Occurrence and seasonal abundance of Thrips tabaci Lindeman on onion in the north transition zone of Karnataka, India

Abstract

Studies were conducted in four consecutive seasons from kharif, 2022 to rabi, 2023, on onion crop to understand the thrips. Thrips tabaci Linderman incidence. The identity of the species was confirmed through morphological characteristics as well as sequence amplified product of Cytochrome c oxidase subunit I (COI) gene (GenBank No. PP838743). The phylogenetic analysis revealed that the T. tabaci population is closely related to the sequence of MZ882441 and MT991561 from China and New Delhi, India, respectively. Incidence in the Kharif season has experienced minimal thrips infestation compared to the Rabi season, where severe infestation was noted. The peak thrips population occurred in the 6th Standard Meteorological Week (SMW) of 2022 and 2023, highlighting the role of weather in thrips population dynamics. Correlation analysis indicated that maximum temperature exhibited a significant positive correlation, while relative humidity showed a significant negative correlation. Additionally, rainfall was found to have a cleansing effect on thrips populations, resulting in lower incidences during the Kharif season. However, during the Rabi season, the coincidence of higher temperatures with low relative humidity contributed to the proliferation of thrips, making them a significant threat to bulb onion production. This study provides a comprehensive information on the occurrence, species confirmation, nature of damage, seasonal incidence and associated weather parameters with T. tabaci in onion crops.