Population dynamics and temporal niche of Grapholita molesta and Cydia pomonella in walnut ogchards in different habitats

Grapholita molesta and Cydia pomonella are two important fruit-boring pests in orchards. To clarify the occurrence regularity and population dynamics of these pests in different planting patterns, we investigated walnut orchards in Southern Xinjiang, where intercropping with wheat, corn, and peach trees is common, using sex pheromone traps and sugar-vinegar trapping methods. The results showed that G. molesta had four full generations and an incomplete generation per year, while C. pomonella had three full generations and an incomplete generation per year. The mature larvae of G. molesta and C. pomonella primarily overwintered in insect-proof cloth. From 2022 to 2023, the overwintering generation of C. pomonella had a longer adult stage, and the occurrence time of adults from the first three generations and the incomplete first generation was more consistent. The peak period of adults from the first to fourth generations of G. molesta in 2022 was about 14 days earlier than in 2023, but the number of adults trapped in 2023 was significantly higher than that in 2022. The variation trend of the number of moths trapped by adults was consistent across each planting pattern. The walnut-wheat-corn orchard attracted the largest number of C. pomonella adults, with 2345 individuals, followed by the walnut-wheat orchard, walnut-peach orchard, and finally monoculture walnut. In 2023, the highest number of adult G. molesta moths was found in the walnut-peach orchard planting mode, which was 6464, followed by walnut-wheat-corn with a count of 4373. This study clarifies the overwintering sites, population dynamics, and temporal niche of the G. molesta and C. pomonella in walnut orchards with different planting patterns. The results provide an important theoretical basis for ecological regulation and the scientific and reasonable formulation of green prevention and control measures.