*4.4. Histopathological Study and Larvicidal Activity*

The histopathological profile of TiO2NPs mediated from a *P. djamor* extract treated mosquito (*Aedes aegypti and Culex quinquefasciatus*) resulted in the complete collapse of caeca, digestive tract, and desertion of the cuticle and epithelial layer, with harsh damage to the mid-and hind-gut, muscles, as well as nerve ganglia of the brush border. The treating of TiO<sup>2</sup> NPs on IVth instar larvae of *Ae. aegypti* and *Cx. quinquefasciatus* resulted in larvicidal activity with LC50 (5.88 and 4.84 µg/L) and LC90 (22.80 and 19.33 µg/L) [44]. The *Ae. aegypti* larvae treated with ZnONPs showed morphological alteration in the digestive tract, wrecked membrane, midgut, and severe damaging of the brush border, cortex with hyperplasia of gut epithelial cells, and variations in the cytoplasmic masses. The larvae of *Cx. quinquefasciatus* showed the complete putrefaction of abdominal parts, specifically in the caeca, mid-gut, and epithelial layer [43].
