Thysanoptera Fauna Associated with Peanut Crops in Córdoba, Argentina

Abstract

Argentina is one of the world's leading exporters of peanuts (Arachis hypogaea L.), and the province of Córdoba accounts for approximately 85% of the national peanut-producing area. Thrips (Thysanoptera: Thripidae) pose a potential threat to peanut crops, causing direct damage through feeding and indirect damage as orthotospovirus vectors. In order to determine the thysanoptera fauna associated with peanut crops in Córdoba, a 3-year prospective study was carried out in different peanut-producing regions of the province. Insects were collected from peanut plants over three consecutive growing seasons (2019-20, 2020-21, and 2021-22). Each growing season involved evaluating six peanut fields (three located in the northern peanut-growing area and three in the southern area of Córdoba), totaling 18 commercial peanut fields over the three years of sampling. In each field, a W-shaped sampling pattern was used, with 20 experimental units (EU) per field. During the 2021-22 growing season, 10 EU per field were evaluated. Each EU consisted of 10 consecutive plants in a row, and the selected plants were monitored throughout the growing season. Two sampling methods were used to collect thrips from foliage and flowers: a) One beat per plant on the upper third (avoiding flowers), with the insects collected on a white tray moistened with 70% alcohol (28 cm long, 19 cm wide, 5 cm deep), and b) During the active flower production period, before beating the plant, 10 flowers were extracted (one per plant). Depending on the field and growing season, sampling was conducted every 10-20 days, covering the period between phenological stages V4 and R5. Collected specimens were placed in tubes with 70% ethanol for later counting and identification. Thrips were mounted on slides in Hoyer's medium and examined under a confocal microscope at 20X magnification. Specific identification keys for Thysanoptera were used to determine the species or genus. A total of 44,811 specimens were identified to genus or species level. This study represents a significant advancement in understanding the thrips fauna in peanut crops, a crop of great regional and national importance. The analysis will contribute to studies on taxonomy, biodiversity, ecological and evolutionary processes, viral disease epidemiology, and the design of tools and strategies for integrated pest management, among other areas. Some of the material was preserved on semi-permanent microscopic slides and in 70% ethanol. The entomological material was deposited at the Instituto de Patología Vegetal of the Instituto Nacional de Tecnología Agropecuaria (IPAVE-INTA, Córdoba, Argentina), and at the Instituto de Biología de la Altura of the Universidad Nacional de Jujuy (INBIAL-UNJu), Jujuy, Argentina.