The mosquito life cycle involves a rapid transition from aquatic larvae to non-feeding pupae, requiring precise synchronization between nutrient allocation and development. While macronutrients are known to drive metamorphosis, the molecular mechanisms that link amino acids to this transition remain poorly understood. This study investigates the impact of branched-chain amino acid (BCAA) supplementation on the growth and metamorphosis of Anopheles stephensi. We found that BCAA supplementation to standard insectary food accelerated larval growth, enabling larvae to reach the pupal stage approximately 1.5 days earlier than unsupplemented controls. This transition was accompanied by a marked upregulation of Hexamerin (AsHex), a dedicated amino acid storage protein, during the late larval (L4) stage. Notably, RNAi-mediated silencing of AsHex significantly impaired pupation, a defect that could not be rescued by BCAA supplementation, suggesting that AsHex-associated nutrient storage contributes to the successful progression of metamorphosis. Next, we evaluated a possible association between AsHex and the nutrient-sensing TOR pathway. Rapamycin treatment delayed the larval-to-pupal transition, similar to AsHex knockdown, suggesting a possible association between AsHex and TOR-dependent developmental regulation. Collectively, our results indicate that AsHex plays a role in coordinating nutritional status with developmental progression during the larval-to-pupal transition. This discovery provides new insights into mosquito growth regulation and identifies AsHex as a potential physiological target for innovative vector control strategies.

Competing interests

The authors declare no competing interests.

Institutional review board statement

All protocols for the cyclic colony of mosquito rearing and maintenance of the mosquito culture were approved by the ethical committee of the ICMR- National Institute of Malaria Research, New Delhi (protocol code NIMR/IAEC/2017-1/07 and date of approval 17 January 2017).

Informed consent statement

Not applicable.

Statement on the use of artificial intelligence (AI)

Artificial intelligence tools were used solely to assist in language refinement, organization of ideas, and improvement of clarity and coherence of the manuscript. However, all scientific concepts, interpretations, experimental design, data analysis, and final content verification were performed by the authors.

Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.

Reprints and permissions