Morphological and physiological changes induced by Achyranthes aspera-mediated silver nanocomposites in Aedes aegypti larvae

Abstract

Aedes aegypti is responsible for the global spread of several ailments such as chikungunya, dengue, yellow fever, and Zika. The use of synthetic chemicals is the primary intervention in mosquito management. However, their excessive utilization resulting in the spread of toxic ingredients in the environment and posing threats to beneficial organisms has prompted the recommendation for the use of biologically synthesized nanocomposites as a promising approach for vector control. Silver nanocomposites were synthesized using leaf (AL-AgNCs) and stem (AS-AgNCs) extracts of Achyranthes aspera. The early fourth instars of A. aegypti were exposed to lethal doses of these nanocomposites to evaluate their effects on larval development, behavior, morphology, and mid-gut histoarchitecture. The cellular damage and deposition of nanocomposite residues in the mid-gut were studied using light and transmission electron microscopy. The A. aspera silver nanocomposite (AA-AgNC)-exposed larvae exhibited dose-dependent extended duration of development and diminished adult emergence, but did not exhibit modified behavior. Intense damage to the cuticle membrane and slight contraction in the internal membrane of anal papillae were noticed. Morphologically, the mid-gut appeared disorganized, darkly pigmented, and shrunk. Histological investigations of the mid-gut revealed significantly disordered internal architecture with lysed cells, damaged peritrophic membrane and microvilli, disintegrated epithelial layer, and a ruptured and displaced basement membrane. Visualization of the larval mid-gut through TEM showed severe cellular damage and aggregation of black spots, indicating the deposition of silver particles released by AA-AgNCs. The investigations revealed the bio-efficacy of A. aspera-mediated AgNCs against A. aegypti inducing stomach and contact toxicity in the larvae. The utilization of AA-AgNCs is recommended for A. aegypti management as a safe and effective intervention.

Sonication and heat‐mediated synthesis, characterization and larvicidal activity of sericin‐based silver nanoparticles against dengue vector (Aedes aegypti)

“…Morphological deterioration (skin pinching, darkening of color) of the larvae after exposure of Se‐AgNPs was also observed which provided a clue for the cuticle damage of the larvae. Similarly, many other studies (Ali et al, 2017; Ragavendran et al, 2019; Sharma et al, 2022) also reported the observable cuticular, anal papillae and other morphological damages including darkening of color after exposure to silver NPs which endorse this study findings regarding the mode of action.…”

“…Morphological deterioration (skin pinching, darkening of color) of the larvae after exposure of Se-AgNPs was also observed which provided a clue for the cuticle damage of the larvae. Similarly, many other studies(Ali et al, 2017;Ragavendran et al, 2019;Sharma et al, 2022) also reported the observable cuticular, anal papillae and other morphological damages including darkening of color after exposure to silver NPs which endorse this study findings regarding the mode of action.Stability and efficacy of individual heat-assisted silver NPs (80-100 C) showed a significant lower larvicidal activity as compared to heat-assisted and sonication-assisted Se-AgNPs. Higher temperature might cause the thermal decomposition of AgNO 3 which could be a possible justification for the reduction in their larvicidal activity.…”

Evaluation of mosquitocidal efficacy of panchgavya from indigenous and crossbreed cows against dengue vector

“…This enhanced larvicidal and pupicidal effect may be attributed to the synergistic actions of their bioactive components (Ozege and Omoregie, 2022) [29] , which could potentially cause structural and functional damage to larvae and pupae thus, impaired larval survival in present study. The larval phase is a feeding stage, so it is possible that larvae ingest active compounds during treatment, which may cross passively to insect mid-gut and induced extensive damage to its cellular composition (Sharma et al, 2022) [35] . On the other side, pupae stage is a non-feeding phase, it is possible that during treatment, active xenobiotic molecules may come into direct contact with the pupae cuticle membrane, leading to disruption of their cellular architecture (Bouabida and Dris, 2022) [8] .…”