Time–Mortality Relationships to Control<i>Tyrophagus putrescentiae</i>(Sarcoptiformes: Acaridae) Exposed to High and Low Temperatures

Abstract

Tyrophagus putrescentiae (Schrank) (Sarcoptiformes: Acaridae) is a widely distributed pest species that is of significant economic importance for dry-cured country hams. Methyl bromide was used for decades in country ham plants to control this pest, but now this fumigant is recognized as an atmospheric ozone-depleting compound and will be phased out for all uses in the near future. Of various chemical and nonchemical alternatives to methyl bromide, extreme temperatures are viable and straightforward nonchemical methods to control pests. This study evaluated the efficacy of high and low temperatures on mortality of mold mite in the laboratory. Ten eggs and a mixture of 40 adults and nymphs were separately exposed to different high and low temperatures, ranging from +35 to 45 °C and from -20 to +5 °C, for several periods of time. Mortality was assessed after a recovery period for each life stage. Tyrophagus putrescentiae eggs were found to be more tolerant to both high and low temperatures than were the mobile stages. Results showed that high temperatures from 40-45 °C killed all mites within 4 to 1 d, respectively, while -10 °C or lower killed all mites in less than 1 d. Regression analyses of mortality data as a function of exposure predicted times for achieving desired levels of mite mortality. This study suggests that extreme temperature treatment can play an important role in integrated pest management programs for dry-cured ham as an alternative to methyl bromide or other chemical treatments.