(Heteropsylla cubana Crawford) in Sri Lanka

Vivekanandan, K. and G. D. Bandara. Forest Department, Rajamalwatta Road, Battaramulla,
Sri Lanka.
LEUCAENA SPECIES RESISTANCE TO PSYLLID
(H E TE R O P SYL L A CU BANA CRAWFORD) IN SRI LANKA
Introduction. Giant leucaena was introduced to Sri Lanka about a decade ago and since then
it is being widely used for fuelwood, fodder, and organic fertilizer by farmers.
Since 1987, however, the leucaena psyllid Heteropsylla cubana (Crawford) has become a serious
pest of leucaena species in Sri Lanka and has spread throughout the country. Resistance to the
leucaena psyllid has been observed in many places (Sorensson and Brewbaker 1987, Fuh-Jiumi
Pan 1987). A trial was established, in collaboration with the International Leucaena Psyllid
Trial (LPT) network, by the forest department of Sri Lanka, with the assistance of the Nitrogen
Fixing Tree Association (NFTA), Hawaii, to select resistance varieties to this pest. This report
provides fifteen-month data on psyllid populations, damage and growth performance of 11
Leucaena species/hybrids used in the trial.
M aterials and methods. The trial was established on 23 November 1988 at Kumbalpola,
Kurunegala, Sri Lanka (7°15’N 80°15’E) at 80 m elevation. The mean annual precipitation is
1,900-2,540 mm with two dry spells - one in January-February and the other in August. Mean
temperature is 25° with a maximum of 28°C and minimum of 22 C. Soils at the trial site are
red yellow Podzols soils containing 60-70% sand, 9-20% silt, and 18-21% clay. Soil pH is 6.2.
The experimental design was a randomized complete block with three replicates. The following
Leucaena species/hybrids were planted in 5 m long, double row plots, with 1 m between rows
and 0.25 m between plants within the row (40 trees/plot). The distance between species plots
was 2 m.
Table 1. Leucaena species/hybrids planted.
Origin___________________
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
Leucaena leucocephala K8
Leucaena leucocephala K636
Leucaena pallida K376
Leucaena hybrid KX1 (K376 x K165) Pal x Div 4N OPF2
Leucaena hybrid KX2 (K8 x K376) Leuca x Pal OPF2
Leucaena hybrid KX3 (Leu) x K156 (Div) F2
Leucaena diversifolia (4n) K156
Leucaena diversifolia (4n) CPI #46568
Leucaena collinsii
Leucaena diversifolia K7851
Leucaena e s c u l e n t a _____________________________
Moyahua, Zacatecas, Mexico
Coahuila, Mexico
Oaxaca, Mexico
Waimanalo, Hawaii
Waimanalo, Hawaii
Waimanalo, Hawaii
Veracruz, Mexico
Veracruz, Mexico
Gliricidia sepium was also included as one entry. The trial has been managed as hedges for
fodder production by cutting trees back after six months of growth to 50 cm above ground
level and subsequently cut to 75 cm height every three months.
The measurements and data collected:
Psyllid count and psyllid damage. Psyllid counts for three stages and damage levels were scored
empirically (1-9 rating) as developed by NFTA (Wheeler 1988). Observations were made on
a monthly basis on young leaves at the end of the growing stem. A 7 cm length of a completely
foliated juvenile leaf comprised one sample. Eight trees were scored for each entry in each
replication.
Predator counts and identification. The number of predators were scored at the same time as
psyllid counts were made.
Growth measurements. Height and basal diameter at 15 cm above ground of eight trees for
each entry in each replication were measured before cutting. Leaf and stem were separated and
weighed separately. A 50 gm sample from each entry was dried and weighed for dry matter
conversion.
Climatological data and soil characteristics. The soil of the trial site was analyzed before
planting for pH and sand, soil, clay, organic matter, N, P, K, Na, Ca and Mg content. Monthly
r ainfall and maximum and minimum temperature were recorded during the trial period.
Results and discussion.
Psyllid population, damage, and climate. Psyllid adult and nymph populations for the 11
leucaena species/hybrids during the period of July, 1988 to April, 1990 are given in Tables 1
and 2. The damage rating of the psyllid are shown in Table 3. Rainfall data is included on
all tables for comparison of weather data with population level. Significant differences in psyllid
tolerance were shown among species, as reflected by damage and psyllid number during all
months. Leucaena species/hybrids K156, #46568, and L. collinsii showed less damage than K8,
K636, and KX3. Leucaena species such as K376, KX1, KX2, K785, and L. esculenta showed
higher tolerance of the psyllid than other entries throughout the trial period.
Rainfall (mm)
There were also significant differences among varieties in monthly counts of adults, nymphs
and eggs (Figures 1 and 2). Psyllid populations and damage increased in July, August,
September and in January, February and March. Infestation and damage were very low from
October to December which was the main rainy season and again in April to June. This
indicates a high correlation between psyllid population and rainfall.
Ju ly
1
Aug.
2
3
Sept.
Oct.
4
Nov.
3
Dec.
6
Jan.
7
Feb. March
1
9
A p ril
10
Figure 1. Seasonal variation in psyllid
adults number for susceptible
(K8, K636) and tolerant (KX1,
KX2, K785) leucaena varieties.
Figure 2. Seasonal variation of psyllid
damage for tolerant (KX1, KX2,
K156, K376, K785) and susceptible
(K8) leucaena varieties.
Table 1. Trial rating means for psyllid adults and monthly rainfall.
Species
KNo
K8
L . leucocephala
K636
L . leucocephala
L . pallida
K376
KX1
KX2
KX3
L. diversifolia
K156
L. diversifolia CPI#46568
L . collinsii
K785
L . diversifolia
L. esculenta
Rainfall (mm)
1989
Sept Oct
July
Aug
7
6
2
2
2
8
5
3
3
1
2
4
7
1
2
2
7
4
2
2
2
1
5
5
1
1
1
4
5
2
1
2
1
3
3
1
1
3
6
2
1
2
1
1
165
44
114
289
1990
Feb Mar
Dec
Jan
3
4
1
1
2
3
4
1
3
2
1
4
6
1
2
3
4
6
1
3
2
1
7
7
2
2
3
3
6
1
5
2
2
8
8
2
2
4
5
4
2
1
1
1
3
5
1
1
1
2
2
1
1
1
1
438
0
5
25
199
54
Nov
Dec
Jan
5
5
1
1
4
5
4
1
2
1
1
6
6
1
1
4
3
5
1
3
1
1
9
8
2
1
5
3
6
1
2
1
1
9
8
2
2
4
4
4
1
1
1
1
5
4
1
1
2
2
2
1
2
1
1
0
5
25
199
54
Nov
Apr
Table 2. Trial rating means for psyllid nymphs.
Species
KNo
K8
L . leucocephala
K636
L. leucocephala
L. pallida
K376
KX1
KX2
KX3
K156
L . diversifolia
L . diversifolia CPI#46568
L . collinsii
L. diversifolia
K785
L . esculenta
Rainfall (mm)
July
Aug
1989
Sept Oct
7
8
1
1
1
8
7
1
3
1
1
7
7
1
1
3
6
9
1
2
3
1
7
6
1
1
1
2
5
1
2
1
1
8
3
1
1
2
5
5
1
2
1
1
165
44
114
289
438
1990
Feb Mar
Apr
Table 3. Trial rating means for psyllid damage to Leucaena spp.
Species
KNo
L. leucocephala
K8
L. leucocephala
K636
K376
L . pallida
KX1
KX2
KX3
L. diversifolia
K156
L . diversifolia CPI#46568
L . collinsii
K785
L . diversifolia
L. esculenta
Rainfall (mm)
1989
Sept Oct
July
Aug
8
7
1
1
2
7
2
1
1
1
1
7
7
1
1
2
8
5
1
2
1
1
6
6
1
1
1
7
2
1
1
1
1
4
2
1
1
1
3
3
1
2
1
1
165
44
114
289
Nov
438
1990
Feb Mar
Dec
Jan
Apr
5
5
1
1
2
5
2
1
2
1
1
6
7
1
1
2
6
2
1
2
1
1
5
4
1
1
3
4
3
1
1
1
1
8
8
1
1
3
4
6
1
1
1
1
2
2
1
1
1
2
2
1
1
1
1
0
5
25
199
54
Table 4. Plant height and diameter.
Species
K No
L. leucocephala
K8
L. leucocephala
K636
L. pallida
K376
KX1
KX2
KX3
L. diversifolia
K156
L. diversifolia CPI#46568
L. collinsii
L. diversifolia
K785
L. esculenta
05/07/89
Ht
Dia
118
133
149
144
134
207
206
95
103
79
89
1.9
1.7
1.6
1.6
1.5
2.3
1.9
2.0
1.5
1.2
1.6
27/10/89
Ht
Dia
25/01/89
Ht
Dia
25/04/90
Ht
Dia
226
191
170
241
160
181
203
150
131
153
189
117
143
164
133
216
136
169
150
128
184
108
379
165
304
275
345
382
331
185
242
267
304
2.3
2.3
1.7
2.6
2.0
1.9
1.9
2.1
1.5
1.6
2.0
2.4
2.4
2.5
2.6
2.3
2.5
2.1
2.1
1.4
2.1
2.2
3.0
2.7
2.8
2.8
3.3
3.0
2.5
2.6
2.2
2.7
2.8
Table 5. Biomass production (leaves and stems) of leucaena species at cuttings (dry weight
_________ kg/2 m hedge).________
Species
KNo.
L. leucocephala
K8
L. leucocephala
K636
L. pallida
K376
KX1
KX2
KX3
L. diversifolia
K156
L. diversifolia CPI#46568
L. collinsii
L. diversifolia
K785
L. esculenta
05/07/89
Leaf Wood
0.24
0.24
0.36
0.25
0.10
0.78
0.23
0.07
0.07
0.08
0.15
0.07
0.07
0.10
0.08
0.02
0.44
0.14
0.03
0.03
0.01
0.03
27/10/89
Leaf Wood
0.23
0.35
1.72
0.53
2.19
0.68
0.58
0.78
0.17
0.35
0.37
0.06
0.12
1.36
0.50
1.55
0.12
0.22
—
0.22
0.40
0.22
05/01/90
Leaf Wood
0.18
0.06
0.45
0.63
1.11
0.34
0.16
0.07
0.08
0.65
0.08
0.42
0.03
0.14
0.21
0.53
0.14
0.04
0.01
0.02
0.14
0.02
25/04/90
Leaf Wood
1.62
2.03
1.33
1.78
3.67
2.62
0.95
0.12
1.25
2.63
0.75
0.88
1.34
0.36
1.47
1.26
1.43
0.70
0.08
0.88
1.02
0.42
Plant growth. Heights and stem diameters (15 cm aboveground) of K8, KX2, and KX3 were
greater than that of other varieties in the trial (Table 4). There were little difference between
remaining varieties.
Biomass production. KX1, KX2, and K785 expressed higher tolerance to psyllid than other
provenances under the trial and at the same time exhibited faster and more active regrowth
after cutting (Table 5). Both K8 and K636 exhibited similar levels of psyllid damage; however,
K636 exhibited quick regrowth and recovery from the damage.
Predators. During the trial period some psyllid predators were observed, mainly indigenous
coccinellid and dragonflies, but their role in controlling psyllid is negligible.
Conclusions. The results from these trials confirm that KX1, KX2, and K785 have greater
psyllid tolerance and high productivity, and that K636 and KX3 have high productivity despite
their low tolerance to the psyllid. The productivity and adaptability to different climatic
conditions of these promising species/hybrids needs further testing.
Acknowledgements. The authors wish to acknowledge the cooperation of NFTA, Waimanalo,
Hawaii, in providing planting materials, advice and other support for the work reported here.
References:
Sorensson, C.T. and J.L. Brewbaker. 1987. Psyllid resistance of leucaena hybrids and species.
Leucaena Res. Reports 7(2):29-34.
Pan, Fuh-jiunn. 1987. Psyllid resistance of Leucaena species in Taiwan. Leucaena Res. Reports
7(2):35-38.
W heeler, R A . 1988. Leucaena psyllid trial at Waimanalo, Hawaii. Leucaena Res. Reports 9:2529.