Abstract—A total of 55 Spodoptera litura larvae collected from marigold fields were reared on an artificial diet in the laboratory and determined for the presence of covert baculovirus infections. Polymerase Chain Reaction (PCR) analysis by using primers specific to the highly conserved baculovirus genes, granulin and polyhedrin, combined with transmission electron microscopy confirmed the presence of granulovirus (GV) and nucleopolyhedrovirus (NPV). Eight out of 55 larvae (14.5%) were PCR positive for S. litura granulovirus (SpltGV), while one larva (1.8%) was PCR positive for S. litura multicapsid nucleopolyhedrovirus (SpltNPV). Electron microscopic observations of the PCR-positive samples revealed the presence of a single baculovirus infection, either GV or NPV. The identification of SpltGV and SpltNPV in the field-collected S. litura larvae indicated that the viruses were found to be present in this population. The findings in the present study suggest that the persistent baculoviruses in the field populations of S. litura may be activated by some stressors rather than by exposure to another baculovirus. It can be speculated that such covert baculovirus infections may lead to the decline in insect populations and also can lead to a collapse of laboratory-reared insect colonies for in vivo production of bioinsecticides.
 

Index Terms—Spodoptera litura, nucleopolyhedrovirus, granulovirus, PCR, electron microscopy

Cite: Sudawan Chaeychomsri, Win Chaeychomsri, and Jindawan Siruntawineti, "Evidence for Covert Baculovirus Infections in the Field-Collected Spodoptera litura Larvae," Journal of Advanced Agricultural Technologies, Vol. 7, No. 2, pp. 20-27, December 2020. Doi: 10.18178/joaat.7.2.20-27

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