# Population Genomics and Morphology Provide Insights into the Conservation and Diversity of Apis laboriosa

## TL;DR

This study combines genomics and morphology to reveal new insights into the Himalayan giant honeybee's population structure and conservation needs.

## Contribution

The discovery of a new monophyletic group in the Sichuan population of Apis laboriosa using genomic and morphological data.

## Key findings

- The Sichuan population of Apis laboriosa forms a new monophyletic group with strong genetic differentiation.
- Four wing vein morphological features show extremely significant differences among populations.
- Population sizes of A. laboriosa have rapidly decreased over the past 10,000 years in four Chinese regions.

## Abstract

The Himalayan giant honeybee (Apis laboriosa) is highly adapted to montane environments, constructing nests on cliffs during the breeding season. This nesting behavior makes honey harvesting extremely difficult, resulting in its high market value. Driven by profit, many harvesters use methods such as smoke fumigation and pesticide spraying to expel colonies, leading to significant mortality rates in populations. Reports have shown that A. laboriosa populations have declined in certain countries and regions over recent decades. Additionally, the lack of clarity regarding population identity hinders the effective prioritization of conservation targets. Therefore, understanding the genetic differentiation among existing populations is essential for developing conservation plans for this species. Through a systematic integration of morphological feature analysis and genomic data, this study reveals via whole-genome resequencing data analysis that the Sichuan population forms a new monophyletic group (Bootstraps = 100). Over the past 10,000 years, the population sizes of A. laboriosa in four different regions of China have rapidly decreased, necessitating conservation measures across their entire distribution range. Significant difference analysis identifies four wing vein morphological characteristics with extremely significant differences. Collectively, this study concludes that the Sichuan population represents a unique geographic population, providing a scientific and theoretical basis for the effective conservation of A. laboriosa genetic resources.

In recent decades, honeybee populations have declined, dramatically owing to destructive honey harvesting practices and the loss of foraging grounds and nesting sites. Among them, Apis laboriosa Smith, 1871 (Hymenoptera, Apidae), an important pollinator species found in the Himalayan region, holds significant economic and ecological value. However, conservation efforts and intraspecific taxonomic studies regarding it have been rather limited, and thus its full geographic range remains elusive. This study is the first to research A. laboriosa in Sichuan. Through a systematic study integrating morphological feature analysis and genomic data, the following conclusions are drawn. Whole-genome resequencing data analysis reveals that the Sichuan population forms a new monophyletic group (Bootstraps = 100). In the past ten thousand years, the population sizes of A. laboriosa in four different regions of China have been decreasing rapidly. Measures should be taken to protect them across the entire distribution range, especially the populations in Tibet and Sichuan, due to their relatively large genetic differences and low intra-population genetic diversity. Based on the significant difference analysis, the following four wing vein morphological features with extremely significant differences were identified: the width of the right forewing (FB), the cubital index a/b (Ci), the forewing vein angle (E9), and the forewing vein angle (K19). These findings are expected to offer a valuable reference for future A. laboriosa conservation endeavors, particularly in protecting populations with a high level of genetic differentiation.