Mechanisms of Resistance to Tobacco Cutworm (Spodoptera litura F.) and their Implications to Screening for Resistance in Groundnut

Abstract

The Tobacco cut worm (Spodoptera litura Fab.), a polyphagous defoliating insect is a major pest on groundnut in Asia. Screening germplasm for resistance to Spodoptera litura in the field under high infestation revealed significant genotypic variation. Low damage was observed on Mutant (28-2), NC Ac 343, ICGV 86031, R 9227 and TAG 24. In the laboratory rearing of insect, the resistant genotypes, NC Ac 343, Mutant 28-2 and R 9227 affected larval growth and survival, pupal development, adult emergence and fecundity indicating antibiosis as the principal mechanism of resistance. The reduction in larval weight reared on ICGV 86031 could be due to the toughness of leaves. Though the genotype TAG 24 suffered low damage in the field, the larval and pupal development was normal in the laboratory revealing avoidance/non-preference as the mechanism of resistance. Based on the insight gained from the growth and development of the insect on resistant genotypes, the gain in weight (GIW) of the pre-starved larvae was assessed for its suitability in rapid screening. GIW in 24 h by III instar larvae fed with fully expanded II leaf was found suitable in screening for resistance based on antibiosis. The method could be adopted for screening large breeding populations in a short time under laboratory conditions. The resistant genotypes with different mechanisms of resistance could be hybridized to pool the resistance genes for enhancing the level and effectiveness of resistance.

Diverse sources of resistance to Spodoptera litura (F.) in groundnut

“…Identification of potential resistant sources for Spodoptera litura is a pre-requisite for developing resistant cultivars. Earlier, ICGV 91180, NC Ac 343, M 28-2 and M 45 (Prasad and Gowda 2006;Naidu et al 2016) were identified as resistant to Spodoptera litura with less leaf damage. Identification of diverse sources of resistance would help in avoiding break down of resistance.…”

Herbivore-induced resistance in different groundnut germplasm lines to Asian armyworm, Spodoptera litura (Fab.) (Lepidoptera: Noctuidae)

“…Spodoptera litura has developed resistance to a number of synthetic insecticides (Kranthi et al 2002). ICGV 86699 and NCAC 343 differ in the maturity period (Prasad and Gowda 2006) and levels of resistance to different insects .…”

Factors promoting efficient in vitro regeneration from de-embryonated cotyledon explants of Arachis hypogaea L.

“…The average yield at around 1,000 kg/ha, is lower than other major peanut growing countries due to losses caused by biotic stresses like diseases and insect pests (Desai et al 1999;Ghewande et al 2002). Although there are some commercial cultivars which show moderate level of resistance but undesirable agronomic features like low shelling, undesirable pod and kernel traits make them less popular (Patil et al 1995;Prasad and Gowda 2006). Some of the wild relatives in Arachis genera carry genes for resistance against certain diseases and pests (Stalker and Moss 1987).…”