Oil in water nanoemulsion formulations of botanical active substances

Abstract Water-based nanoemulsions of insecticidal botanical oils and extracts have advantages over emulsifiable concentrates and macroscopic emulsions, particularly due to the small droplet size ( Pyrethrum extract gave a reduction in RD50 from 0.131%–0.025% if a nanoemulsion was applied instead of a macroscopic emulsion in the choice laboratory bioassay with M. persicae. However, in greenhouse experiments, the number of aphids on pepper plants was not different between both treatments. Obviously, spraying pyrethrum had insecticidal effects in comparison with a control. On the other hand, the preventive application of citral or anise in pepper plants showed some repellence but only if the binary mixture at doses of 0.1%–0.2% was sprayed. A reduction in the number of aphids per plant was observed. Pyrethrum nano was less toxic to Aphidius colemani (LC90 = 0.064%) than the macroscopic pyrethrum emulsion (LC90 = 0.038%). Citral or anise was much safer for natural enemies (parasitoids) and had no residual contact toxicity up to 0.1%.