First record of an entomopathogenic fungus of tomato leafminer, Tuta absoluta (Meyrick) in Tanzania

Abstract

Tuta absoluta (Meyrick) is a destructive pest causing adverse environmental and economic effects globally. Management of T. absoluta by synthetic chemicals is of diminutive achievement due to resistance trick of the pest. Harnessing of biocontrols is currently fascinating and efficient for management of the tremendous pests. This study isolated an entomopathogenic fungus from dead larvae of T. absoluta on tomato leaves from farmer’s field Tanzania. Two Aspergillus fungal isolates were isolated and tested against larvae and adults of T. absoluta under conditions of 19.5°C and 50%RH, 30.4°C and 70% RH, respectively, in the laboratory. Sequence analysis of Aspergillus isolates that we referred as A-Tz1 and A-Tz2 were analysed with the BLAST program available at the National Center for Biological Information (NCBI). The two isolates (A-Tz1 and A-Tz2) showed 100% similarity with Aspergillus oryzae of GeneBank accession numbers EF121337.1 and MG519722.1. Such similarity implied that both A-Tz1 and A-Tz2 isolates were A. oryzae. To confirm pathogenicity, bioassays were conducted against the larvae, pupa and adults of T. absoluta. Results showed that at 1.0 × 108 conidia/mL, fungal isolates caused up to 70% larval mortality 3 days post inoculation and consequently inhibited pupation by 84.5% and adult emergence by 74.4%. The identified A. oryzae reduced the life span of adult T. absoluta up to 5 days post inoculation at 1.0 × 108 conidia/mL whereas in control T. absoluta survived up to 25 days. This study found that isolates of Aspegillus species have the potential to be used as active ingrediennt for the formulation of a new bioinjections for application by farmers to control the pest in fields.