Aquatic seed industry is the foundation of the industry, and seed industry revitalization is the key to promote the high-quality development of the industry. As an important freshwater economic shrimp in China, Macrobrachium rosenbergii has gender differences in growth, and male shrimp has obvious advantages over female shrimp in growth speed, body size and market price, so all-male shrimp seedlings are welcomed by farmers and have huge market prospects. Zhejiang Freshwater Fisheries Research Institute concentrated its efforts on original leading scientific and technological research, set up a technical team for biological breeding of Macrobrachium rosenbergii, and established a technical system for all-male seed production of Macrobrachium rosenbergii, obtaining 2 million all-male shrimp seedlings, further supporting the development of Macrobrachium rosenbergii industry from the provenance, and resolutely winning the battle for key core technologies.
First, the RNA interference technology of fake female shrimp was pioneered. DMRT1 gene is the sex-determining gene of shrimp. On the basis of sequencing the whole genome of Macrobrachium rosenbergii, our institute innovated and broke through the breeding technology of all-male Macrobrachium rosenbergii fry based on RNAi interference of DMRT1 gene, optimized the interference conditions, and increased the interference efficiency to more than 50% by adding self-made nano-liposome coated composite materials and delivering dsRNA and sirna complexes, which successfully turned the male shrimp into a “fake female shrimp” (female in phenotype and male in genotype), effectively ensuring the male ratio in offspring. The application for “a method of all-male Macrobrachium rosenbergii seed production” was authorized by the national invention patent, which broke the technical barrier of Israel and promoted the development of the biological breeding technology industry of Macrobrachium rosenbergii in China.
The second is to construct the whole male Macrobrachium rosenbergii seed production system. Based on the existing 202 families of the national new aquatic product of Macrobrachium rosenbergii “Nantaihu No.2” in our institute, eight fast-growing mating lines were selected, and then the excellent characters of Macrobrachium rosenbergii were enriched through cross combinations to construct the basic population of all-male Macrobrachium rosenbergii seed production. Using RNAi interference technology based on DMRT1 gene, 1080 fake female shrimps were obtained, and the high-quality male parent of Macrobrachium rosenbergii population was selected to mate with the fake female shrimp, so as to cultivate all-male Macrobrachium rosenbergii larvae. In 2022, 2 million male shrimps were produced, and the production comparison test was carried out. Through field production measurement, the male rate is over 97.33%. Compared with Macrobrachium rosenbergii “Nantaihu No.2”, the growth rate is increased by 11.1% and the yield per mu is increased by 33.6%.
The third is to build a supporting model of improved varieties and good laws. In order to speed up the application and popularization of technology, our institute has carried out research on the breeding modes of Macrobrachium rosenbergii in greenhouse, shrimp and crab symbiosis, rice and shrimp rotation and so on. Among them, the yield per mu of the three-crop cultivation mode in greenhouse is 1500-1800 Jin, the output value per mu is 32,000 yuan, and the economic benefit is 16,000 yuan/mu; Shrimp-crab symbiosis model yields 150g/ tail of Macrobrachium rosenbergii 70 kg and 200g/ tail of Eriocheir sinensis 100 kg per mu, with an average benefit of more than 10,000 yuan per mu; Rice-shrimp rotation mode can achieve more than 1,000 kg of rice per mu and more than 150 kg of Macrobrachium rosenbergii with 50g//tail, which is more than 2,000 yuan more than that of single rice, and the output value is increased by 5,000 yuan, providing a new path for increasing agricultural production and increasing farmers’ income.
(Source: Zhejiang Freshwater Fisheries Research Institute)