Antixenosis and antibiosis of common beans to Thrips palmi Karny (Thysanoptera: Thripidae)

Antixenosis and antibiosis in the resistance of common beans (Phaseolus vulgaris L.) to the melon thrips, Thrips palmi Karny, were investigated under laboratory and field conditions. Experiments were conducted for four moderately resistant genotypes ('Brunca', BH-130, EMP 486, and FEB 115) in comparison with one susceptible genotype (APN 18). Multiple-choice tests recorded most thrips on EMP 486 and least on FEB 115. Dual-choice tests conducted in both laboratory and field confirmed the antixenotic effect of FEB 115 and the attractant effect of EMP 486 on thrips. These results demonstrate the significance of antixenosis in the resistance of common beans to T. palmi. Life-table studies showed significant differences in egg duration, immature and adult survivorship, female body length and longevity, daily oviposition rate, and total fecundity among the bean genotypes. The intrinsic rate of natural increase (r(m)) and its associated population parameters varied significantly with the bean genotype on which T. palmi cohorts were reared. Based on mean r(m) values, the five bean genotypes can be divided into two groups, with BH-130 and 'Brunca' being less favorable for the population growth of thrips than EMP 486 and FEB 115; the latter were comparable to the susceptible genotype APN 18. These life-table results indicate the role of antibiosis in enhancing the resistance of common beans to T. palmi.     

Resistance to Thrips palmi (Thysanoptera: Thripidae) in beans

Resistance in beans, Phaseolus vulgaris L., to the melon thrips Thrips palmi Karny was studied under field conditions at two sites in Colombia. Genotypes were rated for resistance on the basis of visual damage scores, bean production ratings (a visual estimate of pod and seed set), and grain yields. Of 1,138 genotypes tested, only 60 (5.3%) were rated as resistant. Repeated testing allowed us to identify potential sources of resistance in five germplasm accessions (G 02402, G 02852, G 03177, G 03569, and G 04055), one commercial variety ('Brunca'), six elite breeding lines (A 216, DOR 714, EMP 486, FEB 115, FEB 161, and FEB 162), 41 recombinant inbred lines derived from the BAT 881 x G 21212 cross, and seven recombinant inbred lines derived from a cross between DOR 364 and BAT 477. Resistance was not associated with maturity, growth habit, pubescence, and seed color or seed size. In general, correlations between visual damage scores and bean production ratings and between damage scores and yield were high and significant meaning that selection on damage rating is useful to identify genotypes that may have tolerance as a mechanism of resistance. The continuous distribution of damage scores of 139 recombinant inbred lines suggested that the inheritance of resistance to the melon thrips might be quantitative. Overall, resistance levels in beans can be considered as moderate, because none of the genotypes tested received damage scores of <3 on a 1-9 scale and none was ever rated as highly resistant in terms of bean production ratings.     

Characterization of alfalfa germplasm expressing resistance to silverleaf whitefly, Bemisia argentifolii

Abstract: Thirty‐eight plants were taken from a University of California alfalfa selection nursery for developing resistance to silverleaf whitefly, Bemisia argentifolii Bellows & Perring. Seventeen of the plants had low whitefly infestation and were categorized as ‘potentially resistant’; 21 of the plants had high whitefly infestation and were categorized as ‘presumed susceptible’. Plants were propagated vegetatively so that replicated measurements of whitefly performance could be made on each genotype. Two colonies of silverleaf whiteflies were used: one reared on alfalfa (alfalfa‐experienced whiteflies), and the other on cotton (alfalfa‐naive whiteflies). The effect of variation among alfalfa genotypes on whitefly performance was similar for both whitefly sources, although on all genotypes, the alfalfa‐experienced whiteflies generally performed better than their alfalfa‐naive counterparts. In greenhouse tests, fecundity of newly eclosed adults (over a 5‐day period) on the 17 potentially resistant genotypes was relatively consistent in being lower than fecundity on the presumed susceptible genotypes. However, in nymphal survival tests, the response on the 17 potentially resistant genotypes was not consistent. Nymphal survival (egg to adult) on some of these was very low, as expected, while nymphal survival on others was as high as on the presumed susceptible genotypes. Fecundity and nymphal survival data were not correlated for alfalfa‐naive whiteflies, and were only weakly correlated (r² = 0.13, d.f. = 32, P = 0.04) for alfalfa‐experienced whiteflies. Thirteen genotypes then were examined in the greenhouse in stage‐specific survival tests, where four genotypes demonstrated high resistance (<10% nymphal survival) and three demonstrated moderate resistance (11–34% survival) compared with the three presumed susceptible genotypes that were tested (51–73% survival). Most of the mortality on the resistant genotypes occurred in the first instar, while mortality was more evenly distributed across the life stages on the susceptible genotypes. Interestingly, if nymphs survived to second instar on the resistant genotypes, then their subsequent survival to adult eclosion was similar to survival of second instar to adult on susceptible genotypes. Six of the genotypes used in the greenhouse stage‐specific survival test also were evaluated in the field for nymphal survival, and these results were consistent with the greenhouse tests.     

Resistance to three thrips species in Capsicum spp. depends on site conditions and geographic regions

Capsicum species are commercially grown for pepper production. This crop suffers severely from thrips damage and the identification of natural sources of thrips resistance is essential for the development of resistant cultivars. It is unclear whether resistance to Frankliniella occidentalis as assessed in a specific environment holds under different conditions. Additionally, other thrips species may respond differently to the plant genotypes. Screening for robust and general resistance to thrips encompasses testing different Capsicum accessions under various conditions and with different thrips species. We screened 11 Capsicum accessions (C. annuum and C. chinense) for resistance to F. occidentalis at three different locations in the Netherlands. Next, the same 11 accessions were screened for resistance to Thrips palmi and Scirtothrips dorsalis at two locations in Asia. This resulted in a unique analysis of thrips resistance in Capsicum at five different locations around the world. Finally, all accessions were also screened for resistance to F. occidentalis in the Netherlands using a leaf disc choice assay, allowing direct comparison of whole plant and leaf disc assays. Resistance to F. occidentalis was only partially consistent among the three sites in the Netherlands. The most susceptible accessions were consistently susceptible, but which accession was the most resistant differed among sites. In Asia, one C. chinense accession was particularly resistant to S. dorsalis and T. palmi, but this was not the most resistant accession to F. occidentalis. Overall, resistance to F. occidentalis correlated with S. dorsalis but not with T. palmi resistance in the C. annuum accessions. Damage inflicted on leaf discs reflected damage on the whole plant level. Our study showed that identifying broad spectrum resistance to thrips in Capsicum may prove to be challenging. Breeding programmes should focus on developing cultivars suitable for growing in defined geographic regions with specific thrips species and abiotic conditions.     

Resistance factors in pepper inhibit larval development of thrips (Frankliniella occidentalis)

The western flower thrips [Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae)] is a major pest in pepper cultivation. Therefore, host plant resistance to thrips is a desirable trait. The objectives of this study were to determine the effect of resistance on the development of thrips and to identify metabolite compounds related to the resistance. Three highly resistant, three medium resistant, and three susceptible pepper accessions were used in this study. Adult and pre‐adult survival, developmental time, and oviposition rate were assessed. Gas chromatography‐mass spectrometry was used to identify compounds that correlate with the level of resistance to thrips. Our results show that resistance of pepper accessions has a significant effect on oviposition rate and larval mortality. Seven compounds were identified that correlate with resistance to thrips and six compounds were identified that correlate with susceptibility to thrips. Some of these compounds, such as tocopherols, were previously shown to have an effect on insects in general. Also, some specific secondary metabolites (alkanes) seem to be more abundant in susceptible accessions and were induced by thrips infestation.     

Species composition of thrips (Thysanoptera: Thripidae) and spider mites (Acari: Tetranychidae) on cultivated chrysanthemum (Asteraceae) in Okinawa,southwestern Japan

We investigated the species composition of phytophagous thrips and spider mites on cultivated chrysanthemum in Okinawa, southwestern Japan. Eight thrips species belonging to the genera Frankliniella, Microcephalothrips, Scirtothrips and Thrips were found on chrysanthemum leaves. Among them, Thrips nigropilosus was the predominant species irrespective of season, island or cultivation environment (meshed greenhouse or open field), with its infestation frequency being 89% of the fields in which thrips occurred. This high frequency of occurrence suggests that T. nigropilosus is a major pest of chrysanthemum in Okinawa, even though this species has rarely been regarded as an important pest of chrysanthemum or other crops in any other areas. Thrips palmi was the second most dominant (infestation frequency 36%) and other species were scarce (<14%). Tetranychus urticae (green form) was the only tetranychid species on chrysanthemum in our survey. This lack of diversity among spider mites on chrysanthemum is peculiar considering that eight Tetranychus species have been found on vegetables in the same area. Since T. urticae (green form) has been shown to be resistant to a number of pesticides, severe pesticide applications might have simplified the spider mite fauna on chrysanthemum in Okinawa.     

Feeding‐induced changes in defence enzymes and PR proteins and their implications in host resistance to Nilaparvata lugens

Six rice genotypes showing susceptible and resistant reactions to brown planthopper (BPH), Nilaparvata lugens were studied for feeding‐induced changes in defence enzymes and pathogenesis‐related (PR) proteins. The high resistant genotypes PTB 33, ADT 45 and ASD 7 and moderately resistant genotypes CO 43 and KAU 1661 recorded the greater expression of defence enzymes peroxidase, polyphenol oxidase, phenylalanine ammonia lyase, total phenol and β‐1,3 glucanase in response to N. lugens feeding at 1 day after infestation (DAI) compared with susceptible genotype TN1. The greater activity of chitinase was observed in resistant cultivars at 3 DAI and the activity was sustained for more than 1 week compared with susceptible TN1. In conclusion, the current study revealed that these defence enzymes and PR proteins might attribute to the resistance mechanisms in rice plants against BPH infestation.     

Evaluation of cowpea mini core accessions for resistance to flower bud thrips Megalurothrips sjostedti Trybom (Thysanoptera: Thripidae)

The flower bud thrips, Megalurothrips sjostedti Trybom (Thysanoptera: Thripidae), is an economically important pest of cowpea in sub‐Saharan Africa. Varietal resistance is the most preferred, environmentally friendly, cost‐effective and sustainable option for controlling this pest. The objective of this study was to identify sources of resistance to M. sjostedti among mini core accessions from the largest world cowpea germplasm collection maintained at the International Institute of Tropical Agriculture (IITA). The study was conducted during the 2015 and 2016 cropping seasons where 365 accessions were screened under field conditions. Each accession was rated visually for thrips damage score, flower abortion rate, number of pods per plant and number of thrips per flower. The resistance levels observed in genotypes TVu8631, TVu16368, TVu8671 and TVu7325 were similar to that of the resistant check “Sanzisabinli” (called Sanzi) during both seasons. In addition, 56 mini core genotypes showed moderate resistance to thrips damage. High heritability values were associated with thrips damage scores at 65 days after planting (0.60), percentage of effective peduncles (0.59), flower bud abortion rate (0.59), number of pods per plant (0.51) and number of peduncles with pods (0.5). The accessions identified with good levels of resistance to flower bud thrips will be used in cowpea breeding programs to develop improved resistant varieties.     

An eco-metabolomic study of host plant resistance to Western flower thrips in cultivated,biofortified and wild carrots

Domestication of plants and selection for agronomic traits may reduce plant secondary defence metabolites relative to their ancestors. Carrot (Daucus carota L.) is an economically important vegetable. Recently, carrot was developed as a functional food with additional health-promoting functions. Biofortified carrots contain increased concentrations of chlorogenic acid as an antioxidant. Chlorogenic acid is involved in host plant resistance to Western Flower Thrips (Frankliniella occidentalis), one of the key agri- and horticultural pests worldwide. The objective of this study was to investigate quantitative host plant resistance to thrips in carrot and to identify candidate compounds for constitutive resistance. As such we explored whether cultivated carrot is more vulnerable to herbivore attack compared to wild carrot. We subjected a set of 14 biofortified, cultivated and wild carrot genotypes to thrips infestation. We compared morphological traits and leaf metabolic profiles of the three most resistant and susceptible carrots using nuclear magnetic resonance spectroscopy (NMR). In contrast to our expectation, wild carrots were not more resistant to thrips than cultivated ones. The most thrips resistant carrot was the cultivar Ingot which is known to be tolerant against carrot root fly (Psila rosae). Biofortified carrots were not resistant to thrips. Plant size, leaf area and number of leaf hairs did not differ between resistant and susceptible carrots. The metabolic profiles of the leaves of resistant carrots were significantly different from those of susceptible carrots. The leaves of resistant carrots contained higher amounts of the flavanoid luteolin, the phenylpropanoid sinapic acid and the amino acid β-alanine. The negative effect of these compounds on thrips was confirmed using in-vitro bioassays. Our results have potential implications for carrot breeders. The natural variation of metabolites present in cultivated carrots can be used for improvement of thrips resistance. This is especially promising in view of the candidate compounds we identified since they do not only confer a negative effect on thrips but as antioxidants also play an important role in the improvement of human health.     

Sources of Resistance to Cowpea Bacterial Blight Disease in Nigeria

The development of resistant crop varieties depends on the reliability of the method of screening for resistance. One of the techniques widely used in evaluating field resistance is the field screening method. However, most cowpea varieties regarded as having field resistance are often found to be susceptible in farmers’ fields, where the inoculum density can be higher. This study rescreened 96 cowpea varieties, evaluated earlier in breeders’ fields as resistant to Xanthomonas campestris pv. vignicola, in field and greenhouse under high inoculum pressure. There were significant differences (P ≤ 0.05) in the reactions of cowpea varieties to bacterial blight in terms of disease incidence and severity. Results from the field screening showed that there were 69 susceptible, 25 moderately susceptible, and 2 resistant varieties. In artificial inoculation in the greenhouse IT81D‐1228‐14, IT82E‐16, IT93K‐2271‐2‐2, TVu 1235, and TVu 4630, which were moderately susceptible in the field showed a susceptible reaction. Tvu 12349 and Tvu 15549 gave consistent reactions in the field and in the greenhouse and are therefore good sources of stable resistance to bacterial blight pathogen. Stem canker incidence also varied significantly (P ≤ 0.05) among the cowpea varieties. Seventeen varieties did not manifest canker symptoms.     

Assessment of genetic diversity among soybean genotypes differing in response to aerial blight (Rhizoctonia solani Kuhn) using SSR markers

Forty‐seven genotypes and one wild relative of soybean, Glycine soja, were screened for resistance against aerial blight under epiphytotic conditions in the field during the Kharif season of two consecutive years viz., 2016 and 2017. Out of the 48 genotypes screened, only 18 genotypes exhibited a moderately resistant response to aerial blight during both the years of study. In order to perform molecular screening of the genotypes for aerial blight resistance, the genomic DNA obtained from the seedlings of the forty‐eight soybean genotypes was subjected to PCR amplification with 12 SSR markers. The SSR markers Satt 119, Sat_076, Satt 433, Satt 281, Satt 277, Satt 245 and Satt 520 were able to clearly amplify different banding pattern for resistant and susceptible genotypes, out of which Satt 433 and Satt 520 were found to exhibit a pattern, highly similar to the results of field screening of the genotypes with respect to resistant and susceptible reaction to the disease. The eighteen soybean genotypes that exhibited moderately resistant reaction to RAB under field conditions during both the years showed a banding pattern similar to resistant check PS‐1583 in the amplification profile produced by the SSR markers. The polymorphism information content (PIC) from the analysis of amplification profile of the SSR markers used in the study, ranged from 0.58 to 0.95. The dendrogram constructed using UPGMA cluster analysis clearly differentiated the resistant and susceptible genotypes of soybean into two separate groups.     

Identification of phloem sieve elements as the site of resistance to silverleaf whitefly in resistant alfalfa genotypes

Experiments were conducted to locate the plant tissue where resistance is expressed against silverleaf whitefly, Bemisia argentifolii Bellows and Perring (Homoptera: Aleyrodidae), in alfalfa, Medicago sativa L. (Fabaceae), genotypes previously shown to have high levels of resistance against this pest. Previous work demonstrated that resistance in the resistant alfalfa genotypes was expressed primarily as high first‐instar mortality; consequently this study focused on first‐instar nymphs. Examination of stylets in cleared leaf tissue indicated that first‐instar nymphs located vascular bundles with equal success on resistant and susceptible alfalfa genotypes. Furthermore, direct current electrical penetration graphs (DC‐EPG) indicated that sieve elements were penetrated and phloem ingestion behavior was initiated with equal success on resistant and susceptible genotypes. Thus, the mechanism of resistance does not reside in tissues encountered by the stylets prior to penetrating a phloem sieve element. Honeydew production (as a proxy for ingestion) was greatly reduced on two resistant genotypes compared to the two susceptible genotypes. The frequency distribution of honeydew production was bimodal, indicating that most individuals on the resistant genotypes produced little or no honeydew while some produced as much honeydew as whiteflies on the susceptible genotypes. This indicates that expression of resistance is an all‐or‐nothing phenomenon; an individual nymph either encounters resistance and cannot sustain ingestion or it does not encounter resistance and ingests just as well as on a susceptible plant. Intermediates are rare. DC‐EPGs indicate that phloem ingestion behavior is significantly reduced on two of the resistant genotypes compared to the susceptible genotypes. The primary reason for this appears to be more frequent termination of phloem ingestion behavior on at least one of the resistant genotypes. On one of the resistant genotypes, the productivity of EPG‐measured phloem ingestion behavior (honeydew produced per min of phloem ingestion behavior) was reduced compared to a susceptible control.     

Decreased preference and reproduction, and increased mortality of Frankliniella occidentalis on thrips-resistant pepper plants

The effect of thrips resistance in pepper (Capsicum annuum L.) – previously shown to result in impeded thrips population development (Maris PC, Joosten NN, Goldbach RW & Peters D (2003a) Restricted spread of Tomato spotted wilt virus in thrips‐resistant pepper. Phytopathology 93: 1223–1227. Maris PC, Joosten NN, Goldbach RW & Peters D (2003b) Spread of Tomato spotted wilt virus and population development of Frankliniella occidentalis in pepper resistant to thrips. Proceedings of the Section Experimental and Applied Entomology Netherlands Entomological Society (NEV) Amsterdam 14: 95–101.) – on thrips’[Frankliniella occidentalis Pergande (Thysanoptera: Thripidae)] reproduction, mortality, host preference, and behaviour was investigated. Reproduction, studied by oviposition and larval survival, was negatively affected by the thrips‐resistant (TR) phenotype, whereas the offspring's developmental rate did not differ on TR and the thrips‐susceptible (TS) phenotype. While thrips’ behaviour was hardly affected by thrips resistance, a significant preference for TS plants over the TR plants was found in different tests. When released on either a TR or a TS plant, thrips dispersed at significantly higher rates from the TR plants, demonstrating that not only an impeded reproduction, but also a reduced residence time adds to the reported lower thrips numbers on TR plants.     

Gut content analysis to study predatory efficacy of Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae) by molecular methods

Nesidiocoris tenuis is considered to make significant contributions to the control of greenhouse pests such as whiteflies, thrips, leafminers, lepidopterans, and spider mites, although there is little information based on direct observation of the predation of N. tenuis on these target pests. We developed a method to perform gut content analysis of N. tenuis based on DNA in which specific PCR primers were designed to detect the DNA of target pests. By means of gut‐content analysis, we found that the percentage of N. tenuis preying on Bemisia tabaci and Thrips palmi was approximately 40% in the field.     

Screening for Barley yellow dwarf virus-Resistant Barley Genotypes by Assessment of Virus Content in Inoculated Seedlings

The content of Barley yellow dwarf virus (BYDV) in roots and leaves of barley seedling plants differing in their level of resistance was assessed by quantitative ELISA 1–42 days after inoculation with the strain of BYDV (PAV). High virus accumulation in roots and low concentration in leaves was characteristic of the period 9–15 days after inoculation. In leaves, the differences in virus content between resistant and susceptible genotypes became significant after 15 days and resistance to virus accumulation was better expressed 30–39 days after inoculation. Roots of resistant materials exhibited evident retardation of virus accumulation and the greatest difference in virus content between resistant and susceptible plants was detected 9 days after inoculation. By these criteria, the selected winter and spring barley cultivars and lines (in total 44 materials) fell in to five groups according to field reactions and the presence or absence of the Yd2 resistance gene. There were highly significant and positive relations between ELISA values and 5‐year field data on symptomatic reactions and grain‐yield reductions due to infection. Using the described method, resistant and moderately resistant genotypes (both Yd2 and non‐Yd2) were significantly differentiated from susceptible genotypes. The possible use of this method in screening for BYDV resistance is discussed.     

THE SIGNIFICANCE OF OUTCROSSING IN AN INTIMATE PLANT-HERBIVORE RELATIONSHIP. I. DOES OUTCROSSING PROVIDE AN ESCAPE FROM HERBIVORES ADAPTED TO THE PARENT PLANT?

Sexual reproduction may be advantageous for hosts that are preyed on or parasitized by enemies that are highly adapted to them. Sexual reproduction can create rare genotypes that may escape predation by virtue of rarity and can create variable progeny that may escape predation if enemies are specialized to only one genotype of host. Populations of the herbivorous thrips, Apterothrips apteris, have been shown to be adapted to individual Erigeron glaucus clones. Here, we show that thrips adapted to the parental clone could better use plant progeny of the “home” clone produced through selfing than progeny derived from selfing of other clones. Thus, despite recombination, progeny produced by selfing presented a resource that was similar to the parental phenotype with respect to use by adapted thrips. We also show that E. glaucus susceptibility to thrips has a genetic basis and then ask whether outcrossing provides a means for E. glaucus clones to escape attack by adapted thrips. When we compared the success of thrips on progeny produced by selfing or outcrossing of the home clone, we found that the merits or disadvantages associated with outcrossing were dependent on the susceptibility to infestation of the parental clones. Selfing by clones characterized by low infestations of thrips appeared to preserve resistant genotypes; all outcrossed progeny had, on average, higher infestation levels than selfed progeny. In contrast, outcrossed progeny of clones characterized by high infestations of thrips had either the same thrips density as progeny from selfing, when the pollen donor was a highly infested clone, or lower density, when the pollen donor was a low infestation clone. The advantages of outcrossing were caused by the alleles contributed to progeny rather than to progeny variability or rarity.     

Olfactory response of the anthocorid predatory bug Orius sauteri to thrips-infested eggplants

The predator Orius sauteri (Poppius) (Heteroptera: Anthocoridae) is an effective arthropod natural enemy of thrips, especially Thrips palmi Karny (Thysanoptera: Thripidae), a serious pest of vegetables. First, we studied O. sauteri's response to the odour from thrips-infested eggplant [Solamum melongena L. (Solanaceae)] in a laboratory by two-choice experiments using a Y-tube olfactometer. When detached eggplant leaves were used as odour sources, O. sauteri preferred the volatiles from uninfested leaves to clean air. Concerning preferences among differently infested leaves, O. sauteri preferred the volatiles from plants infested with 10–100 thrips per leaf to uninfested leaves, but showed no significant preference for artificially damaged leaves over uninfested leaves. Similar results were obtained when complete plants were tested as the odour source. Second, release and recapture experiments in a greenhouse, a more realistic set of conditions, were conducted to confirm whether a significant preference for infested plants occurred at similar infestation levels as in the laboratory. Trends favouring infested plants were detected at densities of five and 500 thrips per plant; however, at the five thrips per plant, this trend was due to the large deviation seen in infested plants in only one replicate. In light of the low tolerable thrips density of eggplant, it is necessary to confirm whether artificial treatments with chemicals induce the emission of herbivore-induced plant volatiles that can attract O. sauteri and prolong its residence time on the leaf.     

Tolerance to reniform nematode (Rotylenchulus reniformis) race A in pigeonpea (Cajanus cajan) genotypes

The reniform nematode (Rotylenchulus reniformis) is an important pathogen of pigeonpea (Cajanus cajan). Forty‐six medium maturity (mature in 151–200 days at Patancheru, India) pigeonpea genotypes were evaluated for resistance and tolerance to the reniform nematode in greenhouse and field tests, over the period 1990–97. Each genotype was screened for number of nematode egg masses on a 1 (no egg mass = highly resistant) to 9 (> 50 egg masses = highly susceptible) scale. Plant biomass production in carbofurantreated plots was compared with that in non‐treated plots in a field naturally infested with R. reniformis. Pigeonpea genotypes C 11, ICPL 87119 and ICPL 270 were used as nematode susceptible checks. Genotypes with good plant growth, both in nematode‐free and nematode‐infested plots, were identified as tolerant and evaluated for plant growth and yield for at least three years. All the tested genotypes were susceptible (7 and 9 egg mass score). Single‐plant‐selections, based on plant vigour and yield, were made from genotypes showing tolerance to nematode infection. The level of tolerance was enhanced by plant‐to‐progeny row selection for plant vigour and seed yield in a nematode‐sick field for at least three years. The most promising nematode tolerant genotypes produced significantly greater yield and biomass than the locally grown pigeonpea cultivars in fields naturally infested with R. reniformis at two locations. Pigeonpea landraces are considered to be the most likely sources of tolerance to the nematode. These reniform nematode tolerant lines represent new germplasm and they are available in the genebank of pigeonpea at ICRISAT bearing accession numbers ICP 16329, ICP 16330, ICP 16331, ICP 16332, and ICP 16333.