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The cotton bollworm (CBW) poses a significant risk to maize crops worldwide. This study investigated whether hyperspectral satellites offer an accurate evaluation method for monitoring maize ear damage caused by CBW larvae. The study analyzed the records of maize ear damage for four maize fields in Southeast Hungary, Csongrád-Csanád County, in 2021. The performance of Sentinel-2 bands, PRISMA bands, and synthesized Sentinel-2 bands was compared using linear regression, partial least squares regression (PLSR), and two-band vegetation index (TBVI) methods. The best newly developed indices derived from the TBVI method were compared with existing vegetation indices. In mid-early grain maize fields, narrow bands of PRISMA generally performed better than wide bands, unlike in sweet maize fields, where the Sentinel-2 bands performed better. In grain maize fields, the best index was the normalized difference of λA = 571 and λB = 2276 (R2 = 0.33–0.54, RMSE 0.06–0.05), while in sweet maize fields, the best-performing index was the normalized difference of green (B03) and blue (B02) Sentinel-2 bands (R2 = 0.54–0.72, RMSE 0.02). The findings demonstrate the advantages and constraints of remote sensing for plant protection and pest monitoring. [ABSTRACT FROM AUTHOR]

The western corn rootworm [Diabrotica virgifera virgifera LeConte (WCR)] is an important pest of maize in USA and Canada, and Europe. Its primary damage is due to larvae feeding on maize roots; yield and quality also occur due to WCR adult silk clipping and interference with ear pollination. WCR economic thresholds for sweet maize hybrids are not available. We aimed to determine whether silk feeding and artificial silk cut in various sweet maize hybrids could be correlated to potential WCR adult levels. The two-year field study was conducted in Hungary using seven different sweet maize hybrids. The silk was cut back to 0, 1, and 2 cm, measured, and compared daily to the silk length of uncut control plants. As a separate treatment, WCR adults were placed in cages on the uncut Suregold hybrid to assess silk clipping activity. After harvest, cob weights were measured, and fertility levels were assessed. Results showed that sweet maize hybrids can tolerate some silk cutting (simulating high WCR density and silk feeding). The action threshold for these hybrids is much higher than that for inbred lines or commercial grain maize, in line with prior studies for the Suregold hybrid (8-12 adults per year). Meteorological conditions and multiple pest presence, phytosanitary regulations, and IPM considerations may help finetune adult WCR control intervention decisions. [ABSTRACT FROM AUTHOR]

The cotton bollworm (Helicoverpa armigera, Lepidoptera: Noctuidae) poses significant risks to maize. Changes in the maize plant, such as its phenology, influence the short-distance movement and oviposition of cotton bollworm adults and, thus, the distribution of the subsequent larval damage. We aim to provide an overview of future approaches to the surveillance of maize ear damage by cotton bollworm larvae based on remote sensing. We focus on finding a near-optimal combination of Landsat 8 or Sentinel-2 spectral bands, vegetation indices, and maize phenology to achieve the best predictions. The study areas were 21 sweet and grain maze fields in Hungary in 2017, 2020, and 2021. Correlations among the percentage of damage and the time series of satellite images were explored. Based on our results, Sentinel-2 satellite imagery is suggested for damage surveillance, as 82% of all the extremes of the correlation coefficients were stronger, and this satellite provided 20–64% more cloud-free images. We identified that the maturity groups of maize are an essential factor in cotton bollworm surveillance. No correlations were found before canopy closure (BBCH 18). Visible bands were the most suitable for damage surveillance in mid–late grain maize (|rmedian| = 0.49–0.51), while the SWIR bands, NDWI, NDVI, and PSRI were suitable in mid–late grain maize fields (|rmedian| = 0.25–0.49) and sweet maize fields (|rmedian| = 0.24–0.41). Our findings aim to support prediction tools for cotton bollworm damage, providing information for the pest management decisions of advisors and farmers. [ABSTRACT FROM AUTHOR]