Aspergillus oryzae and Beauveria bassiana as entomopathogenic fungi of Spodoptera litura Fabricius (Lepidoptera: Noctuidae) infesting corn in Lampung, Indonesia

Abstract

Abstract Background Spodoptera litura Fabricius (Lepidoptera: Noctuidae) is an important pest causing severe damage to many cultivating plants such as corn worldwide, including Indonesia. This study was performed to obtain and identify entomopathogenic fungi (EPF) of S. litura collected from corn fields in 4 corn producing regions of Lampung, Indonesia, as well as to investigate the damage caused by this pest on corn in Lampung Province. Results Three corn fields in each region were selected for collecting soil samples. Soil samples were collected from 5 corn plant rhizospheres, at each field in six months of survey. Ten larvae of Tenebrio molitor Linnaeus (Coleoptera: Tenebrionidae) were laid on each soil sample as a bait, covered with a filter paper and incubated at room temperature. The emerging fungi from T. molitor cadaver were transferred onto Potato Dextrose Agar (PDA) medium and incubated for 7 days at room temperature. Pathogenicity test was determined against 3rd instar of S. litura larvae. Identification was performed based on the sequence of Internal Transcribed Spacer (ITS) Region. Observations on the corn damage caused by S. litura were conducted at all corn producing areas in Lampung. Twelve fungal isolates were obtained causing 0–75% of mortality of S. litura. Four fungal isolates (NKPT, SKHJ, SDHJ and RAHJ), which caused mortality more than 20%, were further identified. One isolate (NKPT) was confirmed as Beauveria bassiana and the other 3 isolates (SKHJ, SDHJ and RAHJ) were Aspergillus oryzae. S. litura generally caused slight damages to the corn which was found in every observation year performed during 2010–2019. Medium plant damage was observed in 2010–2012 and 2018–2019, severe damage was found in 2011 and crop failure was recorded in 2018. Conclusions Aspergillus oryzae and B. bassiana were the EPF recorded infecting S. litura in corn in Lampung Province. This was the first report on the isolates of A. oryzae as EPF of S. litura in Indonesia. Slight damages with S. litura were always recorded in every observation year but not for those of medium and severe damages and crop failure.

Keywords

• Corn
• Spodoptera litura
• Entomopathogenic fungi
• Tenebrio molitor
• ITS region
• Pathogenicity