Occurrence and characterization of two betabaculoviruses isolated from Tuta absoluta (Lepidoptera: Gelechiidae) in Colombia

Abstract: Tuta absoluta is a devastating invasive pest of tomato plants, causing losses of up to 100%. The high use of chemical pesticides for its control, the risk of contamination and the generation of resistance make it necessary to find control alternatives. An interesting tool is the use of entomopathogenic viruses of Baculoviridae family, which are insect-specific and do not generate environmental impacts. Despite its high potential, its use on T. absoluta larvae has been poorly studied. In this work, two betabaculoviruses (granuloviruses) were isolated from 1,186 T. absoluta larvae sampled in tomato crops in Colombia (virus occurrence: 0.3%), which were coded as VG012 and VG013 and morphological, biological and molecularly characterized. The granules of these isolates showed ovoid shape with an approximate size of 514 nm x 250 nm, with a single virion enclosing one nucleocapsid. Restriction endonuclease analysis showed the same pattern compared to Phthorimaea operculella granulovirus but different compared to the granulovirus isolated from Tecia solanivora, although they were classified in the same monophyletic group. The estimated genome size was 120 kbp. The mean lethal concentration (LC50) of viral isolates was 1.6 x 104 and 1.9 x 104 OBs/ml for VG012 and VG013, respectively, and LC90 of 7.0 x 106 and 8.5 x 106 OBs/ml, with an average productivity of 3.0 x 1010 OBs per gram of tissue.