Detection of Chi Gene in Chitinolytic Soil Born Bacteria and Their Efficiency as a Bio-Insecticide against Tuta Absoluta ( Lepidoptera: Gelechiidae )

Abstract

Chitinolytic bacteria were isolated from soil samples of Qassim region, Saudi Arabia and tested to chitinase activities. The bacterial isolates Rn9 and Rn13 were found to be more chitinase producers among other isolated bacteria. Both bacterial isolates were identified based on 16SrDNA gene and were similar to Bacillus subtilis and Serratia sp., respectively. The Chi gene was detected by PCR technique in genomic DNA of both effective isolates.The mortality percentage of 2nd instar larvae of T. absoluta was determined by using the chitinase enzyme or the mixture of enzyme and bacterial cells. B. subtilis showed the highest bio-insecticidal activity compared with Serratia sp. in both treatments (enzyme only or a mixture of enzyme and bacterial cells). Microscopic observation showed that the larvae exoskeleton of T.absoluta became more deformity with the treated larvae compared with untreated larvae.Results of this study indicate that using of chitinase enzyme from B. subtilis may serve as an effective bio-pesticide to control tomato leaf miner T. absoluta. Moreover, it is a less expensive and more accessible one.