Insecticides reduce survival and the expression of traits associated with carnivory of carnivorous plants.

While agrochemical pollution is thought to be an important conservation threat to carnivorous plants, the effects of insecticides on these taxa have not been quantified previously. Using a combination of lab- and field-based experiments, we tested the effects of commercial and technical grades of three widely used insecticides (carbaryl, lambda-cyhalothrin, and malathion) on survival and the expression of traits associated with carnivory of pink sundews (Drosera capillaris) and Venus flytraps (Dionaea muscipula). Commercial grades were generally more harmful than technical grades under lab and field conditions, but all three insecticides were capable of reducing both survival and the expression of traits associated with carnivory within recommended application rates. However, pink sundews appeared to be more susceptible to insecticides than Venus flytraps, perhaps because of larger numbers of digestive glands on the leaf surfaces. We make several recommendations for future research directions, such as examining the long-term effects of insecticides on carnivorous plant populations, for example in terms of growth rates and fitness. Additionally, future research should include representative species from a wider-range of carnivorous plant growth forms, and explore the mechanism by which insecticides are harming the plants. Given the effects we observed in the present study, we suggest that the use of insecticides should be carefully managed in areas containing vulnerable carnivorous plant species.

In vitro cultures of Drosera aliciae as a source of a cytotoxic naphthoquinone: ramentaceone.

A protocol for the in vitro propagation of Drosera aliciae to increase the yield of the naphthoquinone, ramentaceone, was developed. The highest micropropagation coefficient was obtained using half-strength Murashige-Skoog medium supplemented with 0.4 µM 6-benzyladenine (BA). The genetic fidelity and stability of the regenerated plants was confirmed with RAPD markers. The activity of the isolated ramentaceone was determined against four human tumor cell lines: U937, HeLa, MCF-7, HCT-116 with the highest cytotoxic activity towards the leukemic U937 cell line with an IC(50) value of 3.2 µM.

Evaluation of the antioxidant and antimicrobial properties of in vitro cultured Drosera intermedia extracts.

Evaluation of the antioxidant activity of the methanol, water and n-hexane extracts of Drosera intermedia, determined by the Folin-Ciocalteau (F-C), trolox equivalent antioxidant capacity (TEAC) and oxygen radical antioxidant capacity (ORAC) assays showed that the methanol extract had the highest antioxidant activity (F-C: 378.6 +/- 31.5 micromol(GAE)/mg(extract); TEAC: 332.2 +/- 29.1 micromol(TE)/mg(extract); ORAC: 64.7 +/- 7.8 micromol(TE)/mg(extract). Antimicrobial activity was tested against seven bacterial and eight yeast strains using the agar diffusion assay, followed by the determination of minimum inhibitory concentrations (MIC). All tested D. intermedia extracts demonstrated strong antimicrobial properties with a broad spectrum of activity. However, the n-hexane extract exhibited much greater activity than water and methanol extracts. The most susceptible microorganisms to the n-hexane extract were Staphylococcus epidermidis ATCC 12228 and Candida albicans YP0175, for which a MIC value of 13.0 microg/mL was scored.

Regional and habitat differences in 7-methyljuglone content of Finnish Drosera rotundifolia.

The concentration of 7-methyljuglone was studied in the round-leaved sundew Drosera rotundifolia L. collected from different regions in Northern Finland. Samples for analysis were collected from peat bogs and sandpit habitats. The mean concentration of 7-methyljuglone varied from 1.0 to 2.3% of dry weight. Variation between years in the amount of 7-methyljuglone was significant in plants growing on sand, and in the northernmost region studied. Overall, the variation in the production of 7-methyljuglone among different populations of round-leaved sundew in Northern Finland was rather low. The variation between years in the production of 7-methyljuglone was more significant.