Agroforestry Systems 49: 319–326, 2000.  2000 Kluwer Academic Publishers. Printed in the Netherlands.

Relative natural resistance of Populus deltoides clones against defoliator Clostera cupreata (Lepidoptera: Notodontidae) in northern India A. P. SINGH Division of Forest Entomology, Forest Research Institute, P.O. New Forest, Dehra Dun, U.P., India. 248 006; E-mail: [email protected] Key words: feeding potential, pest, poplar, susceptibility Abstract. Populus deltoides (poplar) that is extensively being planted commercially in agroforestry combinations in northern India is prone to attack by a defoliating insect, Clostera cupreata. In order to evaluate the relative susceptibility/resistance of different clones and to identify the resistant ones, 80 clones of American origin were evaluated in Dehra Dun, India. The feeding potential of the pest on different clones varied significantly. The clones were grouped into six categories depending on their susceptibility as most resistant or R1 (12 clones), moderately resistant or R2 (14 clones), marginally resistant or R3 (10 clones), marginally susceptible or S1 (17 clones), moderately susceptible or S2 (18 clones) and most susceptible or S3 (nine clones). Clone ‘110120’ of Tennessee was most resistant where as Oklahoma clone ‘104’ was most susceptible to this pest. Amongst the most resistant clones (R1), only three clones, WSL-4, WSL-12 and WSL-18 (source: WIMCO Seedlings Ltd, India) were found to be superior, in terms of growth increment, as compared to the standard and most widely planted clones in northern India i.e. G-3 and G-48, and are promising clones for plantation in defoliator prone areas.

Introduction Enhancing wood production is an urgent necessity today especially in developing and over-populated countries like India. To achieve this goal hundreds of clones/hybrids of Populus deltoides Bartr. Ex. Marsh. have been introduced in northern India (above 28° N latitude) from USA, Australia and Europe, since 1965. The performance of these clones in terms of survival and growth is being monitored in nurseries as well as in the field plantations throughout north Indian states (Kumar et al., 1999). Several promising clones [G-3, G-48 (Australian), S7C15, S7C8, S7C14, ST-67, ST-121 (American), L-34, L-82, L-83, L-84 (Indian) etc.] of P. deltoides have also been identified and planted extensively under different agroforestry systems (bund, block and row plantations) on a commercial scale (Kumar et al., 1999 and Sharma, 1999). During the period 1984–92 alone, under a collaborative agro-farmforestry project carried out by WIMCO (Western India Match Company Ltd) – NABARD (National Bank for Agriculture and Rural Development, India), 15,837 farmers planted 1.32 million poplars over an area of 26,446 ha in northern states of Uttar Pradesh, Punjab and Haryana (Jones and Lal, 1989).

320 The short rotation time (about eight years), high productivity (above 30 m3 ha–1/annum in 5.25 to seven years for clone G-3 raised in block plantations (Chaturvedi and Rawat, 1994 and Dogra, 1999)), winter deciduous nature (FAO, 1979), increasing demand and good market price for its timber (used as fuelwood, plywood, matchwood, pulpwood, veneer, furniture, planks, etc.) make P. deltoides today a very popular tree among north Indian farmers (Chaturvedi, 1992 and Singh et al., 1999). However, P. deltoides is prone to infestation by a prime insect defoliator, Clostera cupreata Butler (Lepidoptera: Notodontidae) in India. Large-scale defoliation by this pest has been reported from the Tarai region of northern India (Lohani, 1979 and Chaturvedi, 1981). During 1981 an outbreak by this insect pest raged over an area of over 1100 ha in ‘Tarai Central Forest Division’ (Singh et al., 1983). Attack by Clostera spp. significantly decreases the growth increment of poplar trees (Gao et al., 1985). Furthermore, severe and repeated defoliation in young plants by this pest results in their mortality (Singh and Singh, 1986). One way to cope with this pest problem is to find out resistant/susceptible clones and manipulate them against the pest. It is known that resistance to the pest varies amongst clones, hybrids, provenance’s, cultivars and species of the genus Populus (Defauce, 1976; Qin and Gae, 1985; Jodal, 1987; Ahmad, 1993 and Singh and Singh, 1995). Variations also exist among poplar clones in terms of growth characteristics of the insect, such as survival, pupal fresh weight, length of life cycle (Augustin et al., 1994), feeding preference (Robison and Ruffa, 1994), feeding potential (Ahmad, 1993 and Augustin et al., 1993 ), mating (Maxwell and Jennings, 1980) and oviposition (Augustin et al., 1993). In India, only a few studies have been carried out to evaluate clones of P. deltoides for their comparative resistance/susceptibility against this pest. Ahmad (1993) evaluated 109 clones originating from five different countries (Australia, Germany, Italy, the Netherlands and USA), for ‘feeding potential’ under laboratory conditions. This paper reports the results of a study to evaluate 80 clones of P. deltoides for feeding potential of C. cupreata also under laboratory conditions. However, 79 clones out of these are different from those evaluated by Ahmad (1993).

Materials and methods Insect resistance of poplar clones was evaluated on the basis of feeding potential (the amount of food consumed by the insect), which is one of the common criteria used in such studies (Dahms, 1972 and Ahmad, 1993). A total of 80, one-year-old clones of P. deltoides of American origin (except one Italian hybrid), raised at the ‘Poplar Germplasm Bank’ at Forest Research Institute, Dehra Dun, India (30°20′ N latitude and 77°52′ E longitude) were taken up for the study. A culture of Clostera cupreata was maintained in the

321 laboratory for experiments. Five, second instar larvae (newly molted from first to second stage) were released in a petri dish (15 × 2 cm) on a pre-measured leaf taken from the middle portion of the plant of each clone for maintaining homogeneity within it. After 48 h of feeding, the leaves were again measured and replaced with a new pre-measured leaf. The experiment was continued till the formation of pupae by all the larvae. Study was conducted in a randomized complete block design with three replications. Average daily maximum and minimum temperatures during the study period were 22 and 36 °C, respectively. The relative humidity varied between 74 to 96 per cent. Data was analyzed by analysis of variance. Mean leaf area consumed by larvae for each clone ( x), standard deviation (SD), and the over all mean of the leaf area consumed for all the 80 clones ( X) were calculated. Resistant and susceptible clones were grouped into six categories following the procedure of Ahmad (1993) as given below. R1 = Most resistant =x(A) < ( X – SD) R2 = Moderately resistant = ( X – SD ) <x(A) < ( X – SD/2) R3 = Marginally resistant = ( X – SD/2) <x(A) < ( X) S1 = Marginally susceptible = ( X + SD/2) >x(A) > ( X) S2 = Moderately susceptible = ( X + SD) >x(A) > ( X + SD/2) S3 = Most susceptible =x(A) > ( X + SD) Results and discussion Maximum and minimum leaf area consumed by poplar defoliator was 484.0 cm2 and 105.5 cm2, respectively with an overall mean ( X) of 269.5 cm2 and Standard Deviation (SD) = 79.87 (CV = 29.64). Clones were divided into six groups comprising of R1, R2 and R3 as resistant and S1, S2 and S3 as susceptible groups. Only 36 clones were found resistant while the remaining 44 clones were observed as susceptible (Table 1). 12 Clones were found most resistant (R1) against C. cupreata (Table 1) as 105.6 to 187.7 cm2 of the leaf area was consumed. Clone no. ‘110120’ of Tennessee was the most resistant. However, only three clones (WSL-18, WSL-12 and WSL-4) in this category (R1) have been found superior to the standard and most widely planted clones i.e. G-3 and G-48, in northern India, in terms of growth increment (height and diameter) measured after four years of planting in the field (WIMCO, 1998). 14 Clones fall in the second category of resistant clones (R2). The range of foliage consumed was 194.1 to 225.4 cm2. Amongst these only six clones (WSL-71, WSL-30, WSL-1, WSL-34, WSL-36 and WSL-23) had performed better than the standard clones in terms of growth increment. Hybrid ‘Triplo-1-37-61’ which fell in this category (R2) was also ranked by Ahmad (1993) as a ‘moderately resistant clone’ at 50th position amongst 109 clones. Only 10 clones were moderately resistant (R3)

322 Table 1. Comparative resistance of Populus deltoides clones against the defoliator Clostera cupreata, measured in terms of leaf area eaten in Dehra Dun, India. Origin (USA)

Source

Mean ( x) leaf area eaten (cm2)

R1. Most resistant 01.* 110120 02.* WSL-18 03.* CP-82-1-12 04.* ST-153 05.* ST-238 06.* WSL-12 07.* WSL-42 08.* 113520 09.* EL-74 10.* WSL-4 11. EL-89 12.* WSL-7

Tennessee – – Mississippi Mississippi – – – Louisiana – – –

Shelby, USA WIMCO, Bagwala, India WIMCO, Bagwala, India Issaquena, USA Issaquena, USA WIMCO, Bagwala, India WIMCO, Bagwala, India USA UPSFD, Lalkuan, India WIMCO, Bagwala, India UPSFD, Lalkuan, India WIMCO, Bagwala, India

105.57 115.58 119.51 129.30 129.82 134.47 143.54 146.54 154.93 166.50 172.75 187.65

R2. Moderately resistant 13. 149-84-6955 14.* WSL-71 15. ST-261 16. WSL-30 17.* 64-054-01 18.* Triplo 1-37-61 # 19. ST-148 20. WSL-49 21.* WSL-1 22. WSL-34 23. WSL-36 24.* 2 25. ST-92 26. WSL-23

– – – – Pennsylvania Casale (Italy) Mississippi – – – – Kentucky Mississippi –

Portugal WIMCO, Bagwala, India Issaquena, USA WIMCO, Bagwala, India USA Casale, Monferato, Italy Issaquena, USA WIMCO, Bagwala, India WIMCO, Bagwala, India WIMCO, Bagwala, India WIMCO, Bagwala, India USA Issaquena, USA WIMCO, Bagwala, India

194.13 195.40 198.15 200.85 202.60 203.45 206.63 209.47 211.45 211.97 219.92 220.97 221.66 225.41

R3. Marginally resistant 27. WSL-69 28. ST-4 29. WSL-57 30.* 6401 31. WSL-37 32. 110412 33. L-13 34. WSL-61 35. WSL-3 36.* S4C2

– Mississippi – Illinois – Mississippi – – – Texas

WIMCO, Bagwala, India Issaquena, USA WIMCO, Bagwala, India The Netherlands WIMCO, Bagwala, India USA UPSFD, Lalkuan, India WIMCO, Bagwala, India WIMCO, Bagwala, India USA

233.99 237.07 241.55 242.89 247.85 250.48 250.49 253.89 257.36 258.58

S1. Marginally susceptible 37. WSL-21 38.* WSL-28 39. WSL-56 40. WSL-66

– – – –

WIMCO, WIMCO, WIMCO, WIMCO,

274.73 275.57 276.31 277.49

Sl. no.

Clone

Bagwala, Bagwala, Bagwala, Bagwala,

India India India India

323 Table 1. (Continued). Mean ( x) leaf area eaten (cm2)

Sl. no.

Clone

Origin (USA)

Source

41. 42.* 43. 44. 45.* 46. 47. 48. 49. 50.* 51. 52. 53.

WSL-14 WSL-59 ST-124 WSL-51 ST-285 WSL-19 CP-82-6-1 ST-75 2502 WSL-54 CP-82-1-10 ST-70 WSL-70

– – Mississippi – Mississippi – – Mississippi Mississippi – – Mississippi –

WIMCO, Bagwala, WIMCO, Bagwala, Issaquena, USA WIMCO, Bagwala, Issaquena, USA WIMCO, Bagwala, WIMCO, Bagwala, Issaquena, USA Washington, USA WIMCO, Bagwala, WIMCO, Bagwala, Issaquena, USA WIMCO, Bagwala,

S2. Moderately susceptible 54. I-8 55. 110236 56. ST-100 57. SNF-1300 58. ST-71 59. WSL-16 60. WSL-65 61. WSL-22 62. 430-4 63.* WSL-53 64. WSL-20 65. 110610 66. WSL-68 67. SNF-1203 68. CP-82-1-19 69. WSL-52 70. WSL-2 71. ST-67

Oklahoma – Mississippi – Mississippi – – – Louisiana – – Mississippi – – – – – Mississippi

USA USA Issaquena, USA Portugal Issaquena, USA WIMCO, Bagwala, WIMCO, Bagwala, WIMCO, Bagwala, USA WIMCO, Bagwala, WIMCO, Bagwala, USA WIMCO, Bagwala, Portugal WIMCO, Bagwala, WIMCO, Bagwala, WIMCO, Bagwala, Issaquena, USA

S3. Most susceptible 72.* WSL-47 73.* 421-2 74. 61/58 75. L-29 76.* CP-82-6-13 77. CP-82-6-2 78.* 112910 79. 2.000 Verdi # 80.* 104

– Louisiana – – – – – – Oklahoma

WIMCO, Bagwala, India St. Landry, USA Australia UPSFD, Lalkuan, India WIMCO, Bagwala, India WIMCO, Bagwala, India USA Portugal USA

India India India India India

India India India

India India India India India India India India India

282.54 284.72 284.86 285.38 285.99 286.34 286.71 287.23 293.20 295.33 301.66 302.83 307.11 311.22 311.57 315.95 317.47 317.48 319.95 320.33 321.94 322.66 327.65 329.90 332.72 332.99 336.71 339.53 341.11 342.58 342.92 354.82 356.82 359.09 362.30 369.56 377.12 400.55 423.53 483.97

* = Only 1 replication (29 clones); # = Hybrid (Triplo 1-37-61 = P.x euramericana); UPSFD = Uttar Pradesh State Forest Department; WIMCO = Western India Match Company.

324 and the mean leaf area fed by the larvae ranged from 234.0 to 258.6 cm 2. Only four clones (WSL-69, WSL-37, L-13 and WSL-61) amongst these showed better growth than the standard clones . 44 Clones were found susceptible under various categories (S1, S2 and S3) with mean leaf area consumed from 274.7 to 484.0 cm2 (Table 1). A total of 15 clones were marginally susceptible (S1) having defoliation of 274.7 to 307.1 cm2. Out of these as many as nine clones (WSL-21, WSL-28, WSL-56, WSL-14, WSL-59, WSL-19, 82-6-1, 82-1-10 and ST-70) have shown better growth than clones G-3 and G-48 (WIMCO, 1998). 19 Clones were in moderately susceptible category (S2) having defoliation of 311.2 to 342.9 cm2. Of these only four clones (WSL-16, WSL-22, WSL-20 and WSL-68) had greater height and diameter than G-3 and G-48 clones in the field (WIMCO, 1998). Nine clones were most susceptible (S3) with leaf area eaten between 354.8 to 484.0 cm2. The most susceptible clone was ‘104’ from Oklahoma, USA There were only three clones in this category (L-29, CP-82-6-13 and CP-82-6-2) which had better growth than the standard clones. Analysis of variance for 51 clones showed that there was significant difference between the leaf area consumed by C. cupreata amongst different clones. This study reveals that three clones, WSL-18, WSL-12 and WSL-4, are most resistant (R1) to C. cupreata and also have been found suitable for planting in terms of growth performance. Earlier, Ahmad (1993) had also identified 13 clones (ST-17, A-37, ST-92, ST-29, 6330, 73/53, 3276, 2673, 6387, ST-171, 3367, 2647 and ST-82) as ‘most resistant’ out of 108 other P. deltoides clones. Amongst these 13 clones, growth data for six clones (ST-17, ST-92, ST-29, 73/53, ST-171 and D-82) are available and only three clones (ST-67, ST-171and ST-82) having source and origin in Mississippi, USA, have performed better in field trials in terms of growth increment as compared to the standard clone i.e. G-3 (Kumar et al., 1999). The study concludes that these six clones (WSL-4, WSL-12, WSL-18, ST-67, ST-82 and ST-171) are promising clones which can be recommended as for planting in defoliator-prone areas of northern India as a choice amongst 109 clones evaluated by Ahmad (1993) and 80 clones worked out by this study. On the other hand clones, L-29, CP-82-6-13 and CP-82-6-2 which are although superior to the standard clones (G-3 and G-48) in terms of growth should be avoided for plantation in defoliator affected areas as they are most susceptible to this pest.

Acknowledgements The author is thankful to Rajiv Pandey, for statistical analysis of the data and to Dinesh Kumar, a tree breeder and associate-chief technical advisor, in ‘poplar improvement program’, for providing the plant material, both working at Forest Research Institute (Indian Council of Forestry Research and

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