Assessing Pigeonpea Genotypes for Resistance against Maruca vitrata Fabricius and its Sustainable Management through Biorationals

Abstract

Background: The spotted pod borer (SPB), Maruca vitrata Fabricius is a key insect pest of major legume crop i.e. pigeonpea, Cajanus cajan in India and semi-arid tropics. Identifying a SPB resistant genotype will help in sustainable management of SPB and in attaining nutritional security. The SPB has developed insecticide resistance to most of the chemical insecticide like Organophosphorous group of insecticides and also it is expanding its geographic limits. These factors are the driving forces for identifying tolerant genotypes for its sustainable management along with a suitable biorational. Methods: Forty seven pigeonpea genotypes were screened during kharif 2015 to 2017 at ICAR-IIPR, Kanpur based on percent pod damage and Pest Resistance Susceptibility Rating (PRSR) under insecticide free condition. The 4 biorationals were tested against SPB in ICPL 87 along with untreated control in Randomised Block Design. Further the SPB molecular identity was confirmed by phylogenetic analysis of partial Cox 1 gene amplified from M. vitrata adult. Results: Two indeterminate genotypes (Pusa2001 and Pusa33) as SPB resistant based on lowest mean pest resistance susceptibility rating (PRSR 1.7) The next best genotypes were a determinate (AL-15) and indeterminate genotype (LRG-30) with a PRSR of 2.0. The highest PRSR (6.0) was recorded from the ICPL 87, a susceptible check in the present experiment. Spinosad 45SC has recorded significantly lowest mean pod damage (6.67%) and highest mean yield (4.36kg/35m2) compared to 4 other treatments in the field efficacy trial. The phylogenetic analysis of Cox 1 gene from Kanpur population (KY559101) with 19 other M. vitrata populations in India revealed that it is more similar to Raichur population (KT070892) and it confirms M. vitrata has same ancestral homology in India.