Identification of a new nucleopolyhedrovirus isolated from the olive leaf moth, Palpita vitrealis, from two locations in Egypt

Abstract

The olive leaf moth (jasmine moth), Palpita vitrealis (Lepidoptera: Crambidae), is an important insect pest of olives in several Mediterranean countries. A new alphabaculovirus was isolated from diseased larvae of P. vitrealis in Egypt, first in Giza in spring 2005 and again in Marsa Matrouh in 2019.The larvae exhibited typical symptoms of a baculovirus infection. Light and scanning electron microscopy studies revealed polyhedral occlusion bodies. Transmission electron microscopy of ultrathin sections of purified OBs revealed virions with multiple embedded nucleocapsids. The identity of the two virus isolates was confirmed by sequencing the partial polyhedrin and lef-8 genes, and sequence comparison suggested a relationship to group I alphabaculoviruses. Therefore, this virus was termed Palpita vitrealis nucleopolyhedrovirus (PaviNPV). Whole genome sequencing of the PaviNPV isolate from Giza (Gz05) revealed a genome of 117,533 bp, 131 open reading frames (ORFs) and four homologous repeat (hr) regions. Phylogenetic reconstruction and genetic distance analyses using 38 core genes indicated that PaviNPV should be considered to belong to a novel species within the genus Alphabaculovirus. In bioassays, PaviNPV was highly virulent against second-instar larvae of P. vitrealis. The study reports a novel baculovirus that might have potential as a biological control agent of the olive leaf moth.

Keywords: Alphabaculovirus; Baculoviridae; Electron microscopy; Genome sequencing; Jasmine moth; Leaf dipping bioassay; Olive pests; Phylogeny.