Genome Analysis of a Novel Clade b Betabaculovirus Isolated from the Legume Pest Matsumuraeses phaseoli (Lepidoptera: Tortricidae).

Matsumuraeses phaseoli is a Lepidopteran pest that primarily feeds on numerous species of cultivated legumes, such as Glycine and Phaseolus. It is widely distributed in northeast Asia. A novel granulovirus, designated as Matsumuraeses phaseoli granulovirus (MaphGV), was isolated from pathogenic M. phaseoli larvae that dwell in rolled leaves of Astragalus membranaceus, a Chinese medicinal herb. In this study, using next-generation sequencing, we report the complete genome of MaphGV. MaphGV genome comprises a double-stranded DNA of 116,875 bp, with 37.18% GC content. It has 128 hypothetical open reading frames (ORFs). Among them, 38 are baculovirus core genes, 18 are lepidopteran baculovirus conserved genes, and 5 are unique to Baculoviridae. MaphGV has one baculovirus repeat ORF (bro) and three inhibitors of apoptosis proteins (iap), including a newfound iap-6. We found two atypical baculoviral homologous regions (hrs) and four direct repeats (drs) in the MaphGV genome. Based on phylogenetic analysis, MaphGV belongs to Clade b of Betabaculovirus and is closely related to Cydia pomonellagranulovirus (CpGV) and Cryptophlebia leucotretagranulovirus (CrleGV). This novel baculovirus discovery and sequencing are invaluable in understanding the evolution of baculovirus and MaphGV may be a potential biocontrol agent against the bean ravaging pest.

Development of a viral biopesticide for the control of the Guatemala potato tuber moth Tecia solanivora.

The Guatemala potato tuber moth Tecia solanivora (Povolny) (Lep. Gelechiidae) is an invasive species from Mesoamerica that has considerably extended its distribution area in recent decades. While this species is considered to be a major potato pest in Venezuela, Colombia, and Ecuador, currently no specific control methods are available for farmers. To address this issue we developed a biopesticide formulation to be used in integrated pest management of T. solanivora, following three steps. First, search for entomopathogenic viruses were carried out through extensive bioprospections in 12 countries worldwide. As a result, new Phthorimaea operculella granulovirus (PhopGV) isolates were found in T. solanivora and five other gelechid species. Second, twenty PhopGV isolates, including both previously known and newly found isolates, were genetically and/or biologically characterized in order to choose the best candidate for a biopesticide formulation. Sequence data were obtained for the ecdysteroid UDP-glucosyltransferase (egt) gene, a single copy gene known to play a role in pathogenicity. Three different sizes (1086, 1305 and 1353 bp) of egt were found among the virus isolates analyzed. Unexpectedly, no obvious correlation between egt size and pathogenicity was found. Bioassays on T. solanivora neonates showed a maximum of a 14-fold difference in pathogenicity among the eight PhopGV isolates tested. The most pathogenic PhopGV isolate, JLZ9f, had a medium lethal concentration (LC(50)) of 10 viral occlusion bodies per square mm of consumed tuber skin. Third, we tested biopesticide dust formulations by mixing a dry carrier (calcium carbonate) with different adjuvants (magnesium chloride or an optical brightener or soya lecithin) and different specific amounts of JLZ9f. During laboratory experiments, satisfactory control of the pest (>98% larva mortality compared to untreated control) was achieved with a formulation containing 10 macerated JLZ9f-dead T. solanivora larvae per kg of calcium carbonate mixed with 50 mL/kg of soya lecithin. The final product provides an interesting alternative to chemical pesticides for Andean farmers affected by this potato pest.

Pathogenecity of a baculovirus isolated from Arctornis submarginata (Walker) (Lepidoptera:Lymantriidae), a potential pest of tea growing in the Darjeeling foothills of India.

A granulosis virus (GV) was isolated from the diseased caterpillars of Arctornis submarginata (Walker) (Lymantriidae), a defoliating pest of tea from Darjeeling foothill region. The phase contrast and transmission electron microscopic studies identified the virus as granulosis virus. SDS-PAGE analysis of major protein of the occlusion bodies was found to be 31 kDa, characteristic for granulin. The total genomic DNA was isolated. The major band found was of molecular weight 16 kDa. Bioassay conducted with the occlusion bodies (OBs) of the virus showed LC(50) value of 4.46 x 10(4) OBs/ml for the second instar caterpillars. Median lethal time (LT(50)) were 6.6 days for 1 x 10(4)OBs/ml, 5.09 days for 1 x 10(5) OBs/ml, 4.45 days for 1 x 10(6) OBs/ml and 3.87 days for 1 x 10(7) OBs/ml concentrations. The results indicated the potential of the virus for its future application as microbial pesticide against A. submarginata in future.