Stem Tunneling Research Articles

Fungal and herbivore elicitation of the novel maize sesquiterpenoid, zealexin A4, is attenuated by elevated CO2.

Chemical isolation and NMR-based structure elucidation revealed a novel keto-acidic sesquiterpenoid, termed zealexin A4 (ZA4). ZA4 is elicited by pathogens and herbivory, but attenuated by heightened levels of CO 2 . The identification of the labdane-related diterpenoids, termed kauralexins and acidic sesquiterpenoids, termed zealexins, demonstrated the existence of at least ten novel stress-inducible maize metabolites with diverse antimicrobial activity. Despite these advances, the identity of co-occurring and predictably related analytes remains largely unexplored. In the current effort, we identify and characterize the first sesquiterpene keto acid derivative of β-macrocarpene, named zealexin A4 (ZA4). Evaluation of diverse maize inbreds revealed that ZA4 is commonly produced in maize scutella during the first 14days of seedling development; however, ZA4 production in the scutella was markedly reduced in seedlings grown in sterile soil. Elevated ZA4 production was observed in response to inoculation with adventitious fungal pathogens, such as Aspergillus flavus and Rhizopus microsporus, and a positive relationship between ZA4 production and expression of the predicted zealexin biosynthetic genes, terpene synthases 6 and 11 (Tps6 and Tps11), was observed. ZA4 exhibited significant antimicrobial activity against the mycotoxigenic pathogen A. flavus; however, ZA4 activity against R. microsporus was minimal, suggesting the potential of some fungi to detoxify ZA4. Significant induction of ZA4 production was also observed in response to infestation with the stem tunneling herbivore Ostrinia nubilalis. Examination of the interactive effects of elevated CO2 (E-CO2) on both fungal and herbivore-elicited ZA4 production revealed significantly reduced levels of inducible ZA4 accumulation, consistent with a negative role for E-CO2 on ZA4 production. Collectively, these results describe a novel β-macrocarpene-derived antifungal defense in maize and expand the established diversity of zealexins that are differentially regulated in response to biotic/abiotic stress.

Colonization of Beauveria bassiana (Balsamo) Vuillemin strains in maize (Zea mays L.) and their efficacy against stem borer Chilo partellus (Swinhoe)

Glasshouse experiments were conducted to study the endophytic ability of six strains of entomopathogenic fungus Beauveria bassiana in maize leaf and stem tissues when applied through foliar sprays of oil formulations. B. bassiana treated and untreated control plants were artificially infested with second instar larvae of Chilo partellus to assess the stem borer damage. All six strains showed varying percent colonization and persistence in stem and leaf tissues. The mean percent colonization ranged from 16.67-46.67 % in older stem tissues and 22.22-52.22 % in young stem tissues and in leaf, it ranged from 25.56-47.78 % in older leaf tissues and 31.11-57.78 % in young leaf tissues. Among six isolates tested, Bb-45 isolate recorded the maximum mean colonization in older stem (46.67 %), older leaf (47.78%) and in young stem (52.22 %). Bb-5a isolate showed maximum mean colonization in young leaf tissues (57.78 %). Significantly lower percentage of dead hearts (2.2-11.1%) and lower stem tunneling (2.7-4.3cm/plant) was observed in B. bassiana treated plants as compared to the untreated control plants (28.86% of dead hearts and 13.41cm/plant stem tunneling).

Evaluation of Grain Sorghum Entries against Spotted Stem Borer, Chilo partellus (Swinhoe)

Stem borers are the major pest complex contributing to yield reduction in sorghum and stem borer, Chilo partellus is the important one among them. Identification of resistant genotypes is a contributing factor for releasing new varieties. In the present study, 11 sorghum entries along with one resistant (IS 2205) and susceptible (Swarna) checks were evaluated for stem borer resistance in kharif and rabi seasons considering leaf damage, dead heart, stem tunneling, yield plant -1 and 1000 grain weight. The results revealed that sorghum entries TNS 664 and TNS 667 registered the lowest leaf damage score (2.9, 2.8 and 3.0, 3.5), dead heart (9.9%, 13.3% and 11.0%, 15.0%), stem tunnelling (5.7%, 5.1% and 6.6%, 5.5%) and yield loss (25.2%, 22.7% and 25.8%, 25.4%) and was on par with the resistant check, IS 2205 (2.3, 7.5%, 7.4%, 19.7% and 2.5, 9.0%, 8.2%, 26.9%) during rabi, 2016 and kharif, 2017, respectively.

Field evaluation of endophytic entomopathogenic fungi against maize stem borer (Chilo partellus) (Crambidae: Lepidoptera)

The present study was carried out to assess the field efficacy of endophytic isolates of Beauveria bassiana (Bb-5a, Bb-23 and Bb-45) and Metarhizium anisopliae (Ma-35) against maize stem borer (Chilo partellus Swinoe) during kharif seasons of 2015 and 2016 at ICAR-National Bureau of Agricultural Insect Resources (NBAIR), Attur Farm, Bengaluru, Karnataka. All the tested isolates showed suppression of maize stem borer damage during both seasons. Pooled data indicated that lesser dead hearts (9.5-12.71%), stem tunnelling (3.98-4.36 cm/plant) and exit holes (2.59-2.79 /plant) in the treated plants compared to untreated control which showed 21.38% dead hearts, 8.01 cm/plant of stem tunnelling and 6.99 exit holes/plant. Among the four isolates tested, Bb-5a isolate of B. bassiana and Ma-35 isolate of M. anisopliae showed significantly superior effect in lowering the incidence of dead hearts (9.50 and 12.71%), stem tunnelling (3.98 and 4.36 cm/plant) and exit holes (2.59 and 2.79/plant) with higher yields of 72 and 70.0 tonnes/ha respectively.

English

Maize (Zea mays L.) is the staple food in Kenya, and mapping the qualitative trait loci (QTL) associated with resistance to maize stem borer pest is important towards marker assisted breeding for this quantitative trait. The objective of this study was to identify any QTL associated with resistance to Chilo partellus and Busseola fusca, the two important stem borer pests in maize production in Kenya. A total of 203 F2:3 individuals from a cross between CML442, a stem borer susceptible maize inbred line and CKSBL10026, a stem borer resistant maize inbred line; and 152 SNPs were used for mapping the QTL. Data were collected on leaf damage, stem borer exit holes and stem tunneling length as putative stem borer damage traits. A likelihood odds ratio (LOD) scores of 3.0 and maximum recombination frequency of 0.50 were used to declare linkage. LOD scores between 2.5 and 2.9 were considered strong indications of a QTL. Resistance QTL for the three putative traits were detected on chromosomes 1-7 and 9 for both individual locations and stem borer species analysis. In B. fusca sites, one QTL for reduced stem tunnelling was revealed on chromosome 4 while in the C. partellus sites, one QTL for reduced stem tunnelling was identified on chromosome 4 and another for reduced stem borer exit holes was identified on chromosome 5. Phenotypic variances explained ranged from 6 to 10%, suggesting a need to validate these QTL using a larger population and in different environments. Key words: Busseola fusca, Chilo partellus, mapping, quantitative trait loci (QTL), resistance, single nucleotide polymorphisms (SNPs), stem borer.

Effects of Different Insecticidal Concentration Levels on Damage of Busseola fusca (F.) on the Yield of Maize at Jalingo and Yola, Nigeria

The effect of Sherpa plus (Cypennethrin 12g + dimethoate 100 g/l) at four concentration levels was examined on the damage caused by Busseola fusca (F.) [Lepidotera :Noctuidae] on the yield of six maize varieties and cultivars at Jalingo and Yola in 2013 cropping season. The experiment was a split-plot design with six maize varieties/cultivars [T2L-Comp.4c2;BR-9928-DMR-SR-Y; SWAN 1(white); SWAN 2 (yellow) and the cultivars Ex-Jalingo white and yellow] were the sub-plots and the main-plots were the four concentration levels (0.0, 0.5, 1.0 and 1.5 l/ha) on a sub-plot size of 3x3m replicated 3times. Maize plants were sprayed 2 times with Sherpa plus at 4 and 8 weeks after emergence (WAE). The damage recorded were pin-hole stem tunneling and breakage at cob formation soft dough stage. The highest yield was 0.5/ha (4,700 kg/ha) followed by 1.01lha(4,079.69 kg), while lower yield of 3,112.95 was recorded on the control (0.0l/ha).There was less stem tunneling and breakage at 1.5 Vha. The variety that gave the highest yield was T2L-Comp.4c2 (5,022.0Kg/ha) while the least was SWAN 1(white) obtained from Osun State ADP (1,716 kg/ha). The Ex- Jalingo yellow and white cultivars gave moderate yields of 4.500.95 and 4,421.80 kg/ha respectively. Higher yields were obtained from Jalingo than at Yola. It is recommended here that the improved varieties obtained from IITA be used for planting by farmers, while the local cultivars obtained at Jalingo should be improved by breeders since they were relatively more promising than the SWANs.

Hydroxycinnamate Synthesis and Association with Mediterranean Corn Borer Resistance.

Previous results suggest a relationship between maize hydroxycinnamate concentration in the pith tissues and resistance to stem tunneling by Mediterranean corn borer (MCB, Sesamia nonagrioides Lef.) larvae. This study performs a more precise experiment, mapping an F2 derived from the cross between two inbreds with contrasting levels for hydroxycinnamates EP125 × PB130. We aimed to co-localize genomic regions involved in hydroxycinnamate synthesis and resistance to MCB and to highlight the particular route for each hydroxycinnamate component in relation to the better known phenylpropanoid pathway. Seven quantitative trait loci (QTLs) for p-coumarate, two QTLs for ferulate, and seven QTLs for total diferulates explained 81.7, 26.9, and 57.8% of the genotypic variance, respectively. In relation to borer resistance, alleles for increased hydroxycinnamate content (affecting one or more hydroxycinnamate compounds) could be associated with favorable effects on stem resistance to MCB, particularly the putative role of p-coumarate in borer resistance.

Influence of intercropping on the stem borerChilo partellusin maize

A field experiment was conducted to evaluate the intercrops on the incidence of maize stem borer, Chilo partellus at Maize Research Station, S.D. Agricultural University, Khedbrahma, Gujarat. Among intercrops, maize + cotton combination registered minimum (28.32%) damage and it was statistically at par with maize + sesamum (30.94%) followed by maize + pigeonpea (31.71%) and maize + castor (31.81%). Lowest stem tunneling was found in maize intercropped with pigeonpea (4.05%) and it was statistically at par with maize intercropped with cotton (4.22%) followed by black gram (4.23%) and green gram (4.26%). Highest maize equivalent yield was recorded from the pigeonpea (22.31 q/ha), while lowest maize equivalent yield observed was from black gram (16.10 q/ha)

Assessment of yield losses due to girdle beetle,Obereopsis brevisGahan and stemfly,Melanagromyza phaseoli(Zehnt) on soybean

The losses caused by girdle beetle decreased with increasing crop age. At 10 per cent level of girdle beetle infestation the per cent yield losses observed in no. of pod/plant were 3.75, 1.88, 0.30 & 0.12 per cent at 30, 37, 44 and 51 days after germination (dAG) respectively. upto 10 per cent stem tunneling caused by stemfly the losses observed in no. of pod/plant, no. of seed/plant and weight of seed/plant were 14.09, 22.71 and 34.16 per cent respectively.

Correlation between agronomic and stem borer resistant traits in maize: Implications in selection

Objective : The interrelationship between agronomic and resistant traits of two stem borer species, and its influence on selection was studied in a yellow maize population, DMR ESR-Y, at Ibadan between 2009 and 2010. Methodology and results: Two hundred and fifty (250) full-sib progenies of the population with three checks were evaluated. Resistant traits had negative correlations with most agronomic traits including grain yield (GY). GY had significant relationship with days to 50% pollen shed, (DTA) (rg = 0.49**), plant height (PH) (rg = 0.46**) and ear aspect (EA) (rg = -0.98**). Indirect selection of GY via DTA and PH gave gains that were a little lower than direct selection for GY, but they have higher heritability. Indirect selection of stem tunnelling and cob damage through EA would give gains of 150.64 % and 106.94 % respectively. Conclusion and application of results : This result suggested that either days to 50% pollen shed or plant height could be considered in selection for stem borer resistance. Ear aspect is another good criterion to consider instead of cob damage and stem tunnelling to hasten selection. The result indicated that breeders selecting for stem borer resistance and high yield could consider plant height, days to 50% pollen shed, ear aspect and grain yield itself as criteria for selection. In selecting the best genotypes in any crop improvement study therefore, breeders need to consider not only the magnitude of the correlation between pairs of traits, but the desirability of their relationship, ease of measuring the traits, correlated response among the traits, and heritability of the secondary trait selected. Keywords : Correlated responses, heritability, secondary traits, selection, stem borer resistance

Response to S1 recurrent selection for resistance to two stem borers, Busseola fusca and Chilo partellus, in two tropical maize populations

AbstractStem borers, Busseola fusca and Chilo partellus, are among the key devastating lepidopteran insect pests of maize causing grain yield losses. Recurrent selection studies for stem borer resistance in maize are limited. However, maize populations carrying resistance genes to these stem borers have not been exploited fully in breeding programmes. The objective of the study was to separately improve resistance to B.fusca and C.partellus stem borers for two maize populations CML395/MBR C5 Bc and CML444/MBR/MDR C3Bc and therefore grain yield after two cycles of S1 progeny recurrent selection. Cycle 0 and the advanced generations (cycle 1-susceptible, cycle 1-resistant and cycle 2-resistant) were evaluated at three locations in Kenya using a 35 × 12 α-lattice design with 2 replications. The net reductions in cumulative tunneling, number of exit holes and leaf feeding damage scores ranged from 0 to 69 % for both populations after two cycles of selection. In the two populations, each cycle of selection for borer resistance improved grain yield by 0.5–0.8 t ha−1. Actual net gains in grain yield with reference to cycle 0 were 43 % for population CML395/MBRC5 Bc under B. fusca infestation and 70 % under C. partellus infestation. For population CML444/MBR/MDR C3Bc, the actual net gains in grain yield were 25 % under B. fusca infestation and 36 % under C. partellus infestation. The reductions in the injurious effects attributable to leaf feeding damage, cumulative stem tunneling and number of exit holes contributed towards the 43 and 70 % net genetic gain in grain yield under B. fusca and C. partellus infestation respectively, for both populations. Broad sense heritability (H2) for grain yield ranged from 2 to 98 % in both maize populations. The study showed that two cycles of S1 progeny recurrent selection was effective in accumulating favourable alleles for B. fusca and C. partellus stem borer resistance.

Covalent Cross-Linking of Cell-Wall Polysaccharides through Esterified Diferulates as a Maize Resistance Mechanism against Corn Borers

There is strong evidence to suggest that cross-linking of cell-wall polymers through ester-linked diferulates has a key role in plant resistance to pests; however, direct experimentation to provide conclusive proof is lacking. This study presents an evaluation of the damage caused by two corn borer species on six maize populations particularly selected for divergent diferulate concentrations in pith stem tissues. Maize populations selected for high total diferulate concentration had 31% higher diferulates than those selected for low diferulates. Stem tunneling by corn borer species was 29% greater in the population with the lowest diferulates than in the population with the highest diferulates (31.7 versus 22.6 cm), whereas total diferulate concentration was negatively correlated with stem tunneling by corn borers. Moreover, orthogonal contrasts between groups of populations evaluated showed that larvae fed in laboratory bioassays on pith stem tissues from maize populations with higher diferulates had 30-40% lower weight than larvae fed on the same tissues from maize populations with lower diferulates. This is the first report that shows a direct relationship between diferulate deposition in maize cell walls and corn borer resistance. Current findings will help to develop adapted maize varieties with an acceptable level of resistance against borers and be useful in special kinds of agriculture, such as organic farming.

Seasonal incidence of major insect pests of soybean

The incidence of leaf miner, A. modicella (maximum 0.02 larvae/plant in 32nd MW), S. litura (maximum 0.33 larvae/plant in 32nd & 35th MW) and H. armigera (maximum 0.66 larvae/plant in 32nd mw) was very low/negligible. the girdle beetle, O. brevis incidence started in 30th MW by recording 1.36% infestation which at harvest reached 61.22% whereas stem tunneling observed due to stemfly at physiological maturity was 59.45%. Green semiloooper, G. gema recorded a peak of 3.00 larvae/mrl during 34th MW. the infestation of O. brevis in relation to bright sunshine hours (0.714*) was positively significant and negatively significant with wind velocity (−0.674*). the population of G. gema in relation to wind velocity (r = 0.613*) was found positive and significant.

Correlation and regression between weather parameters and major insect pests of soybean

The girdle beetle, Obereopsis brevis infestation started in 30th MW (1.36%) and reached to 61.22% at harvest whereas stem tunneling due to stemfly at physiological maturity was 59.45%. Green semiloooper, Gesonia gema recorded a peak of 3.00 larvae/mrl during 34th MW. The infestation of Obereopsis brevis in relation to bright sunshine hours (0.714*) was positively significant and negatively significant with wind velocity (−0.674*).

Identification of new sorghum genotypes resistant to the African and spotted stemborers

Lepidopteran stemborers, mainly the African stemborer Busseola fusca Fuller and spotted stemborer Chilo partellus Swinhoe, are among the economically important pests of sorghum in Kenya. Identification of sources of resistance is valuable for the development of an integrated pest management strategy to minimize losses. This study evaluated 27 genotypes with artificial infestations (mostly for tolerance) in two different agroecological zones. Data on damage from leaf feeding, dead heart, exit holes, and stem tunnelling; plant height; days to 50% flowering; total grain yield; and hundred-grain mass were collected. Significant differences (P ICSB 464>ICSB 467>ICSA 472>ICSB 472>ICSA 473>ICSA 474>IESV 91131 DL>Macia. The relative contributions of the damage parameters to grain yield loss were partitioned into direct and indirect relationships by path coefficient analysis with grain yield as the resultant variable. The results revealed that damage from exit holes, dead heart, leaf feeding and stem tunnelling had a negative indirect effect on grain yield. The identified genotypes can be used to enhance resistance to both pests in susceptible cultivars that farmers prefer.

Efficacy of the aqueous crude seed extract of Millettia ferruginea (Fabaceae) on the maize stemborer Busseola fusca (Lepidoptera: Noctuidae) in the field

The efficacy of different aqueous dilutions of crude seed extract of Millettia ferruginea (Hochst.) Baker (1, 3, 5 and 10%) was evaluated under field conditions in terms of the level of damage and yield loss of maize caused by the maize stemborer Busseola fusca (Fuller) in Hawassa, southern Ethiopia. The insecticide lambda-cyhalothrin 5EC., applied at a rate of 16g active ingredient/hectare, was used as the reference product. The experiment was carried out in a randomized complete block design with four replications. The maize variety A511 was planted in individual plots of 60 m2. Data on stand count, leaf infestation, bored stem and dead heart were collected weekly. Plots sprayed with the 5% concentration of Millettia showed low levels of damage (9–11% leaf infestation, 0.4% dead heart, 14–17% bored stem and <0.2% bored ear), compared with plots sprayed with lambda-cyhalothrin. The treatments with 1 and 3% concentrations of Millettia were inferior to those with lambda-cyhalothrin and 5 and 10% concentrations of Millettia. In contrast, the treatment with the 10% concentration of Millettia led to the death of plants, thereby lowering the yield. About 80% of the total length of individual maize stalks from the untreated plots was internally tunnelled by the feeding larvae, while the internal stem tunnelling was low (< 7%) in plants treated with Millettia at concentrations of 3,5 and 10%. Among the treatments with Millettia, higher yields (37–48 decitonnes/hectare) were obtained from maize plots treated with 5% concentration. The use of the aqueous crude seed extract of M. ferruginea at a concentration of 5% applied two to three times is recommended for the control of B. fusca in maize.

Maize–planting date interaction and effect of Bt maize on European corn borer (Ostrinia nubilalis (Hubner) (Coleoptera: Crambidae) damage

A study was conducted to determine the influence of planting date and transgenic maize on maize yield following stalk injury by European corn borer, Ostrinia nubilalis (Hubner). Transgenic and non-transgenic maize hybrids with short- and full-season maturity were planted in late April, mid-May and early June from 2006 to 2008 in Ohio, USA. Maize stem tunnelling was significantly higher on non-transgenic maize and increased with delayed planting. Significantly higher yields were obtained from full-season than short-season hybrids when maize was planted early. The results suggest that when planting is delayed and an European corn borer population is known to cause economic damage in an area, selection of short-season hybrids with the Bt gene can be beneficial in controlling damage and improving yield.

Novel source of sorghum tolerance to the African stem borer, Busseola fusca

Sorghum (Sorghum bicolor) is an important cereal food crop in semi-arid tropics, but its productivity is curtailed mainly by insect pests and diseases. The African stem borer,Busseola fusca Fuller (Lepidopteran: Noctuidae), is among the most injurious pests of sorghum in sub-Saharan Africa and is responsible for >15% sorghum grain yield losses. Sorghum from India with records of stem borer invasion could provide supplementary and novel resources of tolerance to this pest. Utilization of tolerant varieties in combination with other methods of control is likely to offer a sustainable strategy for B. fusca management in sorghum production. The objective of this study was to evaluate several local and exotic sorghum genotypes for tolerance to B. fusca. Genotype Swarna from India which is known to be susceptible to Chilo partellus was used as a susceptible check. There is limited information regarding tolerant/resistant sorghum to B. fusca. Seven commercial cultivars and 20 introductions from India were evaluated for B. fusca tolerance at Kabete, in central province of Kenya, during long and short rainy seasons in 2010. Selection index were based on leaf damage, dead hearts, exit holes and stem tunneling. The following genotypes named ICSA 467, ICSA 473, MACIA and ICSB 464 were found to be the most tolerant to B. fusca. These tolerant genotypes, can be used as novel sources of tolerance, and could be introgressed into the local common varieties since they are well adapted to the local environment. Key words: Busseola fusca, Sorghum bicolor, resistance, tolerance, Kenya.

Mechanisms and genetic diversity for host plant resistance to spotted stem borer, Chilo partellus in sorghum, Sorghum bicolor

AbstractLevels of resistance to spotted stem borer, Chilo partellus, in the germplasm are low to moderate and therefore we evaluated 25 sorghum genotypes for resistance to stem borer to identify lines with diverse mechanisms of resistance to this insect. Leaf glossiness was significantly and negatively associated with low deadheart formation. Dwarf genotypes with fewer nodes showed more deadheart formation. Antixenosis and/or antibiosis for leaf feeding, and reduced deadheart formation, tunnelling, and number of exit holes resulted in lower losses owing to C. partellus damage. Axillary tillers compensated for loss in grain yield owing to borer infestation as a result of deadheart formation, but their synchrony for maturity with the main plant is quite important. Path coefficient analysis revealed that direct effects of stem tunnelling on loss in grain yield were greater than leaf feeding and deadhearts. However, leaf feeding via stem tunnelling showed maximum indirect effects on loss in grain yield. Estimates for broad‐sense heritability and genetic advance suggested that it is possible to improve for grain yield under stem borer infestation. Heritability estimates for grain yield were usually higher than for stem borer damage parameters. Multi‐trait cluster analysis placed the test genotypes into four and five clusters in rainy and post‐rainy seasons, respectively. The genotypes placed in different groups, and showing resistance to leaf feeding, deadheart formation, stem tunnelling, and/or compensation in grain yield can be used for sorghum improvement.

Comparison of selection indices to identify sorghum genotypes resistant to the spotted stemborer Chilo partellus (Lepidoptera: Noctuidae)

The resistance or susceptibility of sorghum genotypes to damage by the spotted stemborer Chilo partellus (Swinhoe) is commonly measured in terms of leaf damage, deadheart formation and stem tunnelling. Effect of the host plant on the insect survival and development (antibiosis) and the response of the plant to insect damage (tolerance or recovery resistance) are also important parameters for measuring host plant resistance to stemborers. We compared ten selection indices commonly used to select genotypes for tolerance/resistance to various stresses, namely functional plant loss index (FPLI), antibiosis index (ABI), mean productivity index (MPI), mean relative performance (MRP), relative efficiency index (REI), tolerance index (TOL), Fischer's and Maurer's stress susceptibility index (FMSSI), Fernandez stress tolerance index (FSTI), geometric mean productivity (GMP) and Schneider's stress severity index (SSSI). The results suggest that the indices based on grain yield reduction can be combined with those associated with grain yield response and potential under borer-infested and uninfested conditions, since each index assesses different biological mechanisms (such as tolerance, adaptation and/or productivity). Among these, FPLI can be used to differentiate the sorghum genotypes for different components of resistance by taking into account both foliar damage and deadheart formation. GMP, REI and FSTI provided a better discrimination of the stemborer-tolerant genotypes under borer-infested conditions, and were better predictors of grain yield performance than TOL, MPI, MRP, ABI, SSSI, FMSSI and FPLI. A strong association between GMP and REI indicated that both these indices could be used to select for low grain yield loss and high productivity. However, the selection of genotypes with high grain yield potential and adaptation to borer infestation may be achieved by combining selection indices related to the mean grain yield performance under borer-infested and uninfested conditions (GMP and REI), and low levels of grain yield loss under borer infestation.