Population dynamics of Dalbulus maidis in maize: effects of time of day and sampling technique

Abstract

Understanding the population dynamics of the corn leafhopper Dalbulus maidis (Hemiptera: Cicadellidae), the vector of pathogens responsible for maize stunt diseases, is essential for establishing an integrated management program for this pest. Defining an easy, fast, accurate and representative sampling method for D. maidis would allow both population estimation for monitoring and control decision making. Therefore, we evaluated three sampling methods (yellow sticky traps, direct whorl counts and sweep nets), time of day and variations in climatic factors on D. maidis captures. For this purpose, D. maidis populations in field maize plants at phenological stages V3 to V9 were monitored from September 2022 to May 2024. The numbers of leafhoppers captured by the three sampling methods were correlated with climatic variations during this period. The sampling method affected the number of individuals collected. During the sampling period, 11,520 D. maidis individuals were captured. Among these, yellow sticky traps recorded 957 individuals. Direct whorl counts registered 2,999 individuals in the morning and 2,723 in the afternoon. Sweep net sampling recorded 2,415 individuals collected in the morning and 2,426 in the afternoon. Direct whorl observations showed positive correlations with temperature, relative humidity and accumulated rainfall. The results show that the active direct whorl counting method is the most efficient for monitoring and observing population variations of the corn leafhopper, outperforming sweep nets and yellow sticky traps. This study highlights the importance of adjusting monitoring strategies for more accurate population estimates and control recommendations in integrated management programs for the corn leafhopper D. maidis.