Spatial and temporal population dynamics of Aspergillus flavus in commercial pistachio orchards in Arizona

Aspergillus flavus infects a wide range of crops, including pistachios, and subsequent aflatoxin contamination results in significant economic losses. Application of biocontrol products based on non-aflatoxigenic (atoxigenic) strains of A. flavus is one of the most effective tactics for controlling aflatoxins in crops. Both risk of aflatoxin contamination and effectiveness of biocontrol are influenced by the extent to which A. flavus spores move into pistachio tree canopies during periods of nut development. Thus, the purpose of this study was to evaluate spatial and temporal population dynamics of A. flavus, including the applied biocontrol strain AF36, in canopies of pistachio orchards in Arizona. Propagule densities of A. flavus were quantified on leaf samples collected from lower, middle, and upper canopies from spring through harvest in 2018 and 2019. Aspergillus flavus propagule densities peaked during periods of high temperature and rainfall in 2018 (up to 600 CFU/g) and 2019 (up to 23 CFU/g), which coincided with nut development and maturation. The applied biocontrol strain AF36 was detected at all canopy heights, but overall propagule densities were greater in the upper and middle canopy (mean = 70 CFU/g) compared to the lower canopy (mean = 47 CFU/g). Results suggest June to August is the period during which A. flavus inoculum increases in Arizona pistachio orchards, and to most effectively displace aflatoxin-producing fungi in tree canopies, biocontrol applications should precede this period. In addition, this study demonstrates that soil-applied biocontrol strains can successfully disperse throughout the canopies of commercial tree nut orchards.

Including Mixed Tree Nut Snacks in a Weight Loss and Weight Maintenance Intervention Resulted in Weight Loss and Increased Satiety

Objectives Tree nuts are an excellent dietary source of protein and healthy fat leading to increased satiety. Tree nuts also provide polyphenols, vitamins and minerals supporting the immune response. However, there is a concern that tree nuts are not suitable to be included in a weight loss diet due to their fat content. Therefore, it was the objective of the study to test whether including mixed tree nuts in a weight loss and maintenance program will lead to weight loss by increasing satiety and decreasing inflammation. Methods We performed a randomized, controlled, two-arm study in 95 overweight individuals consuming 1.5 oz of mixed tree nuts daily (n = 56) or equal amount of calories in the form of a pretzel snack (n = 39) as part of a hypocaloric weight loss diet (−500 calories of resting metabolic rate) for 12 wks followed by an isocaloric weight maintenance program for an additional 12 wks. Results The dropout rate was significantly lower in the tree nut (16.4%) compared to the pretzel (35.9%) group. Participants experienced significant weight loss (12 wks: −1.6 and −1.9 and 24 wks: −1.5 kg and −1.4 kg) in the tree nut and pretzel group, respectively, without difference between groups at any time point. In addition, both groups showed a significant decrease in diastolic blood pressure at 12 wks and a significant increase in satiety at 24 wks, but only participants in the mixed tree nut group showed significant decrease in heart rate at 4, 12 and 24 wks. Plasma oleic acid concentration was significantly increased at 12 and 24 wks in the tree nut group, while in the pretzel group plasma oleic acid was significantly increased and stearic acid decreased at 12 wks and linolenic acid was increased at 24 wks. No change in fasting plasma triglyceride, total cholesterol and HDL-cholesterol was observed in both groups. No change in inflammatory markers except plasma MCP-1 was decreased significantly in the tree nut group at 4 wks. Conclusions In summary, including mixed tree nuts in a weight loss and maintenance diet can maintain compliance and promote weight loss similar to standard weight loss and maintenance diets. Although both, the mixed tree nut diet and pretzel diet resulted in decreased diastolic blood pressure, only consumption of the mixed tree nut diet led to significantly decreased heart rate and increased study retention. Funding Sources International Tree Nut Council.

Health Benefits Related to Tree Nut Consumption and Their Bioactive Compounds

Long-term studies with regular tree nut consumption have indicated positive outcomes for multiple health benefits. Here, we review the beneficial effects of tree nuts, highlighting the impact on glucose modulation, body weight management, cardiovascular risk, inflammation, oxidative stress, cognitive performance, and gut microbiota. Nuts are important sources of nutrients and phytochemicals, which, together with a healthy lipid profile, could help prevent certain chronic diseases, protect against oxidative stress and inflammation, and improve cognitive performance, thus reducing the impact of aging and neurodegeneration.