Entomocomplex during storage, species composition of pests, methods of regulating their numbers

Abstract: The article is devoted to the study of the effectiveness of various means of protecting grain from pests during storage. During 2017-2021, the effectiveness of protection products based on phosphine, pirimiphos-methyl and deltamethrin was analyzed.
The material was the grain of the current year’s harvest during storage, insect culture
(Sitophilus oryzae L.), pesticides based on active substances: phosphine, pirimiphos-methyl,
deltamethrin. The last two at different dosage rates. The studies were performed in the
laboratory at a temperature of 20 °C.
Additionally, every 10 days for 12 months, 20 grains of each experimental variant were
placed in a glass jar with a perforated lid, and 10 Sitophilus oryzae L. beetles were put in (three replicates). Subsequently, the number of insects was recorded every 10 days.
In the grain variant with the use of a phosphine-based preparation, the re-population
became already possible after the end of fumigation and aeration.
When using the 4 l/t pirimiphos-methyl preparation, the number of dead insects after 120
days was 50 %, then it began to decrease and in the sample put in on the 180-th day after the
treatment, insects did not die any more, but began to reproduce. For the 8 l/t treatment all insects in the sample put in on 340-th day remained alive.
When using the 10 ml/t preparation based on deltamethrin, the 50 % death rate was
observed in the sample put in on the 120-th day. All insects survived already in the 180-th day
sample. In the variant with the use of the same preparation with a dosage rate of 20 ml/t, the
death of a part of the population was observed for another 300 days. In the sample put in on the 340-th day, all insects have survived.
After observations of the S. oryzae development in the winter wheat grain, which was laid
for storage without treatment (control), the development of the pest occurred normally. The
grain lost its quality completely. In the variant with the use of a phosphine-based preparation, the re-population of the treated grain was possible after airing the storage from the fumigant. In the variants with the use of different dosage rates of pirimiphos-methyl and deltamethrin, it was found that re-population was possible after the period of toxic action expiry as stated by the manufacturer.