The infestation of foodstuffs by mites is connected to health risks and economic losses. Tyrophagus putrescentiae (Schrank, 1781) is a cosmopolitan generalist feeder that prefers foodstuffs of high-fat and high-protein content. The stored product mite T. putrescentiae is an emerging and predominant pest of dry dog food. It is an emerging source of allergens in stored products and homes. The results of this study have important implications for predictive models of stored-product mite populations in dry dog food. High-fat and -protein food accelerated T. putrescentiae population growth compared with the high-carbohydrate diet. The results increase the medical importance of the mite allergens detected in the feces. The cocktail of allergens, i.e. feces covering chitin, mite allergens and bacterial toxins, represent high risks for the mammalian immune system. The association of the mite with Bacillus cereus is to the medical importance.

The objective of this study was to evaluate the effects of using food grade coatings and nettings formulated with xanthan gum and propylene glycol (PG) or carrageenan (CG), propylene glycol alginate and PG on aged Cheddar cheese to control Tyrophagus putrescentiae growth at temperatures of 10°C, 15°C, and 20°C and relative humidity’s of 75% and 85%. Cheddar cheese cubes with treated nets and coatings inhibited mite growth at all temperature and relative humidity combinations. Control cheese cubes either without coatings or in untreated nets had fewer mites (P<0.05) at 10°C than at 15°C or 20°C. The sensory properties of the cheese were not affected by the coatings and nettings at 10°C and 75 % RH. However, all other temperature and RH combinations with the exception of the CG netting at 15°C at 75 % and 85 % RH caused sensory flavor differences (P<0.05).

Since methyl bromide is an ozone depleting substance, there is a significant need to find effective alternative compounds 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 to minimize mite reproduction and mold growth on dry cured hams in untreated and food grade ingredient infused nets. Mites on ham slices in untreated nets were reduced from the initial inoculum level of 50 mites per ham slice when exposed to 85% RH at 24, 28, and 32°C. Results indicated that hams should be stored at 85% RH or greater to minimize mite reproduction when xanthan gum and propylene glycol infused nets are used. Nets infused with carrageenan, propylene glycol alginate, and propylene glycol, completely inhibited mite reproduction at 85% RH and were effective at controlling mold growth.

Distillate solutions that were derived from concentrated ferment were incorporated into either a carrageenan (CG) and propylene glycol alginate (PGA) gum blend or into a CG, PGA, and xanthan gum (XG) blend. Distillate treatments were compared against a 10% propylene glycol treatment, a gum only control, and negative control using three hams that were cut into 2.5 cm thick slices and then cut into 2.5×2.5×2.5cm cubes (n=50) that were dipped into solutions prior to conducting mite bioassays. Coated and control ham cubes were inoculated with 20 adult mites from the species T. putrescentiae (Schrank), and incubated for 2 and 3 weeks. The distilled treatments with CG + PGA + XG had a greater reduction (P<0.05) in mite populations than all other treatments with the exception of the 10% PG coated treatments. In addition, there were no differences between treatments with respect to sensory texture, flavor, and moistness.

Doctor of Philosophy / Department of Entomology / Thomas W. Phillips / Robert "Jeff" J. Whitworth / Dry-cured ham is protected from infestations of Tyrophagus putrescentiae (Schrank) (Sarcoptiformes: Acaridae) with the fumigant methyl bromide. Developing feasible alternatives to methyl bromide is necessary due to the phase out of methyl bromide. The effectiveness of food-safe compounds for preventing infestations of T. putrescentiae on dry-cured hams was evaluated by dipping ham pieces in solutions of various food additives. Propylene glycol (1, 2-propanediol), lard, ethoxyquin and butylated hydroxytoluene prevented or significantly reduced mite population growth. A combination of carrageenan + propylene glycol alginate + 40% propylene glycol was effective in reducing mite numbers on treated whole-aged hams compared with untreated hams. Dose/response tests with twelve registered residual insecticides were conducted to assess contact toxicity to T. putrescentiae. Three of these insecticides were evaluated for persistence over a 2-month period on different surfaces. Commercial formulations of deltamethrin plus chlorpyrifos-methyl, chlorfenapyr, and malathion showed promising results for contact toxicity against T. putriscentiae. Chlorfenapyr applied to metal, concrete, and wood resulted in 100% mortality of treated ham mites for up to 8 weeks. The effect of high and low temperatures on mortality of T. putrescentiae was studied in the laboratory. Groups of 10 eggs and groups of a mixture of 40 adults and nymphs were separately exposed to several high and low temperatures, ranging from +35 to 45°C and from −20 to +5°C, for several time periods. Eggs were found to be more tolerant to both high and low temperatures compared with adults and nymphs. Results showed that high temperatures from 40-45°C killed all T. putrescentiae eggs, adults, and nymphs within 4-1 d, while −10°C or lower killed all the same stages in less than 1 d. Combinations of the fumigant sulfuryl fluoride (SF) applied under high temperatures ranging from 25-40ºC, were studied to determine the highest temperature, shortest exposure time, and the lowest value of a concentration-by-time product (CTP) of SF against T. putrescentiae. Results showed that complete control of all life stages of T. putrescentiae was achieved at 40ºC with SF. More than one day of exposure was required to kill adults and nymphs and eggs at 40ºC at a CTP close to the EPA labeled rate of 1500 gh.m⁻³. Results indicated that adults and nymphs were more susceptible to SF compared to eggs. This study focused on investigating different control methods for T. putrescentiae in dry-cured ham facilities and most of examined techniques are preventive, although some of them can be applied as remedial methods after mite infestations are noticed.

Doctor of Philosophy / Department of Entomology / Thomas W. Phillips / The phase-out of methyl bromide production, the most effective fumigant for the control of the ham mite, Tyrophagus putrescentiae (Schrank) (Acari: Acaridae), on dry-cured ham has necessitated the search for other management methods. The foundation of a successful management program is an effective monitoring program that provides information on pest presence and abundance over time and space to help in making management decisions. By using the standard trap made from disposable Petri dishes and a dog food-based bait, mite activity was monitored weekly in five dry-cured ham aging rooms from three commercial processing facilities from June 2012 to September 2013. Results indicated that mite numbers in traps in facilities typically had a pattern of sharp decline after fumigation, followed by a steady increase until the next fumigation. Average trap captures varied due to trap location, indicating that traps could be used to identify locations where mite infestation of hams may be more likely to occur. Experiments were also conducted in 6 m x 3 m climate-controlled rooms to determine the effects of some physical factors on trap capture. Factors such as trap design, trap location, trap distance, duration of trapping, and light conditions had significant effects on mite capture. Mites also responded differently to light emitting diodes of different wavelengths, either as a component of the standard trap or as a stand-alone stimulus to orientation. To determine the relationship between trap capture and mite density, experiments were carried out in the climate-controlled rooms. Mite density was varied but trap number remained constant for all mite densities. There was strong positive correlation between trap capture and mite density. In simulated ham aging rooms, the distribution of mites on hams was determined and different sampling techniques such as vacuum sampling, trapping, rack sampling, ham sampling and absolute mite counts from whole hams were compared and correlated. Results showed weak or moderate correlations between sampling techniques in pairwise comparisons. Two sampling plans were developed to determine the number of samples required to estimate mite density on ham with respect to fixed precision levels or to an action threshold for making pest management decisions. Findings reported here can help in the optimization of trapping and sampling of ham mite populations to help in the development of efficient, cost-effective tools for pest management decisions incorporated with alternatives to methyl bromide.

Tyrophagus putrescentiae (Schrank) (Sarcoptiformes: Acaridae), also known as the ham mite, may infest dry cured hams during the aging process. The fumigant methyl bromide is currently used to control mite infestations, but eventually will 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, propylene glycol (PG), and lard were evaluated for their impact on mite orientation to or oviposition on treated or untreated ham cubes, mite reproduction and population growth over a 10-week period. When nets were infused with gum and PG, behavioral tests indicated that greater 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 indicated that there were fewer (P < 0.05) T. putrescentiae produced over a two-week period on ham cubes covered with both gum and PG treated nets when compared to the untreated or gum-only treated nets over the 10-week storage period of the experiment. Medium and high concentrations of PG treatments had the lowest mite reproduction rates. No more than four mites could be found on each of these treatments in comparison to 200-300 mites that were on the untreated ham cubes. When nets were infused with gum, PG, and lard, behavioral tests indicated that fewer mites oriented to the ham cubes that were wrapped with gum, lard, and medium PG than those with untreated nets. The oviposition assays revealed that on average less than three eggs were laid on the ham cubes with treated nets in comparison to 69-165 eggs on the untreated ham cubes. Reproduction assays demonstrated 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 weeks 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. With a few exceptions, fungi were not present on ham cubes that were treated with PG-containing nets over 10 weeks of storage. This research demonstrated the efficacy of using 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.

No description available.

Submitted by FERNANDA DA SILVA VON PORSTER (fdsvporster@univates.br) on 2017-01-04T10:58:47Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) 2016MonicaKrauzeSiegert.pdf: 1293165 bytes, checksum: 4e5c4c6cfd0d325dc17164b6e76817f2 (MD5) / Approved for entry into archive by Ana Paula Lisboa Monteiro (monteiro@univates.br) on 2017-01-06T17:32:02Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) 2016MonicaKrauzeSiegert.pdf: 1293165 bytes, checksum: 4e5c4c6cfd0d325dc17164b6e76817f2 (MD5) / Made available in DSpace on 2017-01-06T17:32:02Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) 2016MonicaKrauzeSiegert.pdf: 1293165 bytes, checksum: 4e5c4c6cfd0d325dc17164b6e76817f2 (MD5) Previous issue date: 2017-01 / Ácaros de importância econômica encontrados em armazéns de grãos, farinhas e rações, assim como, nas prateleiras dos estabelecimentos comerciais são comuns no Brasil. Este estudo teve como objetivo reconhecer a fauna acarina, associando a fatores ambientais e locais onde estão presentes em fábrica de rações. As coletas foram realizadas no período de dezembro de 2013 a setembro de 2014 numa fábrica de ração do Município de Estrela, Rio Grande do Sul. As amostragens foram realizadas mensalmente no rada pé do depósito de embalagens (DE), na tampa da moega de farelo de arroz (FA) na fita transportadora de milho (FM), na abertura inferior do silo de farelo de soja (FS), ninhos de pombos (NP), no elevador de produto de origem animal (OA), e na estrutura estrena do resfriador da peletizadora (RP), e telhado (TE) de uma fábrica de rações. Foram encontrados 2.401 ácaros pertencentes às famílias Acaridae, Blattisocidae, Caligonellidae Cheyletidae, Glycyphagidae, Macrochelidae, Macronyssidae, Melicharidae, Phytoseiidae, Pyroglyphidae, Raphignathidae, Tydeidae, além de Uropodidae e a Subordem Oribatida. Cheyletidae apresentou maior riqueza. Em NP e FS houve maior riqueza. Dermatophagoides farinae foi a espécie mais abundante (883 espécimmes), seguido por Tyrophagus putrescentiae (654 espécimes) e Cheyletus malaccensis (506). Em RP, local de maior contaminação, observou-se 36% do total de ácaros coletados, seguido por FM, com 17,5% e FA, FS, com 14%. Entre março e agosto houve maior abundância acarina, sendo que em março houve maiores populações de Dermatophagoides farinae, agosto, Tyrophagus putrescentiae enquanto que de dezembro a fevereiro prevaleceu Cheyletus malaccensis. / Mites of economic importance found in grain warehouse, flour and feed, as well as, on the shelves of commercial establishments are common in Brazil. This study aimed to recognize the acarina fauna, associating environmental factors and localities where they are presented in the feed factory. Samples were collected from December 2013 to September 2014 at a feed mill in the city of Estrela, Rio Grande do Sul. Samples were taken monthly in the foot of the packaging deposit (DE), in the lid of the bran hopper of rice (FA), conveyor belt of corn (FM), the lower opening of the soybean meal silo (FS), pigeon nests (NP), in the animal origin product elevator (OA), And in the structure of the pelletizer cooler (RP), and roof (TE) of a feed mill. We found 2,401 mites belonging to the families Acaridae, Blattisocidae, Caligonellidae Cheyletidae, Glycyphagidae, Macrochelidae, Macronyssidae, Melicharidae, Phytoseiidae, Pyroglyphidae, Raphignathidae, Tydeidae, as well as Uropodidae and Oribatida Suborder. Cheyletidae showed greater resource. In NP and FS there was greater resource. Dermatophagoides farinae was the most abundant species (883 specimens), followed by Tyrophagus putrescentiae (654 specimens) and Cheyletus malaccensis (506). In RP, the most contaminated site, 36% of the total mites were collected, followed by FM, with 17.5% and FA, FS, with 14%. Between March and August there was greater abundance of acarina, and in March there were larger populations of Dermatophagoides farinae, August, Tyrophagus putrescentiae whereas from December to February Cheyletus malaccensis prevailed.

Tyrophagus putrescentiae, (ham mite) is difficult for commercial dry cured ham producers to control. 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 combinations of xanthan gum (XG) or carrageenan (CG), propylene glycol alginate (PGA), and either propylene glycol or C8C9C10 fatty acid. The use of 10% C8C9C10 with XG and CG + PGA in direct coatings and 1% C8C9C10 with XG or 10% with both XG and CG/PGA in saturated nets inhibited mite population growth. Unexpectedly, the soybean oil solvent effectively controlled mite infestation. Sensory evaluation indicated that 10% C8C9C10 mixed with soybean oil and 100% soybean oil did not impart sensory differences to ham when used as a coating but did impact sensory attributes when used with nets.