Auswirkungen von Diatomeenerde auf den Wasserhaushalt des Kornkäfers: Sitophilus granarius (L.) (Col., Curculionidae) und möglicher Einsatz innerhalb des Vorratsschutzes

Effects of diatomoceous earth on water content of Sitophilus granarius (L.) (Col., Curculionidae) and its possible use in stored product protection Increased problems caused by application of chemical pesticides within pest protection has led to the demand for non‐polluting, biologically specific active countermeasures. This study aimed to test the possible use of diatomaceous earth against Sitophilus granarius. It will also examine the physiological effects of amorphous diatomaceous earth against this insect. After 2 weeks, 100% mortality was observed of the adults treated with 2 g Fossil Shield^® per kilogram wheat, at 11–12% corn moisture content and relative humidity of about 62 ± 2%. The rise in grain moisture and relative humidity decreased the effectiveness of the Fossil Shield^®. It was observed, that the diatomaceous earth reduced the number of adult granary weevils and increased the mortality rate at development stages, but they did not completely prevent the hatching of the next generation. After contact with diatomaceous earth, the individuals of S. granarius had lost weight and reduced their water content, respectively. The adults significantly lost weight and body water after 1 day exposure to Fossil Shield^®. This showed that silica dusts break the water barrier of the cuticle. However, it increases the transpiration rate of water across the cuticle and several insects died through dehydration. At higher relative humidity diatomaceous earth was less effective toward S. granarius, because there was a lower permeability for water across the cuticle. This delays or rather prevents the drying action of diatomaceous earths. Furthermore, the addition of food affected the effectiveness of dusts against S. granarius. A lot of stored product beetles are able to produce metabolic water in the feed substrates. This ability protects them and works contrary to the loss of water.