# Comprehensive Identification and Male-Biased Expression Analysis of Odorant-Binding Protein Genes in the Hawaiian Flower Thrips, Thrips hawaiiensis (Thysanoptera: Thripidae)

## TL;DR

This study identifies 12 odorant-binding protein genes in the Hawaiian flower thrips, finding they are more active in males, suggesting a role in male-specific behaviors like mating and foraging.

## Contribution

The first comprehensive identification and expression analysis of odorant-binding protein genes in Thrips hawaiiensis, revealing male-biased expression patterns.

## Key findings

- Thrips hawaiiensis has 12 OBP genes, a number lower than most insects but comparable to other thrips.
- OBPs and CSPs show male-biased expression, suggesting roles in male-specific olfactory behaviors.
- The study provides a foundation for future functional studies of olfactory proteins in insects.

## Abstract

The Hawaiian flower thrips, Thrips hawaiiensis, is a widespread pest that infests the flowers of numerous horticultural crops. We characterized the previously unknown olfactory system of Thrips hawaiiensis by analyzing its odorant-binding proteins (OBPs). Our genome survey revealed 12 OBP genes, a count comparable to other thrips but low relative to most insects. Subsequent transcriptomic and RT-qPCR analyses identified consistent male-biased expression, implicating these OBPs in male-specific olfactory behaviors, such as mate location and foraging. We further identified 11 CSPs, the majority of which showed a male-biased expression pattern similar to that of the OBPs.

Olfaction is essential for key insect behaviors, such as host-seeking and mating, and is initiated by odorant-binding proteins (OBPs), which bind and transport hydrophobic odors. Thrips hawaiiensis is a major pest that infests the flowers of numerous horticultural crops, yet its chemosensory mechanisms remain poorly understood. Now, the availability of its genome assembly allows us to address this gap. To this end, we performed a comprehensive exploration and comparative analysis of its OBP genes. Our genome-wide analysis identified a total of 12 OBP genes in T. hawaiiensis, whereas the repertoire across other published thrips genomes ranges from 10 to 17, a count significantly lower than that in most other insects. Notably, transcriptomic and RT-qPCR analyses revealed consistent male-biased expression of OBPs in T. hawaiiensis, supporting their role in mate-finding and foraging behaviors. Furthermore, we identified 11 chemosensory proteins (CSPs). Transcriptomic and RT-qPCR analyses revealed that these CSPs exhibit an expression pattern similar to that of the OBPs, with over half of the genes showing significantly higher expression in males. This work provides a foundational framework for future functional studies of olfactory proteins, both in T. hawaiiensis and the wider insect community.