Biological activity of hemp (Cannabis sativa L.) ethanol extract

Abstract

Cultivation and use of industrial hemp (Cannabis sativa L.) predates written history. Industrial hemp is a fast growing, annual herb with a multitude of uses covering a range of products derived from seed or fiber. The aim of this work was to determine the effects of ethanol extract of industrial hemp on life history parameters (mean developmental duration - MDD, number of emerged adults, female fecundity) of Indian meal moth - IMM (Plodia interpunctella Hübner), mortality of IMM larvae and adults and allelopathic effect on germination energy and seed germination of sunflower and soybean). The 2% ethanol extract of industrial hemp (cultivar Helena) was prepared with 1 g of air-dried plant material extracted with 50 ml of 70% ethanol solution during 24 h. Total phenolics, flavonoid and tannin content was determined with standard spectrophotometric methods. Antioxidant capacity of hemp ethanol extract was determined by several different tests (DPPH, ABTS, FRAP). In bioassays, the extract was applied at 0.5, 1 and 2 % concentrations. Insecticidal activity of extracts on IMM larvae (L3) was assessed in a “No-choice test“, by placing 10 L3 per replicate into jars with sunflower seeds treated with hemp ethanol extract. Mortality was recorded after 24, 48, 72 h and 7days of exposure. Life history parameters were monitored weekly until the adult emergence began, and then assays were checked every 24 h Newly emerged unmated adults from were immediately paired to obtain fecundity MDD was calculated, as the average time (in days), from the start of the experiment to each adult emergence. Mortality of adults was also recorded depending on the seed treatment. Allelopathic effect was assessed according to changes in germination energy and seed germination of sunflower and soybean Tests and were carried out according to a standard filter paper method. TR results of this study indicate that industrial hemp extract had different effect on Plodia interpunctella larvae and adults. The highest mortality of larvae was caused by the highest concentration of hemp extract, and it ranged from 35% after 24 h of exposure, up to 80% after 7 days of exposure. Mortality of adults, on the other hand was not influenced by the applied extract. However, all tested concentrations of the extract had significant effect on emergence of the adults, fecundity and MDD, by inhibiting these life history parameters. Treatment with ethanol extract of industrial hemp in concentration of 2% had positive effects on germination and germination energy of sunflower and soybean seeds.