Screening of cowpea germplasm for resistance to Aphis craccivora Koch. in India

This article was downloaded by: [York University Libraries] On: 21 November 2014, At: 05:08 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK Tropical Pest Management Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/ttpm19 Screening of cowpea germplasm for resistance to Aphis craccivora Koch. in India B. G. Jayappa a b & S. Lingappa a c a Department of Agricultural Entomology , University of Agricultural Sciences , Hebbal, Bangalore, 560 024, India b Assistant Agricultural Officer , Hosadurga, Chitradurga, Karnataka, India c Department of Ag. Entomology , U. A. S. , Dharwad, 580005, India Published online: 13 Nov 2008. To cite this article: B. G. Jayappa & S. Lingappa (1988) Screening of cowpea germplasm for resistance to Aphis craccivora Koch. in India, Tropical Pest Management, 34:1, 62-64, DOI: 10.1080/09670878809371209 To link to this article: http://dx.doi.org/10.1080/09670878809371209 PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. 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Terms & Conditions of access and use can be found at http://www.tandfonline.com/page/terms-and-conditions http://www.tandfonline.com/loi/ttpm19 http://www.tandfonline.com/action/showCitFormats?doi=10.1080/09670878809371209 http://dx.doi.org/10.1080/09670878809371209 http://www.tandfonline.com/page/terms-and-conditions TROPICAL PEST MANAGEMENT, 1988, 34(1) 62-64 Screening of cowpea germplasm for resistance to Aphis craccivora Koch. in India (Keywords: Screening, cowpea, resistance, Aphis craccivora) B. G. JAYAPPA† and S. LINGAPPA‡ Department of Agricultural Entomology, University of Agricultural Sciences, Hebbal, Bangalore-560 024, India Abstract. Four hundred and eight entries of cowpea Vigna unguicu- lata (L.) Walp were screened for aphid resistance in three field trials during 1982 and 1983. In a preliminary trial, entries were evaluated on an infestation index and on percentage plants showing leaf curl symptoms, and in later trials on the aphid population in the terminal shoot and a foliar damage index. Mandya local, MS-370, TVU-2740, P-912 and P-1475 entries exhibited greater consistency in resisting aphid attack. Introduction Next to pod borers, aphid (Aphis craccivora Koch.) is an important pest of cowpea, Vigna unguiculata (L.) Walp. causing considerable damage, especially during dry sea- sons. They attack all vegetative parts and cause leaf curling, loss of vitality and reduction in growth. In severe cases, plants fail to bear flowers and pods resulting in 20-40% loss in yield in Asia (Singh and Allen, 1980). The use of insecticides has been the recomended control practice, but is expensive in a low value crop, destroys natural enemies and causes toxic hazards in the environment. Therefore, the use of resistant varieties was thought to be an alternative method in the integrated control of aphids. Singh (1977) found TVU-408 P2, TVU-416, TVU-2740, TVU-3417 and TVU-3509 to be resistant, on the basis of average aphid population per 2-5 cm length of terminal shoots. Charles Bell (1980) rated P-1476, EC-4276, T-4222 as being resistant among 259 cowpea germplasms screened. Karel and Malinga (1980) evaluated 11 cowpea entries for resistance to Acyrthosiphon gossypii Mordv. based on a foliar damage scale of 0-5, and rated TVU-408 P2, TVU-410 and lebrown as resistant. Dhanorkar and Dawäre (1980) screened 14 cultivars by counting the number of aphids per leaf and per 2-5 centimetre length of stem and pods. P-1473 and P-1476 were completely free from aphids while HG-22 and CM-11 had the highest infestation. Anony- mous (1982) reported TVU series as resistant to aphids. Jayappa (1984) studied the response of cowpea germplasm to aphids and pod borer attack. Materials and methods 1982 Trial Four hundred and eight entries maintained at the All India Co-Ordinated Research Project on Pulses, University of Agricultural Sciences (U. A. S.), Bangalore were screened for aphid resistance in field under natural infestation during June—August 1982. The entries were raised in single row plots of two meter length at the Main Research Station, U. A. S. Hebbal, Bangalore. Weekly observations were recorded on the aphid infestation 30 d.a.s. The intensity of infestation on five plants per entry were placed on a 0—4 scale: (0, free from aphids; 1, less than 26%; 2, 26 to 50%; 3, 51 to 75%; and 4, 76 to 100% of the plant area covered by aphids). The mean infestation index was worked out by multiplying the number of plants falling in each class with class value and dividing by the number of observations. The percentage of plants showing leaf curl symptoms was also recorded. Based on these two values, entries were grouped into 4 classes (0-0-1-0,1-1-2-0, 2-1-3-0 and 3-1-4-0 infestation index and 0-10,11-20,21—30 and more than 30% plants showing leaf curl symptoms), described as resistant, moderately resistant, susceptible and highly susceptible, respectively. Intensive trial 1983 During April—June 1983, 197 entries were selected for screening from the preceeding trial. The entries were sown in 2 m length rows. The aphid population was recorded weekly from 30 d.a.s. Aphid population was recorded according to Hanifa ei at. (1973). Since the aphids mostly colonize the terminal shoots, the population was recorded from the 2-5 cm length of terminal shoots. The mean population from two shoots per plant and ten plants was then computed. The extent of foliar damage was also recorded by the method of ' Karel and Malinga (1980). The entries were scored on 0-4 scale (0-No damage; 1-1 to 25%; 2-26 to 50%; 3-51 to 75% and 4 more than 75% of the plan showing foliar damage). The mean damage index (FDI) was calculated as before. The mean population of aphids on terminal shoots and mean FDI were used jointly to assess the varietal reaction to aphid infestation as indicated in Table 1. Advanced trial 1983 From the preceding trial, 13 entries listed in Table 4 as resistant were retested along with three susceptible and four highly susceptible entries selected as check to compare the performance in the field screening trial during July- September 1983. The entries were sown in single row, 2 m long, replicated three times in a randomized block design. Part of the M.Sc. (Agri.) thesis submitted to the University of Agricultural Sciences, Bangalore, India, by the first author. Present address: †Assistant Agricultural Officer, Hosadurga, Chitradurga, Karnataka, India, ‡Department of Ag. Entomology, U. A. S., Dharwad 580005, India. D ow nl oa de d by [ Y or k U ni ve rs ity L ib ra ri es ] at 0 5: 08 2 1 N ov em be r 20 14 Screening covvpea for resistance to Aphis craccivora 63 Screening techniques were similar to the preceding trial. Table 1. Index used for rating aphid damage to cowpea. Table 4. Reaction of selected cowpea entries to aphid attack in the advanced screening trial. Mean aphid population per 2-5 cm length of terminal shoots 100 100-200 100-200 200 200 Foliar damage Index 00-1-0 0-0-1-0 1-1-3-0 1-1-3-0 3-1-4-0 Resistance rating Resistant Moderately resistant Intermediate Susceptible Highly susceptible Results The performance of entries in the preliminary 1982 trial is given in Table 2. A fairly large number of entries, 86 based on the infestation index and 131 based on percentage plants showing leaf curl symptoms were classed as resistant. However, only 20 entries were common to both groups. One hundred and ninty seven entries considered as promising based on either or both of the above parameters were then included in the intensive screening trial in which only 13 were graded as resistant (Table 3) based on aphid population per 2-5 cm length of terminal shoot and foliar damage index. Table 2. Aphid resistance rating based on infestation index. (June- August 1982). Rating Resistant Moderately resistant Susceptible Highly susceptible Infestation index 0-0-1-0 1-1-2-0 2-1-3-0 3-1-4-0 No. of entries 86 76 159 87 Aphid resistance rating based on leaf curl symptoms (June-August Rating Resistant Moderately resistant Susceptible Highly susceptible 1982) Percentage plants showing leaf curl symptoms 0-10 11-20 21-30 30 No. Of entries 131 126 63 . 88 Table 3. Classification of varietal performance based on aphid population on terminal shoot and foliar damage index (April-June 1983). Class Aphid population per 2-5 cm length of terminal shoot Foliar damage index No. of entries Resistant Moderately resistant Intermediate Susceptible Highly susceptible 100 100-200 100-200 200 200 00-1-0 00-1-0 1-1-30 1-1-3-0 3-1-4-0 13 27 96 54 Entries Mandya local P-912 P-1475 MS-370 TVU-2740 TVU-857 P-560 EC-1957 P-1473 TVU-851 TVU-1948 C-152X Lolita 9558-1 C-2085 TVU-410 EC-2056 P-1115 S-488-B ECR-169 5-19-4-1 L.S.D. at 5% level at 1% level Average no. of aphids per 2-5 cm length of terminal shootf 710 71-2 780 84-1 99-5 100-1 101-2 102-7 104-4 106-6 110-8 118-5 1230 166-2 188-2 215-1 221-3 232-4 234-2 253-7 36-7 48-2 Average foliar damage indexf 0-7 0-9 0-8 0-8 0-7 0-8 10 1-1 0-8 1-2 0-8 1-1 2 0 2-2 2-8 3 0 3-2 3-1 3-1 3-7 0-3 0-3 Resistance rating R R R R R MR MR 1 MR 1 MR 1 1 S S S HS HS HS HS tAverage of 30 observations from three replications. R-Resistant, MR-Moderately resistant, l-lntermediate S-Susceptible, HS-Highly Susceptible. Advanced trial 1983 Table 4 shows that the aphid population ranged from 71 -0 to 253-7 and FDI ranged from 0-7 to 3-7. The most promising entries were: Mandya local, P-912, P-1475, MS-370 and TVU-2740, rated finally as resistant. It was interesting that despite the same technique of screening, eight entries rated as resistant in the preceding trial exhibited varying degrees of susceptibility. Of these, TVU-857, P-560, P-1473 and TVU- 1948 with more than 100 aphids per 2-5 cm terminal shoot and more than 0·75 FDI were classed as moderately resistant, while EC-1957, TVU-851, C-152 X Lolita and 9558-1 were rated as intermediate. EC-2056 which recorded 215-1 aphids and 3-03 FDI was classed as highly suscepti- ble. Seven entries which were used as a check confirmed their graded response as susceptible except for EC-2056 which was rated as highly susceptible. Morphological and anatomical characters studied in these 20 entries did account for the variation in the level of resistance, either singly or in combination. Discussion In the initia) stages of a screening programme quicker, easier and reliable techniques are desired to reduce the bulk of entries, and to eliminate potentially susceptible ones. For the same reasons, a mean infestation index and the percentage of plants showing leaf curl symptoms were used as criteria to evaluate varietal performance in the preliminary screening trial. However, in the advanced screening trial more detailed observations of the aphid population on the D ow nl oa de d by [ Y or k U ni ve rs ity L ib ra ri es ] at 0 5: 08 2 1 N ov em be r 20 14 64 B. G. Jayappa and S. LIngappa terminal shoot and the FDI was recorded following Hanifa et al. (1973) in fieldbean and Karel and Malinga (1980) in cowpea. Both criteria were employed concurrently. In the preliminary trial nearly 50% of the test entries (197) appeared to be resistant mainly because the criterion was employed independently. However, only"20 entries were resistant when both criteria were considered. Of the large number of entries in the advanced screening trial, only 13 were classified as resistant to aphid attack. Of these, only five finally emerged as resistant. Both resistant and mod- erately resistant entries were recorded with FDI less than one, while the latter had 100-200 aphid per terminal shoot (Table 4) and less than 100 in the former. The findings suggest that moderately resistant entries are able to with- stand the damage by a higher aphid population than resistant ones, and regarded as tolerant. The susceptible and highly susceptible entries used as checks responded true to character, indicating the techniques of screening in the intensive trial were acceptible. The entry TVU-2740 recorded as resistant and TVU-3509 as intermediate are in partial agreement with Singh (1977) who recorded both as resistant. The entry P-1476 which was reported to be resistant by Charles Bell (1980) and Dhanorkar and Dawäre (1980) was found to be moderately resistant here. P-1473 observed as moderately resistant, was rated as resistant by Dhanorkar and Dawäre (1980). Contrary to the report of Karel and Malinga (1980), TVU-410 was found to be susceptible in the current study, while TVU-310 and TVU-3273 recorded as susceptible and moderately resistant respectively, is in disagreement with the investigations of Anonymous (1982). Differences in the performance of specific entries could be due to variation in the species involved, the evaluation standards or the population level in the field. Field screening against a pest is often confronted with variation in the infestation level of the pest, and repeated trials are necessary before making conclusions about the performance of a variety. Here a large number were eliminated at different stages in the three trials. Mandya local, MS-370, TVU-2740, P-912 and P-1475 were resistant in all the trials, while the majority of the others were partially resistant. The cause of this could be due to any or all of the factors listed by Painter (1951). Another problem is the absence of standard screening techniques, and different evaluation standards have been formulated by various workers. In order to compare results a common standard technique is most wanted. References ANONYMOUS, 1982. Annual Report of the International Institute of Tropical Agriculture. Ibadan, Nigeria, pp. 217. CHARLES BELL, R., 1980. Studies on the resistance in cowpea Vigna unguiculata (L.) Walp, to the aphid Aphis craccivora Koch. M.Sc. (Ag.) thesis, Tamil Nadu Agricultural University, Coimba- tore, India, pp. 79. DHANORKAR, B. K. and DAWARE, D. G., 1980. Differences in number of aphids found on lines of cowpea in a replicated trial. Tropical Grain Legume Bulletin No. 19, 3-4. HANIFA, A. M., BALASUBRAMANIAN, G., LEELA DAVID and SUBRAMANIAM, T. R., 1973. Screening of lablab varieties for resistance to the black bean aphid, Aphis craccivora Koch. South Indian Horticulture 21, 131-133. JAYAPPA, B. G., 1984. Screening of cowpea germplasm for resistance to pod borers and aphids. M.Sc. (Agri.) thesis, University of Agricultural Sciences, Bangalore, India, pp. 111. KAREL, A. K. and MALINGA, Y., 1980. Leafhopper and aphid resistance in cowpea varieties. Tropical Grain Legume Bulletin No. 20, 10-11. PAINTER, R. H., 1951. Insect Resistance in Crop Plants. MacMillan Co. New York, pp. 520. SINGH, S. R., 1977. Cowpea cultivars resistant to insect pests in world germplasm collection. Tropical Grain Legume Bulletin No.9, 3-7. SINGH, S. R. and ALLEN, D. T., 1980. Pests, diseases resistance and protection in cowpeas, pp. 419-443 In: Advances in Legume Science Ed. Summerfield, R. J. and Bunting, A. H., University of Reading, England. D ow nl oa de d by [ Y or k U ni ve rs ity L ib ra ri es ] at 0 5: 08 2 1 N ov em be r 20 14