title: Influence of concentration, temperature and humidity on the toxicity of phosphine to the strongly phosphine-resistant psocid Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelididae).
abstract: BACKGROUND
  The psocid Liposcelis bostrychophila Badonnel, is a widespread, significant pest of stored commodities, has developed strong resistance to phosphine, the major grain disinfestant. The aim was to develop effective fumigation protocols to control this resistant pest.
  
  
  RESULTS
  Time to population extinction of all life stages (TPE) in days was evaluated at a series of phosphine concentrations and temperatures at two relative humidities. Regression analysis showed that temperature, concentration and relative humidity all contributed significantly to describing TPE (P<0.001, R(2)=0.95), with temperature being the dominant variable, accounting for 74.4% of the variation. Irrespective of phosphine concentration, TPE was longer at lower temperatures and high humidity (70% RH) and shorter at higher temperatures and low humidity (55% RH). At any concentration of phosphine, a combination of higher temperature and lower humidity provides the shortest fumigation period to control resistant L. bostrychophila. For example, 19 and 11 days of fumigation are required at 15 degrees C and 70% RH at 0.1 and 1.0 mg L(-1) of phosphine respectively, whereas only 4 and 2 days are required at 35 degrees C and 55% RH for the same respective concentrations.
  
  
  CONCLUSIONS
  The developed fumigation protocols will provide industry with flexibility in application of phosphine.
authors.affiliation: Department of Primary Industries and Fisheries, 80 Meiers Road, Indooroopilly, Queensland 4068, Australia. manoj.nayak@dpi.qld.gov.au
authors.forename: Manoj K
authors.initials: MK
authors.lastname: Nayak
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Collins
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D004777:Environment; D005651:Fumigation; D006813:Humidity; D007300:Insect Control / Q000379:methods*; D007313:Insecta / Q000187:drug effects* / Q000502:physiology; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology*; D010720:Phosphines / Q000494:pharmacology*; D013696:Temperature; D013997:Time Factors
chemical_list: D007306:Insecticides; D010720:Phosphines; C044646:phosphine