In a study last week researchers at Ben-Gurion University of the Negev have highlighted how the development of mono-sex prawns could increase the aquaculture yield whilst reducing the spread of the second most devasting parasitic disease: schistosomiasis. Additionally, in a triple whammy the sterility of a single-sex population negates the ecological risk of the crustacean becoming an invasive species.

These so-called “super shrimp” are a result of biotechnology being utilised for the first time to achieve an all-female population of the economically important giant prawn Macrobrachium rosenbergii. The adult males of the species are characterised by three morphotypes, all of which yield a significantly larger harvest than that of female specimens. Despite it therefore appearing advantageous to cultivate an all-male population, social behaviours such as high degrees of territorialism and aggression reduce their overall profitability in comparison to females.

Through androgenic gland cell transplantation, the group was able to achieve for the first time full sex-reversal of WW females to functional WW neo-males (of which the wildtype is ZZ). By subsequently crossing WW males with WW females cultivation of an all-female progeny, lacking the Z chromosome is possible by non-genomic or hormonal means.

The higher overall potential profits of an all-female yield compared to mixed populations was also validated. By virtue of higher survival rates and the ability to stock female specimens in greater densities a higher yield was recorded in sample ponds.

This work follows a July publication in Nature Sustainability evidencing the role freshwater shrimp, including M. rosenbergii may play in biological control of the schistosomiasis parasite in sub-Saharan Africa. Giant prawns are natural predators of aquatic snails – the obligate intermediate host of the schistosomiasis parasite. M. rosenbergii, along with another native prawn species was found to significantly reduce host snail populations and thereby aid schistosomiasis control efforts.

This marks a promising strategy in the control of the disease, also known as Bilharzia, which afflicts over 252 million people annually across 78 countries. The disease is symptomatic of abdominal pain, persistent diarrhoea and blood in the stools as the blood fluke, Schistosoma usually infects through the urinary tract or intestines. Left untreated urogenital schistosomiasis can affect the sex organs of men and women and severely stunt growth and developmental development in children.

The group led by Prof. Guilio De Leo of Stanford University found that aquaculture of prawn populations and mass preventative drug administration were superior in combination in controlling parasite spread. However, current mass drug administration which relies on the anthelmintic Praziquantel is blighted by concerns, and evidence, of drug resistance.

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