Insecticidal effect of Eucalyptus globulus and Rosmarinus officinalis essential oils on a stored food pest Ephestia kuehniella (Lepidoptera, Pyralidea).

For the purpose of evaluating the local heritage of eastern Numidia, an ethnobotanical survey was conducted on a population located in the province (department) of El-Tarf (North-East of Algeria) on a frequency of use of two plants known in traditional health; Eucalyptus globulus (Myrtaceae) and Rosmarinus officinalis (Lamiaceae). After processing data, our results show a female dominance when using these plants on a fairly advanced age group (40 to 60 years old). These plants are used by the people at their fresh state and deem the leaf as the most used part for therapeutic and cosmetic purposes. Furthermore, steam baths and infusion remain the most widespread preparation methods. Most consumers use these plants to treat influenza, respiratory illnesses as well as diseases of the digestive tract. GC-MS of essential oils extracted from the plants studied disclose a dominance of the alcohols portrayed by the monoterpenes (42.73%), sesquiterpenes (32.6%) and oxides (10.48%) in E. globulus. Data also indicate a high content of oxides (38.11%) monoterpene alcohols (20.43%) and monoterpenes (19.70%) in R.officinalis. Toxicological contact tests were achieved on a store-products pest Ephestia kuehniella. The test results were assessed with E.globulus (LC50=0.013; LC95=0.081 µl/cm2) and R.officinalis (LC50=0.011; LC95=0.059 µl/cm2). The lethal time changes according to the dose used and the tested plant. In E.globulus, we observe (concentration: 0.005 µl/cm2; LT50=56.2 h), (Concentration: 0.01 µl/cm2; LT50=49.53h) and (Concentration: 0.04µl/cm2; LT50=20.93h). Whereas in R.officinalis, we recorded (Concentration: 0.005 µl/cm2; LT50=55.7h), (Concentration: 0.01µl/cm2; LT50=54.99 h) and (Concentration: 0.04µl/cm2; LT50=29.13 h). The bioinsecticide has also been administered by fumigation and underpins toxicity by the reduction of adults longevity in E.kuehniella with R.officinalis (LC50=4.03 µl/l air; LC95=14.73 µl/l air) and E.globulus (LC50=7.76 µl/lair; LC95=21.23 µl/l air). In addition, the tested plants show an outstanding repellent effect as long as E.globulus and  R.officinalis essential oils respectively demonstrate a slightly repellent power at 42.22% (RD50=0.09 µl/cm2 ; RD95=0.24 µl/cm2) and repellent at 60.00% (RD50=0.06 µl/cm2 ; RD95= 0.35 µl/cm2) towards E.kuehniella adults. The plant resources represent a genuine reserve of bioactive molecules, which can create solutions to sustainable development issues. These plants might be the source of new molecules of combat against some pests in order to protect human health and safeguard the environment.

Encapsulation of α-Pinene in Delivery Systems Based on Liposomes and Cyclodextrins.

The essential oil component α-pinene has multiple biological activities. However, its application is limited owing to its volatility, low aqueous solubility, and chemical instability. For the aim of improving its physicochemical properties, α-pinene was encapsulated in conventional liposomes (CLs) and drug-in-cyclodextrin-in-liposomes (DCLs). Hydroxypropyl-ß-cyclodextrin/α-pinene (HP-ß-CD/α-pinene) inclusion complexes were prepared in aqueous solution, and the optimal solubilization of α-pinene occurred at HP-ß-CD:α-pinene molar ratio of 7.5:1. The ethanol-injection method was applied to produce different formulations using saturated (Phospholipon 90H) or unsaturated (Lipoid S100) phospholipids in combination with cholesterol. The size, the phospholipid and cholesterol incorporation rates, the encapsulation efficiency (EE), and the loading rate (LR) of α-pinene were determined, and the storage stability of liposomes was assessed. The results showed that α-pinene was efficiently entrapped in CLs and DCLs with high EE values. Moreover, Lipoid S100 CLs displayed the highest LR (22.9 ± 2.2%) of α-pinene compared to the other formulations. Both carrier systems HP-ß-CD/α-pinene inclusion complex and Lipoid S100 CLs presented a gradual release of α-pinene. Furthermore, the DPPH radical scavenging activity of α-pinene was maintained upon encapsulation in Lipoid S100 CLs. Finally, it was found that all formulations were stable after three months of storage at 4 °C.

Phytochemical profile and insecticidal activity of Agave americana leaf extract towards Sitophilus oryzae (L.) (Coleoptera: Curculionidae).

The main objective of the present study is to introduce a new and ecologically safe method for managing the rice weevil, Sitophilus oryzae. Therefore, the Agave americana leaf extract's phytochemical profile, and its insecticidal activity against the adults of S. oryzae were evaluated. The A. americana leaf extract was screened for the following phytochemicals: total phenolics (14.70 ± 0.31 mg GAE/g FW), total flavonoids (5.15 ± 0.18 mg RE/g FW) and saponins (10.32 ± 0.20 mg OAE/g FW). The HPLC-ESI/TOF-MS analysis results revealed that flavonoid glycosides (kaempferol, quercetin, and isorhamnetin derivates) were the major phenolic compounds of the A. americana leaf extract. In addition, the GC-MS analysis identified n-alkanes (77.77%) as significant compounds of the lipophilic fraction from the leaf extract. Moreover, the insecticidal potential was assessed through contact and repellent bioassays towards the rice weevil adults. The LD50, LC50, and RC50 values were 10.55 µg/insect, 8.99 µg/cm2, and 0.055 µg/cm2 for topical application method, treated filter-paper method, and repellent bioassay, respectively. Furthermore, the A. americana leaf extract inhibited digestive enzyme activities, and median inhibition concentrations IC50 were evaluated to be 146.06 ± 1.74 and 86.18 ± 1.08 µg/mL for α-amylase and protease, respectively. Overall, our results highlighted the promising potential of the leaf extract against S. oryzae adults, allowing us to recommend the extract under investigation as an ecofriendly alternative to synthetic insecticides.

Post-harvest management control of Ectomyelois ceratoniae (Zeller) (Lepidoptera: Pyralidae): new insights through essential oil encapsulation in cyclodextrin.

BACKGROUND: Essential oils are reported to be bio-insecticides. However, problems related to their volatility, oxidation and poor water solubility need to be solved before they can be considered as replacement pest control methods. Thus, an appropriate formulation is needed for commercial use. In this work, a new control method based on the use of a powdered cyclodextrin (CD)/1,8-cineole inclusion complex was assessed against larvae and adults of Ectomyelois ceratoniae (Zeller) in comparison with two Rosmarinus officinalis (L.) essential oils, free 1,8-cineole (oils major compound) and a mixture of 50% CD/1,8-cineole inclusion complex and 50% free 1,8-cineole. RESULTS: Solid CD/1,8-cineole complex was more toxic against E. ceratoniae larvae than the two crude essential oils. At a concentration of 15 µL liter-1 air, the respective mortalities were 94.12%, 35.29% and 19.61% for solid CD/1,8-cineole complex, Thala and Cap Zbib oils after 37 days of exposure. Moreover, the solid CD/1,8-cineole complex achieved 5% adult emergence versus 68.33% for Cap Zbib and 55% for Thala oils. The half-life of solid CD/1,8-cineole inclusion complex (10.98 days) was considerably longer than that of the mixture (7.53 days) or free 1,8-cineole (3.43 days). CONCLUSION: This work highlights the utility of essential oil encapsulation in CD to overcome restrictions when used to control the date moth E. ceratoniae during storage. © 2019 Society of Chemical Industry.