Specificities of rearing the laboratory population of Uscana senex (Grese, 1923) and its adaptation potential against Bruchus pisorum (Linnaeus, 1758) in the agrocenoses of common pea

The aim of the study was to evaluate the bioecological properties and reproductive potential of egg parasitoid Uscana senex (Grese, 1923) (Hymenoptera: Trichogrammatidae) with the purpose of using it within the programs of biological control over pea weevil Bruchus pisorum (Linnaeus, 1758) (Coleoptera: Chrysomelidae). Methods. The belonging of a parasite to a particular species was determined by morphological traits and a detailed analysis of the structure of the genitalia and the form of the imago club. Common entomological methods were used in laboratory and field conditions to study the impact of various ratios of parasite:host (from 1:1 to 1:45) on the reproductive characteristics of entomophages. The main viability indices of the laboratory and natural populations of the parasite were compared: motor activity, searching capacity, restoration rate, and the share of deformed insects. The impact of the periodic passage of a laboratory culture via the natural host on the quality of biomaterial was also evaluated. The statistical results were processed by the dispersion analysis (ANOVA), and the data were presented as x +/- SD. Results. The results demonstrated that the fecundity of female entomophages was increasing considerably with the increase in the host number; however, the efficiency of the parasite utilization decreased with the following generations. The highest biological efficiency in field conditions on the plots with Oplot pea cultivar was registered at the 1 : 5 ratio, where the parasitism rate was 39.8%, and the seed damage was minimal - 5.59%. Statistically significant differences between the native and laboratory populations of U. senex were found, and the native population demonstrated higher viability indices as compared to the laboratory population. The periodic passaging of the laboratory population via the natural host partially compensated for the viability loss and reduced reproductive potential. Conclusions. The obtained results demonstrated high efficiency of Uscana senex as a biological agent in the integrated systems of protecting pea from Bruchus pisorum. It was proven that maintaining the reproductive potential and viability of the parasite was ensured on condition of periodic contacts between the laboratory population and the natural host, and adherence to the optimal parasite:host ratio, which promotes the preservation of stable quality of the biomaterial.