فهرست نشریات علمی دسترسی آزاد ایران

The English grain aphid, Sitobion avenae (Fabricius), is a major sucking pest of wheat, causing direct yield loss and acting as a vector for plant viruses, thereby threatening both grain quantity and quality. Comprehensive field data on its population ecology in Middle Eastern agroecosystems, particularly Iraq, remains scarce. This study investigated the relative abundance, seasonal dynamics, and key influencing factors of S. avenae in wheat fields across Najaf province, Iraq, during the 2022-2023 growing season. Weekly sampling from five representative fields was conducted, with aphids collected from tillers and identified morphologically. Population density (individuals per tiller) was quantified and analyzed against spatiotemporal and climatic variables. Results revealed a distinct unimodal population trend, with initial colonization in early March and a peak abundance (52% of the seasonal total) occurring in mid-March, coinciding with the wheat ear formation stage. A sharp decline ensued from late March, with populations falling to minimal levels (13% of total) by May. Significant spatial variation was observed, with the highest mean density recorded at Al-Mishkhab (924 aphids/plant) and the lowest at Al-Haideria (466 aphids/plant). The population composition was consistently dominated by apterous viviparous females. Statistical analysis identified strong correlations between aphid density and climatic factors: a significant negative correlation with mean temperature (r = -0.943) and a significant positive correlation with relative humidity (r = 0.997). The population collapse in late spring was attributed to the combined effects of host plant maturation and abiotic stress from rising temperatures and aridity.