Diel flight activity in response to attractants in the predatory beetle, Cathartus quadricollis (Coleoptera: Silvanidae) in macadamia nut in Hawaii.

The diel flight activity in Cathartus quadricollis (Guerin-Meneville) (Coleoptera: Silvanidae), a predator of two important pests in Hawaii, coffee berry borer, Hypothenemus hampei (Ferrari) and tropical nut borer, Hypothenemus obscurus (F.) (Coleoptera: Curculionidae: Scolytinae) was studied in a macadamia nut orchard using yellow sticky traps baited with pheromone and fungal volatile attractants. The study was conducted at different months throughout the year and at different times during the lunar cycle (new moon and full moon). Flight activity peaked in the late hours of the photophase into the early hours of the scotophase, between 1830 and 2000 h; flight activity also occurred but to a lesser extent in the early morning hours between 0700 and 1030 h. Numbers of captured C. quadricollis during periods of flight activity were negatively correlated with wind speed. The implications of these findings for the development of optimal pest management strategies including biological control are discussed.

Physiochemical and Sensory Properties of a Turmeric, Ginger, and Pineapple Functional Beverage with Effects of Pulp Content.

Beverage mixtures based on pineapple juice (80-100%), with varying concentrations of turmeric (0-20%) and ginger (0-20%) juice were developed. The pineapple juice alone exhibited a total soluble solid (TSS) content of 15.90-16.03 °Brix. The total polyphenols content (TPC) varied between 0.32 and 1.79 mg GAE/mL, and the 1,1-diphenyl-2-picrylhydrazyl (DPPH) inhibition was between 40.56% and 86.19% and correlated with the TPC and curcumin and other curcuminoids. The formulations with a high pulp content showed a significantly higher TPC and greater DPPH inhibition than those with a low pulp content. Turmeric and ginger with a high amount of pulp had a higher abundance of volatile compounds. Significant differences were observed by the panelists in the taste and mouthfeel attributes and the low-pulp juices were associated with increased palatability due to the better mouthfeel, higher sweetness, and decreased bitterness, pepperiness, pulpiness, and spiciness. The pineapple juice mixtures with 10% turmeric juice and 10% or less ginger juice were most preferred by sensory panelists.

Efficacy of X-Ray Phytosanitary Irradiation on the Infectivity and Reproduction of Angiostrongylus cantonensis in Experimentally Infected Rats.

Angiostrongylus cantonensis is a globally distributed nematode and the leading cause of eosinophilic meningitis in humans. As a global hotspot for this disease, Hawaii's agricultural exports may be contributing to the spread of A. cantonensis. Phytosanitary irradiation doses of 150 or 400 Gy provide quarantine security against multiple insect pests. We evaluated the in vitro and in vivo effects of phytosanitary irradiation on infectious, third-stage, A. cantonensis larvae. In vitro experiments directly exposed larvae to irradiation doses ranging from 200 to 1,000 Gy. Results showed low mortality and no dose response across all treatments 27 days post-irradiation. In vivo studies isolated larvae from wild-caught Parmarion martensi after exposure to x-ray irradiation at doses of 0, 150, and 400 Gy and infected them into laboratory rats. Fourteen rats were assigned to each treatment and infected with 50 larvae from their assigned irradiation dose. Results at 3 and 6 weeks post-infection demonstrated a significant negative dose response in regard to the number of larvae that migrated to the brain and adults found in the pulmonary artery. No irradiated larvae that grew into adults were able to produce eggs. These findings indicate that x-ray irradiation does not result in the direct mortality of A. cantonensis larvae; however, it does affect the infectivity and reproduction of A. cantonensis within its definitive host, the rat. Phytosanitary irradiation at doses ≥150 Gy appears to be an effective means of preventing the establishment of viable populations of A. cantonensis, thus reducing the potential for global spread due to agricultural exports from Hawaii.

Pilot Testing of an Area-Wide Biological Control Strategy against the Coffee Berry Borer in Colombia Using African Parasitoids.

The coffee berry borer (CBB), Hypothenemus hampei (Ferrari, 1867) (Coleoptera: Curculionidae: Scolytinae), native to Africa, is a major global insect pest of coffee. It has invaded many coffee production areas around the world that do not have natural enemies. In this study, two African parasitoids, Prorops nasuta Waterston (Hymenoptera: Bethylidae) and Phymastichus coffea Waterston (Hymenoptera: Eulophidae), were mass-reared for field release against H. hampei in Chinchiná, Colombia. More than 1.5 million wasps of each species were released on a 61-hectare coffee farm in replicated plots, resulting in parasitism rates of up to 7.7% for P. nasuta and 56.3% for P. coffea. This led to a maximum reduction in H. hampei field populations of 81% from dispersal coffee plots (old coffee crops before plant stumping) and 64.3% in colonization coffee plots (new coffee crops with active growing and fruiting plants) within the farm. As a result of this area-wide strategy, the percentage of CBB-infested coffee berries in colonization coffee plots decreased from 51.1 to 77.5% compared to coffee plots without parasitoid releases. This approach offers a promising alternative to the use of chemical insecticides and could be integrated into current pest management programs to control H. hampei.

Physical, Chemical, and Sensory Properties of a Turmeric-Fortified Pineapple Juice Beverage.

Beverage mixtures based on pineapple (Ananas comosus) and turmeric (Curcuma longa) juice as a ready-to-drink product were developed, and their physicochemical, nutritional, and sensory properties were evaluated. Four different concentrations of turmeric juice (5%, 10%, 15%, and 20% (v/v)) were added to pineapple juice to make turmeric-fortified pineapple (TFP) juice samples. Pineapple juice without turmeric was the control. The L*, a*, b*, titratable acidity (TA), total antioxidant capacity, and %DPPH scavenging values, as well as the concentrations of the phenolic compounds curcumin and demethoxycurcumin, were significantly increased with increasing turmeric concentration. Thirty volatile compounds were detected in the mixed juice samples with turmeric. Most of the turmeric-specific compounds, including monoterpenes, sesquiterpenes and turmerones, were detected in the TFP juice samples. While the antioxidant activity of the juice samples increased with increasing turmeric concentration, the pineapple juice fortified with 10% turmeric (10%T) had the best overall quality as determined by panelists. Greater concentrations of turmeric were associated with decreased palatability due to reduced mouthfeel and sweetness and increased aftertaste and sourness. These results suggest that the 10%T juice could be developed into a commercial functional beverage with increased overall flavor and nutritional quality.

Evaluation of bioactive low-density polyethylene (LDPE) nanocomposite films in combined treatment with irradiation on strawberry shelf-life extension.

A low-density polyethylene (LDPE) film reinforced with cellulose nanocrystals (CNCs) with an encapsulated bioactive formulation (cinnamon essential oil + silver nanoparticles) was developed for preservation of fresh strawberries. Antimicrobial activity of the active LDPE films was tested against Escherichia coli O157:H7, Salmonella typhimurium, Aspergillus niger, and Penicillium chrysogenum by agar volatilization assay. The optimal condition of the films showed ≥75% inhibitory capacity against the tested microbes. Strawberries were stored with different types of films: Group 1 (control): (LDPE + CNCs + Glycerol), Group 2: (LDPE + CNCs + Glycerol + AGPPH silver nanoparticles), Group 3: (LDPE + CNCs + Glycerol + cinnamon), Group 4: (LDPE + CNCs + Glycerol + active formulation), and Group 5: (LDPE + CNCs + Glycerol + active formulation + 0.5 kGy γ-radiation) at 4°C for 12 days. Weight loss (WL) (%), decay (%), firmness (N), color, and total phenolics and anthocyanin content of the strawberries were measured. Results showed that the most effective LDPE-nanocomposite film for reducing the microbial growth was LDPE + CNCs + Glycerol + active formulation film (Group 4). When combined with γ-irradiation (0.5 kGy), the LDPE + CNCs + Glycerol + active formulation (Group 5) significantly reduced both decay and WL by 94%, as compared to the control samples after 12 days of storage. Total phenols (from 952 to 1711 mg/kg) and anthocyanin content (from 185 to 287 mg/kg) increased with storage time under the different treatments. The mechanical properties, water vapor permeability (WVP), and surface color of the films were also tested. Though the WVP of the films were not influenced by the types of antimicrobial agents, they did significantly (p ≤ 0.05) change color and mechanical properties of the films. Therefore, combined treatment of active film and γ-irradiation has potential as an alternative method for extending the shelf-life of storage strawberries while maintaining fruit quality. PRACTICAL APPLICATION: Bioactive Low-density polyethylene (LDPE) nanocomposite film was developed in the study by incorporating active formulation (essential oil and silver nanoparticle) to extend the shelf life of stored strawberries. The bioactive LDPE-based nanocomposite film along with γ-irradiation could be used to preserve fruits for long-term storage by controlling the growth of foodborne pathogenic bacteria and spoilage fungi.

Susceptibility of 'Malama' Avocados to Bactrocera dorsalis (Diptera: Tephritidae) in Hawai'i and a Proposed Systems Approach for Market Access.

Avocados are generally poor hosts or nonhosts for tephritid fruit flies, which can influence the type of mitigation measures required by export protocols for trade. We conducted experiments to determine the susceptibility of the avocado, Persea americana, cv. 'Malama' to infestation by Oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), in Hawai'i using laboratory and field no-choice cage tests, together with field sampling. In no-choice cage tests, infestation rates increased with decreasing fruit firmness over time after harvest. Although risk of infestation was negatively correlated with fruit firmness, about 50% of mature hard fruit exposed immediately after harvest became infested. In field cage tests, mature hard fruit on the tree at the 25% purple color stage were not infested, whereas fruit at the 50, 75, and 100% purple color stages were infested at relatively low rates. Field sampling of fallen 'Malama' fruit over two seasons showed no natural infestation by B. dorsalis and trap captures in avocado orchards using McPhail traps containing protein bait lures averaged 0.13 ± 0.03 (mean ± SE) flies per trap per week, underscoring the low prevalence of fruit flies in avocado orchards and the poor host quality of this cultivar. A systems approach based on poor host status, low prevalence, and a limited harvest period (October to March) and distribution area (northern tier states) is proposed to export 'Malama' avocados from Hawai'i to the continental United States.

Evaluation of macadamia felted coccid (Hemiptera: Eriococcidae) damage and cultivar susceptibility using imagery from a small unmanned aerial vehicle (sUAV), combined with ground truthing.

BACKGROUND: Macadamia felted coccid, Acanthococcus ioronsidei (Williams) (Hemiptera: Eriococcidae), is a significant pest of macadamia nut, Macadamia integrifolia Maiden & Betche (Protaceae), in Hawaii, and heavy infestations can kill branches, resulting in characteristic dead, copper-colored leaves. Small Unmanned Aerial Vehicles (sUAV) or 'drones,' combined with spatial data analysis, can provide growers with accurate and high-resolution detection of plant stress due to pest infestations. We investigated the feasibility of using RGB (red-green-blue) color images from sUAV to detect dieback caused by macadamia felted coccid infestation and compared sUAV estimates with ground-based damage estimates (ground truthing). RESULTS: Spatial analysis showed clustering of foliar damage that reflected cultivar susceptibility to macadamia felted coccid infestation, with cultivars 344 and 856 being susceptible, and cultivars 800 and 333 being tolerant. sUAV and ground-based estimates of foliar damage were similar for the cultivar 344, but ground-based assessments were higher than sUAV for cultivar 856, possibly due to the differences in canopy architecture and significant early dieback in the lower canopy. At foliar damage levels <10%, sUAV and ground truthing data were significantly positively correlated, suggesting sUAV may be useful in detecting early stages of macadamia felted coccid infestation. CONCLUSIONS: Cultivars showed varying susceptibility to macadamia felted coccid infestation and the foliage damage appeared in clusters. sUAV was able to detect the foliage damage under high and low infestation scenarios suggesting that it can be effectively used for the early detection of infestations. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

In vivo efficacy of pyrantel pamoate as a post-exposure prophylactic for rat lungworm (Angiostrongylus cantonensis).

Rat lungworm (Angiostrongylus cantonensis) is a neurotropic nematode, and the leading cause of eosinophilic meningitis worldwide. The parasite is usually contracted through ingestion of infected gastropods, often hidden in raw or partially cooked produce. Pharmaceutical grade pyrantel pamoate was evaluated as a post-exposure prophylactic against A. cantonensis. Pyrantel pamoate is readily available over-the-counter in most pharmacies in the USA and possesses anthelmintic activity exclusive to the gastrointestinal tract (GIT). Administering pyrantel pamoate immediately after exposure should theoretically paralyze the larvae in the GIT, causing the larvae to be expelled via peristalsis without entering the systemic circulation. In this study, pyrantel pamoate (11 mg/kg) was orally administered to experimentally infected rats at 0, 2-, 4-, 6-, or 8-h post-infection. The rats were euthanized six weeks post-infection, and worm burden was evaluated from the heart-lung complex. This is the first in vivo study to evaluate its efficacy against A. cantonensis. This study demonstrates that pyrantel pamoate can significantly reduce worm burden by 53-72% (P = 0.004), and thus likely reduce the severity of infection that is known to be associated with worm burden. This paralyzing effect of pyrantel pamoate on the parasite may also be beneficial for delaying the establishment of infection until a more suitable anthelmintic such as albendazole is made available to the patient.

Poor Host Status of Australian Finger Lime, Citrus australasica, to Ceratitis capitata, Zeugodacus cucurbitae, and Bactrocera dorsalis (Diptera: Tephritidae) in Hawai'i.

We examined the host status of the Australian finger lime, Citrus australiasica F. Muell. (Rutaceae), to Hawai'i's tephritid fruit fly pests using laboratory and field studies. In high-density (500 flies, 1:1 males and females) no-choice cage exposures (25 × 25 × 25-cm cage size), both undamaged and punctured finger limes were infested by Ceratitis capitata and Zeugodacuscucurbitae at a low rate compared to papaya controls, whereas Bactrocera dorsalis did not infest undamaged fruit, suggesting finger lime is a nonhost. In low-density (50 females) no-choice cage exposures, C. capitata and Z. cucurbitae readily oviposited in undamaged fruit but individuals rarely developed to the pupal or adult stage. For C. capitata, 274 finger limes exposed to 2000 gravid females, which laid an estimated 14,384 eggs, produced two pupae and no adults. For Z. cucurbitae, 299 fruit exposed to 2000 gravid females, which laid an estimated 4484 eggs, produced four pupae and one adult. Field sampling of undamaged fruit from the tree and off the ground from commercial farms produced five C. capitata pupa and one adult from 1119 fruit, for an infestation rate of 0.05 flies per kilogram of fruit; field collections found no natural Z. cucurbitae or B. dorsalis infestation, but the number of fruit available was too low to demonstrate nonhost status with a high degree of confidence.

Silver nanoparticles-essential oils combined treatments to enhance the antibacterial and antifungal properties against foodborne pathogens and spoilage microorganisms.

Plant-derived essential oils (EOs) and commercial silver nanoparticles (AgNPs) were tested to evaluate their antibacterial and antifungal efficiency against two pathogenic bacteria (Escherichia coli O157:H7 and Salmonella Typhimurium) and three spoilage fungi (Aspergillus niger, Penicillium chrysogenum, and Mucor circinelloides). A broth microdilution assay was used to determine the minimal inhibitory concentration (MIC) of EOs and AgNPs. In the MIC assay, the cinnamon EO, Mediterranean formulation, citrus EO and spherical-shaped silver nanoparticles (AgNPs) (AGC 1, AGC 0.5, AGPP and AGPPH) showed moderate to high antibacterial and antifungal properties, with MIC ranging from 7.8 to 62.5 ppm for AgNPs and 312.5-1250 ppm for EOs against the tested bacteria and fungi. The possible interaction between the EOs and the AgNPs was determined using a checkerboard method by evaluating fractional inhibitory concentration (FIC) values. The combination of two or more EOs and AgNPs (Active combination 1: AGPPH+cinnamon EO, Active combination 2: AGC 0.5+Mediterranean formulation+citrus EO, Active combination 3: AGPP+cinnamon EO+Asian formulation+lavang EO) showed synergistic effects (FIC <1.0) against all tested bacteria and fungi. A modified Gompertz model was used to evaluate growth parameters including maximum colony diameter (A), maximum growth rate (Vm), and lag phase (λ), under the three active combinations suggested by the checkerboard method using a vapor assay. The three active combinations 1, 2 and 3 reduced the growth rate and maximum colony diameter of E. coli, S. Typhimurium, A. niger, P. chrysogenum, and M. circinelloides, and extended their lag phase from 1 to 5 days. In in situ tests with inoculated rice, the three active combinations showed a significant reduction of all tested bacteria and fungi at 27 °C for 28 days.

Phytosanitary irradiation using X-rays prevents reproduction in the semi-slug Parmarion martensi (Stylommatophora: Ariophantidae), a host of the human pathogenic nematode Angiostrongylus cantonensis (Rhabditida: Angiostrongylidae).

BACKGROUND: Phytosanitary irradiation is used to control insect pests of quarantine concern on exported fresh horticultural products. Generic irradiation doses of 150 and 400 Gy are approved for tephritid fruit flies and all other insects, respectively. Other invertebrates such as gastropods (snails and slugs) may be classified as quarantine pests and require a disinfestation treatment. Parmarion martensi Simroth (Stylommatophora: Ariophantidae) is a semi-slug quarantine pest sometimes found on fresh sweet potatoes and other fruits and vegetables exported from Hawai'i to the continental USA. Also, P. martensi is a host of the parasitic nematode Angiostrongylus cantonensis (Rhabditida: Angiostrongylidae), the causative agent of neuroangiostrongyliasis or rat lungworm disease in humans. We conducted a study to determine if phytosanitary irradiation could control P. martensi and thereby reduce the risk of transmitting A. cantonensis in the USA. RESULTS: Two-, 12-, and 21-week-old P. martensi were treated with X-ray radiation at a dose of 150 or 400 Gy or left untreated as controls then held in the laboratory for up to 250 days. Survivorship and reproduction were recorded every 2-3 days and individual weights were measured biweekly. Irradiation at 150 and 400 Gy reduced growth and increased the mortality rate compared to untreated controls and prevented reproduction. CONCLUSION: Phytosanitary irradiation treatment at doses ≥150 Gy will prevent the establishment of viable populations of P. martensi. The literature on radiation tolerance in gastropods suggests that the internationally approved generic dose for tephritid fruit flies of 150 Gy may be effective against many slug and snail pest species.

Mixture design methodology and predictive modeling for developing active formulations using essential oils and citrus extract against foodborne pathogens and spoilage microorganisms in rice.

The antibacterial and antifungal effects of six plant-derived essential oils (EOs) and two types of citrus extracts (CEs) were studied against two pathogenic bacteria (Salmonella Typhimurium and Escherichia coli O157:H7) and three fungi (Aspergillus niger, Penicillium chrysogenum, and Mucor circinelloides). A broth microdilution assay and checkerboard method were used to measure the minimal inhibitory concentration (MIC) of each extract and the possible interactions between them. The MIC assay showed that cinnamon EO, Mediterranean EO, Southern formulation, citrus EO, organic citrus extract (OCE), and natural citrus extract (NCE) had the highest antimicrobial and antifungal activity. The checkerboard method showed that the Mediterranean EO+OCE combination acted in synergy against all tested pathogens. A centroid mixture design was used to develop active formulations by predicting optimal concentrations of EO/CEs for increased antibacterial/antifungal activity. A mixture of four formulations (625 ppm OCE, 313 ppm Mediterranean EO, 625 ppm citrus EO, and 313 ppm cinnamon EO) named as active formulation 1, and the mixture from five formulations (625 ppm NCE, 625 ppm Asian formulation, 313 ppm Southern formulation, 625 ppm cinnamon EO, and 313 ppm savory thyme EO) named as active formulation 2, were formulated and tested because of their high microbicidal effectiveness. In situ tests with rice showed a significant reduction (P ≤ 0.05) of all tested pathogenic bacteria and fungi from the vapor of active formulations 1 and 2 after 28 days of storage. PRACTICAL APPLICATION: Active formulations (essential oils and citrus extracts) developed in the study are highly effective against foodborne pathogens. Active formulations in this study could be used as natural preservatives in the food industry for controlling foodborne diseases and spoilage organisms in stored foods.

Host Suitability Index for Polyphagous Tephritid Fruit Flies.

Tephritid fruit flies are major economic pests for fruit production and are an impediment to international trade. Different host fruits are known to vary in their suitability for fruit flies to complete their life cycle. Currently, international regulatory standards that define the likely legal host status for tephritid fruit flies categorize fruits as a natural host, a conditional host, or a nonhost. For those fruits that are natural or conditional hosts, infestation rate can vary as a spectrum ranging from highly attractive fruits supporting large numbers of fruit flies to very poor hosts supporting low numbers. Here, we propose a Host Suitability Index (HSI), which divides the host status of natural and conditional hosts into five categories based on the log infestation rate (number of flies per kilogram of fruit) ranging from very poor (<0.1), poor (0.1-1.0), moderately good (1.0-10.0), good (10-100), and very good (>100). Infestation rates may be determined by field sampling or cage infestation studies. We illustrate the concept of this index using 21 papers that examine the host status of fruits in five species of polyphagous fruit flies in the Pacific region: Bactrocera tryoni Froggatt, Bactrocera dorsalis (Hendel), Bactrocera latifrons (Hendel), Zeugodacus cucurbitae (Coquillett), and Ceratitis capitata (Wiedemann) (Diptera: Tephritidae). This general-purpose index may be useful in developing systems approaches that rely on poor host status, for determining surveillance and detection protocols for potential incursions, and to guide the appropriate regulatory response during fruit fly outbreaks.

Demographics of the semi-slug Parmarion martensi, an intermediate host for Angiostrongylus cantonensis in Hawai'i, during laboratory rearing.

The semi-slug, Parmarion martensi, is an intermediate host of the zoonotic nematode, Angiostrongylus cantonensis, the aetiological agent of neuroangiostrongyliasis or rat lungworm disease in humans. Rearing methods were developed for P. martensi to facilitate studies on nematode transmission and control. Parmarion martensi exhibited high survivorship when reared on a diet of dog food and fresh fruits and vegetables in temperature-controlled cabinets at 21.4°C, 98% relative humidity and 12:12 L:D cycle. Rearing containers were lined with moist paper towels for substrate and plastic pots were provided for hiding/resting and egg-laying. Under these conditions, time to first reproduction was 165.3 ± 12.3 days, fecundity was approximately 34.5 ± 7.8 eggs per adult, and hatch rate was 52.7 ± 3.2%. Survivorship post egg hatch was 86.2 ± 2.9% at 30 days (neonates had a mortality rate of about 14%) and 99% thereafter for up to a year. The demographics of laboratory-reared and wild-caught P. martensi were similar except for the weight of reproductive adults, which was significantly higher in laboratory-reared adults (4.0 ± 0.2 g) than in field-collected adults (1.5 ± 0.1 g).

Microbial radiosensitization using combined treatments of essential oils and irradiation- part B: Comparison between gamma-ray and X-ray at different dose rates.

Stored rice and rice products are prone to contamination by pathogenic fungi and bacteria such as Aspergillus niger, Bacillus cereus, and Paenibacillus amylolyticus. Treatment with antimicrobial essential oils (EOs) and irradiation are options to control spoilage organisms. Microbial samples with or without fumigation with an oregano/thyme EO mixture were irradiated at 0.5, 0.75, 1.0, 1.5, 2.0, 2.5, 3.0 and 3.5 kGy for calculation of a D10 value. The relative sensitivity was calculated as the ratio of D10 values for the irradiation plus oregano and thyme EO combination and irradiation alone treatments. In all cases, irradiation plus fumigation with the oregano and thyme EO mixture showed increased efficacy compared with irradiation alone. The relative sensitivity of γ-ray irradiation against A. niger was 1.22, 1.33, and 1.24 for radiation dose rates of 10.445, 4.558, and 0.085 kGy/h, respectively, however against B. cereus it was 1.28, 1.45, and 1.49, and against P. amylolyticus it was 1.35, 1.33, and 1.38, for respective γ-ray irradiation dose rates. The relative sensitivity of X-ray irradiation against A. niger, B. cereus, and P. amylolyticus was 1.63, 1.21, and 1.31, respectively, at the X-ray dose rate of 0.76 kGy/h. The results showed that the relative sensitivity of γ-ray irradiation was higher against the two bacteria than the fungus, whereas X-ray showed higher sensitivity against the fungus than the two bacteria. There was no consistent positive or negative relationship between dose rate and relative sensitivity. The results demonstrated the potential of an oregano and thyme EOs mixture as an antimicrobial agent and its efficacy to increase the radiosensitization of A. niger, B. cereus, and P. amylolyticus during γ-ray or X-ray irradiation treatments.

Potential synergistic antimicrobial efficiency of binary combinations of essential oils against Bacillus cereus and Paenibacillus amylolyticus-Part A.

The checkerboard method was used to study the potential interactions between eight essential oils (Basil, Cinnamon, Eucalyptus, Mandarin, Oregano, Peppermint, Tea tree, and Thyme) when used as antibacterial agents against Bacillus cereus LSPQ 2872 and Paenibacillus amylolyticus ATCC 9995. The minimum inhibitory concentration (MIC) of each essential oil (EO) and the fractional inhibitory concentration (FIC) index for the binary combinations of essential oils (EOs) were determined. According to FIC index values, some of the compound binary combinations showed an additive effect; however, Thyme/Tea tree and Cinnamon/Thyme EOs exhibited a synergistic effect against P. amylolyticus and B. cereus, respectively. Cinnamon/Thyme EOs mixture exhibited no interactive effect against P. amylolyticus, but a synergistic effect against B. cereus. The combination of Oregano/Thyme EOs displayed the best antibacterial activity and showed a synergistic effect against B. cereus and P. amylolyticus bacteria. The Oregano/Thyme EOs mixture has potential application in food preservation to reduce the contamination of B. cereus and P. amylolyticus.

Coffee berry borer (Hypothenemus hampei) (Coleoptera: Curculionidae) development across an elevational gradient on Hawai'i Island: Applying laboratory degree-day predictions to natural field populations.

Coffee berry borer (CBB, Hypothenemus hampei) (Coleoptera: Curculionidae: Scolytinae) is the most destructive pest of coffee worldwide. Information on CBB development times can be used to predict the initiation of new infestation cycles early in the coffee-growing season and thus inform the timing of insecticide applications. While laboratory estimates of CBB development under constant conditions exist, they have not been applied under the heterogeneous environmental conditions that characterize many coffee-growing regions. We measured CBB development times and abundance in commercial coffee farms across an elevational gradient on Hawai'i Island and applied thermal accumulation models from previous laboratory studies to test their fit to field data. Artificial lures were used to infest coffee berries at five farms ranging in elevation from 279-792 m, and weather variables were monitored at macro (farm-level) and micro (branch-level) scales. CBB development was followed in the field from the time of initial berry infestation by the founding female through the development of F1 mature adults. Mean development time from egg to adult across all sites was 38.5 ± 3.46 days, while the mean time required for the completion of a full life cycle (from time of infestation to presence of mature F1 females) was 50.9 ± 3.35 days. Development time increased with increasing elevation and decreasing temperature. Using macro-scale temperature data and two different estimates for the lower temperature threshold (14.9°C and 13.9°C), we estimated a mean requirement of 332 ± 14 degree-days and 386 ± 16 degree-days, respectively, from the time of berry infestation to the initiation of a new reproductive cycle in mature coffee berries. Similar estimates were obtained using micro-scale temperature data, indicating that macro-scale temperature monitoring is sufficient for life-cycle prediction. We also present a model relating elevation to number of CBB generations per month. Our findings suggest that CBB development times from laboratory studies are generally applicable to field conditions on Hawai'i Island and can be used as a decision support tool to improve IPM strategies for this worldwide pest of coffee.

ß-cyclocitral synergizes the response of adult Drosophila suzukii (Diptera: Drosophilidae) to fruit juices and isoamyl acetate in a sex-dependent manner.

Semiochemicals play a pivotal role in the location, evaluation, and utilization of hosts by herbivorous insects. Mixtures of host plant-derived compounds are often required to elicit appropriate levels of response to olfactory stimuli. In multiple-choice bioassays, we characterized the response of adult Drosophila suzukii to foliage- and fruit-based synthetic compounds tested alone and in association with grape and tart cherry juices, and assessed whether synergistic interactions among olfactory stimuli are involved in the olfactory-driven behavior of D. suzukii. Our results established (1) significant attraction of females (but not males) to ß-cyclocitral and isoamyl acetate when tested singly, (2) the presence of a synergistic interaction between ß-cyclocitral and cherry juice only for females, and (3) the presence of a synergistic interaction between ß-cyclocitral and isoamyl acetate but only in the case of males. Our findings increase our understanding of male and female D. suzukii olfactory responses to synthetic compounds and fruit juices as sources of attractants. Combinations of foliage- and fruit-based compounds may be needed to increase SWD attraction.

Synergistic Effects of Nanocomposite Films Containing Essential Oil Nanoemulsions in Combination with Ionizing Radiation for Control of Rice Weevil Sitophilus oryzae in Stored Grains.

The fumigant toxicity of eight individual essential oils (EOs; basil, cinnamon, eucalyptus, mandarin, oregano, peppermint, tea tree, and thyme) and one binary combination (thyme and oregano) for control of the rice weevil, Sitophilus oryzae, were investigated. In bioassays, all individual and combined EOs were toxic to the rice weevil. Eucalyptus EO exhibited the highest toxicity among the individual EO treatments, causing 100% mortality at a minimum concentration of 0.8 µL/mL after 24 hr of exposure. The combination treatment of oregano and thyme EO displayed higher fumigant activity than the individual oregano or thyme treatments. A stable oil-in-water nanoemulsion was evaluated using high-pressure homogenization (microfluidization [MF]) and varying the pressure and number of cycles. The droplet size of the emulsions was found to decrease from 217 to 71 nm and encapsulation efficiency increased from 37% to 84% with increasing MF pressure and number of cycles. The optimum conditions for preparing the mixture of oregano and thyme EO nanoemulsions were evaluated to be homogenization pressure of 103 MPa and three cycles. Incorporating an oregano:thyme nanoemulsion (0.75%) into cellulose nanocrystal (CNC) containing chitosan (CH/CNC), methyl cellulose (MC/CNC), and polylactic acid (PLA/CNC) composite films resulted in extended diffusion matrices causing 32% to 51% rice weevil mortality after 14 days exposure. Irradiation at 200 Gray alone caused 79% mortality and increased to 100% when combined with the bioactive chitosan film containing the oregano:thyme nanoemulsion. PRACTICAL APPLICATION: A binary combination of oregano:thyme has potential as a biopesticide against stored product pests. The encapsulation of EO nanoemulsions into biopolymeric support could be used for bioactive packaging to prevent food spoilage and extend shelf life. Combining bioactive films with irradiation can provide complete control of rice weevil in packaged rice. The system developed in this research may also be extended to explore other food-packaging films with various food models to control different types of stored pests.