Assessment of a cricket, Acheta domesticus, bioassay for Chequa Iflavirus and bunya-like virus from redclaw crayfish Cherax quadricarinatus

- Chequavirus & bunya-like virus may cause 20-40% mortalities in crayfish.
- To prove River's postulates of causation, virus-free animals are needed.
- >85% of crayfish are already infected so a cricket bioassay was tested.
- Mortality was not significantly different between controls & infected crickets.
- By PCR, no trace of either virus was found after 30 days.

Chequa iflavirus and a bunya-like virus infect redclaw crayfish (Cherax quadricarinatus) and they may cause mortality reaching 20-40% after about three weeks after a stress event. To complete River's postulates for viruses, virus-free animals are needed. Due to a lack of chequa iflavirus and bunya-like virus-free crayfish (testing shows >85% infection rate) coupled with the facts that iflavirus and bunyaviruses are found in insects and that crickets had been successful alternate hosts for crustacean viruses before, Acheta domesticus was trialled as a bioassay animal. There was no significant difference (P > 0.05) in mortality rates between uninfected control crickets and infected crickets. Reverse transcriptase polymerase chain reaction for both viruses failed to find any trace of the RNA viruses in fed or inoculated crickets after 30 days. The search for an alternative bioassay host will have to be widened.

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