QSAR Study of Biologically Active Essential Oils against Beetles Infesting the Walnut in Catamarca, Argentina.

Essential oils from six species of aromatic plants collected in the Catamarca Province of Argentina were evaluated for their chemical composition and repellent and insecticidal activities against beetles of the genus Carpophilus (Coleoptera: Nitidulidae) and Oryzaephilus (Coleoptera: Silvanidae) that infest the local walnut production. Experimental data were analyzed using generalized estimating equations, with normal distribution and the identity link function. From the spectral information from the tested essential oils, we worked their molecular modeling as mixtures by developing mixture descriptors ( Dmix) that combined the molecular descriptor of each component in the mixture ( d i) and its relative concentration ( x i), i.e., Dmix = f( d i, x i). The application of chemoinformatic approaches determined that a combination of mixture descriptors related to molecular size, branchedness, charge distribution, and electronegativity were useful to explain the bioactivity profile against Carpophilus spp. and Oryzaephilus spp. The reported models were rigorously validated using stringent statistical parameters and essential oils reported with repellent activity against other beetle species from the Nitidulidae and Silvanidae families. This model confirmed each essential oil as a repellent with a comparable performance to the experimental reports.

Cultivation of black soldier fly larvae on almond byproducts: impacts of aeration and moisture on larvae growth and composition.

BACKGROUND: The increasing production of almonds worldwide has resulted in the significant generation of byproduct streams that require end uses. One potential use for byproducts is for cultivation of additional food sources including insects. Studies were performed to determine if black soldier fly larvae (Hermetia illucens L.) could be cultivated on almond byproducts (hulls and shells) and to examine the effect of aeration and moisture on larvae growth and hull composition. RESULTS: Increasing aeration from 0.04 to 0.36 mL min-1 g dry weight-1 tripled the harvest weight of larvae and increased larvae yield by a factor of five. Larvae calcium content increased by 18% with an increase in aeration from 0.04 to 0.95 mL min-1 g dry weight-1 . Moisture content also affected harvest dry weight and yield; increasing moisture content from 480 g kg-1 (wet basis) to 680 g kg-1 increased harvest weight by 56% and yield by a factor of 2. Variables did not affect larvae methionine and cysteine content. Low moisture content and aeration rate yielded an environment that supported microbial consumption of hulls over larvae consumption and growth. CONCLUSIONS: The results demonstrate that almond hulls are a suitable feedstock for larvae production under controlled management of moisture content and aeration. © 2018 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Variable developmental rate and survival of navel orangeworm (Lepidoptera: Pyralidae) on pistachio.

A series of laboratory and field studies were conducted using two lines of navel orangeworm, reared on different stages of new crop and mummy pistachios, Pistacia vera L. This study demonstrated the potential importance of malformed pistachios (pea splits) to the population dynamics of navel orangeworm, because these nuts, which are available as early as two months before mature nuts, supported navel orangeworm development and survival. Overall, the developmental rate on new crop pistachios is fastest on mature nuts, 422.3 +/- 123 degree-days (DD, degrees C), but other factors such as exposure to insecticide residue also sped development, although survival decreased. Development took the longest on unharvested nuts (mummies) dried at 90 degrees C for 24 h, 2664.7 +/- 131.4 DD. In most trials development was variable and two generations could develop at the fastest rate before the slowest individual completed development, which in turn calls into question the concept of discrete generations. Generally, survival was highest on mature pistachios and other stages of new crop nut and lowest on mummies collected in May. Survival was also higher on the new varieties 'Lost Hills' and 'Golden Hills' (24.7 and 32.0%, respectively) than on the most extensively planted variety 'Kerman' (13.3%). In our trials, both the rate of development and survival were dependent on nut stage, age, variety, and quality, indicating that pistachios, like almonds, Prunus dulcis (Mill.) D. A. Webb, are a dynamic rather than a static nutrient source for navel orangeworm.

Protracted emergence of overwintering Amyelois transitella (Lepidoptera: Pyralidae) from pistachios and almonds in California.

The navel orangeworm, Amyelois transitella (Walker), is the primary insect pest of pistachios and almonds in California. Four years of research (2002-2006) were conducted in Madera and Kern Counties to elucidate the pattern of adult emergence of the overwintering navel orangeworm population. Springtime emergence from unharvested (mummy) nuts was protracted (600 degree-days or more from 1 January of each year) and in 2004 and 2006 extended to mid-July. The population structure, sex ratio, and timing of emergence differed between pistachio and almond mummies. Pistachio populations had a significantly greater proportion of late stage individuals compared with almond mummies, 85.7 versus 34.1%. The sex ratio of adults emerging from pistachio mummies was significantly skewed with a ratio 57:43 male:female compared with 50:50 in almond mummies. Emergence from mummies held outdoors (variable temperature) began in early March and continued through early June in both pistachio mummies and almond mummies. The adult emergence pattern from pistachio mummies contained a single emergence peak, whereas emergence from almond mummies occurred in multiple peaks. These same patterns occurred when mummies were held at constant temperature, and the emergence peak from pistachio mummies occurred sooner. The impact of these findings on understanding navel orangeworm population dynamics and current control recommendations is discussed.

Response of postharvest tree nut lepidopteran pests to vacuum treatments.

Industry concerns over insect resistance, regulatory action, and the needs of organic processors have renewed interest in nonchemical alternative postharvest treatments to fumigants used for California tree nuts. The development of inexpensive polyvinyl chloride containers capable of holding low pressures has increased the practicality of vacuum treatments for durable commodities such as tree nuts. To develop vacuum treatment protocols, we determined the relative tolerance to vacuum (50 mmHg) at 25 and 30 degrees C of different life stages of three postharvest pests of tree nuts: codling moth, Cydia pomonella (L.), navel orangeworm, Amyelois transitella (Walker), and Indianmeal moth, Plodia interpunctella (Hübner). At both temperatures, nondiapausing codling moth larvae were the least tolerant stage tested. LT95 values for diapausing Indianmeal moth larvae were similar to Indianmeal moth eggs at both temperatures. Indianmeal moth diapausing larvae and eggs were the most tolerant at 25 degrees C, whereas navel orangeworm eggs were most tolerant at 30 degrees C. Field tests using GrainPro Cocoons (GrainPro, Inc., Concord, MA) to treat shelled almonds, Prunus dulcis (Mill.) D. A. Webb, in bins at vacuum levels of 18-43 mmHg at average winter temperatures (6-10 degrees C) showed that diapausing codling moth larvae were the most tolerant under these conditions and that exposures of 7-13 d provided incomplete control. Summer field tests treating in-shell almonds in bags at average temperatures of 25-30 degrees C provided complete control with 48 h exposure to average vacuum levels of 50 mmHg, and navel orangeworm eggs were the most tolerant stage.

Nezara viridula (Hemiptera: Pentatomidae) feeding patterns in macadamia nut in Hawaii: nut maturity and cultivar effects.

Nezara viridula L. (Hemiptera: Pentatomidae) is a serious pest of macadamia nuts, Macadamia integrifolia, in Hawaii. Using ruthenium red dye to stain stink bug feeding probes, feeding activity was determined for nuts of various maturity levels harvested from the tree and off the ground throughout the growing season in five commercial cultivars. Damage occurred in the tree and on the ground during all nut growth stages. Damage on the ground was often higher than in the tree. Cultivar 246 was more susceptible to attack than cultivars 333 and 800. It was previously thought that cultivar susceptibility was related to husk and shell thickness, but cultivar 246 showed higher damage than other cultivars even during early nut development when the nuts are small and before the shell has formed. This suggests that shell and husk thickness may play a secondary role in susceptibility to feeding by N. viridula. Monitoring N. viridula feeding activity during early nut development may help alert growers to potential problems later in the season, but early-season probing activity in immature nuts was not a good predictor of damage levels in mature nuts later in the season in our study.

Long-term patterns and feeding sites of southern green stink bug (Hemiptera: Pentatomidae) in Hawaii macadamia orchards, and sampling for management decisions.

Southern green stink bug (Nezara viridula, Hemiptera: Pentatomidae) is a pest of macadamia nuts, causing pitting to kernels by feeding. In spite of its pest status, many aspects of the ecology of this insect in macadamia orchards are poorly understood. This study analyzes long-term N. viridula damage to macadamia nuts and investigates the extent to which damage to nuts occurs in the tree canopy, prior to nut-drop. We show that there are distinct seasonal peaks in damage detected after harvest and that, over six years of data collection, mean damage levels were fairly low, albeit with spikes in damage levels recorded. Sampling nuts at peak harvest periods from different strata in the trees and from the ground showed that incidence of damaged nuts within the canopy was typically half as high as on the fallen nuts. Damage to fallen nuts may have occurred prior to nut-drop, and continued to accumulate after nut-drop. These results show that management of N. viridula within macadamia canopies, as opposed to only on fallen nuts, is important. A sampling procedure and predictive model for estimating late-season damage based on early-season damage samples is provided. The model uses January and March damage measurements (based on samples with set level of accuracy), mean temperature and month of the year for which damage is predicted. Early-season damage of 6-10% predicts late-season damage levels that should justify N. viridula suppression based on the nominal threshold (13% damage) used by kernel processors to reject nuts based on damage.

Assessing Nezara viridula (Hemiptera: Pentatomidae) feeding damage in macadamia nuts by using a biological stain.

Damage caused by southern green stink bug, Nezara viridula (L.), to macadamia nuts, Macadamia integrifolia Maiden & Betche, is normally determined after nuts are harvested and processed, which may be many months after damage occurred in the field. We developed a method using ruthenium red dye to stain stink bug feeding probes and indirectly assess feeding activity in macadamia nuts. By using the staining method, feeding probes were easily detected on the husk, shell, and kernel. Husk probing was highly correlated (0.80-0.90) with feeding and damage to the kernel. Failure rate to detect kernel damage from stained husk probes was generally <6%. The staining method was equally effective for immature and mature nuts; therefore, N. viridula feeding activity can be monitored throughout the season to evaluate pest management tactics and forecast outbreak populations.

Post-harvest entomology research in the United States Department of Agriculture-Agricultural Research Service.

This is a review of current post-harvest entomology research conducted by the Agricultural Research Service, the research branch of the US Department of Agriculture. The review covers both durable and perishable commodities. Research on biochemistry, genetics, physiology, monitoring and control of insects infesting stored grain, dried fruits and nuts, and processed commodities is reviewed. Research on development of quarantine treatments, particularly for fruit flies, is also reviewed, including research on thermal and irradiation treatments and a discussion of risk management for quarantine pests. Two areas of research are covered more extensively: a project to map the genome of the red flour beetle, Tribolium castaneum, and the use of near-infrared spectroscopy for detection of hidden infestations in grain, quantification of insect fragments in food, determination of quality in dried fruits, identification of insect species and age-grading insects. Future research directions are identified.

Dependence of aflatoxin in almonds on the type and amount of insect damage.

The aflatoxin distribution of single insect damaged Nonpareil almonds (1999 crop) has been measured. Separate distributions were obtained for pinhole, insect (feeding), and gross damage. Only a low level of aflatoxin contamination ( = 0.0003 ng/g) was found for pinhole-only damaged nuts. The distributions for insect and gross damage did not differ, but did differ significantly from the distribution previously obtained for gross damaged Ne Plus almonds from a different producer (Schatzki, T. F.; Ong, M. S. J. Agric. Food Chem. 2000, 48, 489-492; also 1999 crop). The Nonpareil almond distribution could be explained on the basis of a preharvest hull splitting, similar to previous results in pistachios (0-4 weeks versus 2-6 weeks preharvest). The Ne Plus distribution differs in detail from pistachio results and from the Nonpareil results found here. This may indicate additional cultural damage of Ne Plus almonds around harvest time and/or use of different sorting parameters. Aflatoxin lot averages of 31.7 and 3.47 ng/g were obtained for 100% insect damaged Ne Plus and Nonpareil almonds, respectively. (The previous Ne Plus work contained a calculation error, which is corrected here.) The distribution functions were used to compute the seller's risk of nonacceptance of lots in the European Union. To obtain a 95% acceptance rate, aflatoxin B(1) levels of 0.12 and 0.22 ng/g would be required, which would correspond to 3.8 and 1.2% (feeding and gross) insect damage in Nonpareil and Ne Plus almond lots, respectively.

Distribution of aflatoxin in almonds. 2. Distribution in almonds with heavy insect damage.

The aflatoxin distribution function in individual insect-damaged NePlus Ultra almonds was determined and found to be the sum of two distributions. Substantially all almonds exhibited a positive aflatoxin level between 0.02 ng/g (the detection level) and 0.3 ng/g, the precise form of this distribution depending on the lot studied. In addition, 1/1000 of the nuts showed contamination between 60 and 600 000 ng/g, independent of the lot. The latter distribution showed a smooth decrease with log concentration in this range, with no evidence of a minimum, as had been found previously for pistachios. No distribution data between 0.3 and 60 ng/g could be obtained. The distribution below 0.3 ng/g was assigned to contamination during post-harvest storage. The distribution above 60 ng/g was tentatively assigned to navel orange worm damage occurring when insects enter the kernel during split hulls late in the growing season. Considerable additional work will be required to verify these assignments.