Determination of population development and damage status of the nut weevil (Curculio nucum L.) (Col .: Curculionidae) and the green shield bug (Palomena prasina L.) (Hemiptera: Pentatomidae) in Sakarya province

Hazelnut (Corylus avellana L.) is an important plant as utilized in food, agriculture, health and industrial fields. Turkey ranks of the first in the world in base on hazelnut production and number of trees. In the western Black Sea region, Sakarya is the most important province of hazelnut production. Nut weevil Curculio nucum L. (Coleoptera: Curculionidae) and Green shield bug Palomena prasina L. (Hemiptera: Pentatomidae), which causes serious loss in hazelnut fruits, are the main pests in Sakarya province. In this study, population developments and damage rages of C. nucum and P. prasina were determined in four hazelnut orchards in Sakarya province in 2017-2018. In 2017 in Sakarya province, Nut weevil adults in the hazelnut orchards were first time determined on 16 April. Nut weevil adults were determined in these orchards for eight weeks (16 April-11 June). Green shield bug adults were first time determined in April 30, while the first nymphs were observed in the same date. The highest number of nymphs reached on June 4 (44 / 10 units). The number of adults of Green shield bug reached the highest number (33/10 units) on 3 September and was not determined after 24 September. In this study, the nymphs of Green shield bugs were seen from late April to mid-September. In 2018 P. prasina nymphs were determined for the first time on 6 May, while the first adults were observed on 22 April. C. nucum was not detected in the orchards in 2018. Nymphs of Green shield bugs were found feeding on weed species of Nerve grass, sugar dye, nettle, shepherd's bag, euphorbia, hibiscus, efelek, crowbar, wild mustard, blackberry and field ivy. Temperature was found to be an important factor in two pest species. Perforated fruit damage ratio caused by Nut weevil was 0.77-1.77% in 2017 and was 0.00-0.23% in 2018, empty interior in 2017 was 8.15-11.00% and in 2018 in the range of 7.36-10.00%, while the Green shield bugs damaged in 2017, amorphous interior was between 0.69-1.38%, and was 1.23-1.92% in 2018, stained internal damage was determined between 0.54-1.08% in 2017, and 0.69-1.31% in 2018, and the common damage of the two species, yellowpecker and blackcurrant damage was 1.85-3.15%, 13.46-21.92 respectively.