# Population Dynamics and Biological Control of Leucoptera malifoliella in Apple Orchards in Hebei Province, China

## TL;DR

This study tracks the life cycle and control of a damaging apple orchard pest in China, showing how a natural wasp can help manage it sustainably.

## Contribution

The study provides new ecological data on Leucoptera malifoliella and validates Trichogramma dendrolimi as an effective biocontrol agent.

## Key findings

- The moth has five annual generations with peak damage in July–August and can disperse over 1.2 km.
- Trichogramma releases increased egg parasitism and reduced leaf damage by up to 49.6%.
- A rapid pupal sexing method was developed using genital opening morphology.

## Abstract

Environmentally benign pest control is critical for apple orchards. The pear-leaf blister moth has emerged as a major pest, particularly in low-chemical-input orchards, yet modern ecological data on this pest remain insufficient for effective management. From 2023 to 2025, we examined this moth in Hebei apple orchards, monitoring population phenology, developing a rapid pupal sexing method, quantifying adult flight capacity, and evaluating Trichogramma-mediated egg parasitism. The results showed five annual generations, with peak damage in July–August; adults flew over 1.2 km, enabling inter-orchard dispersal. Timely Trichogramma releases enhanced egg parasitism and reduced leaf damage. This study indicates that the moth may proliferate under climate warming and that Trichogramma application is an effective, eco-friendly tactic, laying the groundwork for precise, ecological pest management and reduced chemical use.

Leucoptera malifoliella has become a severe leaf-mining pest in Chinese apple orchards, especially under expanding organic and green cultivation practices, with effective management hindered by insufficient contemporary ecological data. To fill this gap, this 2023–2025 study conducted in Shijiazhuang, Hebei, combined field monitoring, morphological analysis, flight mill assays, and parasitoid release trials to clarify the moth’s phenology, develop rapid pupal sexing methods, quantify adult flight capacity, and assess Trichogramma dendrolimi biocontrol potential. The results showed five annual generations (overwintering as pupae), peak damage in July–August, and marked generational overlap. A reliable pupal sexing method was established via genital opening morphology. Adult flight peaked at 3 days post-emergence (max distance: 1.223 km), with no sexual dimorphism. Timely T. dendrolimi releases boosted parasitism rates, achieving 23.4–49.6% control efficacy during peak damage, with the parasitism rate positively correlated with efficacy. This study confirms the moth’s potential for generational increase under climate warming and medium-distance dispersal capacity, validating Trichogramma’s utility and laying a scientific foundation for precise, regionally coordinated ecological management.