An improved screening method for identification of resistance to bruchids in pulses

Abstract

The screening method involving key modifications in the existing ‘Freechoice’ and ‘No-choice’ tests was developed at ICAR-IIPR, Kanpur for the identification of sources of resistance in three pulse crops to bruchids. The methodology challenged the genotypes to intense oviposition by the bruchids in both the tests and incubated infested seeds for F1 adult emergence after providing a sufficient time for insect development under controlled conditions. The genotypes exhibiting resistant reactions in the free-choice test were further validated by challenging them to bruchid infestation in a single chamber. In no-choice test, the genotypes were challenged in individual plastic vials. The infestation parameters were recorded and the seed parameters were correlated to the bruchid preference for different germplasm. Modifications in square shaped free-choice chamber used for free-choice, exposing seeds to intense oviposition for 3–7 days, and F1 emergence/seed damage count on daily basis from the first day of emergence till 20th-day post-emergence were the key modifications adopted in the methodology. Using this methodology, 104 mungbean, 50 urdbean and 25 cowpea germplasm were screened against three bruchid species. This methodology may serve as an essential tool to identify potential resistance sources in legume crops against bruchids and can provide a way to further elucidate the physical, biochemical, and molecular basis of resistance.