Effect of feeding by Metadelphax propinqua (Fieber)(Homoptera,
Delphacidae) on barley

Mikko Raatikainen, Terttu Raatikainen and Arja Vasarainen

Raatikainen, M., Raatikainen, T. & Vasarainen, A. 1994. Effect of feeding by
Metadelphax propinqua (Fieber) (Homoptera, Delphacidae) on barley. Agricul-
tural Science Finland 3: 513-517. (University of Jyväskylä, Department of Biological
and Environmental Science, P, O. Box 35, FIN-40351 Jyväskylä, Finland and Agri-
cultural Research Centre ofFinland, Institute of Plant Protection, FIN-3 1600 Jokioi-
nen, Finland.)

The effect of feeding by the Turkish Metadelphax propinqua on barley was investi-
gated in Finland. The number of M. propinqua nymphs and the length of their
feeding period on barley did not have any major effects on the barley plants. M.
propinqua males had a greater effect on the properties of barley than did the
nymphs. The effect of M. propinqua females on the barley was much greater than
that of either the nymphs or males. Their number and the length of feeding time
lowered the length and weight of plants, the number of grains, the grain yield and
the 1000-grain weight.

Key words; feeding period, female, male, nymph

Introduction

In 1969-1970 we investigated cereal diseases
transmitted or caused by aphids and leafhoppers
in Turkey. Our interest focused on the biology of
Metadelphax propinqua (Fieber) (Homoptera, Del-
phacidae), also (Raatikainen and Vasarainen
1990), a planthopper widely distributed in the
Palaearctic and Nearctic region (Metcalf 1943).
According to Dlabola (1957), it is also common
in Turkey. We were primarily concerned with the
damage it does to barley.

Material and methods

We started with an investigation of the ecology
of M. propinqua at Bornova in western Turkey
and continued with trials at Tikkurila in Finland.
The planthoppers were collected from a field at

Bornova. The tests were conducted from Sep-
tember 1971 to March 1972 in a glasshouse at a
temperature of 20-25°C. The test plant was bar-
ley (cultivar Tammi). The plants were sown in
43 x 25 x 12-cm wooden boxes lined with poly-
ethylene film. The bottoms of the boxes were
perforated to allow drainage. Seeds of test plants
were sown in six parallel rows, four seeds to
each row, at equal distances from one another
and at a depth of 3 cm. During test feeding peri-
ods each planthopper was caged with one seed-
ling under a cylinder of PVC plate, 3 cm in di-
ameter and 25 cm tall; the upper end was cov-
ered with gauze. There were also two ventilation
openings near the bottom. Control plants were
caged in the same manner.

The number of planthoppers on one plant in
the rearing box was 0,1, 2 or 4 and the length of
the feeding period was 4, 8 or 16 days. The trials
were made with nymphs, males and females. The

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Table 1.Effect of feeding by Metadelphax propinqua nymphs on barley.

Property measured No. of planthoppers/plant Feeding period, days Planthopper
0124 F 4 8 16 F x feeding

F

Length of plant after
22 days, cm 19.9 19.6 19.7 17.8 1.89 19.5 18.7 19.5 0.53 3.56**
Total length of mature
plant, cm 64.7 60.0 58.2 56.7 1.91 60.9 60.6 58.1 0.51
No. of shoots 2.1 2.2 2.1 2.2 0.06 2.2 2.1 2.2 0.11
Dry weight of plant, mg 1489.9 1364.0 1274.2 1147.1 4.15** 1439.1 1347.1 1170.2 4.94** 2.27**
No. of grains on
main shoot 11.1 9.3 9.1 10.0 0.73 10.1 10.0 9.5 0.12
No. of grains on
secondary shoots 10.2 10.7 9.3 7.6 0.80 10.3 9.8 8.3 0,61
No. of grains on plant 21.3 20.0 18.4 17.6 2.14 20.4 19.8 17.8 1.92
Grain yield per main
shoot, mg 398.8 313.5 313.2 333.8 1.26 348.8 345.6 325,0 0.17
Grain yield per
secondary shoots, mg 298.3 326.6 275.3 225.7 0.82 315.9 219.8 236.8 0.99
Grain yield per plant, mg 697.1 640.1 588.5 559.4 2.86* 664.6 637.4 561.8 2.95 2.43*
1000-grain weight on
main shoot, g 32.0 24.6 26.5 24.5 2.65* 27.0 27.6 26.1 0.15
1000-grain weight on
secondary shoots, g 15.7 18.7 15.3 14.9 0.69 16.0 15.7 16.8 0.09

test plants were six days old at the beginning of
the trials. The length of the day was 16-19 h.
The plant properties measured are listed in
Tables 1-3.

The statistical method used was analysis of
variance, and statistical significance is indicated
by asterisks as follows: *** = P < 0.001, ** = P
<O.Ol and * = P < 0.05.

Results

The number of M. propinqua nymphs and the
length of their feeding period (time of stay) on
barley did not have any major effect on the plant
properties measured (Table 1). The most impor-
tant change occurred in the dry weight of the
plants, which decreased significantly due to the
effect of both the number of nymphs and the
length of their feeding period. The combined ef-

feet of the number of nymphs and the length of
their feeding period on the length of barley plants
was significant 22 days after sowing. The number
of nymphs lowered the grain weight of whole
plants and the 1000-grain weight of the main shoot
almost significantly.

M. propinqua males had a more marked effect
on the properties of barley than did the nymphs
(Table 2). The greater the number of males and
the longer the time that had passed since feeding,
the less the barley grew in length. Further, the
greater the number of males on a plant, and the
longer the feeding period, the more the weight of
the plant decreased. Feeding led to a decrease in
the number and weight of grains of the whole
plant and secondary shoots.

The effect ofM. propinqua females on the prop-
erties of barley was much greater than that of
either males or nymphs (Table 3). The number of
females and the length of their feeding period

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Table 2. Effect of feeding by Meladelphax propinqua males on barley.

Property measured No. of planthoppers/plant Feeding period, days Planthopper
0124 F 4 8 16 F

* feeding

Length of plant after
22 days, cm 19.2 19.0 17.3 16.4
Length of plant after
30 days, cm 29.7 32.2 29.3 29.0
Length of plant after
39 days, cm 50.8 51.5 48.5 47.3
Length of plant after
46 days, cm 57.7 54.7 51.6 50.6

Length of mature plant
(tip of uppermost sheath
to base of panicle), cm 59.2 56.4 52.6 52.5
Total length of mature
plant, cm 68.7 65.6 60.4 61.1
No. of shoots 1.4 1.7 1.8 1.8
Dry weight of main
shoot, mg 1129.3 845,7 744.9 692.8
Dry weight of secondary
shoots, mg 241.3 359.8 371.0 260.6
Dry weight of plant, mg 1370.7 1205.5 1115.9 953.4
No. of grains on
main shoot 10.5 8,8 7.6 7.0
No. of grains on
secondary shoots 4.3 7.2 7.2 5.2
No. of grains on plant 14.8 16.0 14.8 12.2
Grain yield per main
shoot, mg 391.3 318.5 275.1 249.9
Grain yield per secondary
shoots, mg 91.4 165.2 152.7 107.5
Grain yield per plant, mg 482.8 483.7 427,8 357.4
Age of main shoot, days 95.9 93.6 95.4 93.9
1000-grain weight on
main shoot, g 29.9 33.1 27.5 28.4
1000-grain weight on
secondary shoot, g 5.7 10.0 9.3 8.4

5.12** 18.3 17.0 18.6 2.82

1.33 31.0 30.0 29.1 0.75

1.24 50.6 49.9 47.8 1.07

4.70** 54.1 54.3 52.5 0.60

6.77*** 55.2 56.7 53.6 2.03

5.52*** 63.6 66.5 61.7 2.85
3.10* 1.7 1.5 1.7 1.75

10.57*** 895.8 918.0 745.8 3.23*

1.01 470.5 227.3 226.8 5.98**

6.4l*** 1366.3 1145.3 972.6 10.96***

1.77 8.3 9.9 7.2 1.79

1.05 9.3 4.8 3.9 5.50**
1.21 17,6 14.6 11.1 6.80**

2.32 329.8 341.6 2544.7 1.79

1.29 206.9 102.1 78.5 6.42**
2.16 536.8 443.8 333.2 B.3B***
0.34 94.3 94.4 95.4 0.14

0.89 30.6 30,5 28.0 0.41

1.27 10.7 6.1 8.2 2.51

usually lowered very significantly or significant-
ly the length and weight of plants, the number of
grains, the grain yield and the 1000-grain weight.
The effect on growth was most striking at the
end of the feeding period, but thereafter the plant
seeded and gradually recovered.

Discussion

Our earlier studies (Bremer and Raatikainen
1975) indicated that the planthopper individuals
we investigated did not transmit viruses.

M. propinqua is a small planthopper that dam-

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Table 3. Effect of feeding by Metadelphax propinqua females on barley.

Property measured No, of planthoppers/plant Feeding period, days Planthopper

16 f x
feeding

F
0 12 4 F 4 8

Length of plant after
22 days, cm 19.4 13.5 11.8 8.2
Length of plant after
30 days, cm 30.2 23.4 21.4 14.3
Length of plant after
39 days, cm 50.7 41.1 37.2 25.7
Length of plant after
46 days, cm 56.8 46.7 42.7 31.2
Length of mature plant
(tip of uppermost sheath
to base of panicle), cm 58.4 50.2 46.7 38.4
Total length of mature
plant, cm 67.9 58.0 54.9 45.4
No. of shoots 1.8 1.3 1.3 1.2
Dry weight of main
shoot, mg 1081.9 766.4 605.1 433.7
Dry weight of secondary
shoots, mg 586.8 149.1 110.7 118.6
Dry weight of plant, mg 1668.8 915.5 715.8 552.3
No. of grains on
main shoot 9.3 8.1 5.8 4.8
No. of grains on
secondary shoots 10.1 2.7 2.3 1.7
No. of grains on plant 19.3 10.8 8.1 6.5
Grain yield per main
shoot, mg 337.7 278.6 187.3 129.3
Grain yield per secondary
shoots, mg 248.3 54.0 48.0 48.6
Grain yield per plant, mg 586.0 332.6 235.3 177.8
Age of main shoot, days 98.4 101.5 101.8 95.5
1000-grain weight on
main shoot, g 28.9 28.1 22.0 16.1
1000-grain weight on
secondary shoot, g 9.4 4,0 2.9 2.9

85.42*** 16.013.4 10.3 43.04*** B.lo***

39.92*** 26.923.8 16.4 35.89*** 4.3l***

38.96*** 46.141.5 28.4 41.06*** 2.87*

36.36*** 52.147.0 33.9 38.18*** 2.49*

24.67*** 54.650.8 39.8 28.30***

20.07*** 64.259.6 45.8 28,33***
7.l2*** 1.61.3 1.3 4.96**

26.06*** 918.6760.4 486.4 21.83***

B.B2*** 403.8179.2 141.0 4.44*
34.38*** 1322.3939.6 627.4 22.82***

4,38** 8.37.5 5.2 3.66*

B.B2*** 6.62.9 3.0 3.39*
17.19*** 14.910.4 8.2 B.24***

B.64*** 290.4249.3 159.9 5.95**

B.lo*** 167.275.1 56.9 3.84*
21.04*** 457.6324.4 216.8 12.55***
0.9695.8 99.3102.8 1.78

5.95*** 29.225.3 16.8 B.93***

4.83** 7.13.6 3.7 2,55

ages a plant in two ways. It draws nourishment
out of the plant and simultaneously injects into it
saliva which helps to digest the food and injuri-
ous to the plant. The combined effect of these
measures is less with nymphs than with adults,
and with male than with female adults. This may
be due to the fact that females start laying eggs
approximately 1-5 days after emergence and the

number of eggs is greater than that of other plan-
thoppers studied (Raatikainen and Vasarainen
1990). Females thus need more food than males

and so cause more injury to the plant than either
males or nymphs.

There is great variation in the abundance of M.
propinqua and, from time to time, it may cause a
significant decrease in the yield of grasses.

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References

Bremer, K. & Raatikainen, M. 1975. Cereal diseases
transmitted or caused by aphids and leafhoppers in
Turkey, Annales Academiae Scientiarum Fennicae Se-
ries A, IV Biologica 203: 1-14,

Dlabola, I. 1957. Results of the zoological expedition of
the National Museum in Prague to Turkey. 20. Homop-
tera, Auchenorrhyncha. - Acta Entomologica Musei
Nationalis Prague 31,469: 19-68.

Metcalf, Z.P. 1943. General catalogue of the Hemiptera
IV, Fulgoroidea. 3, Araeopidae (Delphacidae). - North-
ampton, Mass. U.S.A. 552 p.

Raatikainen, M. & Vasarainen, A. 1990. Biology of
Metadelphax propinqua (Fieber) (Homoptera, Delphaci-
dae). - Entomologica Fennica 1: 145-149.

Manuscript received April 1993

SELOSTUS

Metadelphax propinqua -kaskaan imennän vaikutus ohraan

Mikko Raatikainen, Terttu Raatikainen ja Arja Vasarainen

Jyväskylän yliopisto ja Maatalouden tutkimuskeskus

Metadelphax propinqua -kaskaan imennän aiheuttamia
vioituksia ohralle tutkittiin 1970-luvun alussa. Kokeissa
M. propinqua -lajin toukkia, koiraita ja naaraita laitettiin
0,1, 2 ja 4 kappaletta ohrille neljäksi, kahdeksaksi ja
kuudeksitoista vuorokaudeksi. Kokeessa olleen ohran la-
jike oli Tammi.

Toukkien imennän vaikutuksesta ohran kuivapaino, jy-
vien paino ja pääverson 1000-jyvän paino jäivät vähän
pienemmiksi kuin terveiden ohrien.

Koiraiden imennän vaikutuksesta ohran pituus, kuiva-
paino, jyvämäärä ja jyväsato jäivät pienemmiksi kuin ter-
veiden ohrien.

Naaraiden imennän vaikutuksesta melkein kaikki tutki-
tut ominaisuudet jäivät paljon pienemmiksi kuin tervei-
den ohrien. Naaraat olivat ohran pahoja tuholaisia, jos
niitä oli paljon ja ne pääsivät ohriin kasvin ollessa pieninä
oraina. Vioitus aiheutunee kaskaan kasviin laskemasta syl-
jestä ja kasvista ottamasta ravinnosta. Viimeksi mainittu
lienee pääsyy, sillä naaras alkaa munia 1-5 vuorokautta
aikuistumisen jälkeen ja ottaa siitä alkaen usean viikon
aikana paljon ravintoa ohrista.

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