MANAGEMENT AND CONTROL OF RESSELIELLA THEOBALDI (DIPTERA: CECIDOMYIIDAE) IN BIOLOGICAL RASPBERRY PRODUCTION

This study was carried out in. raspberry plantation (2017-2019) in the experimental field of the Institute of Agriculture - Kyustendil, Bulgaria. The purpose of the study was to investigate the effect of organic fertilizer application on the larvae density of Resseliella theobaldi (Barnes) and population management, using biological plant protection products. Our results indicate that the use of organic fertilizers has a negative effect on the survival of R. theobaldi larvae but has no effect on the larval endoparasitoid Aprostocetus epicharmus (Walker) in the cultivars 'Willamette' and 'Lyulin'. The interrelationship between R. theobaldi and A. epicharmus in organic raspberry production has also been studied. The assessed rate of parasitism by A. epicharmus (24.94-36.11%). is considered to be enough to reduce the population of R. theobaldi in cv. 'Lyulin' effectively without chemical control. Two treatments with bioinsecticides have been carried out for the protection of cv. 'Willamette' due to a significantly lower rate of parasitism in this cultivar (11.68-20.05%). The most effective insecticides for the control of adults of R. theobaldi have been identified as follows: Pyrethrum FS EC - conc. 0.05% and NeemAzal (R)-T/S - conc. 0.3%.