A contribution to standards for freezing as a pest control method for museums

Abstract

The mortality of larvae of Anthrenus museorum (L.), Anthrenus verbasci (L.), Attagenus smirnovi Zhantiev, Attagenus woodroffei Hallstead and Green, Reesa vespulae (Milliron), Trogoderma angostura (Solier) (Coleoptera: Dermestidae) and Tineola bisselliella (Hummel) (Lepidoptera: Tineidae) was studied in freezing experiments at -18° to -20°C. An infestation by these pests was simulated inside heavy woolen material and upholstered furniture, i.e., in wood enclosed in heavy material. It is vitally important that air can circulate around the treated objects in the freezer. Times necessary for the temperature to reach equilibrium were 20 and 36 hours, respectively. Larvae that had been exposed to temperatures lower than -17.6°C for about 50 hours had all died, either immediately or as observed several months later. Freezing procedures using moderate temperatures must be based on time-temperature-mortality relationships for different stages of the relevant species. Previous conclusions that A. museorum is more resistant to low temperatures than several other dermestids are confirmed and acclimatisation suggested as the reason. Further investigations on the biochemical processes occurring in the insects during exposure to low temperatures could elucidate this further.