Temperature and relative humidity effects on Stegobium paniceum (L.) (Coleoptera: Anobiidae) in controlled atmospheres

Abstract: Key ecological factors such as temperature and water influence the distribution and population dynamics of terrestrial arthropods, so the speed of the anoxia treatment in killing insects is dependent upon temperature, relative humidity (RH) and on oxygen percentage. Thepresent study reports on the efficacy of temperature and relative humidity on controlled atmosphere treatment, as an alternative to insecticide management, against the drugstore beetle Stegobium paniceum (Linnaeus), one of the most widely encountered insect causing serious damages to stored products and cultural heritage. The aim of the research is also to verify the feasibility of anoxia at percentages of oxygen significantly higher than those normally used (< 1%), in order to define the application conditions of the method, easier and less expensive. Larvae and adults were exposed to atmospheres containing low oxygen percentages (3-5%), at four different relative humidities (15% – 35% – 55% – 75%) and two different temperatures (23-30 °C) for periods of 7 days. Temperature affects S. paniceum, mainly the adult stage. They seem to be more susceptible, while larvae appear very tolerant, showing a modest mortality at 23 °C, with no difference in values. Only at 30 °C and low humidity (dry conditions) they reach 70-80% of mortality, with significant difference between the worst and the “best” humidity condition (15-75%). Adults show a higher mortality compared to the larvae, however it seems that there are no differences between the relative humidity percentages, except at 5% oxygen percentage. The important role of controlled atmospheres can be improved by studying the sensitive relationships between these environmental parameters critical to the survival of insects and testing more possible combinations to achieve the highest efficiency in less time and at lower cost.