The Integrative Imperatives of Locust Phase Polyphenism Research: A Bibliometric Analysis.

Abstract

Locust phase polyphenism, a classic example of phenotypic plasticity, has been studied for over a century, generating an extensive body of literature. However, a quantitative synthesis of the field's structure, evolution, and disparities has been lacking. Here, we present the first comprehensive bibliometric analysis of locust phase polyphenism research, quantitatively mapping its intellectual structure, collaborative networks, and thematic evolution. Analyzing 400 peer-reviewed primary studies published from 1921 through February 2025, we reveal a field at a critical inflection point. Publication trends demonstrate robust growth since the 1990s, reflecting the refinement of classical methods and the emergence of molecular and neurobiological approaches. However, this expansion rests upon a narrow foundation: research concentrates almost exclusively on two model species-Schistocerca gregaria and Locusta migratoria-while ecologically important non-model taxa remain critically understudied. Co-authorship network analysis exposes significant geographical disparities: research leadership concentrates in a small number of countries (UK, China, Japan, Belgium, Israel, Kenya, Germany, and USA), while most other locust-affected regions across the Sahel, the Horn of Africa, and the Middle East remain peripherally integrated. Keyword co-occurrence mapping identifies critical thematic blind spots within the phase polyphenism literature, including a complete absence of explicit climate change framing and limited representation of socioeconomic dimensions and non-model species. The field thus exhibits a notable disconnect: deep mechanistic knowledge of how phase change occurs exists alongside limited understanding of when and why outbreaks occur under changing environmental conditions. Transformative advances require strategic reorientation: from model-organism focus to comparative ecology, from episodic collaboration to equitable partnership with range-state scientists, from descriptive mechanism to functional validation, and from neglected frontiers (microbiome, epigenetics, and climate) to systematic investigation. This bibliometric mapping provides an evidence-based framework to guide future research toward greater impact on global food security.