Aedes aegypti (Ae. aegypti) is a competent vector for transmitting important viral diseases such as yellow fever, dengue, chikungunya, and Zika. Several strategies have been applied to avoid Ae. aegypti proliferation by using environmental management, biological, and chemical approaches. However, the development of new methods for effective control of the insect vector population is still needed. Photodynamic control is an alternative way to control the vector population by using a physical approach based on the larval phototoxicity of a photosensitizer. In this context, the present study evaluated the use of eosin-methylene blue (EMB) as a new photosensitizer for photodynamic control of Ae. aegypti larval populations. The photodynamic assays were performed submitting Ae. aegypti third-instar larvae to different EMB concentrations (0.0, 0.5, 1.0, 5.0, 10.0, 50.0, and 100.0 µg mL⁻¹) in combination of three different light doses (24.3, 48.6, and 97.2 J cm⁻²) under either white-light radiation from RGB LEDs or sunlight. The results demonstrated that EMB presented a rapid internalization into the larvae and was phototoxic. The photodynamic action induced 100% of larval mortality after about 40 min of sunlight irradiation even using low EMB concentration (0.5 µg mL⁻¹). The findings reveal EMB as an effective photoactive compound to control larval populations of Ae. aegypti by photodynamic process induced by either sunlight or white-light from RGB LEDs.

This study evaluates the photosensitizing effectiveness of sodium copper chlorophyllin, a natural green colorant commonly used as a food additive (E-141ii), to inactivate methicillin-sensitive and methicillin-resistant Staphylococcus aureus under red-light illumination. Antimicrobial photodynamic inactivation (aPDI) was tested on a methicillin-sensitive reference strain (ATCC 25923) and a methicillin-resistant Staphylococcus aureus strain (GenBank accession number Mh087437) isolated from a clinical sample. The photoinactivation efficacy was investigated by exposing the bacterial strains to different E-141ii concentrations (0.0, 1.0, 2.5, 5.0, 10.0, and 20.0 µM) and to red light (625 nm) at 30 J cm⁻². The results showed that E-141ii itself did not prevent bacterial growth for all tested concentrations when cultures were placed in the dark. By contrast, E-141ii photoinactivated both methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) under red-light illumination. However, different dose responses were observed for MSSA and MRSA. Whilst the MSSA growth was inhibited to the detection limit of the method with E-141ii at 2.5 µM, >10 µM concentrations were required to inhibit the growth of MRSA. The data also suggest that E-141ii can produce reactive oxygen species (ROS) via Type I reaction by electron transfer from its first excited singlet state to oxygen molecules. Our findings demonstrate that the tested food colorant has great potential to be used in aPDI of MRSA.

This study reports curcumin as an efficient photolarvicide against Aedes aegypti larvae under natural light illumination. Larval mortality and pupal formation were monitored daily for 21 days under simulated field conditions. In a sucrose-containing formulation, a lethal time 50 ($L{T}_{50}$) of 3 days was found using curcumin at 4.6 mg L⁻¹. This formulation promoted no larval toxicity in the absence of illumination, and sucrose alone did not induce larval phototoxicity. The photodegradation byproducts (intermediates) of curcumin were determined and the photodegradation mechanisms proposed. Intermediates with m/z 194, 278, and 370 were found and characterized using LC-MS. The ecotoxicity of the byproducts on non-target organisms (Daphnia, fish, and green algae) indicates that the intermediates do not exhibit any destructive potential for aquatic organisms. The results of photodegradation and ecotoxicity suggest that curcumin is environmentally safe for non-target organisms and, therefore, can be considered for population control of Ae. aegypti.

Considerable efforts have been spent on environmentally friendly particles for the encapsulation of essential oils. Polymeric particles were developed to encapsulate the essential oil from Piper nigrum based on gelatin and poly–ε–caprolactone (PCL) carriers. Gas Chromatography ((Flame Ionization Detection (GC/FID) and Mass Spectrometry (GC/MS)), Atomic Force Microscopy (AFM), Nanoparticle Tracking Analysis (NTA), Confocal Laser Scanning Microscopy (CLSM), Attenuated Total Reflectance–Fourier-transform Infrared Spectroscopy (ATR–FTIR), and Ultraviolet–Visible (UV–VIS) spectroscopy were used for the full colloidal system characterization. The essential oil was mainly composed of β-caryophyllene (~35%). The stability of the encapsulated systems was evaluated by Encapsulation Efficiency (EE%), electrical conductivity, turbidity, pH, and organoleptic properties (color and odor) after adding different preservatives. The mixture of phenoxyethanol/isotialzoni-3-one (PNE system) resulted in enhanced stability of approximately 120 and 210 days under constant handling and shelf-life tests, respectively. The developed polymeric system presented a similar controlled release in acidic, neutral, or basic pH, and the release curves suggested a pulsatile release mechanism due to a complexation of essential oil in the PCL matrix. Our results showed that the developed system has potential as an alternative stable product and as a controlling agent, due to the pronounced bioactivity of the encapsulated essential oil.

The control of pests and vector-borne diseases (VDBs) are considered public health issues Worldwide. Among the control techniques and pesticides used so far, photodynamic inactivation (PDI) has been shown as an eco-friendly, low cost, and efficient approach to eliminate pests and VDBs. PDI is characterized using a photosensitizing molecule, light and molecular oxygen (O₂) resulting in production of reactive oxidative species which can promote the oxidation of biomolecules on pests and vectors. Herein, we review the past 51 years (1970–2021) regarding the use of photo pesticides, reporting the most important parameters for the protocol applied, the results obtained, and limitations. Moreover, we described the mechanism of action of the PDI, main classes of photopesticides used so far as well as the cell death mechanism resulting from the photodynamic action.