Control Mite Infestations Research Articles

Uses and commercialization of food grade and effectiveness of coated ham nets to combat Tyrophagus putrescentiae: a review

Since the 1930s, the dry-cured ham industry has used methyl bromide fumigation to control Tyrophagus putrescentiae (ham mite) infestations. However, due to methyl bromide being a class I ozone depleting substance and no longer being manufactured, alternatives to methyl bromide have been studied extensively. Direct contact food-grade coatings and coated ham nets of various materials have shown efficacy in controlling ham mite growth and reproduction. These coated nets, often including propylene glycol, can be dried to ease application and reduce shipping cost, but chemical and thermal treatments on fabrics may cause the fabrics to become more brittle, which negatively impacts stretchability and bursting strength, and ultimately the effectiveness of the net. Scanning electron microscopy can provide precise visual inspection of fabric surface morphology, allowing for a detection of potential damage to the fibers. This purpose of this review is to summarize the application of food-grade coatings on nets used in the dry-cured ham industry to control mite infestations. More importantly, the review provides comprehensive information on coated nets, covering various aspects such as the selection of netting materials, evaluation of fabric properties, techniques for coating nets, net drying method, all in relation to their efficacy for mite control. This review contributes to the broad area of this applied technology by highlighting efficacious treatments to control mites, ineffective treatments, a discussion of processes to evaluate their properties, and future prospectives regarding this area of study.

Carvone and citral, two promising compounds for controlling the honey bee ectoparasitic mite, Varroa destructor

AbstractVarroa destructor (Acari: Varroidae) is an external parasitic mite that has compromised honey bee (Hymenoptera: Apidae) health worldwide. Varroa mite resistance to commercial formulations of synthetic acaricides has led to an increasing need for new compounds to control mite infestations in honey bee colonies. Thus, essential oils and plant extracts have been used by organic producers concerned about the environment because they are low‐risk pesticides. This study tested the toxicity of four natural compounds: carvone, citral, cineole and limonene to mites and bees under laboratory conditions. Tau‐fluvalinate was used as positive control. Seven concentrations with logarithmic interval were used to test each compound. The safety margin of the compounds for the bees was calculated from selectivity ratios. Carvone was significantly more toxic to varroa mites (LC50 = 272.74 μg/ml) than the other three compounds but did not differ with tau‐fluvalinate (LC50 = 272.30 μg/ml). Citral was the second most toxic compound to mites (LC50 = 318.54 μg/ml), followed by cineole (LC50 = 3897.65 μg/ml) and limonene (LC50 = 3003.94 μg/ml). Citral and carvone showed low toxicity to worker bees at both 24 and 48 hpt. The LD50 values for citral, carvone and tau‐fluvalinate were 78,459, 106,620 and 143.02 μg/ml at 24 hpt, respectively, which were significantly different from each other. The relative selectivity ratios calculated for carvone, citral and tau‐fluvalinate were 390.9, 246.3 and 0.53, respectively. This study provides preliminary laboratory evidence for the effectiveness and safety of two plant compounds, carvone and citral, that could potentially be used for the control of V. destructor infestations in honey bee colonies.

Efficacy of a dinotefuran, permethrin and pyriproxyfen combination product in the treatment of rabbits (Oryctolagus cuniculus) naturally infested by Psoroptes ovis

The main of this study was to evaluate the efficacy of dinotefuran, pyriproxyfen and permethrin-combination (Vectra 3D-CEVA) in the topical treatment of rabbits naturally infested with P. ovis. Adult New Zealand rabbits (n = 18) with plaques of crust in both ears were divided into three groups (one control and two treated). On day 0, the animals belonging to the treated groups received a single dose of a commercial ectoparasiticide formulation, recommended for use in dogs. The control group (G1) (n = 6) received no treatment, the treated group (G2) (n = 6) received one drop in each ear, and the remaining volume was applied along the back of the animal in the dorsal midline with the commercial formulation. In the other treated group (G3) (n = 6), animals received the same product used in G2, but all the volumes of 0.5 mL were applied only to the back of the animal (dorsal midline). On days 0, +7, +14, +21, +28 and +35, lesion scores and mites per gram (MPG) of each ear scab were evaluated. Statistical analysis was performed using the statistical software Bioestat 5.01. As the Shapiro-Wilk test determined that the data were nonparametrically distributed, the Kruskal–Wallis test was performed, followed by the Student-Newman–Keuls test, to determine the significance levels among the mean values of mite counts per gram of crusts compared to the three experimental groups. The efficacies for remission of lesion scores were 19.87 % on day +7 to 83.44 % on day +35 for G2 and 70.67 % on day +7 to 92.20 % on day +35 for G3. The efficacies obtained by evaluation of MPG were 100 % on day +7 to 99.86 % on day +35 for G2 and from 93.05 % on day +7 to 99.89 on day +35 for G3. The topical administration of the combination of dinotefuran (4.95 %), pyriproxifen (0.44 %) and permethrin (36 %) on the ears and back or only on the back in rabbits was shown to be effective in naturally controlling mite infestations by P. ovis.

Use of nets treated with food grade coatings on controlling mold growth and mite infestation in dry-cured ham aging facilities

Dry-cured hams are frequently infested by mold and Tyrophagus putrescentiae in the aging facility during the 3 mo to 2-year aging period. Food grade coatings and these coating treated nets have been developed to control mold and mite growth on dry-cured hams to curtail the use of methyl bromide. Ham nets treated with food-grade coating of 1% propylene glycol alginate + 1% carrageenan + 40% propylene glycol were tested in a commercial research trial in 3 lots with approximately 100 hams in each lot, which also had approximately 100 control hams (untreated). Six of these hams were sent back to the research team. Three of these hams (already aged for 8 mo) were kept in a mite-infested simulated aging room for further evaluation of mold occurrence and mite population growth for another 6 mo. The other 3 hams from each lot of each treatment were tested by gas chromatography for propylene glycol residual. Mold evaluation indicated that the treatment hams reduced mold occurrence compared to the control hams, and there were no mite activities in any of these hams per inspection. In the mite-infested aging room, these coating-treated nets reduced mold and mite growth on whole hams (8–14-month-old). There was no difference in propylene glycol concentration between the control (0.072%) and net treated samples (0.053%). This concentration is 4 times less than 2%, the maximum acceptable concentration of this GRAS compound based on CFR 21,184.1666. Therefore, these hams met the legal requirements for commerce and were safe for human consumption and can be used to mitigate and help control mite infestations and mold growth of hams that are aged longer than 5 months.

Biological control of mites by xerophile Eurotium species isolated from the surface of dry cured ham and dry beef cecina

The aim of this article is to study the possible biological control of mites by fungi that form part of the normal microbiota of these meat products. Some yellow/orange pigmented fungi growing on the ham surface decreased the proliferation of mites; therefore, we isolated from ham and cecina xerophilic yellow/orange coloured fungal strains that were identified as members of the genus Eurotium (recently reclassified as Aspergillus section Aspergillus). Using molecular genetic tools, we have identified 158 strains as Eurotium rubrum (Aspergillus ruber), Eurotium repens (Aspergillus pseudoglaucus) and Eurotium chevalieri (Aspergillus chevalieri). Two strains, E. rubrum C47 and E. rubrum C49, showed strong miticidal activity. The toxic compound(s) are associated with the formation of cleistothecia. In synchronized mite development experiments, we observed that all stages of the mite lifecycle were inhibited by the E. rubrum C47 strain. In addition, we searched for miticidal activity in 13 culture collection Eurotium strains isolated from different habitats, and found that only one, Eurotium cristatum NRRL 4222 (Aspergillus cristatus) has a strong miticidal activity. These fungal strains have proliferated on the surface of ham and cecina for decades, and possibly have acquired miticidal activity as a resistance mechanism against fungivores. Biological control of infecting mites by favouring growth of E. rubrun C47, in place of the normal mixed population of Aspergillus and Penicillium, is an attractive approach to control mite infestations.

The application of food grade short chain fatty acids to prevent infestation of Tyrophagus putrescentiae on dry cured ham and the effects on sensory properties

Tyrophagus putrescentiae (ham mite) is difficult for commercial dry cured ham producers to control. Methyl bromide is an effective fumigant but is now banned as an ozone depleting substance, meaning alternative methods to control mite infestation must be found. This research was conducted to test the efficacy of C8C9C10 fatty acids combined with and without food grade coatings to control mite infestations on dry cured hams. Ham cubes were coated directly or wrapped in nets saturated with C8C9C10 with combinations of either soybean oil, xanthan gum (XG) or carrageenan (CG) + propylene glycol alginate (PGA). Cubes were then inoculated with 20 large mixed sex ham mites and stored for 14 days at 22 ± 2 °C and 70 ± 5% relative humidity. The soybean oil alone or in combination with 10% C8C9C10 in direct coating, and 1% and 10% C8C9C10 in coated nets controlled mite population growth. In addition, the use of 10% C8C9C10 + XG and 10% C8C9C10 + CG + PGA in direct coatings or in saturated nets, and 1% C8C9C10 + XG in saturated nets also inhibited mite population growth. Unexpectedly, the soybean oil solvent by itself effectively controlled mite population growth as well. Sensory evaluation was performed using a difference from control test (n = 8) and indicated that only 10% C8C9C10 mixed with soybean oil and 100% soybean oil did not impart sensory differences to ham when used as a coating. However, for ham slices treated in saturated nets and gum with C8C9C10 mixtures in either coating or saturated nets did impart sensory differences. Results indicated that C8C9C10 and soybean oil could be used in coating formulations to control ham mites but long-term testing, sensory evaluation, and scaled up testing is needed prior to industrial implementation.

Effects of temperature, relative humidity, and protective netting on Tyrophagus putrescentiae (Schrank) (Sarcoptiformes: Acaridae) infestation, fungal growth, and product quality of dry cured hams

Since methyl bromide is an ozone depleting substance, there is a need to find effective alternative methods to control mite infestations on dry cured hams. Therefore, the objective of this study was to determine the most effective relative humidity and/or temperature combination to minimize mite reproduction and mold growth on dry cured hams in untreated and food-grade ingredient infused nets. Food grade coating formulations of 1) xanthan gum and propylene glycol, and 2) carrageenan, propylene glycol alginate, and propylene glycol nets were infused into nets. Dry cured ham cubes and slices were wrapped with untreated and treated nets, inoculated with 20 large mixed-sex mites per cube or 50 large mixed-sex mites per slice, and then stored for 14 d at each temperature (24, 28, and 32 °C) and RH (55, 65, 75, and 85%) combination in an environmental chamber. Tyrophagus putrescentiae on ham slices in untreated nets were reduced from the initial inoculum level of 50 mites per ham slice when exposed to 85% r.h. at 24, 28, and 32 °C. Nets infused with xanthan gum and propylene glycol or carrageenan, propylene glycol alginate, and propylene glycol, completely inhibited mite reproduction at 85% r.h. In addition, the nets infused with carrageenan, propylene glycol alginate, and propylene glycol, controlled mite reproduction below the initial inoculum level on ham cubes and ham slices at all temperatures and relative humidities that were evaluated. Six to eight trained panelists rated the amount of mold on the ham slice surfaces on a 0–100% scale and both treated nets evaluated were effective at preventing mold growth on the ham slices.

Use of Lard, Food Grade Propylene Glycol, and Polysaccharides in Infused Nets to Control Tyrophagus putrescentiae (Schrank; Sarcoptiformes: Acaridae) Infestation on Dry Cured Hams

Tyrophagus putrescentiae (Schrank) is controlled in the U.S. dry cured ham industry with methyl bromide (MB) fumigation. However, MB fumigation is being phased out of use since it is an ozone depleting substance. The objective of this research was to evaluate ham nets that were infused with lard, propylene glycol (PG) and polysaccharide coating for their efficacy at controlling mite infestations on dry cured ham cubes from hams that were aged for 4 to 6 mo. Results indicated that fewer T. putrescentiae (P < 0.05) were on ham cubes with treated nets containing PG when compared to the number of mites on ham cubes with untreated nets over 10 wk of storage. Lard infused nets without PG did not decrease the mite population (P > 0.05). The net without coating slowed the growth and reproduction of T. putrescentiae since net controls had fewer mites (P < 0.05) than controls without nets. Fungi were not present on ham cubes that were treated with PG-containing nets over 10 wk of storage with a few exceptions. In conclusion, lard and xanthan gum, or carrageenan + propylene glycol alginate treated nets containing the medium concentration of PG effectively inhibited mite reproduction and fungal growth on dry cured ham and could potentially be used in an integrated pest management program to control mites on dry cured hams.

Use of nets treated with food-grade coatings on dry-cured ham to control Tyrophagus putrescentiae infestations without impacting sensory properties

Dry-cured hams may become infested with the ham mite Tyrophagus putrescentiae during aging. Food-grade coatings have been developed to control mite infestations as a potential alternative to replace methyl bromide, but dipping or spraying these coatings requires additional labor and processing steps. Nets composed of polyester, a polyester/cotton blend and cotton were infused with coatings that consisted of propylene glycol, and either propylene glycol alginate and carrageenan or xanthan gum. Results indicated that the polyester/cotton blend and cotton nets that contained propylene glycol were effective at controlling mite infestations in assays with ham cubes covered in nets. The polyester nets slowed mite growth but were not effective at controlling mite reproduction due to low absorbance of the coatings. Polyester/cotton blend nets treated with coatings on whole hams were not different from control hams with respect to flavor, texture and moistness. Mite infestation tests on whole hams indicated that coated nets with greater stitch densities were effective at controlling mite growth. Future research will include the optimization of coating formulations and scaled-up testing in dry-cured ham plants.

Mite Control and Sensory Evaluations of Dry-Cured Hams with Food-Grade Coatings

The ham mite, Tyrophagus putrescentiae (Schrank; Sarcoptiformes: Acaridae), is the predominant pest of dry-cured pork during aging. This research was conducted 1) to determine the minimal concentrations of propylene glycol necessary for food grade coatings to control mites; and 2) to determine if sensory differences could be detected in hams that were treated with food grade coatings in commercial facilities using difference from control sensory tests. Ham cubes coated with either xanthan gum + 15% propylene glycol or propylene glycol alginate + carrageenan + 7.5% propylene glycol were the lowest propylene glycol concentrations that were effective (P < 0.05) at controlling mite infestations under laboratory conditions. Whole hams from commercial plants that were dipped with coatings were slightly different (P < 0.05) from the non-dipped control hams with respect to flavor, texture and moistness in the first trial. However, hams sprayed with coatings, a lower-cost application than dipping, did not cause sensory differences (P > 0.05) when compared to the control with respect to flavor, texture, moistness, and weight loss in trial 2. This research indicated that dry-cured ham processors could potentially spray these coatings on dry-cured hams during aging to control mite infestations in their plants without negatively impacting the sensory quality of the hams.

Application of Food Grade Coatings to Prevent Mite Infestion in Dry Cured Ham Processing Facilities

ObjectivesThe ham mite (Tyrophaus putrescentiae Schrank) is the predominant target pest for dry cured ham during aging. Methyl bromide is currently the only effective fumigant for controlling mite infestations in the dry-cured ham industry. However, methyl bromide is being phased out of all industries based on the Montreal Protocol. The objective of this research was to find viable, effective and economical alternatives for the dry cured ham processing facilities.Materials and MethodsFood grade coatings (patent pending) were made from combinations of 1) propylene glycol (PG), xanthan gum (XG), and water or 2) PG, propylene glycol alginates (PGA), carrageenan (CA) and water. Trials were conducted in the summers of 2014 and 2015 in 4 commercial processing facilities and a simulated aging house at Mississippi State University. Whole hams were dipped in coatings or applied to hams with a high pressure spray nozzle and aged for 5 to 8 mo. Difference from control sensory tests (6 to 10 trained panelists, 3 reps per plant) were conducted on ham slices that were removed from the treatment hams to determine the impact of the coatings on sensory quality.To make the coatings more applicable to the dry-cured ham industry, ham nets were infused with the coatings mentioned above and tested for their efficacy at controlling mite infestation. On the laboratory benchtop, 20 mites were inoculated onto single ham cubes (2.5cm × 2.5cm × 2.5cm) that were wrapped with ham nets that were treated with different coatings (n = 5/trt). Total numbers of mites were counted after 14 d of storage at 25°C and 70% relative humidity.Completely randomized design was utilized and Tukey’s test was used to separate the means for data analysis.ResultsControl and treated hams from the commercial trials in both years received sensory scores between 1.6 and 3.2 on the 5 point scale where 1 = no difference and 5 = very large difference. In 3 out of 5 plants, the CA + PGA and low concentration PG treatment hams were not different (p > 0.05) from the blind control treatments. However the high PG treatment was not different (p > 0.05) from the control in 2 out of 5 plants (only in trial 1). In addition, the XG and low concentration PG treatment was only different (P > 0.05) from the blind control in 1 out of 5 plants in both trials. This indicates that the coatings did not impact the flavor in some of the plants but did impact the flavor in the other plants. This may have been due to differences among the plants in non-meat ingredients that were used, aging temperature and humidity, and aging time.For coating infused nets, the mite infestation tests showed that cubes wrapped with nets that were treated with coatings had significantly lower numbers of mites, varying from 3 to 62, after 2 wk, while cubes from the negative control and the positive control with untreated nets had up to 554 mites each. This demonstrates that the treated nets inhibited the reproduction of mites on hams, with some nets performing better than others.ConclusionThe food grade coatings may be applicable for some, but not all, processors. In addition, the coating infused ham nets demonstrate the potential to control mite infestations and should be scaled up for commercial testing.

Impact of Relative Humidity and Net Treatments on Tyrophagus Putrescentiae (Schrank) Infestations and Mold Growth on Dry Cured Ham

ObjectivesDry cured hams are susceptible to mite infestations which are currently controlled in the U.S. dry cured ham industry via fumigation with methyl bromide. Since methyl bromide is an ozone depleting substance, food grade ingredient infused nets have been researched as an alternative to control mite infestations on dry cured hams. Mite infestations and mold growth vary on dry cured ham in untreated and treated nets due to environmental changes in relative humidity (RH) and temperature. Therefore, the objective of this research was to evaluate the effect of RH and infused nets on mite infestations and mold growth on dry cured hams.Materials and MethodsPatent pending food grade coating formulations consisting of 1) xanthan gum (XG) and propylene glycol (PG) and 2) carrageenan (CG), propylene glycol alginate (PGA), and PG were infused into ham nets. Dry cured ham cubes (2.5 cm3) and slices (2.5 cm × 9.0 cm × 15.5 cm) were wrapped with untreated (control) and 2 types of infused (treated) nets (XG + PG and CG + PGA + PG) and stored in ventilated glass jars. Three cubes and slices from each treatment were inoculated with 20 and 50 adult mites respectively, and stored in an environmental chamber for 14 d at 24°C and 65 ± 2, 75 ± 2, and 85 ± 2% RH. Mite infestation was determined by counting the mobile mites on ham cubes, slices, and nets using a microscope. Nine trained panelists rated the moldiness of ham slice surfaces on a 0 to 100% scale. A 3 × 3 factorial structure within a completely randomized design was used to determine the impact of RH and net treatment on mite infestations and mold growth. The least square means method was applied to separate treatment means.ResultsAt 65 and 75% RH, samples with treated nets had fewer (P < 0.05) mites than the control, but there were no differences (P > 0.05) between treated and control nets at 85% RH. On average, across net treatments, there were fewer mites (P < 0.05) at 75 and 85% RH in comparison to 65% RH. In addition, when averaged over RH, samples in XG and CG coated nets had fewer (P < 0.05) mites on ham slices compared to samples in untreated nets. Though there was no difference between XG and CG (P > 0.05) with respect to the number of mites on ham slices, the CG treatments were effective at controlling mites at all RHs. In contrast, the XG treatment did not control mites at 65% RH. There was a strong correlation (r = 0.98) between percentage of the ham slices covered with mold and number of mites present. Mold growth was greater (P < 0.05) at 65% RH in comparison to 75 and 85%, and XG and CG treatments had less mold growth than the control treatments, with the CG treatment completely inhibiting the presence of visual mold.ConclusionTreated nets inhibited mite infestations and mold growth on ham cubes at 65 and 75% RH and on ham slices at 65% RH. Results indicate that 75 and 85% RH would be more desirable in the ham industry if hams were aged at 24°C. Further testing will be performed to observe the impact of temperature on mite infestations and mold growth on ham cubes and slices at various RHs to optimize aging conditions that can used to help control mite infestations.

Application of Food-Grade Ingredients to Nets for Dry Cured Hams to Control Mite Infestations

Infestations of Tyrophagus putrescentiae (Schrank; Sarcoptiformes: Acaridae), known as the ham mite, may occur on dry cured hams during the aging process. The fumigant methyl bromide is currently used to control mite infestations, but it will eventually not be available for use since it contributes to the depletion of the ozone layer. The use of ham nets treated with xanthan gum, carrageenan, propylene glycol alginate, and propylene glycol food-grade ingredients on mite orientation to or oviposition on treated or untreated ham cubes, and mite reproduction and population growth over a 10-wk period was evaluated. Behavioral tests indicated that more than 95% of the mites oriented to the ham cubes that were wrapped in untreated nets when compared to treated nets and no eggs were laid on the latter. The reproduction assays demonstrated that there were fewer (P &lt; 0.05) T. putrescentiae produced over a 2-wk period on ham cubes covered with both gum and propylene glycol treated nets, when compared to the untreated or gum-only treated nets over the 10-wk storage period of the experiment. Medium and high concentrations of propylene glycol treatments showed the lowest reproductive rates of mites. No more than 4 mites could be found on each of these treatments in comparison to 200 to 300 mites that were recorded on the untreated hams. This study demonstrated efficacy of using the nets treated with food-grade ingredients during ham aging to control mite infestations on a laboratory scale. Further research will be conducted to determine the effectiveness of the same treated nets on whole hams in commercial aging rooms.

Developing food-grade coatings for dry-cured hams to protect against ham mite infestation

Dry-cured hams may become infested with ham mites, Tyrophagus putrescentiae, during the aging process. Methyl bromide is the only known available fumigant pesticide that is effective at controlling ham mite infestations in dry cured ham plants. However, methyl bromide will be phased out of all industries as early as 2015 due to its status as an ozone-depleting substance. Research was conducted to develop and evaluate the potential of using food-grade film coatings to control mite infestations, without affecting the aging process and sensory properties of the dry-cured hams. Cubes coated with xanthan gum+20% propylene glycol and carrageenan/propylene glycol alginate+10% propylene glycol were effective at controlling mite infestations under laboratory conditions. Water vapor permeability was measured to estimate the impact of coatings during the aging process. It was evident that carrageenan/propylene glycol alginate coatings were permeable to moisture, which potentially makes them usable during aging.

Acaricide Resistance in Northern Fowl Mite (Ornithonyssus sylviarum) Populations on Caged Layer Operations in Southern California

Southern California caged layer operations were visited over 3 yr. Northern fowl mites from 26 field populations were tested for acaricide resistance using a capillary pipette and glass dish bioassay. One was a susceptible field population with no pesticide exposure for over 30 yr (reference site for resistance ratio calculation). Technical and commercial formulations of malathion, carbaryl (Sevin), permethrin, and a commercial formulation of tetrachlorvinphos/dichlorvos (Ravap) were tested. Malathion did not have high activity for mites relative to other materials, but resistance to both technical and commercial formulations was low (< 5×). Resistance to other materials was moderate to extreme. Frequency of carbaryl resistance (> 10×) was higher with the commercial (88%) than the technical material (41%); 19% of the populations had resistance > 100x to commercial carbaryl. Frequency of Ravap resistance (> 10×) was 68%; 8% of populations had resistance > 100x. Frequency of permethrin resistance (> 10×) was 72% for the technical material and 88% for the commercial formulation. Extreme permethrin resistance (> 1,000×) was observed in 56 and 50% of mite populations assayed using the technical and commercial formulations, respectively. Among sites, resistance to permethrin was uncorrelated with resistance to other chemicals, suggesting a different resistance mechanism. Resistance to carbaryl and Ravap was highly correlated [r = 0.76 at the LC50 level (concentrations estimated to be lethal to 50% of the test population) and r = 0.99 at the LC95 level], suggesting a common resistance mechanism. Producers currently depend completely on pesticides to control mite infestations. Mite resistance to registered materials emphasizes the need for integrated control measures.

Use of Beta Beta' Dithiocyano Diethyl Ether (RID-O) to Control Mite Infestations in Mice.

SummaryBeta beta' dithiocyano diethyl ether (RID-O) has been found to be very effective in controlling mites and exhibits a relatively low toxicity in mice. This chemical may be found useful as an insecticide or an acaricide on other laboratory and domestic animals.