Storage mites consume stored products in interaction with environmental microorganisms, resulting in the destruction of infested food and providing specific odours. Here we simulated the effect of mite grazing on oat flakes. Spent growth medium (SPGM) was obtained from seven mite cultures and mixed with oat flakes as the source of faeces and microbes. SPGM-treated diets were offered to 4 mite cultures. The microbiomes were analysed using sequencing of V4_16S_DNA. Mite growth tests, food preferences, and microbiome changes were observed in correlation with SPGM type and mite cultures. The microbiome consisted of 41 OTUs belonging to mite-associated bacteria and faeces bacteria. The composition of the microbiome depends more on the source of SPGM than on mite culture. The SPGM diet accelerated mite population growth and influenced mite food choice, although the effect was dependent on both types of SPGM and mite culture. Kocuria, Brevibacterium, Virgibacillus, and Staphylococcus profiles in SPGM added into diets showed positive correlations to mite population growth. The Kocuria profile in the bodies of mites was positively correlated with mite population growth. The results showed that mites are influenced by SPGM-treated diets, and mite feeding influences the environmental microbiome. The most beneficial was the mite interaction with Kocuria.

• Keywords
• allergens, bacteria, digestion, faeces, interaction,
• MeSH
• Acaridae * microbiology   growth & development   MeSH
• Bacteria * classification   genetics   isolation & purification   MeSH
• Feces microbiology   MeSH
• Environmental Microbiology * MeSH
• Microbiota * MeSH
• RNA, Ribosomal, 16S genetics   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• RNA, Ribosomal, 16S MeSH

Blomia tropicalis is an allergen-producing mite in the human environment in tropical regions. The microbiome of B. tropicalis was described using the barcode sequencing region of V4 16S rDNA and genome assemblage. Mixta mediterraneensis, previously isolated from human skin swabs, was identified as a B. tropicalis gut symbiont based on genome assembly. The microbiome contains two bacteria, Staphylococcus and M. mediterraneensis. The number of M. mediterraneensis 16S DNA copies was 106 per mite and 109 per feces in the rearing chamber based on qPCR quantification. The profile of this bacterium reached 50% of reads in the mite gut and feces. Genomic analyses revealed that the bacterium has several metabolic pathways that suggest metabolic cooperation with the mite host in vitamin and amino acid synthesis, nitrogen recycling, and antimicrobial defense. Lysozyme is present in the symbiotic bacterium but absent in the mite. The B. tropicalis microbiome contained Staphylococcus, which accelerates mite population growth. Mites can digest Staphylococcus by using specific enzymes with hydrolytic functions against bacterial cell walls (chitinases and cathepsin D), leading to endocytosis of bacteria and their degradation in lysosomes and phagosomes. Gene expression analysis of B. tropicalis indicated that phagocytosis was mediated by the PI3-kinase/Akt pathway interacting with the invasins produced by M. mediterraneensis. Moreover, the symbiont had metabolic pathways that allowed it to recycle the mite metabolic waste product guanine, known as a mite attractant. The mite host symbiont enhances mite aggregation in the feces, and the fecal-oral transmission route is excepted.

• Keywords
• Allergen, Digestion, Enzyme, Mite, Symbionts,
• MeSH
• Allergens * MeSH
• Humans MeSH
• Mites * MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Allergens * MeSH

Arthropods can host well-developed microbial communities, and such microbes can degrade pesticides and confer tolerance to most types of pests. Two cultures of the stored-product mite Tyrophagus putrescentiae, one with a symbiotic microbiome containing Wolbachia and the other without Wolbachia, were compared on pesticide residue (organophosphate: pirimiphos-methyl and pyrethroid: deltamethrin, deltamethrin + piperonyl butoxide)-containing diets. The microbiomes from mite bodies, mite feces and debris from the spent mite diet were analyzed using barcode sequencing. Pesticide tolerance was different among mite cultures and organophosphate and pyrethroid pesticides. The pesticide residues influenced the microbiome composition in both cultures but without any remarkable trend for mite cultures with and without Wolbachia. The most influenced bacterial taxa were Bartonella-like and Bacillus for both cultures and Wolbachia for the culture containing this symbiont. However, there was no direct evidence of any effect of Wolbachia on pesticide tolerance. The high pesticide concentration residues in diets reduced Wolbachia, Bartonella-like and Bacillus in mites of the symbiotic culture. This effect was low for Bartonella-like and Bacillus in the asymbiotic microbiome culture. The results showed that the microbiomes of mites are affected by pesticide residues in the diets, but the effect is not systemic. No actual detoxification effect by the microbiome was observed for the tested pesticides.

• Keywords
• Antibiotics, Microbiome, Mold mite, Pesticide, Wolbachia,
• MeSH
• Acaridae * microbiology   MeSH
• Bacillus * genetics   MeSH
• Bartonella * MeSH
• Microbiota * MeSH
• Pesticides * pharmacology   MeSH
• Pyrethrins * pharmacology   MeSH
• Pesticide Residues * pharmacology   MeSH
• Mites * microbiology   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• decamethrin MeSH Browser
• Pesticides * MeSH
• Pyrethrins * MeSH
• Pesticide Residues * MeSH

Dermatophagoides farinae is an important house dust mite species that causes allergies in humans worldwide. In houses, these mites are commonly found in actively used mattresses and pillows, which provide food (i.e. sloughed skin and microorganisms), moisture, and increased temperature for faster mite development. In mattresses, feeding mites prefer the upper sector, as close as possible to the resting human (temperature 32-36 °C, humidity between 55 and 59%). However, mites that are not actively feeding prefer staying at deeper zones of the mattress. Here, we analyzed mite responses to different temperatures (15-35 °C) and relative humidity (62-94% RH) in terms of their population size growth and respiration (CO2 production) using lab mite cultures. The intrinsic rate of population increase had a single maximum at approximately 28 °C and 85% RH. At 30 °C, there were two respiration peaks at RH 90% (smaller peak) and 65% (larger peak). Therefore, there is a mismatch between the optimal temperature/humidity for the population size increase vs. respiration. We propose preliminary hypotheses explaining the two respiration peaks and suggest that future research should be done to elucidate the nature of these peaks.

• Keywords
• Dermatophagoides farinae, House dust mites, Humidity, Physiology, Population growth, Respiration, Temperature,
• MeSH
• Allergens MeSH
• Antigens, Dermatophagoides MeSH
• Dermatophagoides farinae * physiology   MeSH
• Humans MeSH
• Population Growth * MeSH
• Dust MeSH
• Temperature MeSH
• Humidity MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Allergens MeSH
• Antigens, Dermatophagoides MeSH
• Dust MeSH

Feces have been suggested as a major source of microorganisms for recolonization of the gut of stored product mites via coprophagy. The mites can host microorganisms that decrease their fitness, but their transmission is not known. To address the role of fecal microbiota on mite fitness, we performed an experimental study in which the surfaces of mite (Tyrophagus putrescentiae) eggs were sterilized. Mites eggs (15 per experimental box) were then hatched and grown on feedstock with and without feces. These experiments were conducted with four distinct T. putrescentiae populations (5L, 5K, 5N, and 5P), and mite population density after 21 day of cultivation was used to assess mite fitness and the impact of fecal microbiota on fitness. Population density was not affected by the presence of feces in two of the cultures (5L and 5K), while significant effects of feces were observed in the other cultures (5N and 5P). Mite culture microbial communities were analyzed using cultivation-independent next-generation amplicon sequencing of microbial 16S and 18S ribosomal RNA (rRNA) genes in the fitness influenced populations (5N and 5P). Several microbial taxa were associated with fecal treatments and reduced mite fitness, including Staphylococcus and Bartonella-like bacteria, and the fungal genera Yamadazyma, Candida, and Aspergillus. Although coprophagy is the transmission route mites used to obtain beneficial gut bacteria such as Bartonella-like organisms, the results of this study demonstrate that fecal-associated microorganisms can have negative effects on some populations of T. putrescentiae fitness, and this may counteract the positive effects of gut symbiont acquisition.

• Keywords
• feces, feeding, microorganisms, mite, transmission, yeasts,
• Publication type
• Journal Article MeSH