Determination of species belonging to the curcolonidae family and the population density and damage of hypera postica gyllenhal in alfalfa fields in Siirt province

The study was carried out in the alfalfa fields of Siirt University Kezer campus in Siirt province in the years 2022 - 2023 in order to determine the damage status and intensity of the harmful species of Curculionidae family and especially the important species, the alfalfa weevil Hypera postica (Gyllenhal, 1813). In order to identify the species and to determine the density and damage status of the important species, observations and inspections were carried out at intervals of 1-2 weeks between March and November and once a month between December and February. Visual control, sweept neet and frame method were used in the study. As a result of the study, 9 species belonging to the family Curculionidae (Coleoptera) were identified. These are; Hypera postica (Gyllenhal, 1813) (37,30%), Sitona humeralis (Stephens, 1831) (18,30%), Sitona macularius (Marsham 1802) (9,75%), Sitona lineatus (Linnaeus, 1758) (9,58%), Aspidapion radiolus (Marsham, 1802) (7,42%), Eutrichapion arrogans (6,13%), Sitona lividipes (Fahraeus, 1840) (4,92%), Sitona concavirostris (Hochhuth, 1851) (4,83%), Hypera nigrirostris (Fabricius, 1775) (1,72%). The most abundant species was alfalfa weevil, Hypera postica. As a result of the study, it was determined that the alfalfa weevil, Hypera postica caused economically important damages in the alfalfa fields in the study area. This damage was observed in the form of defeats on the leaves, shoots and top buds of the plants. This damage intensified until the first harvest of alfalfa and damage symptoms were detected in 70-80% of the plants. Fertilization and irrigation practices or the rapid development of plants in the spring rainy years have been found to reduce the amount of damage. In the examinations carried out on the pest, it was determined that adult individuals started to be seen from March and the most intense periods of the main pest were April and May. In addition, it was observed that estivation period was recorded between June- October. Moreover small density adults of Alfalfa weevil was determined in October - December and the overwintering adult stage. This research contributes to our understanding of the density and damage status of Curculionidae species in the region and constitutes an important starting point for understanding future pest status and developing control strategies.