Objective Assessment of the Damage Caused by <i>Oulema melanopus</i> in Winter Wheat with Intensive Cultivation Technology Under Field Conditions

Abstract

Oulema melanopus L., 1758 (Coleoptera: Chrysomelidae) is one of the significant pests affecting cereal crops in Europe. Its damage is evident in the destruction of leaves during the spring growing season, leading to substantial impacts on both the quantity and quality of the harvested yields. The study aimed to evaluate the extent of leaf surface damage, changes in chlorophyll content caused by this pest, and the subsequent effects on yield quality. To achieve this, two experimental parcels were established, each subjected to different pesticide treatments during the spring vegetation cycle, but notably, with the difference that one parcel did not receive insecticide applications. The phytosanitary status, yield quantity, and quality parameters of thes parcels were compared. Chlorophyll content in damaged and undamaged plants was monitored in vivo using SPAD measurements, while the extent of leaf surface damage was assessed through image analysis using GIMP software 2.10.32. Harvested grain underwent milling and baking analysis, with milling and baking-quality indicators measured using a NIR grain analyzer. The results revealed that omitting springtime insecticide treatments during the emergence of O. melanopus led to significant reductions in leaf area and yield quality. In untreated parcels, leaf decession followed linear progression, reaching 35–40% within 20 days. This damage correlated with the decline in SPAD index values, indicating a 40–50% reduction in chlorophyll content dependent photosynthetic activity. Consequently, there were substantial decreases in milling and baking qualities, including nearly 30% reductional protein-content indicators and 10% in the Hagberg falling number. In summary, our large-scale field experiments demonstrated that persistent O. melanopus damage in wheat fields significantly reduced both the quantity and quality of yields, particularly protein content. These facts underscore the economic importance of timely pest-control measures to mitigate damage and preserve crop value.

Keywords

• image analysis
• in-crop treatment
• cereal leaf beetle
• leaf damage
• NIR
• nutrient content changing