The IAG gene in the invasive crayfish Procambarus clarkii - towards sex manipulations for biocontrol and aquaculture.
The red swamp crayfish Procambarus clarkii (Girard, 1852) is considered a voracious invasive species that gained this reputation through the displacement of native crustaceans and is threatening the biodiversity of many freshwater ecosystems through Europe, Africa and Asia. At the same time, this crayfish is an important aquaculture species since it is easy to grow and has high production rates. It is crucial to develop tools to control and prevent invasive populations to reconcile conservation objectives with aquaculture goals. Thanks to recent biotechnological progress in crustacean monosex aquaculture, we present here novel insights in crayfish reproductive biology that might pave the way for the production of monosex populations through "IAG-switch"-manipulation based on the identification of the P. clarkii insulin-like androgenic gland hormone (IAG) encoding gene. Our data indicate that this manipulation can be used to create "neo-females", which produce all-male progeny. This approach is a promising avenue for increasing food production in regions where crayfish is cultured, while greatly reducing risk of invasion in case of accidental release in the wild. We also explored potential use of stocking neofemale crayfish to control invasive populations by generating a strong bias in male-to-female sex-ratio. Specifically, we developed a simple demographic model and used it to investigate whether and under what assumptions stocking neofemale P. clarkii can cause the eradication of an invasive population. Our work suggests that all-male crayfish production could be further developed towards an effective control of wild invasive populations as part of an integrated pest management approach.