Possible use of some entomopatogenic fungal isolates in the control of potato tuber moth [(Phthorimaea operculella) (Zeller) (Lepidoptera: Gelechiidae)]

This study was carried out to determine the effectiveness of local entomopathogenic fungus isolates (Beauveria bassiana (Balsamo-Crivelli Voillemin) and Metarhirzium brunneum (Petch)) and commercial preparation (Nostalgist BL) against potato moth [(Phthorimaea operculella Zeller (Lepidoptera: Gelechiidae)] eggs and 3rd instar larvae under laboratory conditions. Three different methods were used: Spraying method of entomopathogenic fungi on tubers and leaves to control 3rd instar larvae of potato moth and ovicidal effect study on it's egg stage. GOPT-DYYLD, GOPT-228, GOPT-562 and ORP-13 entomopathogenic fungus isolates produced in the laboratory were prepared at 1x105, 1x106, 1x107 and 1x108 conidia/ml spore concentrations and by using commercial preparation (Nostalgist BL) dose-mortality trials were performed. According to the results of the analysis, in the tuber spraying method, the 1x108 spores/ml concentration of the local isolates and Nostalgist BL had below 50% percent mortality rate on the 14th day. According to the percent mortality data on the 5th day in leaf spray trials, mortality rates caused by GOPT-DYYLD, GOPT-228, GOPT-562 and ORP-13 were %61.0±2.76, %67.0±2.13, %69.0±1.00 ve %75.0±1.66 respectively. At the end of 9th day, all the local isolates had over %95 mortality rate. On the other hand, the commercial preparation caused %37.0±2.13, %64.5±5.51 at the end of 5th and 9th day respectively. While ORP-13 was the most effective isolate in ovicidal effect trials, ovicidal effects of GOPT-562, GOPT-228, GOPT-DYYLD and Nostalgist BL were %47.5±1.34, %28.0±2.49, %19.0±2.08, and %11.0±0.6 respectively. The rate of hatched lavae reaching adult stages in ORP-13, GOPT-562, GOPT-228, GOPT-DYYLD and Nostalgist BL aplications were %73.0±1.0, %61.9±2.0, %47.2±2.45, %34.3±2.59 ve %14.7±1.43 respectively. The LT50 of ORP-13, GOPT-228, GOPT-562, GOPT-DYYLD isolets at 1x108 were 2.18(1.86-2.50)/day, 2.82(2.46-3.19)/day, 2.86(2.5-3.1)/day and 3.09(2.75-3.44)/day respectively. It was determined that Nostalgist BL had a lower killing ability than local isolates with a LT50 value of 6.74(5.7-8.1)/day. As a result of this study, it has been seen that entomopathogenic fungi ORP-13 ve GOPT-228 local isolates have a potential to control the larva in leaf spraying method and egg stages of the potato moth. It is thought that the more detailed studies should be carried out under field conditions.