BACKGROUND: Piperonyl butoxide (PB)-synergised natural pyrethrins (pyrethrin : PB ratio 1 : 4) were evaluated both as a grain protectant and a disinfestant against four Liposcelidid psocids: Liposcelis bostrychophila Badonnel, L. entomophila (Enderlein), L. decolor (Pearman) and L. paeta Pearman.
These are key storage pests in Australia that are difficult to control with the registered grain protectants and are increasingly being reported as pests of stored products in other countries. Firstly, mortality and reproduction of adults were determined in wheat freshly treated at 0.0, 0.75, 1.5, 3 and 6mg kg−1 of pyrethrins+ PB (1 : 4) at 30 ± 1 ◦C and 70 ± 2% RH. Next, wheat treated at 0.0, 1.5, 3 and 6mg kg−1 of pyrethrins + PB (1 : 4) was stored at 30 ± 1 ◦C and 70 ± 2% RH andmortality and reproduction of psocids were assessed after 0, 1.5, 3 and 4.5months of storage. Finally, the
potential of synergised pyrethrins as a disinfestant was assessed by establishing time to endpoint mortality for adult psocids exposed to wheat treated at 3 and 6mg kg−1 of synergised pyrethrins after 0, 3, 6, 9 and 12 h of exposure.
RESULTS: Synergised pyrethrins at 6mg kg−1 provided 3 months of protection against all four Liposcelis spp., and at this rate complete adultmortality of these psocids can be achieved within 6 h of exposure.
CONCLUSION: Piperonyl butoxide-synergisedpyrethrinshaveexcellent potentialbothasagrainprotectantandasadisinfestant
against Liposcelidid psocids.