Biodistribution of degradable polyanhydride particles in Aedes aegypti tissues

Abstract

Insecticide resistance poses a significant threat to the control of arthropods that transmit disease agents. Nanoparticle carriers offer exciting opportunities to expand the armamentarium of insecticides available for public health and other pests. Most chemical insecticides are delivered by contact or feeding, and from there must penetrate various biological membranes to reach target organs and kill the pest organism. Nanoparticles have been shown to improve bioactive compound navigation of such barriers in vertebrates, but have not been well-explored in arthropods. In this study, we explored the potential of polyanhydride microand nanoparticles (250 nm-3 μm), labeled with rhodamine B to associate with and/or transit across insect biological barriers, including the cuticle, epithelium, midgut and ovaries, in female Ae. aeygpti mosquitoes. Mosquitoes were exposed using conditions to mimic surface contact with a residual spray or paint, topical exposure to mimic contact with aerosolized insecticide, or per os in a sugar meal. In surface contact experiments, microparticles were sometimes observed in association with the exterior of the insect cuticle. Nanoparticles were more uniformly distributed across exterior tissues and present at higher concentrations. Furthermore, by surface contact, topical exposure, or per os, particles were detected in internal organs. In every experiment, amphiphilic polyanhydride nanoparticles associated with internal tissues to a higher degree than hydrophobic nanoparticles. In vitro, nanoparticles associated with Aedes aegypti Aag2 cells within two hours of exposure, and particles were evident in the cytoplasm. Further studies demonstrated that particle uptake is dependent on caveolae-mediated endocytosis. The propensity of these nanoparticles to cross biological barriers including the cuticle, to localize in target tissue sites of interest, and to reach the cytoplasm of cells, provides great promise for targeted delivery of insecticidal candidates that cannot otherwise reach these cellular and subcellular locations.

Nutritional status significantly affects toxicological endpoints in the CDC bottle bioassay

“…Interestingly, mosquitoes feeding on sugar alone were significantly more susceptible to the effects of permethrin, although sugar‐only‐fed mosquitoes weighed the same as sugar‐water‐fed, suggesting mosquitoes did in fact feed on the sugar. This is also supported by previous studies that demonstrated mosquitoes can feed on dry sugar 17,18 . These results suggest that insecticide tolerance is not primarily mediated by carbohydrate reserves.…”

“…This is also supported by previous studies that demonstrated mosquitoes can feed on dry sugar. 17,18 These results suggest that insecticide tolerance is not primarily mediated by carbohydrate reserves. Water-only-fed mosquitoes weighed the same as starved, which may reflect the lack of feeding stimulus or carbohydrate storage provided by the sugar.…”

dsRNA Uptake in Plant Pests and Pathogens: Insights into RNAi-Based Insect and Fungal Control Technology

“…Fluorescent confocal imaging appeared to show caveolae-mediated endocytosis is a primary pathway for lipoplexes, but the other two endocytic pathways also had some role in uptake. A similar study [ 141 ] in mosquitoes ( A. aegypti ) found caveolae-mediated endocytosis is essential for nanoparticle (anhydride) internalization into epithelial cells. This is especially true for smaller particles (<100 nm) but could also allow larger particles such as lipoplexes which can easily exceed that size.…”

From tissue engineering to mosquitoes: biopolymers as tools for developing a novel biomimetic approach to pest management/vector control

“…For example, synthetic hydrogels are applied in agriculture for nutrient or pesticide release, for absorption and sustained release of water, particularly in dryland farming in soil-less agriculture, or hygiene products such as diapers [20,21]. Synthetic hydrogels are already used in pest management, mainly for the release of chemical insecticides through beads as baits or for controlled release in water or microencapsulation for spraying and release of active substances [22,23]. Examples are PAM or silica and talc-based gels [24,25] inserted in a polyethylene container to slowly release an insect growth regulator or other synthetic insecticides in pest and vector control [26,27].…”