Identification of bacterial endosymbionts in rice weevil, Sitophilus oryzae Linnaeus (Coleoptera: Curculionidae) populations of North India

Abstract

Aim: The present study was undertaken to screen the most commonly occurring endosymbionts in S. oryzae populations from varied geographical regions of North India. Methodology: The six most common endosymbionts (Wolbachia, Arsenophonus, Spiroplasma, Rickettsia, Cardinium and Hamiltonella) were screened in 15 different populations of S. oryzae, representing five different agro-climatic zones of India. For this, the samples of S. oryzae were collected and identified using taxonomic keys and through PCR amplification of the COI gene followed by Sanger sequencing and comparison of obtained sequences with the NCBI database. Thereafter, the screening of endosymbionts was performed using 16S rRNA gene-specific primers for the respective endosymbionts. Results: The results showed the presence of Wolbachia and Spiroplasma in all 15 populations with infection rates of 100 and 85 per cent, respectively. Arsenophonus was detected in only 12 populations with 60 per cent infection rate. Concurrent infections of Wolbachia, Arsenophonus and Spiroplasma within the same individuals of S. oryzae were also detected. However, no infections of Cardinium, Rickettsia and Hamiltonella were found. Interpretation: Thus, it can be inferred that Wolbachia, Spiroplasma and Arsenophonus are the most common endosymbionts which can be exploited for the development of better management strategies against S. oryzae. Key words: 16S rRNA, Co-infection, Endosymbionts, Rice weevil, Sitophilus oryzae