| Summary: | The use of environmentally friendly bio-pesticides is crucial for higher root and sugar yield
in sugar beets. The economic importance of beet moth [Scrobipalpa ocellatella Boyd. (Lepi-
doptera: Gelechidae)] losses in the field and storage highlight the need for evaluation of ap-
propriate, environmentally friendly methods for pest control. The aims of the present study
were to i) assess azadirachtin (AZN) effects on the life cycle and activity of the pest, and ii)
manage the beet moth on roots under laboratory conditions. For the experiments, the main
concentrations were prepared on the basis of the field-recommended dose of this pesticide
(1–1.5 l/1000 l water). The LC50 was estimated for 3rd instar larvae. Later, at sublethal
concentrations, the relative time for the emergence of each developmental stage was de
termined. The mean female fecundity was 37% (±4) for treated tests at the lowest AZN
concentration (0.5 ml · l–1). Assess azadirachtin at 0.5 ml · l–1 concentration resulted in
62 (±4) deposited eggs per plant for the treated roots and 326 (±1) for roots in the control
test. Mortality increased in response to increased AZN concentrations. The results revealed
that after 72 h, the highest AZN concentration (2.5 ml · l–1) caused 100% repellency and 82% (±1.38) mortality on 3rd instar larvae. According to our findings, a concentration of
2 ml · l–1 AZN (20 gr active ingredient per 1 hectare) after 4 days affected 1st instar larvae
and the larvae with no further development had 92.2% (±1.2) mortality. In conclusion, the
results revealed that AZN as a biorational pesticide can significantly minimize the losses of
S. ocellatella on sugar beet crops.
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