title: Development of a viral biopesticide for the control of the Guatemala potato tuber moth Tecia solanivora.
abstract: 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.
authors.affiliation: Pontificia Universidad Católica del Ecuador, Facultad de Ciencias Naturales y Biológicas, Quito, Ecuador. fccarpio@yahoo.com
authors.forename: Carlos
authors.initials: C
authors.lastname: Carpio
authors.forename: Olivier
authors.initials: O
authors.lastname: Dangles
authors.forename: Stéphane
authors.initials: S
authors.lastname: Dupas
authors.forename: Xavier
authors.initials: X
authors.lastname: Léry
authors.forename: Miguel
authors.initials: M
authors.lastname: López-Ferber
authors.forename: Katerine
authors.initials: K
authors.lastname: Orbe
authors.forename: David
authors.initials: D
authors.lastname: Páez
authors.forename: François
authors.initials: F
authors.lastname: Rebaudo
authors.forename: Alex
authors.initials: A
authors.lastname: Santillán
authors.forename: Betty
authors.initials: B
authors.lastname: Yangari
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Zeddam
mesh_terms: D000818:Animals; D001681:Biological Assay; D005964:Glucosyltransferases / Q000235:genetics; D025722:Granulovirus / Q000201:enzymology / Q000235:genetics / Q000472:pathogenicity*; D007306:Insecticides; D009036:Moths / Q000502:physiology / Q000821:virology*; D010572:Pest Control, Biological / Q000379:methods*; D011198:Solanum tuberosum / Q000469:parasitology*
chemical_list: D007306:Insecticides; D005964:Glucosyltransferases; C086659:ecdysteroid UDP-glucosyltransferase