Abundance Patterns of the Wheat Aphid, Sitobion avenae (F.) (Hemiptera: Aphididae) and Beneficial Insects in Wheat Field

Aphids were previously considered insignificant pests in wheat production areas in the Mediterranean region of Türkiye. However, in recent years, it has been observed that the honeydew they produce negatively affects plant development due to the increase in their population density. Although abiotic factors (primarily climate) and natural enemies may play an important role in the population development of aphids, their effects are not yet well understood, revealing this information may contribute to aphid’s pest management. The field study was conducted in 2022 and 2023 in the Soil and Water Research Station in Tarsus, Mersin province located in the eastern Mediterranean region of Türkiye. The wheat aphid Sitobion avenae (F.) (Hemiptera: Aphididae) and their predators and parasitoids were randomly sampled from leaves and ears and counted in the wheat field (cultivar Adana 99). A significant number of aphids and beneficial insects such as coccinellids, syrphids and mummified aphid individuals were collected from the ears. Although no significant relationship was observed between aphid population and climatic factors, relatively warmer (daily average temperature exceeded 20 °C) and drier (varying between 0.95 and 2.27 kg/m2) spring period may have shortened the vegetation period, leading to earlier plant maturation, thereby reducing aphid development and density in 2023. Despite the positive and strong relationships found between aphid and beneficial insect population densities (total) in both years, this was not sufficient to prevent aphid density when on average, there was slightly more than 20 aphids per leaf + ear, while the number of predators was approximately 2, consequently leading to formation of honeydew and sooty mold in 2022. Therefore, to avoid chemical control, first, habitat planning is recommended to promote earlier colonization of beneficial insects in wheat fields.