Mycobiology.  2017 Sep;45(3):160-171. 10.5941/MYCO.2017.45.3.160.

Cutaneous Microflora from Geographically Isolated Groups of Bradysia agrestis, an Insect Vector of Diverse Plant Pathogens

Affiliations
  • 1School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, Institute for Microorganisms, Kyungpook National University, Daegu 41566, Korea. ghimsa@knu.ac.kr
  • 2Microorganism Resources Division, National Institute of Biological Resources, Incheon 22689, Korea.
  • 3Horticultural & Herbal Crop Environment Division, National Institute of Horticultural & Herbal Science, Rural Development Administration, Wanju 55365, Korea. plantdoctor7@korea.kr

Abstract

Larvae of Bradysia agrestis, an insect vector that transports plant pathogens, were sampled from geographically isolated regions in Korea to identify their cutaneous fungal and bacterial flora. Sampled areas were chosen within the distribution range of B. agrestis; each site was more than 91 km apart to ensure geographical segregation. We isolated 76 microbial (fungi and bacteria) strains (site 1, 29; site 2, 29; site 3, 18 strains) that were identified on the basis of morphological differences. Species identification was molecularly confirmed by determination of universal fungal internal transcribed spacer and bacterial 16S rRNA gene sequences in comparison to sequences in the EzTaxon database and the NCBI GenBank database, and their phylogenetic relationships were determined. The fungal isolates belonged to 2 phyla, 5 classes, and 7 genera; bacterial species belonged to 23 genera and 32 species. Microbial diversity differed significantly among the geographical groups with respect to Margalef's richness (3.9, 3.6, and 4.5), Menhinick's index (2.65, 2.46, and 3.30), Simpson's index (0.06, 0.12, and 0.01), and Shannon's index (2.50, 2.17, and 2.58). Although the microbial genera distribution or diversity values clearly varied among geographical groups, common genera were identified in all groups, including the fungal genus Cladosporium, and the bacterial genera Bacillus and Rhodococcus. According to classic principles of co-evolutionary relationship, these genera might have a closer association with their host insect vector B. agrestis than other genera identified. Some cutaneous bacterial genera (e.g., Pseudomonas) displaying weak interdependency with insect vectors may be hazardous to agricultural environments via mechanical transmission via B. agrestis. This study provides comprehensive information regarding the cutaneous microflora of B. agrestis, which can help in the control of such pests for crop management.

Keyword

Biodiversity; Bradysia agrestis; Insect microflora; Insect vector

MeSH Terms

Bacillus
Biodiversity
Cladosporium
Databases, Nucleic Acid
Genes, rRNA
Insect Vectors*
Insects*
Korea
Larva
Plants*
Rhodococcus
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