Nanoformulations with exopolysaccharides from cyanobacteria: enhancing the efficacy of bioactive molecules in the Mediterranean fruit fly control

Abstract

The increasing demand for food has required intensive use of pesticides which are hazardous to the ecosystem. A valid alternative is represented by biopesticides; however, these molecules are often insoluble in water, and poorly bioavailable. Nanopesticides can be engineered to reach a selected target with controlled release of the active principle. In this work, capsaicin, an irritant alkaloid from hot chili peppers, and hydroxytyrosol, a phenolic compound obtained from extra-virgin olive oil by-products, were loaded into innovative nanocarriers. These were designed ad hoc combining exopolysaccharides from the cyanobacteria Neocyanospira capsulata, and a lipid component, i.e., egg phosphatidylcholine. The polysaccharide was chosen for chemical affinity with the chitin of insect exoskeleton, while the lipids were introduced to modulate the carrier rigidity. The newly formed nanosystems were characterized by physico-chemical techniques and tested for their possible use in pest control programs. The Mediterranean Fruit Fly Ceratitis capitata Wiedemann, 1824 (Diptera, Tephriditae), a pest of the Mediterranean Region causing high economic losses, was used as a model insect. We found that the nanoformulations nanocarriers prepared in this work, were able to increase the ovicidal effect of hydroxytyrosol. Moreover, the formulation encapsulating either hydroxytyrosol or capsaicin were able to reduce the number of females landing on treated apricots. Graphical Abstract

Nanoformulations from olive pomace to enhance the efficacy of hydroxytyrosol as a natural pest control agent

“…As previously stated, compounds containing HT repel B. oleae and C. capitata upon surface contact. 53,58 Our study's results show that repellency was induced in the beetles without direct contact with the treated kernels, indicating a distinct process from contact-based effects. It suggests a possible involvement of volatile elements influencing the behavior of S. oryzae.…”

“…In a previous study, application of encapsulated HT at the same dose of 2.5 mg mL −1 was able to prevent fruit flies from landing on treated fruits. 53 Here, this effect obtained`with EPC-OP-HT 5 might be explained by the restricted space of the setup used in these experiments, which could hamper the females from flying and finding better egg laying sites. 42,54 Therefore, a concentration higher than 2.5 mg mL −1 was needed in the present case to achieve the aversive effect.…”

Environmentally Friendly and Cost-Effective Approaches to Reduce Toxin Content in Toxic Cyanobacterial Biomasses

“…Nonetheless, cyanobacteria have been recognized as important biological resources, from which biochemically active natural substances can be isolated [18]. Many biotechnological applications can be exploited, namely, in the development of novel drugs and treatment of human illnesses, food supplements, cosmetics, antibiotics, environmental friendly pesticides, or anti-fouling paints [19][20][21], and cyanotoxins at very low concentrations may have positive effects on plant growth [22]. Cyanobacterial mats also can be used in agriculture as biofertilizers, plant stimulants, and soil amendments [23] or in control of plant pests [20].…”

“…Many biotechnological applications can be exploited, namely, in the development of novel drugs and treatment of human illnesses, food supplements, cosmetics, antibiotics, environmental friendly pesticides, or anti-fouling paints [19][20][21], and cyanotoxins at very low concentrations may have positive effects on plant growth [22]. Cyanobacterial mats also can be used in agriculture as biofertilizers, plant stimulants, and soil amendments [23] or in control of plant pests [20]. The interest in this bioresource is increasing worldwide since cyanobacteria can be obtained from the environment in abundance or can be grown in controlled environment (in bioreactors, vessels, large outdoor tanks, or indoors).…”