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Cultivable bacteria associated with larval gut of prothiofos-resistant, prothiofos-susceptible and field-caught populations of diamondback moth, Plutella xylostella and their potential for, antagonism towards entomopathogenic fungi and host insect nutrition

Author:
Indiragandhi, P., Anandham, R., Madhaiyan, M., Poonguzhali, S., Kim, G.H., Saravanan, V.S., Sa, Tongmin
Source:
Journal of applied microbiology 2007 v.103 no.6 pp. 2664-2675
ISSN:
1364-5072
Subject:
Acinetobacter, Brachybacterium, Hirsutella thompsonii, Metarhizium anisopliae, Paecilomyces, Plutella xylostella, Pseudomonas, Serratia marcescens, Stenotrophomonas, bacteria, chitinase, digestive system, entomopathogenic fungi, insect nutrition, insect pests, insecticide resistance, intestinal microorganisms, larvae, larval development, microbial communities, nucleotide sequences, pest management, phylotype, ribosomal RNA, sequence analysis, siderophores
Abstract:
To evaluate whether the gut bacteria of insecticide-resistant, insecticide-susceptible and field-caught populations of the lepidopteran insect pest diamondback moth (DBM) -Plutella xylostella (L.) - are variable and their role in host protection and nutrition. The gut bacterial populations of the three DBM larvae populations were found to be significantly different, irrespective of the developmental stage. The 16S rRNA gene sequence analysis of the DBM gut bacteria revealed that the bacterial population from the prothiofos-resistant larval gut was more diversified with Pseudomonas sp., Stenotrophomonas sp., Acinetobacter sp., and Serratia marcescens. Meanwhile, the susceptible larvae were associated with Brachybacterium sp., Acinetobacter sp. and S. marcescens and the field-caught population harboured a rather simple gut microflora of phylotypes belonging to Serratia. The siderophore-producing Pseudomonas sp. strain PRGB06 showed antagonistic activity towards entomopathogenic fungi, including Beaveria bassiana, Hirsutella thompsonii, Metarhizium anisopliae, Paecilomyces sp., and Paecilomyces tenuipes, while the chitinase-producing S. marcescens enhanced the larval growth and development. There was a significant variation in the gut bacteria from the three different populations of DBM. The production of antifungal siderophore compounds, like pyoverdine, may contribute to host antagonism against entomopathogens. The production of chitinase by gut bacteria appeared to contribute to host nutrition. The results provide the first comprehensive description of the gut microbial communities in three different populations of an important crucifer pest DBM and suggest that the bacteria associated with the insect pest could be of interest for developing a pest management strategy.
Agid:
2926629