Cultivated lentil suffers yield loss from stemphylium blight, caused by Stemphylium botryosum Wallr. Identification of sources of stemphylium blight resistance and knowledge of the mode of inheritance of resistance are important for developing resistant cultivars. The interspecific recombinant inbred line (RIL) population developed from a cross between the moderately resistant parent Lens culinaris cv. ‘Eston’ and the resistant parent L. ervoides (Brign.) Grande accession IG 72815 was evaluated for stemphylium blight resistance under controlled conditions at the University of Saskatchewan, Saskatoon, Canada, and under field conditions at the Pulses Research Centre (PRC), Ishurdi, Bangladesh. We hypothesized that resistance from both parents will lead to transgressive segregation indicative of pyramiding of resistance genes from the same. However, no resistant transgressive segregants were observed in the RIL population. A large proportion (50%) of the RILs had disease severity levels similar to the resistant parent IG 72815 in experiments conducted under natural disease pressure in Bangladesh. Under controlled conditions in Saskatoon, 38% of RILs had resistance levels similar to IG 72815. Across all environments, 14 RILs consistently had resistance levels similar to IG 72815. The distribution of disease severity scores for all RILs indicated polygenic inheritance of stemphylium blight resistance in the population. RILs with consistent resistant reactions should prove useful for lentil improvement programmes. This will contribute to increasing the productivity of lentil crops in North America and the Indo-Gangetic region, which account for more than 68% of world lentil production.

The potential of plant genetics in the overall context of integrated pest control could be viewed simply as the potential of plant resistance in pest management. Genetic resistance in plants is one of the most effective and economic means of controlling plant pests. Resistant plants are the first line defence against pests. Successes in breeding for pest resistance depend upon the sound knowledge of the plant genes controlling resistance to pests.

Recent report on the existence of two nonatlelic and independent genes, Rac1 and Rac2 in cowpea cultivars ICV 10 and TVu 310, and ICV 11 and ICV 12, respectively, from the ICIPE has broadened the scope of cowpea breeding against aphid biotypes. Use of biotechnology as a plant breeding tool in transferring resistance genes into agronomically suitable cultivars appears to hold good promise for the future.

Once a resistant cultivar is developed, the hope is that the resistance which has been selected is durable. One way of making sure that the resistance obtained lasts long is the development of multiple resistance.

The International Institute of Tropical Agriculture (IITA), located in Ibadan, Nigeria, developed a maize population (TZBR) resistant to the stem-borer, Sesamia calamistis. The International Centre of Insect Physiology and Ecology (ICIPE), Nairobi, Kenya crossed this population with some of their lines resistant to Chilo partellus. The resultant crosses and lines derived from them were screened under natural infestation for multiple resistance to C. partellus and Eldana saccharina. Since the population had previously been screened for resistance to S. calamistis, lines identified in this study to have resistances to either C. partellus or E. saccharina or both, will be assumed to have maintained their resistance to S. calamistis unless proved otherwise.

Therefore, new sources of multiple resistance to stem-borers particularly S. calamistis, C. partellus and E. saccharina have been identified. Crosses between them would certainly offer a wide scope in the multiple resistance approach towards pest management.