Comparative study of the toxicity of phenolic compounds of coriander (Coriandrum sativum) and false fennel (Aneth graveolens) on Galleria mellonella (Lepidoptera, Pyralidae)

Using plant extracts as an insecticide has long been known. Indeed, several plants have been used as control agents against insects. Moreover, the wax moth (Galleria mellonella) is widely distributed around the world, causing serious problems in beekeeping. These problems are related to the wax destruction and pathogens transmission to bees. This study seeks toxic effects assessment of total polyphenols and tannins of two Apiaceae (Umbelliferae); coriander (Coriandrum sativum) and false fennel (Aneth graveolens) on L5 larvae of the wax moth Galleria mellonella and their effects on food intake and repellency. A phytochemical screening, for the purpose of isolation and identification of phenolic compounds of the false fennel and coriander, was realized. After this, we have proceeded to the extraction of total polyphenols and tannins, in order to test them on the fifth stage larvae of Galleria mellonella. Treatment of larva by polyphenols resulted in high mortality rates, especially for the high dose (30 µl/ml), which gave 100% mortality within 3 days for the false fennel, and after 4 days for coriander. For the treatment by tannins, it was noted that their insecticidal activity against Galleria mellonella is less than that of polyphenols for the two studied plants. Feed intake results show that the amount consumed by the larvae treated with polyphenols is low, and these individuals stop eating beginning at the third day after treatment. This indicates that the chemical composition of phenolic compound has antifeeding properties towards G. mellonella.