Population dynamics of noctuid moths and damage forecasting in sugar beet

Abstract

Abstract The most damaging Noctuidae pests in sugar beets in Croatia are classified into two groups based on the injuries that their larvae produce: the cutting species (Agrotis ipsilon and Agrotis segetum) and the surface‐feeding species (Mamestra brassicae, Lacanobia oleracea and Autographa gamma). The flight activity of male moths was detected and monitored using traps baited with sex pheromone. The study aimed to determine the population dynamics of noctuid pests in sugar beet crops and to propose damage forecasts and thresholds based on male moths capture in pheromone traps in specific weather conditions. A strong positive correlation between captured male moths in pheromone traps and the level of damage to sugar beet crops was established. The population densities were extremely affected by the weather conditions that prevailed in the sugar beet growing period. If the weather conditions are not optimal, the population of the second generation of moths and larvae will be smaller, and the level of damage to plants will decrease accordingly. Thus, intensive monitoring of noctuid male moth flights and weather conditions in the sugar beet growing season enabled forecasting of future damage to a larger area, although visual inspections are necessary to plan insecticide applications.