Damage and weight losses of stored cereals caused by the lesser grain borer Rhyzopertha dominica F. (Coleoptera: Bostrichidae)

Observations on stored grain, products from its manufacture and materials from plant origin in the storage-silo bases in Bulgaria were conducted from 2000 till 2019 to establish the damage and weight losses from the lesser grain borer Rhyzopertha dominica F. (Coleoptera: Bostrichidae). It was found that the grain beetle adults consumed 0.905 ± 0.00374 mg of food per day. With an average adult lifespan of 130 days, an adult consumes 117.678 mg of dry matter from the grain. In experiments aimed to determine the weight losses caused by the larvae of the grain beetle during their development, it was found that they amounted to 13.7861 ± 0.04632 mg per individual. Thus, losses for the development of individual amount to an average of 131.6647 mg. A test for the presence of mycotoxins (fumonisins - FB1 and FB2 total in ng/g) was done on maize attacked up to 5% and 25% with latent infection by the grain beetle. The results showed that at 5% latent infection the quality of mycotoxins was almost 5 times higher -lower than that at 25% corn infestation - 693.9 ± 69 ng/g and 3436.1 ± 34 ng/g, respectively. This shows that the development of the species in the grain stocks also leads to secondary processes of decay accompanied with an increase of mycotoxins consentrations. Keywords: Rhyzopertha dominica, the lesser grain borer, damage, stored cereals