Abstract
Tyrophagus putrescentiae, Pygmephorus mesembrinae, Tarsonemus sp. are common mushroom pest mites in Japan. These mites can not increase in numbers when transferred to a mushroom cultivation medium of sawdust and rice bran, which has been pre-colonized with Hypsozygus marmoreus (cultivated for 7 d at 23°C). Tyrophagus putrescentiae and P. mesembrinae established their populations in both the media not pre-colonized with H. marmoreus and ones with only a weed fungus, Trichoderma harzianum. The initial numbers of mites inoculated to the medium was crucial for certain species. Only 10 female T. putrescentiae whereas 100 females of P. mesembrinae were required for population establishment. Initial conditions such as invasion by numbers of females and/or fungal contamination before mite migration accelerated population increase. Tyrophagus putrescentiae invaded fresh mushroom media in bottles from old ones with high mite density. DNA sequencing confirmed that the fungus growing in the bottles, where originally the mite was inoculated, was the same as that in bottles the mite migrated into. No contamination occurred in media without mites. We, therefore conclude that fungivorous pest mites are important vectors that disperse weed fungi throughout mushroom cultivation facilities.
