Notes on biology of alfalfa weevil, Sitona humeralis Stephens, 1831 (Coleoptera: Curculionidae) in alfalfa fields of Iğdır/Turkey province

The adults of Sitona humeralis Stephens, 1831 (Coleoptera: Curculionidae) cause serious damages by feeding on the leaf and shoot parts of the clover plant (Medicago sativa L.), and the larvae on the capillary root and nodocytes. This article was carried out in the clover fields and laboratory in Igdir province in 2019-2020 in order to determine the morphology and biology of S. humeralis. In the studies, in order to determine the egg stages of S. humeralis, a 1-4 cm deep topsoil containing clover plants in 5 different parts of the field, a soil plant with a depth of 20 cm and a surface area of 20 x 20 cm to determine the larva, pupa and adult stages were taken with the root with a shovel and examined in the laboratory. As a result of the studies, it was determined that S. humeralis overwinters in egg, larva and adult stages. Female insects lay some of their eggs in October and November in the autumn, pause their egg laying with the decrease of the air temperature, and continue to lay eggs until the end of March and early May as the weather gets warmer. The eggs were laid on the soil surface in the root zone of the clover plant. While the larvae emerging from the eggs laid in early October are active in the soil until the beginning of November, they spend the winter without feeding until the end of March to the beginning of April as the weather gets colder, and the larvae that come out of the eggs laid in the late April-early May and enter the pupa stage in the late May-June. Natural deaths start in April-May in adults who spend the winter, a new generation of adults start to emerge from June and the emergence continues until mid-July. From August to mid-October, the new generation adults spend their rest in the soil around the plant roots. In the studies, it was understood that S. humeralis produce a generation a year.