NARDI FUNDULEA, ROMANIA ROMANIAN AGRICULTURAL RESEARCH, NO. 40, 2023 www.incda-fundulea.ro; doi.org/10.59665/rar4052 Print ISSN 1222-4227; Online ISSN 2067-5720 ________________________________________ Received 14 October 2022; accepted 4 November 2022. First Online: November, 2022. DII 2067-5720 RAR 2023-72 EVALUATION OF Beauveria bassiana AND Beauveria pseudobassiana AGAINST Tanymecus dilaticollis Ana-Cristina Fătu 1* , Emil Georgescu 2 , Maria Iamandei 1 , Marinela Mateescu 3 , Ioana Andra Vlad 4* 1 Research and Development Institute for Plant Protection, Ion Ionescu de la Brad Blvd, no. 8, District 1, Bucharest 2 National Agricultural Research and Development Institute Fundulea, 915200 Fundulea, Călărași County, Romania 3 National Institute of Research-Development for Machines and Installations Designed for Agriculture and Food Industry, Ion Ionescu de la Brad Blvd, no. 6, District 1, Bucharest 4 Department of Food Engineering, University of Oradea, Oradea, Bihor County, Romania * Corresponding authors. E-mail: cristina.fatu@icdpp.ro; ioana_andravlad@yahoo.co.uk ABSTRACT The grey corn weevil, Tanymecus (Episomecus) dilaticollis Gyll., (Curculionidae: Entiminae) is the most destructive pest of maize and sun flower crops in Romania. In this article we report result of evaluation of native strains of entomopathogenic fungus Beauveria bassiana (Bals.) Vuill. (Deuteromicotina: Hyphomycetes) and B. pseudobassiana Rehner et Humber against Tanymecus dilaticollis (Curculionidae: Entiminae) both in laboratory and field. In laboratory assay, two different strains of B. bassiana and one strain of B. pseudobassiana (BbLy) were applied on insects as 1×10 8 conidia/ml aqueous suspensions. The pure ATCC 74040 commercial strain of B. bassiana and the commercial mycoinsecticide based on this strain (Naturalis) were included in the laboratory assay for comparison. Adult mortalities were recorded daily, 14 days post-exposure. All the fungal strains have been shown to be pathogenic to T. dilaticollis. The B. bassiana strain (BbTd1) and the B. pseudobassiana strain (BbLy) were effective against adults of T. dilaticollis and comparable in percentage of mycosis and virulence to the B. bassiana strain ATCC 74040. The commercial product Naturalis was superior to the tested fungal strains killing the insects within a day. In the field, the strains BbTd1 and BbLy applied as conidia multiplied on barley grains (1×10 9 /g d.w) in the soil did not affect the T. dilaticollis density in maize crop. Keywords: Beauveria bassiana, B. pseudobassiana, Tanymecus dilaticollis, maize. INTRODUCTION aize or corn (Zea mays) is an important commercial crop in Romania, in the last year being the largest cultivated area and with the biggest production in the EU (Brodeală et al., 2022). Maize leaf weevil, T. (Episomecus) dilaticollis Gyll., (Curculionidae: Entiminae) is a major pest of maize in south, south-east and east of Romania, where 1 million ha of maize are attacked every year to varying degrees of intensity (Georgescu et al., 2018; Georgescu et al., 2021a, b). In Europe T. dilaticollis was also recorded in Turkey, Bulgaria, Greece, Serbia, Croatia, Hungary, Slovakia, Ukraine, Moldavia, Austria (Roşca and Istrate, 2009; Georgescu et al., 2014; Schuh et al., 2015; Yunakov et al., 2018) but the most severe economic damages are to maize and sunflower crops, in Romania, Bulgaria, and Serbia. Evidence from the literature shows that maize is attacked preferentially in all locations, followed by sunflower and wheat. At maize, the pest commonly feed on young plants at ground level, cutting of the stem and often causing the mass destruction of culture or consuming only the lateral parts of the leaf blade and delaying the vegetative growth and significantly decreasing the yield. The management of the grey corn weevil, T. dilaticollis in Romania has become more and more difficult on the one hand because of the restrictions for pesticides and the lack of alternatives to the methods of chemical control and on the other hand because of the climatic conditions increasingly favorable for the multiplication of this pest. Further M