Determination of the insecticidal effect of some entomopatogenic fungi isolates on colarado potato beetle[leptinotarsa decemlineata (SAY) (coleoptera: chrysomelidae)]in in-vivo and in-vitro conditions

This study was carried out to determine the effectiveness of 14 entomopathogenic fungi isolates (GOPT-123, GOPT-158, GOPT-228, GOPT-247, GOPT-258, GOPT-259, GOPT-283, GOPT-321, GOPT-331, GOPT-375, GOPT-PB-2, GOPT-DYYLD, GOPT-5-2, GOPT-228-1), consisting of Beauveria bassiana and Metarhizium anisopliae species isolated from soil samples from different agricultural areas in Tokat, on adult, 3rd larvae stage and egg stages of potato beetle (Leptinotarsa decemlineata)which is an important pest of the potato plant and causes high yield loss. The studies consisted of 2 parts as laboratory and greenhouse. Different application methods were used in laboratory studies including insect dipping,spraying, injection, and food spraying, ovicidal effect tests and antifidant effect tests. In single-dose screening trials, the entomopathogenic fungi isolates were tested at a dose of 1x108 conidiaml-1. Indose-mortality trials isolates GOPT-228 and GOPT-375, which were found to be more effective than other isolates, tested at 1x103, 1x105, 1x107, 1x108 and 1x109 conidia ml-1 concentrations. Based on the results of laboratory studies, greenhouse tests were carried out with GOPT-228 isolate at a dose of 1x108 conidia ml-1 concentration. The effects of the application methods used in the study showed variations on the basis of isolates. It was observed that adult insects were more resistant to the entomopathogenic fungi isolates than the larvae in both single-dose screening tests and dose-mortality tests. While the increase in mortality rates in adults was significantly higher than the control after the 7-day incubation period, this occurred after the three-day incubation period in larvae and some isolates caused 90% or more death on the 5th day. In ovicidal effect tests, the control egg opening rate reached 100% on the third day, while the egg hatching rate decreased to 50% and below in the entomopathogenic fungi applications after 3 day postinoculation at the dose of 1x107 conidia ml-1. At the highest spore concentration (1x109 conidia ml-1), the egg hatching rate was 3.8%. The efficiency of the B. bassiana isolate we used in the greenhouse experiments was much lower than in the in vitro tests, 40% of the 3rd stage larvae and 12% of the adult insects died. It has been observed that our entomopathogenic fungi applications have an antifidant effect. As a result of the studies, it has been observed that the entomopathogenic fungi have the potential to be used in biological control of the potato beetle, and it is thought that further detailed studies should be carried out under the field conditions.