Experimental Transmission of the Yeast, Metschnikowia bicuspidata, in the Chinese Mitten Crab, Eriocheir sinensis

Abstract

The Chinese mitten crab, Eriocheir sinensis, is an important farmed crustacean species in China, outranking other farmed crabs in yield and economic importance. An infection called “milky disease”, caused by the yeast, Metschnikowia bicuspidata, has emerged in E. sinensis farms in northeast China and has caused progressive economic losses. The diseased crabs present with opaque, whitish muscles and milky hemolymph. Currently, there are no effective drugs to treat the infection. Clarifying the transmission route of M. bicuspidata would help to treat and prevent the disease. We investigated the effects of three different M. bicuspidata infection methods (feeding, immersion, and cohabitation) on E. sinensis. All three infection methods led to a high infection rate in healthy crabs. After 35 d, the infection rate was 76.7%, 66.7%, and 53.3% in the feeding, immersion, and cohabitation groups, respectively. Diseased crabs exhibited the typical symptom of hemolymph emulsification, with a high pathogen load of M. bicuspidata. The yeast was not detected in the oocytes of infected crabs. Fertilized embryos, zoea larvae, and megalopae of infected ovigerous crabs tested negative for yeast, indicating that direct transmission from mother to offspring does not occur. Our results highlight avenues for the prevention and control of this yeast.

Transmission Routes and a New Freshwater Crustacean Host for Infectious Precocity Virus (IPV)

“…In general, the routes of transmission for a pathogen are horizontal transmission, vertical transmission, or both [12][13][14]. Viruses with low virulence spread vertically, which keeps the host alive, whereas those with high virulence are more likely to spread through vertical transmission, which can facilitate diffusion following the death of the host [15,16].…”

“…M. rosenbergii is militant and frequently engages in cannibalism with other prawns, which is invariably followed by attacks made on animals undergoing molt [21]. For cultured crustaceans, cannibalism is hard to avoid, especially in high-density breeding conditions [14]. Thus, dead or moribund disease-carrying organisms can be a source of pathogen transmission, such as with the WSSV and IHHNV in L. vannamei [22].…”

Metabolomic and metagenomic analyses of the Chinese mitten crab Eriocheir sinensis after challenge with Metschnikowia bicuspidata

“…From May 2001 to December 2003, M. bicuspidata was the dominant pathogen in 6-to 11-month-old Macrobrachium rosenbergii giant freshwater prawns (8-12 cm) at water temperatures below 17°C in Taiwan, and the cumulative mortality of prawns during this period was 20-95% (Chen et al, 2007). Recent research on M. bicuspidata has focused on the molecular phylogeny, histopathology, and possible control methods of this pathogen (Ma et al, 2022;Sun et al, 2022;Jiang et al, 2022aJiang et al, , 2022b). However, limited information is available about host responses to M. bicuspidata (Jiang et al, 2021).…”

Development of a nested PCR assay for specific detection of Metschnikowia bicuspidata infecting Eriocheir sinensis

“…Therefore, strengthening prevention has become the key to controlling this disease. Although M. bicuspidata cannot spread vertically, it can rapidly spread through water, cannibalization, and co-habitation (Jiang et al, 2022) as well as through the food chain (Moore and Strom, 2003), which makes prevention difficult. Therefore, it is necessary to establish an accurate and sensitive detection technology to ensure that environmental organisms, water, sediment, stocking seedlings, and feed do not carry pathogens.…”