, the second step was done with increasing the granite and pistachio mass and irradiation time. In this step, the aflatoxin level of 1 kg pistachios was reduced up to 4949 ± 2.6 percent by 6 kg granite after 9 days. According to the results, the aflatoxin reduction of 1 kg pistachios by 1 kg granite after 1 days (as aflatoxin Reduction Coefficient (ARC)) was calculated as ARC = 0.0090 ± 0.0025 (kg. day)^-1. The aflatoxin types of detected in this research were B1 and B2 types that AFB2 level was much less than one. Therefore the effect of granite irradiation on AFB2 reduction wasn't considered. The final step was designed for testing the aflatoxin Reduction Coefficient (ARC). This step was shown that the confidence level between practical result and aflatoxin Reduction Coefficient (ARC) result is about 97 percent. The results indicated that the level of fat and protein of pistachios by granite gamma radiation did not change after 9 days. Therefore the granite irradiation can be used for aflatoxin reduction of pistachios.

Aflasafe SN01 is the First Biocontrol Product Approved for Aflatoxin Mitigation in Two Nations, Senegal and The Gambia

Aflatoxin contamination is caused by Aspergillus flavus and closely related fungi. In The Gambia, aflatoxin contamination of groundnut and maize, two staple and economically important crops, is common. Groundnut and maize consumers are chronically exposed to aflatoxins, sometimes at alarming levels, and this has severe consequences on their health and productivity. Aflatoxin contamination also impedes commercialization in local and international premium markets. In neighboring Senegal, an aflatoxin biocontrol product containing four atoxigenic isolates of A. flavus, Aflasafe SN01, has been registered and is approved for commercial use in groundnut and maize. We detected that the four genotypes composing Aflasafe SN01 are also native to The Gambia. The biocontrol product was tested during two years in 129 maize and groundnut fields and compared with corresponding untreated fields cropped by smallholder farmers in The Gambia. Treated crops contained up to 100% less aflatoxins than untreated crops. A large portion of the crops could have been commercialized in premium markets due to the low aflatoxin content (in many cases no detectable aflatoxins), both at harvest and after storage. Substantial aflatoxin reductions were also achieved when commercially produced groundnut received treatment. Here we report for the first time the use and effectiveness of an aflatoxin biocontrol product registered for use in two nations. With the current scale-out and -up efforts of Aflasafe SN01, a large number of farmers, consumers, and traders in The Gambia and Senegal will obtain health, income, and trade benefits.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.

Aflatoxin reduction in nuts by roasting, irradiation and fumigation: a systematic review and meta-analysis

The present study aimed to investigate the reduction of aflatoxins as a potent hazard for human health in nuts during roasting, irradiation, and fumigation processes. A systematic search was performed in PubMed, Scopus, and ISI Web of Science on 6 April 2020 to find interventional studies assessing the effects of roasting, fumigation, and irradiation methods on total and individual aflatoxins concentration in nuts. Study-specific results were pooled by using a random-effects model. A total of 19 trials were included in the analyses. In most studies, the influence of method on aflatoxin reduction was assessed on peanuts. The results showed that the roasting method significantly reduced aflatoxin B1, B2, G1, and G2 concentrations by 46.91%, 30.66%, 40.88%, and 26.19%, respectively. Such results for the fumigation method were 20.88% and 22.56% for aflatoxin B1 and aflatoxin total, respectively. There was a 58.60% reduction in aflatoxin B1 and a 74.97% reduction in aflatoxin total concentrations in nuts following the irradiation method. The findings indicated that the evaluated processes could be influential for reducing aflatoxin levels in nuts.

Effect of Blanching on Aflatoxin Contamination and Cross-Contamination of Almonds

ABSTRACT

Blanching of almonds was examined for reducing the aflatoxin content of contaminated nuts. Almonds with intact pellicles were spiked with aflatoxin B1 (AFB1) and blanched at 85°C. Following blanching, almond kernels and pellicles contained 20 and 19% of the spiked AFB1, respectively. The blanching water contained an additional 41% of the spiked AFB1. In a separate study, postblanching water was spiked with AFB1 and used for subsequent blanching of uncontaminated almonds. The resulting blanched kernels acquired 3.3% of the AFB1 from the spiked water, demonstrating a low level of cross-contamination from reused contaminated blanching water. The effect of the blanching temperature on partitioning of AFB1 from almonds to blanching water was significant at a 20-ppb spiking level, but not at 100 ppb. AFB1 levels that were unaccounted for in the mass balance of blanching components were presumed to be lost due to binding to water-solubilized almond components and were independent of pH and blanching time. Blanching reduced total aflatoxins in naturally contaminated almonds by 13 to 76%, depending on almond quality, as well as blanching time and temperature. These results indicate that the association between almond components and aflatoxin generated through mold contamination is more complex than in spiking experiments.

HIGHLIGHTS

X-Ray-Based Irradiation of Larvae and Pupae of the Navel Orangeworm (Lepidoptera: Pyralidae)

The suitability of adult male the navel orangeworm, Amyelois transitella (Walker) for Sterile Insect Technique (SIT) has been reported for both high energy gamma (>1 MeV) and low energy x-ray (90 keV) sterilization. However, research regarding sterilization of NOW larvae and pupae by gamma irradiation indicated nonsuitability due to high mortality. Here, NOW larvae and pupae were irradiated to doses up to 50 Gy with 90 keV x-rays, then paired with nonirradiated colony mates. Sterility of surviving insects was determined by the presence or absence of hatched neonates. While presence of offspring does not guarantee viability, the absence does guarantee sterility (as is appropriate for SIT) and was thus the measure used here. Early stage larvae experienced 77% mortality at a dose of 30 Gy, versus 20% for nonirradiated control. At 40 Gy, mortality reached 98%. Of surviving early stage larvae at 30 Gy, 29% of moth pairs produced offspring. For late stage larvae, no offspring were produced at 40 Gy, but mortality was 73%. For pupae, mortality reached 53% at 30 Gy with 13% still producing neonates, while mortality reached 98% at 40 Gy. These results are consistent with reported results for gamma irradiation of NOW larvae where sterility was observed somewhere between the 30 Gy and 60 Gy data points, but mortality was high. This further confirms the lack of suitability of NOW irradiated in the larval stage, whether by gamma or x-ray, and supports the hypothesis that x-ray and gamma treatments are biologically equivalent at equal doses.

Nuts and Grains: Microbiology and Preharvest Contamination Risks

Low-water-activity foods have been involved in recalls and foodborne disease outbreaks. Increased consumption; better detection methods and reporting systems; improved surveillance, trace-back, and ability to connect sporadic foodborne illnesses; and inadequate implementation of food safety programs are some of the likely reasons for the increase in frequency of recalls and outbreaks linked to dry foods. Nuts and grains can be contaminated with foodborne pathogens at any stage during production, processing, storage, and distribution. Focusing on preharvest contamination, the various potential sources of contamination include soil, animal intrusion, contaminated harvesting equipment, harvest and preharvest handling, storage conditions, and others. The low water activity of nuts and grains prevents the growth of most foodborne pathogens on their surfaces. The long-term survival of bacterial foodborne pathogens (Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes) on dry foods has been documented in the literature for different nut types. Preventing contamination is the key to avoiding foodborne disease risks linked to dry foods. The implementation of good agricultural practices and other food safety systems provides a proactive approach to address concerns thoroughly. A plethora of research is available on preventing the growth of mycotoxin-producing fungi on the surface of nuts and grains. Milling is an effective mechanism to reduce the microbial load on grains. This review focuses on providing information about associated foodborne microorganisms, preharvest contamination sources, and good agricultural practice recommendations for nuts and grains.

Risk assessment of exposure to aflatoxin B1 and ochratoxin A through consumption of different Pistachio (Pistacia vera L.) cultivars collected from four geographical regions of Iran

Iran is one of the main suppliers of pistachio for the European market accounting for over 90% of its demands; hence, efficient analytical methods are required for detection of mycotoxins contamination in pistachio kernels before exporting them. In this study, aflatoxin B1 (AFB1) and ochratoxin A (OTA) levels in five pistachio cultivars collected from four sites of Iran, were measured by HPLC. Based on the results, risk assessment for AFB1 and OTA residues was done. The highest mean concentrations of AFB1 and OTA were found in Ahmad-aghaei (4.33 and 2.19 ng/g, respectively) and Akbari (4.08 and 1.943 ng/g, respectively) cultivars from Rafsanjan, Iran. Even the highest concentrations of AFB1 and OTA in analyzed samples were lower than the corresponding maximum limits set by EU authorities. The hazard index (HI) value for consumers of Iranian pistachio is below one. It could be concluded that consumption of pistachio cultivated in these regions poses no health risk of mycotoxins exposure.

Aflatoxin-Contaminated Nut Separation by Applied Machinery and Processing Stages in Fresh Pistachio Processing Plant

In pistachio nuts, aflatoxin is mainly concentrated in the green hull-cracked nuts in the orchard even prior to harvest. However, during the hull-removal process, the hulls of all nuts including the cracked, identifiable nuts are removed causing an important characterization criterion of the contaminated nuts, to be lost. This, in turn, makes it harder to detect the contaminated nuts. However, during the processing stage, there is a good possibility of sorting the contaminated nuts based on their other inherent features, such as specific gravity and stain on the hard shell. In this study, we aimed to explore the effect of applied processing machinery and related sequences in the aflatoxin flow during post-harvest processing and the possible ways of reducing aflatoxin contamination in the Iranian pistachio industry. We planned a systematic sampling from the main and reject streams in two major prevailing processing methods, namely, wet and dry. In the dry processing method, the reject streams such as the adhering-hull rejects, air floaters, and manual hand pick-outs from the final inspection were found to be significantly more contaminated than the main stream. However, in the wet processing method, the input stream was considered highly contaminated. Among the sorting stages, only the adhering-hull rejects of the sinkers were considered more contaminated than the main stream. A contamination removal index was developed and applied to compare the effectiveness of the processing procedures. The water flotation tank was deemed responsible for 52.5% of aflatoxin contamination removal compared to 2.1% in the air flotation system. More effective sorting was achieved by the adhering-hull remover, which was preceded by a rubber-drum huller instead of the metal-drum type. Thus, by combining the most effective techniques of aflatoxin removal, an improved and more efficient method may be designed for pistachio processing plants.

Biological Control of Aflatoxin Contamination in U.S. Crops and the Use of Bioplastic Formulations of Aspergillus flavus Biocontrol Strains To Optimize Application Strategies

Aflatoxin contamination has a major economic impact on crop production in the southern United States. Reduction of aflatoxin contamination in harvested crops has been achieved by applying nonaflatoxigenic biocontrol Aspergillus flavus strains that can out-compete wild aflatoxigenic A. flavus, reducing their numbers at the site of application. Currently, the standard method for applying biocontrol A. flavus strains to soil is using a nutrient-supplying carrier (e.g., pearled barley for Afla-Guard). Granules of Bioplastic (partially acetylated corn starch) have been investigated as an alternative nutritive carrier for biocontrol agents. Bioplastic granules have also been used to prepare a sprayable biocontrol formulation that gives effective reduction of aflatoxin contamination in harvested corn kernels with application of much smaller amounts to leaves later in the growing season. The ultimate goal of biocontrol research is to produce biocontrol systems that can be applied to crops only when long-range weather forecasting indicates they will be needed.

Walnuts (Juglans regia) Chemical Composition and Research in Human Health

Walnuts are among the most widely consumed commercially grown tree nuts in the world. Many health benefits have been claimed for the consumption of these, including reduced risk of cardiovascular disease, coronary heart disease, type II diabetes treatment, and prevention and treatment of certain cancers, and the lessening of symptoms attributed to age-related and other neurological disorders. The health-promoting benefits of walnut consumption are ascribed to its fatty acid profile, which is rich in polyunsaturated fatty acids with a particularly high ω3:ω6 ratio-the highest among all the tree nuts. The content of polyphenols and other phytochemicals in walnuts, with their claimed cytotoxic properties, also make them an attractive candidate for research for the prevention of free radical-induced nucleic acid damage. Research of walnut consumption in humans and animals employing a range of data sets and statistical methods suggest that walnuts may be considered a safe potential nutraceutical or possibly pharmaceutical substance. Nevertheless, few reviews of scientific research on the proposed benefits of these nuts exist, in spite of the numerous claims attributed to them in the lay media. This brief review article attempts to disseminate much of the information surrounding walnut consumption, and human health benefits, to other scientists and the interested general reader.

Inhibition of aflatoxin B1 production by verbascoside and other olive polyphenols

In this study, the effects of pure olive phenolic compounds and olive mill wastewater (OMWW) (after membrane filtration treatments) on Aspergillus flavus growth and aflatoxin B1 (AFB1) production, were investigated. Five OMWWs coming from Greek (Lianolia, Koroneiki and Asprolia) and Italian (Cellina di Nardò and Coratina) olive oil cultivars, opportunely filtered using a membrane system, were added at two concentrations (5 and 15%) to growth medium, in order to evaluate their effect on A. flavus growth and AFB1 production. The OMWW fractions treatment, after 6 days of incubation, did not inhibit the fungal growth rate, but at 15% concentration significantly reduced the AFB1 production (ranging from 88 to 100%). A similar approach was used for caffeic acid, hydroxytyrosol, tyrosol and verbascoside, the major pure phenolic compounds identified in OMWW fractions. They were evaluated at increasing doses (10, 50 and 100 µg/ml) following both AFB1 production and fungal growth. At the highest concentration (100 µg/ml) all pure compounds showed a reduction of about 99% of AFB1 production without any influence on fungal growth. This is the first time in which OMWWs and their main phenolics were used in the treatments against AFB1 production. The results obtained could provide possible new strategies for preventing AFB1 food contamination using olive polyphenols and OMWW fractions with anti-aflatoxigenic effect, and permitting to harness in a sustainable way an olive oil by-product.

Control and Monitoring of Codling Moth (Lepidoptera: Tortricidae) in Walnut Orchards Treated With Novel High-Load, Low-Density "Meso" Dispensers of Sex Pheromone and Pear Ester

Low-density per ha "meso" dispensers loaded with pear ester, ethyl (E,Z)-2,4-decadienoate, kairomone and codlemone, (E,E)-8,10-dodecadien-1-ol, pheromone of codling moth, Cydia pomonella (L)., were evaluated versus meso dispensers loaded with pheromone alone for mating disruption control in walnut orchards receiving no insecticide sprays. Meso dispensers loaded with codlemone alone (Ph meso) were applied at 50 ha-1 and compared with mesos combining codlemone and pear ester (Ph + PE meso) at 25 and 50 ha-1. Various lures containing pear ester (PE), Ph-PE combo, and an experimental codlemone plus (E)-4,8-dimethyl-1,3,7-nonatriene lure were tested alone and with acetic acid (AA) lures for moth capture efficacy. Male moth capture in pheromone traps was significantly reduced by 88% in Ph meso plots and 96% in Ph + PE meso plots versus control plots. Moth capture in Ph-PE combo traps was significantly reduced for both sexes in all meso plots. Harvest damage by both the codling moth and the secondary pest, navel orangeworm, Amyelois transitella (Walker), was significantly lower in all meso treatment plots compared with damage in control plots. Nut injury level with the Ph + PE meso treatment (50 ha-1) was significantly lower than in Ph meso plots for both codling moth and combined pest injury. Regression analysis suggested that nut infestation levels by navel orangeworm were influenced by codling moth levels. In all meso plots, the most effective lures attracting both codling moth sexes were PE & AA or Ph-PE combo & AA. Demonstrated disruption and control efficacy of these pheromone plus PE-meso dispensers applied at low densities supports development of the meso dispenser tactic for practical pest management use in walnut orchards with inherent low planting densities.

Larval Preference and Performance of Amyelois transitella (Navel Orangeworm, Lepidoptera: Pyralidae) in Relation to the Fungus Aspergillus flavus

The navel orangeworm, Amyelois transitella (Walker), is a polyphagous pest of California nut crops and is responsible for extensive losses in the United States. It directly damages crops by feeding and contaminating nuts with frass and webbing and vectors saprophytic fungi that infect crops. The navel orangeworm is commonly associated with Aspergillus species, including the toxigenic Aspergillus flavus, which causes crop loss by producing carcinogens, including aflatoxin B1. This lepidopteran-fungus association is the most economically serious pest complex in Central Valley orchards, and evidence indicates that this relationship is mutualistic. We assessed preference and performance of navel orangeworm larvae associated with A. flavus in behavioral bioassays in which neonates were allowed to orient within arenas to media with or without fungal tissue, and performance bioassays in which larvae were reared with and without A. flavus on potato dextrose agar (PDA) and a semidefined almond PDA diet to evaluate effects on development and pupal weight. Navel orangeworm larvae were attracted to A. flavus and developed faster in its presence, indicating a nutritional benefit to the caterpillars. Larvae reached pupation ∼33% faster on diet containing A. flavus, and pupal weights were ∼18% higher for males and ∼13% higher for females on this diet. Our findings indicate that A. flavus plays an important role in larval orientation and development on infected hosts. The preference-performance relationship between navel orangeworms and Aspergillus flavus is consistent with a facultative mutualism that has broad implications for pest management efforts and basic understanding of Lepidoptera-plant interactions.

Reduction of Aflatoxins in Apricot Kernels by Electronic and Manual Color Sorting

The efficacy of color sorting on reducing aflatoxin levels in shelled apricot kernels was assessed. Naturally-contaminated kernels were submitted to an electronic optical sorter or blanched, peeled, and manually sorted to visually identify and sort discolored kernels (dark and spotted) from healthy ones. The samples obtained from the two sorting approaches were ground, homogenized, and analysed by HPLC-FLD for their aflatoxin content. A mass balance approach was used to measure the distribution of aflatoxins in the collected fractions. Aflatoxin B₁ and B₂ were identified and quantitated in all collected fractions at levels ranging from 1.7 to 22,451.5 µg/kg of AFB₁ + AFB₂, whereas AFG₁ and AFG₂ were not detected. Excellent results were obtained by manual sorting of peeled kernels since the removal of discolored kernels (2.6%–19.9% of total peeled kernels) removed 97.3%–99.5% of total aflatoxins. The combination of peeling and visual/manual separation of discolored kernels is a feasible strategy to remove 97%–99% of aflatoxins accumulated in naturally-contaminated samples. Electronic optical sorter gave highly variable results since the amount of AFB₁ + AFB₂ measured in rejected fractions (15%–18% of total kernels) ranged from 13% to 59% of total aflatoxins. An improved immunoaffinity-based HPLC-FLD method having low limits of detection for the four aflatoxins (0.01–0.05 µg/kg) was developed and used to monitor the occurrence of aflatoxins in 47 commercial products containing apricot kernels and/or almonds commercialized in Italy. Low aflatoxin levels were found in 38% of the tested samples and ranged from 0.06 to 1.50 μg/kg for AFB₁ and from 0.06 to 1.79 μg/kg for total aflatoxins.

Effect of Piperonyl Butoxide on the Toxicity of Four Classes of Insecticides to Navel Orangeworm (Amyelois transitella) (Lepidoptera: Pyralidae)

Amyelois transitella (Walker) (Lepidoptera: Pyralidae), the navel orangeworm, is a highly polyphagous economic pest of almond, pistachio, and walnut crops in California. Increasing demand for these crops and their rising economic value has resulted in substantial increases of insecticide applications to reduce damage to acceptable levels. The effects of piperonyl butoxide (PBO), a methylenedioxyphenyl compound that can act as a synergist by inhibiting cytochrome P450-mediated detoxification on insecticide metabolism by A. transitella, were examined in a series of feeding bioassays with first-instar A. transitella larvae from a laboratory strain. PBO, however, can have a variety of effects on metabolism, including inhibition of glutathione-S-transferases and esterases and induction of P450s. In our study, PBO synergized the toxicity of acetamiprid, λ-cyhalothrin, and spinosad, suggesting possible involvement of P450s in their detoxification. In contrast, PBO interacted antagonistically with the organophosphate insecticide chlorpyrifos, reducing its toxicity, an effect consistent with inhibition of P450-mediated bioactivation of this pesticide. The toxicity of the anthranilic diamide insecticide chlorantraniliprole was not altered by PBO, suggestive of little or no involvement of P450-mediated metabolism in its detoxification. Because a population of navel orangeworm in Kern County, CA, has already acquired resistance to the pyrethroid insecticide bifenthrin through enhanced P450 activity, determining the effect of adding a synergist such as PBO on detoxification of all insecticide classes registered for use in navel orangeworm management can help to develop rotation practices that may delay resistance acquisition or to implement alternative management practices where resistance is likely to evolve.

Augmenting the Activity of Monoterpenoid Phenols against Fungal Pathogens Using 2-Hydroxy-4-methoxybenzaldehyde that Target Cell Wall Integrity

Disruption of cell wall integrity system should be an effective strategy for control of fungal pathogens. To augment the cell wall disruption efficacy of monoterpenoid phenols (carvacrol, thymol), antimycotic potency of benzaldehyde derivatives that can serve as chemosensitizing agents were evaluated against strains of Saccharomyces cerevisiae wild type (WT), slt2Δ and bck1Δ (mutants of the mitogen-activated protein kinase (MAPK) and MAPK kinase kinase, respectively, in the cell wall integrity pathway). Among fourteen compounds investigated, slt2Δ and bck1Δ showed higher susceptibility to nine benzaldehydes, compared to WT. Differential antimycotic activity of screened compounds indicated "structure-activity relationship" for targeting the cell wall integrity, where 2-hydroxy-4-methoxybenzaldehyde (2H4M) exhibited the highest antimycotic potency. The efficacy of 2H4M as an effective chemosensitizer to monoterpenoid phenols (viz., 2H4M + carvacrol or thymol) was assessed in yeasts or filamentous fungi (Aspergillus, Penicillium) according to European Committee on Antimicrobial Susceptibility Testing or Clinical Laboratory Standards Institute M38-A protocols, respectively. Synergistic chemosensitization greatly lowers minimum inhibitory or fungicidal concentrations of the co-administered compounds. 2H4M also overcame the tolerance of two MAPK mutants (sakAΔ, mpkCΔ) of Aspergillus fumigatus to fludioxonil (phenylpyrrole fungicide). Collectively, 2H4M possesses chemosensitizing capability to magnify the efficacy of monoterpenoid phenols, which improves target-based (viz., cell wall disruption) antifungal intervention.

Effects of X-Ray Irradiation on Male Navel Orangeworm Moths (Lepidoptera: Pyralidae) on Mating, Fecundity, Fertility, and Inherited Sterility

Male adult navel orangeworm, Amyelois transitella (Walker), were irradiated using a laboratory scale x-ray irradiation unit to determine the required dose for complete egg sterility of mated female moths and inherited sterility of F1 and F2 generations. Adult male A. transitella were irradiated in two separate experiments at 100-300 Gy and 50-175 Gy. Mating frequency, fecundity, and fertility of normal females crossed with irradiated parental males was compared with the mating of nonirradiated moths. Mating frequency was 100% for females crossed with nonirradiated control males. At male treatment doses of ≥150 Gy the percentage of females found unmated increased, while multiple-mated females decreased. Female fecundity was not affected while fertility was affected in a dose-dependent relationship to exposure of parental males to x-ray irradiation. Embryonic development of eggs to the prehatch stage and egg eclosion did not occur at radiation doses ≥125 Gy. Emergence of F1 adults was low and occurred only for progeny of parental males exposed to doses ≤100 Gy, with no emergence at ≥125 Gy. Though fecundity appeared similar for control and irradiated F1 females, no F2 eggs hatched for the test exposures of 50-100 Gy. Based on our results, a dose of ≥125 Gy had efficacy in inducing both primary parental sterility in treated male moths and inherited sterility in F1 male and female moths. Results suggest that A. transitella might be considered a candidate for the sterile insect technique using adults irradiated at these relatively low x-ray exposure doses.

Mechanism of Resistance Acquisition and Potential Associated Fitness Costs in Amyelois transitella (Lepidoptera: Pyralidae) Exposed to Pyrethroid Insecticides

The polyphagous navel orangeworm, Amyelois transitella (Walker) (Lepidoptera: Pyralidae), is the most destructive pest of nut crops, including almonds and pistachios, in California orchards. Management of this insect has typically been a combination of cultural controls and insecticide use, with the latter increasing substantially along with the value of these commodities. Possibly associated with increased insecticide use, resistance has been observed recently in navel orangeworm populations in Kern County, California. In studies characterizing a putatively pyrethroid-resistant strain (R347) of navel orangeworm, susceptibility to bifenthrin and β-cyfluthrin was compared with that of an established colony of susceptible navel orangeworm. Administration of piperonyl butoxide and S,S,S-tributyl phosphorotrithioate in first-instar feeding bioassays with the pyrethroids bifenthrin and β-cyfluthrin produced synergistic effects and demonstrated that cytochrome P450 monooxygenases and carboxylesterases contribute to resistance in this population. Resistance is therefore primarily metabolic and likely the result of overexpression of specific cytochrome P450 monooxygenases and carboxylesterase genes. Resistance was assessed by median lethal concentration (LC50) assays and maintained across nine generations in the laboratory. Life history trait comparisons between the resistant strain and susceptible strain revealed significantly lower pupal weights in resistant individuals reared on the same wheat bran-based artificial diet across six generations. Time to second instar was greater in the resistant strain than the susceptible strain, although overall development time was not significantly different between strains. Resistance was heritable and may have an associated fitness cost, which could influence the dispersal and expansion of resistant populations in nut-growing areas in California.

Aflatoxin-producing fungi in maize field soils from sea level to over 2000 masl: a three year study in Sonora, Mexico

Aflatoxins, highly toxic carcinogens produced by several members of Aspergillus section Flavi, contaminate crops in temperate zones. In the state of Sonora, Mexico, maize is cultivated from 0 to 2100 masl with diverse cultivation practices. This is typical of the nation. In order to design better sampling strategies across Mexico, aflatoxin-producing fungal communities associated with maize production during 2006, 2007, and 2008 in Sonora were investigated in four agro-ecological zones (AEZ) at varying elevation. Fungal communities were dominated by the Aspergillus flavus L strain morphotype (46%), but variation occurred between years and among AEZ. Several atoxigenic isolates with potential to be used as biocontrol agents for aflatoxin mitigation were detected in all AEZ. The characteristics of each AEZ had minimal influences on fungal community structure and should not be a major consideration for future sampling designs for Mexico. Insights into the dynamics and stability of aflatoxin-producing fungal communities across AEZ are discussed.

Effect of almond processing on levels and distribution of aflatoxins in finished products and byproducts

The fate of aflatoxins during processing of contaminated almonds into nougat, pastries, and almond syrup was evaluated by testing the effect of each processing step (blanching, peeling, roasting, caramelization, cooking, and water infusion) on the distribution and levels of aflatoxins. Blanching and peeling did not reduce total aflatoxins that were distributed between peeled almonds (90-93%) and skins (7-10%). Roasting of peeled almonds reduced up to 50% of aflatoxins. Up to 70% reduction of aflatoxins was observed during preparation and cooking of almond nougat in caramelized sugar. Aflatoxins were substantially stable during preparation and cooking of almond pastries. The whole process of almond syrup preparation produced a marked increase of total aflatoxins (up to 270%) that were distributed between syrup (18-25%) and spent almonds (75-82%). The increase of total aflatoxins was probably due to the activation of almond enzymes during the infusion step that released free aflatoxins from masked aflatoxins.

Mold contamination of untreated and roasted with salt nuts (walnuts, peanuts and pistachios) sold at markets of tabriz, iran

BACKGROUND

Nuts are one of the main consumed snacks worldwide and a significant component of Iranian's diet. Natural contamination of nuts with fungus is unavoidable and is a major challenge to nuts safety and quality.

OBJECTIVES

The purpose of this research was to study fungal contamination in commercially available nuts (pistachios, walnuts and peanuts) in the markets of Tabriz, Iran.

MATERIALS AND METHODS

100 samples of 50 gr roasted with salt peanuts and pistachios and 300 samples of 50 gr pure pistachios, walnuts and peanuts were collected from different areas of the local markets. After initial preparation, the samples were cultured on Sabouraud's dextrose agar (SDA). 19 fungal isolates were identified.

RESULTS

The results show that Aspergillus niger was the predominant mold among pure (44%) and roasted with salt (14%) nuts (P < 0/001). In addition, percentage of mycotoxigenic fungal contamination was 18% for roasted with salt nuts and 11% for pure samples.

CONCLUSIONS

The overall results of the analysed samples showed that the rate of fungal contamination in pure samples was higher than roasted with salt ones (P < 0.005). Results of the current survey could be useful for minimizing fungal contamination and can educate people about the dangers of mold in nuts.

Quasi-double-blind screening of semiochemicals for reducing navel orangeworm oviposition on almonds

A three-step, quasi-double-bind approach was used as a proof-of-concept study to screen twenty compounds for their ability to reduce oviposition of gravid female navel orangeworm(NOW), Ameylois transitella (Lepidoptera: Pyralidae). First, the panel of compounds, whose identity was unknown to the experimenters, was tested by electroantennogram (EAG) using antennae of two-day old gravid females as the sensing element. Of the twenty compounds tested three showed significant EAG responses. These three EAG-active compounds and a negative control were then analyzed for their ability to reduce oviposition via small-cage, two-choice laboratory assays. Two of the three compounds significantly reduced oviposition under laboratory conditions. Lastly, these two compounds were deployed in a field setting in an organic almond orchard in Arbuckle, CA using black egg traps to monitor NOW oviposition. One of these two compounds significantly reduced oviposition on black egg traps under these field conditions. Compound 9 (later identified as isophorone) showed a significant reduction in oviposition in field assays and thus has a potential as a tool to control the navel orangeworm as a pest of almonds.

Gene targets for fungal and mycotoxin control

It was initially shown that gallic acid, from hydrolysable tannins in the pelliele of walnut kernels, dramatically inhibits biosynthesis of aflatoxin byAspergillus flavus. The mechanism of this inhibition was found to take place upstream from the gene cluster, including the regulatory gene,aflR, involved in aflatoxin biosynthesis. Additional research using other antioxidant phenolics showed similar antiaflatoxigenic activity to gallic acid. Treatment ofA. flavus withtert-butyl hydroperoxide resulted in an almost doubling of aflatoxin biosynthesis compared to untreated samples. Thus, antioxidative response systems are potentially useful molecular targets for control ofA. flavus. A high throughput screening system was developed using yeast,Saccharomyces cerevisiae, as a model fungus. This screening provided an avenue to quickly identify fungal genes that were vulnerable to treatment by phenolic compounds. The assay also provided a means to quickly assess effects of combinations of phenolics and certain fungicides affecting mitochondrial respiration. For example, theS. cerevisiae sod2† mutant was highly sensitive to treatment by certain phenolics and strobilurins/antimycin A, fungicides which inhibit complex III of the mitochondrial respiratory chain. Verification of stress to this system in the target fungus,A. flavus, was shown through complementation analysis, wherein the mitochondrial superoxide dismutase (Mn-SOD) gene (sodA) ofA. flavus in the ortholog mutant,sod2†, ofS. cerevisiae, relieved phenolic-induced stress. Mitochondrial antioxidative stress systems play an important role in fungal response to antifungals. Combined treatment of fungi with phenolics and inhibitors of mitochondrial respiration can effectively suppress growth ofA. flavus in a synergistic fashion.

Textural, rheological and sensory properties and oxidative stability of nut spreads&#8212;a review

Tree nuts are rich in macro and micronutrients, phytochemicals, tocopherols and phenolic compounds. The development of nut spreads would potentially increase the food uses of nuts and introduce consumers with a healthier, non-animal breakfast snack food. Nut spreads are spreadable products made from nuts that are ground into paste. Roasting and milling (particle size reduction) are two important stages for the production of nut spreads that affected the textural, rheological characteristic and overall quality of the nut spread. Textural, color, and flavor properties of nut spreads play a major role in consumer appeal, buying decisions and eventual consumption. Stability of nut spreads is influenced by its particle size. Proper combination of ingredients (nut paste, sweetener, vegetable oil and protein sources) is also required to ensure a stable nut spread product is produced. Most of the nut spreads behaved like a non-Newtonian pseudo-plastic fluid under yield stress which help the producers how to start pumping and stirring of the nut spreads. Similar to other high oil content products, nut spreads are susceptible to autoxidation. Their oxidation can be controlled by application of antioxidants, using processing techniques that minimize tocopherol and other natural antioxidant losses.

Hull split and damaged almond volatiles attract male and female navel orangeworm moths

A blend of volatiles derived from the emissions of almonds at hull split and mechanically damaged almonds was compared to almond meal, the current monitoring standard for the insect pest navel orangeworm (NOW). Field trapping studies were performed to determine the blend's ability to attract adult NOW. The blend comprised racemic 1-octen-3-ol, ethyl benzoate, methyl salicylate, acetophenone, and racemic (E)-conophthorin. Ethyl acetate was used as a solvent with a blend component concentration of 100 mg/mL. The blend attracted both sexes of NOW when tested in five 2-week intervals spanning the first three flights of NOW in commercial almond orchards in the southern Central Valley of California. The blend demonstrated consistently higher capture rates for female NOW throughout the evaluation period, but unlike almond meal it significantly attracted males. Reported is a survey of the major and minor volatiles emitted from almonds at hull split, the key period of vulnerability to NOW infestation. Also reported is the attractancy of a formulated test blend based on the host plant volatile emissions, electroantennographic screening experiments, and field trapping studies. The results of this test blend highlight progress toward a host-plant-based attractant for NOW, a major insect pest of California tree nuts that presently lacks an adequate monitoring tool.

Effects of a naturally occurring and a synthetic synergist on toxicity of three insecticides and a phytochemical to navel orangeworm (Lepidoptera: Pyralidae)

The navel orangeworm, Amyelois transitella (Walker) (Lepidoptera: Pyralidae), is the most destructive lepidopteran pest of almonds [Prunus dulcis (Mill.) D.A.Webb] and pistachios (Pistacia vera L.) in California and is a serious problem in figs (Ficus carica L.) and walnuts (Juglans spp.). In addition to direct damage, larval feeding leaves nuts vulnerable to infection by Aspergillus spp., fungi that produce toxic aflatoxins. A potentially safe and sustainable approach for managing navel orangeworm in orchards may be to use natural essential oil synergists to interfere with this insect's ability to detoxify insecticides and phytochemicals. We tested the effects of a naturally occurring plant-derived chemical, myristicin, and a synthetic inhibitor of cytochrome P450 monooxygenases (P450s), piperonyl butoxide, on the toxicity of three insecticides (alpha-cypermethrin, tau-fluvalinate, and methoxyfenozide [Intrepid]) and a phytochemical (xanthotoxin) to A. transitella. Piperonyl butoxide significantly synergized alpha-cypermethrin and tau-fluvalinate, whereas myristicin synergized only alpha-cypermethrin. Piperonyl butoxide synergized the toxicity of xanthotoxin as early as 72 h after exposure, whereas myristicin synergized xanthotoxin after 120 h. In view of these findings and the limited availability of environmentally safe synthetic insecticides for sustainable management, particularly in organic orchards, myristicin is a potential field treatment in combination with insecticides to reduce both navel orangeworm survival and aflatoxin contamination of nuts. In addition, this study demonstrates that in A. transitella the insect growth regulator methoxyfenozide is not detoxified by P450s.

Microencapsulated pear ester enhances insecticide efficacy in walnuts for codling moth (Lepidoptera: Tortricidae) and navel orangeworm (Lepidoptera: Pyralidae)

The efficacy of combining insecticides with a microencapsulated formulation of ethyl (2E,4Z) -2,4-decadienoate (pear ester, PE-MEC) was evaluated in walnuts, Juglans regia L., for codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), and navel orangeworm, Amyelois transitella Walker (Lepidoptera, Pyralidae). Two types of studies were conducted to compare the use of insecticides with and without PE-MEC. In the first study, PE-MEC in combination with reduced rates of insecticides, including chlorpyrifos, phosmet, methoxyfenozide, and codling moth granulovirus were evaluated in single tree replicates. PE-MEC was tested at one to three rates (0.6, 1.8, and 4.4 g active ingredient ha(-1)) with each insecticide. In the second study, seasonal programs including sprays of esfenvalerate, chlorpyrifos, and ethyl parathion at full rates were evaluated in replicated two ha blocks. Significant reductions in nut injury occurred in the single-tree trial with treatments of PE-MEC plus insecticide compared with the insecticides used alone against both pest species; except with methoxyfenozide for navel orangeworm. Similarly, nut injury in the large plots was significantly reduced with the addition of PE-MEC, except for navel orangeworm in one of the two studies. These results suggest that adding pear ester as a microencapsulated spray can improve the efficacy of a range of insecticides for two key pests and foster the development of integrated pest management tactics with reduced insecticide use in walnut.

A substrate-specific cytochrome P450 monooxygenase, CYP6AB11, from the polyphagous navel orangeworm (Amyelois transitella)

The navel orangeworm Amyelois transitella (Walker) (Lepidoptera: Pyralidae) is a serious pest of many tree crops in California orchards, including almonds, pistachios, walnuts and figs. To understand the molecular mechanisms underlying detoxification of phytochemicals, insecticides and mycotoxins by this species, full-length CYP6AB11 cDNA was isolated from larval midguts using RACE PCR. Phylogenetic analysis of this insect cytochrome P450 monooxygenase established its evolutionary relationship to a P450 that selectively metabolizes imperatorin (a linear furanocoumarin) and myristicin (a natural methylenedioxyphenyl compound) in another lepidopteran species. Metabolic assays conducted with baculovirus-expressed P450 protein, P450 reductase and cytochrome b(5) on 16 compounds, including phytochemicals, mycotoxins, and synthetic pesticides, indicated that CYP6AB11 efficiently metabolizes imperatorin (0.88 pmol/min/pmol P450) and slowly metabolizes piperonyl butoxide (0.11 pmol/min/pmol P450). LC-MS analysis indicated that the imperatorin metabolite is an epoxide generated by oxidation of the double bond in its extended isoprenyl side chain. Predictive structures for CYP6AB11 suggested that its catalytic site contains a doughnut-like constriction over the heme that excludes aromatic rings on substrates and allows only their extended side chains to access the catalytic site. CYP6AB11 can also metabolize the principal insecticide synergist piperonyl butoxide (PBO), a synthetic methylenedioxyphenyl compound, albeit slowly, which raises the possibility that resistance may evolve in this species after exposure to synergists under field conditions.

Chemosensitization of aflatoxigenic fungi to antimycin A and strobilurin using salicylaldehyde, a volatile natural compound targeting cellular antioxidation system

Various species of fungi in the genus Aspergillus are the most common causative agents of invasive aspergillosis and/or producers of hepato-carcinogenic mycotoxins. Salicylaldehyde (SA), a volatile natural compound, exhibited potent antifungal and anti-mycotoxigenic activities to A. flavus and A. parasiticus. By exposure to the volatilized SA, the growth of A. parasiticus was inhibited up to 10-75% at 9.5 mM ≤ SA ≤ 16.0 mM, while complete growth inhibition was achieved at 19.0 mM ≤ SA. Similar trends were also observed with A. flavus. The aflatoxin production, i.e., aflatoxin B(1) and B(2) (AFB(1), AFB(2)) for A. flavus and AFB(1), AFB(2), AFG(1), and AFG(2) for A. parasiticus, in the SA-treated (9.5 mM) fungi was reduced by ~13-45% compared with the untreated control. Using gene deletion mutants of the model yeast Saccharomyces cerevisiae, we identified the fungal antioxidation system as the molecular target of SA, where sod1Δ [cytosolic superoxide dismutase (SOD)], sod2Δ (mitochondrial SOD), and glr1Δ (glutathione reductase) mutants showed increased sensitivity to this compound. Also sensitive was the gene deletion mutant, vph2Δ, for the vacuolar ATPase assembly protein, suggesting vacuolar detoxification plays an important role for fungal tolerance to SA. In chemosensitization experiments, co-application of SA with either antimycin A or strobilurin (inhibitors of mitochondrial respiration) resulted in complete growth inhibition of Aspergillus at much lower dose treatment of either agent, alone. Therefore, SA can enhance antifungal activity of commercial antifungal agents required to achieve effective control. SA is a potent antifungal and anti-aflatoxigenic volatile that may have some practical application as a fumigant.

Mycobiota and Ochratoxin A in laboratory mice feed: preliminary study

The occurrence of mycotoxin-producing moulds in animal feed is a hazard for animals. When these undesirable substances contaminate laboratory animal feed, convey an additional problem in experimental animal assays confidence levels. The aim of this study was to evaluate fungal contamination and to determine natural occurrence of Ochratoxin A (OTA) in 31 samples. OTA is a mycotoxin produced by fungi of two genera: Penicillium and Aspergillus. OTA has been shown to be nephrotoxic, hepatotoxic, teratogenic and immunotoxic to a number of animal species and to cause kidney and liver tumors in mice and rats. In this preliminary study, feed mould counts ranged from 3 to 4.2 log(10) cfu/g (colonies forming units per gram). When these species are present, there is a significant risk of contamination with mycotoxins resulting in both acute diseases called mycotoxicoses and chronic conditions, often recognized as situations involving mycotoxins. The most frequent genus isolated was Cladosporium sp. (84%), followed by Aspergillus niger and Penicillium (81%) and Mucor sp. (77%). All rat feed samples were examined for OTA, using High Performance Liquid Chromatography (HPLC). The detection limit was 2.0 microg OTA kg(-1) and all samples revealed to be negative for this mycotoxin. These mycotoxicological researches put in evidence the importance of the use contaminant-free experimental animal feed in order to prevent any interference on the health of experimental animals and emphasizes the need for systematic control of the feed as a key issue in animal experimentation.

Essential oil yield and composition of Pistacia vera 'Kerman' fruits, peduncles and leaves grown in California

BACKGROUND

Pistacia vera 'Kerman' is the predominant pistachio nut cultivar in the United States (California), the world's second largest producer. Despite several reports on the essential oil (EO) content in the genus Pistacia, data on 'Kerman' are limited. The EO content and volatile organic compound (VOC) emissions of tree nut orchards are of current interest to researchers investigating insect pests and the potential role of EO and VOCs as semiochemicals. To establish a basis for the VOC output of pistachios, the EO content of fruits, peduncles, and leaves was analyzed.

RESULTS

Evaluated plant parts contained limonene as the primary EO component, followed by alpha-terpinolene. Peduncles were unique in containing relatively high levels of alpha-thujene. The results were reproducible between two different geographical locations. In situ solid phase microextraction (SPME) studies demonstrated the volatile emission was representative of the EO composition.

CONCLUSION

This is the first report detailing the content and distribution of EO and the unique limonene-dominant profile for this Pistacia vera cultivar which may influence pistachio insect pest semiochemical research.