Effectiveness of insecticidal and fungicidal seed treatments in reducing hooded crow (Corvus cornix) predation on sunflower and maize seeds under field conditions

The present study evaluated the effectiveness of two insecticidal seed treatments—ethoprophos (Meritan ^® 10% GR) and oxamyl (Viva ^® 24% SL)—and a fungicide, tolclofos-methyl + thiram (Rizolex-T ^® 50% WP), as seed treatments, alone or in combination, in reducing seed predation caused by the hooded crow ( Corvus cornix ) on sunflower ( Helianthus annuus L.) and maize ( Zea mays L.) during the summer season of 2024. The experiment was conducted at the Experimental Farm of Nubaria Agricultural Research Station, Behaira Governorate, Egypt, using a Randomized Complete Block Design (RCBD) with three replicates. Sunflower and maize seeds were treated before planting with eight treatments, including ethoprophos, oxamyl, tolclofos-methyl + thiram, and various mixtures of these compounds at full and half doses, in addition to an untreated control. The percentage of empty holes caused by crow feeding was recorded after planting until complete germination, and reduction percentages were calculated relative to the control treatment. Meritan ^® (2 g/kg) and the Viva ^® + Rizolex-T ^® (2 ml+ 3 g/kg) combination provided the highest level of protection, reducing empty holes by up to 81.21% in sunflower and 78.89% in maize. Viva ^® alone or in mixtures provided moderate deterrence, whereas Rizolex-T ^® alone showed minimal effect in reducing hooded crow feeding activity. These results indicate that insecticidal seed treatments, particularly organophosphate and carbamate chemicals, can significantly reduce early-season seed loss caused by hooded crows, whereas fungicidal treatment alone is ineffective in reducing seed predation by the hooded crow. This effect may be associated with post-ingestive effects reported in previous studies. Thus, the study supports the beneficial effects of chemical seed treatments in protecting sunflower and maize throughout the susceptible seed-to-seedling period.