Investigation of population fluctuations and damage of lucerne beetle, Gonioctena fornicata (Bruggeman) (Coleoptera: Crysomelidae) in lucerne field

This study was conducted at Çukurova University Faculty of Agriculture Research and Application Farm in Adana between 2017 and 2018. The field trial (1 decare) was divided into the 8 equal parts of 100 m2, and the study followed a split plot design with 4 replications. The study examined the fluctuations of population of Lucerne beetle, Gonioctena fornicata (Bruggeman) (Coleoptera: Chrysomelidae), the factors affecting these fluctuations, and the yield loss. Infestation of G. fornicata was detected towards the end of March. Adults and larvae reached the highest population density towards the end of April, while their population declined during the first weeks of May. New generation adults were detected in May. It was found that the pest gave one generation per year. Especially the larvae of G. fornicata was found to feed extensively on the leaves, shoots, flowers, and seeds of plants, almost turning them into shrubs. In the untreated plots, there was a % 14.68 and % 14.57 loss in wet weight and dry weight respectively in 2017. There was a loss of % 26.27 and % 27.44 in wet weight and dry weight respectively in 2018. It was found that G. fornicata becomes the major pest influencing the plant development in period March - May.