Effects of Olea europaea L. Leaf Metabolites on the Tilapia (Oreochromis niloticus) and Three Stored Pests, Sitophilus granarius, Tribolium confusum and Acanthoscelides obtectus

Abstract

Olea europea L. emerged as a good source of traditional medicine for the treatment of various ailments of various countries of the world, in particular Mediterranean countries. In this study, oleuropein (1), oleanolic acid (2), maslinic acid (3), a mixture of erythrodiol and uvaol (4 and 5) isolated from the leaves of olive were added at two concentrations (1g/100g feed and 4g/100 g feed) into fish feed. Oreochromis niloticus (Nile tilapia) were fed twice a day with the feed during 96 hours. The levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP) enzymes and glucose levels in the serums of fishes fed with pure compounds were found to be higher as compared with the control group. Pure metabolites affect the liver metabolism of Nile tilapia. These results suggested that the compounds tested affect the liver metabolism of Nile tilapia. Compounds 1, 2, 3 and 4+5 (2.5, 5.0 and 7.5 mg/Petri dish concentrations) were also tested for contact toxic effects against three important stored pests, Sitophilus granarius (weevil), Tribolium confusum (confused flour beetle) and Acanthoscelides obtectus (bean weevil). The toxic effects of the metabolites were lower than those of the insecticide, dichlorvos (DDVP). DDVP caused complete mortality of the insects after 48 hours of treatments, the metabolites caused the mortality rates T. confusum and A. obtectus, respectively. Maslinic acid (3) has the most toxic compound with the lowest LC 50 values (0.66 mg/Petri, 0.61 mg/Petri and 1.71 mg/Petri for S. granarius, T. confusum and A. obtectus, respectively). These results show that maslinic acid (3) as well as other substances can be used as natural insecticides against these pests.

Chemical composition and larvicidal activities of Azolla pinnata extracts against Aedes (Diptera:Culicidae)

“…pinnata were widely used as fish feeds, as it promotes growth of fingerlings and adults [ 68 , 69 ]. Toxic materials are present in all plant materials; however, the effects of toxic material on the environment differs according to the plant species [ 70 ]. As an example, the Olea europea leaf contains maslinic acid, which has lower toxic effects on the environment compared to that of chemical insecticides [ 70 ].…”

“…Toxic materials are present in all plant materials; however, the effects of toxic material on the environment differs according to the plant species [ 70 ]. As an example, the Olea europea leaf contains maslinic acid, which has lower toxic effects on the environment compared to that of chemical insecticides [ 70 ]. Hence, depending on the plant species, natural insecticides from plants may possess lesser effects on the environment.…”

Toxic, Oviposition Deterrent and Oxidative Stress Effects of Thymus vulgaris Essential Oil against Acanthoscelides obtectus

“…Compounds of botanical origin which coevolved as defense mechanisms against herbivores and pathogens have been proposed as a promising strategy but few are commercially produced [9,10]. Numerous investigations of their protective power against storage pests is taking place, and insecticidal and repellent properties of plant powders [11][12][13], plant extracts [14][15][16], and essential oils are tested [17,18].…”

Investigation of the toxicity of ethanol extracts obtained from six different Satureja L. species on Colorado Potato Beetle, Leptinotarsa decemlineata (Say, 1824), (Coleoptera: Chrysomelidae)

“…Toxic effects of plant extracts, essential oils and various secondary metabolite products have been reported in different researches (Kesdek et al, 2015;Usanmaz et al, 2016;Kısa et al, 2018). The present study showed that under in vivo (between 2.22 and 100%) and in vitro (between 8.88 and 100%) conditions, the ethanol extracts of six Satureja plant species had the strong insecticidal activity based on the mortality of all the tested (1 st , 2 nd , 3 rd and 4 th ) instars larvae and adults of L. decemlineata.…”