Patancheru 502 324, Andhra Pradesh, Indiawww.icrisat.org

Science with a human faceDec 2009

Wild Relatives of Chickpea as Sources of Genes for Resistance to Helicoverpa armigera

For more information contact: HC Sharma, Principal Scientist (Entomology), email: h.sharma@cgiar.org

1 International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru 502 324, Andhra Pradesh, India.2 USDA, ARS Plant Germplasm Introduction and Testing Research Unit, Washington State University, Pullman, WA 99164-6402 USA.

3 Commonwealth Scientific and Industrial Research Organization (CSIRO), Entomology, Private Bag 5, Wembley 6913, Western Australia, Australia.

IntroductionChickpea (Cicer arietinum L.) is an important grain legume in Asia and parts of East and North Africa, Mediterranean Europe, Australia, Canada and USA. The noctuid pod borer, Helicoverpa armigera (Hubner) is one of the most important constraints to chickpea production worldwide, causing an estimated loss of $325 million annually in the semi-arid tropics. Due to widespread use of insecticides, particularly on cotton and other high value crops, it has developed resistance to conventional insecticides (Kranthi et al. 2002). Development of resistant cultivars would minimize the losses due to this pest. However, only moderate levels of resistance are available in the cultivated germplasm of chickpea, and thus, there is need to identify wild relatives as sources of genes for resistance to this pest (Sharma 2005).

Results and DiscussionLarval weights at 10-days after release (DAR) were less than 51 mg on twelve accessions of C. reticulatum, compared to 225 mg on ICCC 37 (susceptible check), and 136 mg on ICC 506 (resistant check) (Fig 1).

Weights on annual wild relatives at 10 DAR ranged from 11.72 to 26.66 mg compared to 46.48 mg on ICC 506 and 80.94 mg on ICCC 37 (Fig 2). There was a significant reduction in both leaf feeding (except in ICC 17242) and larval weights when the larvae were fed on the leaves of perennial wild relatives of chickpea (Table 1).

There was considerable reduction in larval survival and weights of survivors on many accessions of the wild relatives, indicating that antibiosis is an important component of resistance to H. armigera.

Table 1. Evaluation of perennial wild relatives of chickpea for resistance to H. armigera.

Accession Species Damage rating* Larval survival (%) Larval weight (mg)

ICC 17202 Cicer canariense 3.7 90.0 1.985

ICC 17146 Cicer microphyllum 3.2 85.8 0.999

ICC 17234 Cicer microphyllum 4.8 82.0 1.456

ICC 17236 Cicer microphyllum 2.0 85.2 0.769

ICC 17242 Cicer microphyllum 7.0 86.0 2.280

ICC 506 Cicer arietinum 4.8 94.0 4.686

ICCC 37 Cicer arietinum 7.2 86.0 6.602

* Damage rating (1=<10% leaf area damaged; 9=>80% leaf area damaged).

Fig. 2. Weights of Helicoverpa armigera larvae at 10 days after release on leaves of wild relatives of chickpea.

Materials and MethodsAccessions of wild relatives of chickpea, along with three cultivated chickpea genotypes (ICC 506 – moderately resistant, ICCC 37- susceptible check, and Annigeri – local landrace) were evaluated for resistance to H. armigera under field conditions.

The accessions showing resistance were also bioassayed under greenhouse conditions and evaluated in three sets belonging to Cicer reticulatum (secondary gene pool), annual wild species (C. judaicum, C. bijugum and C. pinnatifidum), and perennial wild species (C. microphyllum and C. canariense).

The terminal leaf branches were evaluated for resistance to the neonate larvae of H. armigera using the detached leaf assay at the flowering stage. Terminal branches (2 to 3 fully expanded leaves and a bud) were used to measure genotypic resistance to H. armigera (Sharma et al. 2005). Observations on leaf feeding were recorded on a 1 to 9 scale (1 = <10% leaf area damaged, and 9 = >80% leaf area damaged), number of larvae surviving after the feeding period, and weights of the surviving larvae.

Detached leaf assay to screen for resistance to H. armigera

Wild relatives of chickpea evaluated for resistance to pod borer

Malic acid and oxalic acid are the principal components of resistance to H. armigera in the cultivated chickpea, which result in oviposition nonpreference and antifeedant effects (Yoshida et al. 1995).

However, antibiosis seems to be the major component of resistance in the wild relatives of chickpea, which may be due to isoflavones such as judaicin, maackiain, and 2-arylbenzofuran, which have shown antifeedant and antibiotic activity towards the larvae of H. armigera (Simmonds and Stevenson 2001).

Thus, wild relatives of chickpea seem to have different mechanisms of resistance to H. armigera unlike cultivated chickpeas. Therefore, wild species showing resistance can be exploited to increase the levels and diversify the basis of resistance to H. armigera in cultivated chickpea.

AcknowledgmentsThe funding support provided by the Grains Research and Development Corporation (GRDC), Australia; and USAID Linkage Grant, USA, is gratefully acknowledged.

ReferencesKranthi KR, Jadhav DR, Kranthi S, Wanjari RR, Ali SS and Russel DA. 2002. Insecticide resistance in five major insect pests of cotton in India. Crop Protection 21:449-460.

Sharma HC. 2005. Heliothis/Helicoverpa Management: Emerging Trends and Strategies for Future Research. New Delhi, India: Oxford and IBH Pvt. Ltd. 469 pp.

Sharma HC, Pampapathy G, Dhillon MK and Ridsdill-Smith JT. 2005. Detached leaf assay to screen for host plant resistance to Helicoverpa armigera. Journal of Economic Entomology 98:568-576.

Simmonds MSJ and Stevenson PC. 2001. Effects of isoflavnoids from Cicer on larvae of Helicoverpa armigera. Journal of Chemical Ecology 27:965-977.

Yoshida M, Cowgill SD and Wightman JA. 1995. Mechanisms of resistance to Helicoverpa armigera (Lepidoptera: Noctuidae) in chickpea – role of oxalic acid in leaf exudates as an antibiotic factor. Journal of Economic Entomology 88:1783–1786.

Cicer arietinum. Cicer bijugum.

Cicer reticulatum.

Cicer judaicum. Cicer cuneatum. Cicer bijugum.

Cicer chrossanicum. Cicer pinnatifidum.

Fig. 1. Weights of Helicoverpa armigera larvae at 10 days after release on leaves of 12 wild accessions of C. reticulatum and three cultivated chickpea genotypes (ICC 506, Annigeri, and ICCC 37).

HC Sharma1, G Pampapathy1, SL Clement2 and TJ Ridsdill-Smith3

Adult. Eggs. Larva. Damaged crop.