# D-Limonene: Promising and Sustainable Natural Bioactive Compound
## 7 Application: Nanotechnology and D-Limonene
### Applications
#### 7.2.2 Agriculture  
Along with the increasing concern for environmental protection, the search for a non-hazardous natural compound to replace chemical pesticides has attracted the interest of researchers. As a potential alternative to chemical pesticides, a large number of studies have demonstrated D-limonene's ability to combat a wide range of pathogenic bacteria and pests, but its use has been challenged by properties such as high volatility, low solubility, and thermal instability. It has been found that nanoencapsulation can overcome these issues, providing better stability, protection, release control, and bioavailability [207].  
[PERSON] et al. [188] reported greater antifungal activity of D-limonene nanoemulsions against _Pyricularia oryzae_, _Rhizoctonia solani_, _Collettotrichum gloosporiodes_, and _Phomopsis amygdali_ compared to free D-limonene at the concentration of EC\({}_{508}\), with an increase in inhibition from 22.2%, 30.4%, 24.4%, and 32.5% to 48.7%, 50.9%, 47.4%, and 51.7%, respectively, which could be attributed to the increased permeability and water solubility of the nanoemulsions.  
_Anopheles stephensi_ and _Culex quinquetesiatus_ are vectors of several diseases. [PERSON] et al. [208] found that, compared to D-limonene, nanoliposomes of D-limonene had a stronger larvicidal effect on these two mosquitoes, with the LC\({}_{508}\) decreasing from 20.12 and 16.36 \(\mathrm{\SIUnitSymbolMicro m}\)/mL to 13.6 and 6.41 \(\mathrm{\SIUnitSymbolMicro m}\)/mL, respectively, and the LC\({}_{908}\) decreasing from 80.05 and 31.29 \(\mathrm{\SIUnitSymbolMicro m}\)/mL to 25.08 and 12.71 \(\mathrm{\SIUnitSymbolMicro m}\)/mL, respectively, and the D-limonene nanoemulsions prepared by [PERSON] et al. [142] showed larvicidal properties against the third- to fourth-instar larvae of _Aedes albopictus_ and _Culex pipiens molestus_, with LC\({}_{508}\) and LC\({}_{908}\) showing the same decreasing trend compared to D-limonene; this may be due to the fact that nanoencapsulation enhances the physical stabilization, permeation, and propagation of D-limonene.  
_Columbicola columbae_ is the main cause of ectoparasitic infections in pigeons, which can lead to symptoms such as anemia, dermatitis, decreased egg production, and slow weight gain, and the general method of counteracting this is the use of deltamethin but this not only leads to environmental contamination but also negatively affects the pigeons and their products. Therefore, [PERSON] et al. [24] proposed the use of D-limonene instead of deltamethin and showed that 30 mg/mL of D-limonene and its nanoemulsion exhibited equivalent lousicidal activity to 0.025 mg/mL of deltamethin without affecting pigeons, both through the neuromuscular inhibition of AchE and contact distortion of the body wall, with the difference that D-limonene and its nanoemulsion did not affect the pigeons and, remarkably, the D-limonene nanoemulsion remained stable after 50 days of storage and exhibited significant insecticidal activity.  
Although studies have shown that nanoencapsulated D-limonene has enhanced physical stability and bioactivity, there is a need for more extensive research and evaluation as nanoencapsulated D-limonene has been studied to control fewer pest species and has not been validated in practical applications.