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Main Authors: Li, Xueheng, Wang, Yu, Hu, Tao, Huang, Ji, Cao, Ke, Yang, Qize, Li, Rui, Zhang, Jie, Xie, Chengjun
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2605.06121
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author Li, Xueheng
Wang, Yu
Hu, Tao
Huang, Ji
Cao, Ke
Yang, Qize
Li, Rui
Zhang, Jie
Xie, Chengjun
author_facet Li, Xueheng
Wang, Yu
Hu, Tao
Huang, Ji
Cao, Ke
Yang, Qize
Li, Rui
Zhang, Jie
Xie, Chengjun
contents Pest-induced crop losses pose a major threat to global food security and sustainable agricultural development. While recent advances in Multimodal Large Language Models (MLLMs) have shown strong potential for visual understanding and smart agriculture, their direct application to pest recognition remains limited due to the domain's unique challenges such as high inter-species complexity, intra-species variability, and the scarcity of expert-annotated data. In this work, we introduce Pest-Thinker, a knowledge-driven reinforcement learning (RL) framework that enables MLLMs to reason over fine-grained pest morphology. We first construct two high-definition pest benchmarks, QFSD and AgriInsect, comprising diverse species and expert-annotated morphological traits. Leveraging these datasets, we synthesize Chain-of-Thought (CoT) reasoning trajectories to facilitate structured learning of pest-specific visual cues through Supervised Fine-Tuning (SFT). Subsequently, we employ Group Relative Policy Optimization (GRPO) with a novel feature reward that guides the model to focus on observable morphological evidence, assessed by an LLM-as-a-Judge strategy. Extensive experiments demonstrate that Pest-Thinker substantially improves both in-domain and out-of-domain morphological understanding, marking a step toward expert-level visual reasoning for intelligent agricultural pest analysis. The datasets and source code are available upon acceptance.
format Preprint
id arxiv_https___arxiv_org_abs_2605_06121
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Pest-Thinker: Learning to Think and Reason like Entomologists via Reinforcement Learning
Li, Xueheng
Wang, Yu
Hu, Tao
Huang, Ji
Cao, Ke
Yang, Qize
Li, Rui
Zhang, Jie
Xie, Chengjun
Computer Vision and Pattern Recognition
Pest-induced crop losses pose a major threat to global food security and sustainable agricultural development. While recent advances in Multimodal Large Language Models (MLLMs) have shown strong potential for visual understanding and smart agriculture, their direct application to pest recognition remains limited due to the domain's unique challenges such as high inter-species complexity, intra-species variability, and the scarcity of expert-annotated data. In this work, we introduce Pest-Thinker, a knowledge-driven reinforcement learning (RL) framework that enables MLLMs to reason over fine-grained pest morphology. We first construct two high-definition pest benchmarks, QFSD and AgriInsect, comprising diverse species and expert-annotated morphological traits. Leveraging these datasets, we synthesize Chain-of-Thought (CoT) reasoning trajectories to facilitate structured learning of pest-specific visual cues through Supervised Fine-Tuning (SFT). Subsequently, we employ Group Relative Policy Optimization (GRPO) with a novel feature reward that guides the model to focus on observable morphological evidence, assessed by an LLM-as-a-Judge strategy. Extensive experiments demonstrate that Pest-Thinker substantially improves both in-domain and out-of-domain morphological understanding, marking a step toward expert-level visual reasoning for intelligent agricultural pest analysis. The datasets and source code are available upon acceptance.
title Pest-Thinker: Learning to Think and Reason like Entomologists via Reinforcement Learning
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2605.06121