Potential of piperonyl butoxide-synergised pyrethrins against psocids (Psocoptera: Liposcelididae) for stored-grain protection.
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 6 mg kg(-1) of pyrethrins + PB (1:4) at 30 +/- 1 degrees C and 70 +/- 2% RH. Next, wheat treated at 0.0, 1.5, 3 and 6 mg kg(-1) of pyrethrins + PB (1:4) was stored at 30 +/- 1 degrees C and 70 +/- 2% RH and mortality and reproduction of psocids were assessed after 0, 1.5, 3 and 4.5 months 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 6 mg kg(-1) of synergised pyrethrins after 0, 3, 6, 9 and 12 h of exposure.


RESULTS
Synergised pyrethrins at 6 mg kg(-1) provided 3 months of protection against all four Liposcelis spp., and at this rate complete adult mortality of these psocids can be achieved within 6 h of exposure.


CONCLUSIONS
Piperonyl butoxide-synergised pyrethrins have excellent potential both as a grain protectant and as a disinfestant against Liposcelidid psocids.
Nayak
Manoj K
MK
Primary Industries and Fisheries, Department of Employment, Economic Development and Innovation, Indooroopilly, Queensland, Australia. manoj.nayak@dpi.qld.gov.au
D000818:Animals; D004357:Drug Synergism; D002523:Edible Grain; D023381:Endpoint Determination; D007300:Insect Control; D007313:Insecta / Q000187:drug effects* / Q000502:physiology; D007306:Insecticides / Q000633:toxicity*; D009068:Movement / Q000187:drug effects; D010882:Piperonyl Butoxide / Q000633:toxicity*; D011722:Pyrethrins / Q000633:toxicity*; D012098:Reproduction / Q000187:drug effects; D015996:Survival Rate; D013997:Time Factors
D007306:Insecticides; D011722:Pyrethrins; D010882:Piperonyl Butoxide