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The beet armyworm (Spodoptera exigua Hübner) is a polyphagous pest that causes significant economic losses and has a large host range that contains 170 plant species from 35 families in many countries. Feeding with leaves and fruits, S. exigua larvae cause plant growth to slow down and decrease, and significant crop losses. While various cultural, chemical, and biological methods are used for pest control, their effectiveness is low and the pest is still harmful to agricultural areas. In this study, we isolated two novel Spodoptera exigua multiple nucleopolyhedrovirus (SeMNPV) strains from S. exigua larval cadavers collected from provinces of Igdir and Sanliurfa in Turkey, and named them SeMNPV-I and SeMNPV-U, respectively. Light microscopy confirmed that both cadavers died from baculovirus infection. Scanning electron microscope observations showed that the polyhedral occlusion bodies (OBs) of the SeMNPV-I and SeMNPV-U were irregularly shaped. Transmission electron microscopy revealed that OBs of SeMNPV-I and SeMNPV-U were occupied with several virions in which multiple nucleocapsids were packaged by a viral envelope. Sequences and phylogenetic analyzes of polh, lef-8 and lef-9 revealed that these strains are closely related to baculoviruses isolates from Spodoptera species. Dose-response experiments with the isolates at 105-109 OBs/ml concentrations against S. exigua larvae led to varied mortality between 47% to 100%. The results of this study revealed that two local SeMNPV strains both have the potential to be used to control S. exigua. [ABSTRACT FROM AUTHOR]

In this study,Lymantria dispar disparlarvae, collected from three different localities in Turkey, were examined for the presence of inclusion bodies under phase contrast and electron microscopes. Inclusion bodies from infected larvae were subjected to polymerase chain reaction using the conserved primers forpolyhedrin(polh),late expression factor8 (lef-8) andlate expression factor9 (lef-9) genes. Sequence analysis confirmed that larvae collected from the three different localities contained multiple nucleopolyhedrosis viruses (MNPVs). These isolates were designated LdMNPV-T1, LdMNPV-T2 and LdMNPV-T3. Phylogenetic analyses of these isolates were performed using target genespolh,lef-8 andlef-9. Restriction endonuclease analysis of the three geographic isolates withEcoRI andPstI enzymes demonstrated some differences existed among the isolates. According to theEcoRI profile, the mean estimated size for the complete genome of each isolate (LdMNPV-T1, LdMNPV-T2 and LdMNPV-T3) was calculated to be approximately 170, 153 and 170 kb,respectively. Insecticidal activities of each isolate were tested onL. d. disparlarvae using four different viral concentrations between 103and 106 OBs/ml. Results showed that the mortalities for LdMNPV-T1, -T2 and -T3 ranged between 13–53%, 47–100% and 46–93%, respectively. The LC50and LC95values of LdMNPV-T2 were not significantly different from the respective corresponding values of the other two isolates. However, isolate LdMNPV-T2 killed larvae with a LC50value that was lower than the other two isolates. Our results suggested there are promising LdMNPV isolates in Turkey that can be used for microbial control ofL. d. disparlarvae. [ABSTRACT FROM AUTHOR]