Diversity of gut bacteria in developmental stages of whitefly, Bemisia tabaci (Gennadius)
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Date
2014
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Division of Entomology Indian Agricultural Research Institute New Delhi
Abstract
Whiteflies are cosmopolitan insect pest with a wide host range. Among all whiteflies,
Bemisia tabaci (Aleyrodidae:Hemiptera) is very notorious by acting as vector of plant viruses
mostly begomoviruses. These insects have an association with bacterial endosymbionts which
play significant role in the host insect morphogenesis, food digestion, nutrition, antifungal toxin
production, pheromone production, regulation of pH, synthesis of vitamins, temperature
tolerance, and resistance against parasitoid development and detoxification of noxious
compounds.
In the present study, gut bacterial association was addressed in six developmental stages
of two populations of B. tabaci, Asia II1 and AsiaI collected from two locations of India (Delhi
and Andhra Pradesh). As whole 17 genera with 32 species belonging to Firmicutes, Alpha-,
Beta-, Gamma- proteobacteria and Actinobacteria has been identified. Among these, six genera
viz., Bacillus, Lysinibacillus, Kocuria, Acinetobacter, Pseudomonas and Staphylococcus were
found to be common in both the populations. Additionaly, Ralstonia, Paenibacillus,
Herbaspirillum, Brevundimonas, Prolinoborus, Brevibacterium, Proteus, Erwinia and
Microbacterium were also present in Asia II1. Cupriavidus and Sphingomonas were also
associated with Asia I. Bacillus for Asia II1 and Bacillus, Lysinibacillus in Asia I was
associated throughout all the developmental stages revealing their importance. Bacillus was
predominant in both the populations.
Shannon diversity index estimated to be 3.13 and 2.41 for Asia II1 and Asia I
populations respectively, revealing more diversity in Asia II1 than Asia I whereas, evenness
was greater in Asia I (0.94) than Asia II1 (0.93) which was again supported by Whittakers rank
abundance curve.
Phylogenetic analysis of 16S rDNA sequences of isolated gut bacteria showed that few
of these bacterial strains formed separate cluster when compared to their respective
counterparts from other parts of the world. While other bacterial isolates have formed cluster
with their respective counterparts isolated from different insects.
Alkaline phophatases (ALP) are key enzymes ubiquitously present in diverse group of
insects and these are involved in several physiological processes including digestion,
absorption and detoxification of insecticides and toxins. In whitefly it has been documented to
present in salivary gland. ALP activity was also assayed in this study in whole insect for 4
nymphal stages and adult of selected whitefly population. The activity was found to be higher
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in adult stages for both the populations. There was significantly higher activity in Asia II1 than
Asia I. Reason behind this difference in activity may be relatively high diversity in Asia II1.
Description
t-9036
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