Chemical profiling of selected medicinal plants and their nanoemulsion formulation against papaya mealybug (Paracoccus marginatus Williams & Granara de Willink)
The papaya mealybug, Paracoccus marginatus (Hemiptera: Pseudococcidae), is considered a treacherous pest for many tropical and subtropical vegetables, fruits and ornamental plants. Synthetic insecticides are one of the methods available for controlling the papaya mealybugs. Nevertheless, mealybug...
Saved in:
Main Author: | |
---|---|
Format: | Thesis |
Language: | English |
Published: |
2018
|
Subjects: | |
Online Access: | http://psasir.upm.edu.my/id/eprint/83733/1/FP%202019%2022%20-%20ir.pdf |
Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
Summary: | The papaya mealybug, Paracoccus marginatus (Hemiptera: Pseudococcidae), is
considered a treacherous pest for many tropical and subtropical vegetables, fruits and
ornamental plants. Synthetic insecticides are one of the methods available for
controlling the papaya mealybugs. Nevertheless, mealybugs have developed a
genetic resistance to synthetic insecticides which adversely affects the environment
by polluting the air, soil, and water. The alternative approach to control the pest with
minimum harmfulness is to use bioactive compounds present in plants. Many studies
have revealed the possibility of utilizing essential plant oils to control insects as an
eco-friendly pesticides. Therefore, the study endeavours to prepare and determine the
effectiveness of nanoemulsion formulations of Artemisia herba-alba, Myrtus
communis, Mentha longifolia and Salvia spinosa essential oils against papaya
mealybugs, P. marginatus. The essential oils of selected medicinal plants
were extracted by hydrodistillation and solvent extraction methods, and their chemical
profiles were identified using GC-MS system. The insecticidal activities of the
essential oils were firstly evaluated against female adults of the papaya mealybug.
Then, the most effective essential oil of each plant was selected to prepare water in oil
(W/O) nanoemulsion formulations. Three mineral oils as carriers and 18 types of
surfactants were screened to prepare and characterize nanoemulsion formulations, and
their toxicity was determined against the papaya mealybugs. The GC-MS analysis
exhibited that the essential oils of the plants contain various active components such
as; eucalyptol, piperitone, cineron, dehydroabietic acid, α.terpineol α-pinene, linderol
and alcanfor. The quality and quantity of these components depend on the type of the
plant and the method of extraction. The biological screening of the essential oil
toxicity of A. herba-alba, M. longifolia, and M. communis extracted by
hydrodistillation, and S. spinosa essential oil obtained by solvent extraction showed a
high toxicity against papaya mealybug. After the miscibility screening, three surfactants (EW70, Termul 3540 and DB10) and two mineral oils (paraffin and methyl
ester) were chosen to prepare nanoemulsion formulation of the selected plants
essential oil. Three ternary phase diagrams were constructed from these materials, and
three points (FN5, FN8, and FN11) were selected from each ternary phase diagrams.
After miscibility and stability test, it was prepare nine formulations with 20% of A.
herba-alba, M. longifolia. M. communes essential oil and three formulations with
15% of S. spinosa essential oil. The results of characterization tests confirmed that all
formulations with essential oils were nanoemulsion formulations within nano-particle
size at range 26.94 to 108.00mm. The formulations exhibited high stability under
centrifugation and storage conditions with good physical characterizations. The
toxicity of the essential oil nanoformulations against P. marginatus showed the nano
formulation code FN5 (paraffin oil and DB10 surfactant) achieved the highest toxicity
against papaya mealybugs and largest droplet spreading area on papaya leaves
followed by nano formulation codes FN8 (methyl ester and Termul 3540 surfactant)
and FN11 (methyl ester and EW70 surfactant) with all selected plants essential oils.
The nanoemulsion formulation code FN5 with M. longifolia essential oil revealed the
best results compared with other nanoemulsion formulations with selected plant
essential oils. The present study found that nanoemulsion formulations of essential
oils of A. herba-alba, M. communis, M. longifolia and S. spinosa are safe and ecofriendly
insecticides. These botanical pesticides can be utilized as an alternative
approach to control the papaya mealybug. |
---|