Behavioral and ultrastructural effects of novaluron on Aedes aegypti larvae

https://doi.org/10.1016/j.meegid.2021.104974Get rights and content
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Highlights

  • The present study reveals the non-target cytotoxic effects of novaluron.

  • Histopathology and cytotoxicity caused by novaluron on Aedes aegypti were evaluated.

  • We demonstrate for the first time that novaluron has ability to induce severe alterations in midgut cells of Aedes aegypti.

Abstract

Chitin synthesis inhibitors (CSI) are supposed to inhibit formation of chitin microfibrils in newly synthesized cuticle during molting process. Conversely, there has been comparatively few data on morphological effects of CSI on non-target insect organs. In this work, the effects of the CSI novaluron on behavior and midgut of A. aegypti were evaluated. Toxicity bioassays revealed that novaluron is toxic to A. aegypti larva with LC50 = 18.57 mg L−1 when exposed in aqueous solution for 24 h. Novaluron treated larvae were less active and spent more time resting compared to the control group. Histopathology showed that midguts of novaluron-treated larvae had cytoplasm vacuolization and damaged brush border. Cytotoxic effects in midguts of treated larvae induced necrosis, autophagy and damage to mitochondria. Despite being chitin synthesis inhibitor, novaluron did not induce alterations in the integument of A. aegypti larvae. Fluorescence microscopy revealed that the number of digestive cells were higher in novaluron-treated larvae than in control, in response to digestive cell apoptosis. The present study highlights the importance of novaluron against A. aegypti larvae by causing injuries to non-target organs, altering behaviors, inducing cell death and inhibiting cell proliferation.

Keywords

Autophagy
Aedes aegypti
Ultrastructure
Chitin synthesis inhibitor
Locomotory behavior

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