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Cucurbit Genetics Cooperative Report 1:38 (article 34) 1978

White Fly Resistance in Cucumis Species

E. Kowalewski3 and R. W. Robinson

New York State Agricultural Experiment Station, Geneva, NY 14456

Cucumis species were evaluated for resistance to natural infestation with white flies in the greenhouse. Scanning electron and stereoscope microscope studies were made to determine if white fly resistance is related to morphology or density of leaf trichomes. White fly resistance was compared to cucurbitacin content as determined by ultraviolet fluorescence of chloroform leaf extracts treated with antimony trichloride.

The three species with the greatest density of trichomes, C. dinteri, C. angolensis and C. asper, were the species most resistant to white flies (Table 1). Overall, trichome density was inversely correlated with frequency of adults (r = -.89), pupae (r = -.39), larvae (r = -.61), and eggs (r = -.53) of the white fly, but this relationship was not evident among species having trichomes spaced further apart than the size of the white flies. White fly resistance did not appear to be related to any morphological feature of the trichomes, and none of the species had glandular trichomes. No correlation was noted between cucurbitacin content and white fly infestation.

Table 1. Number of Trichomes and Different Stages of the White Fly on Leaves of Cucumis species.

Species

Trichomes1

Eggs1

Larvae1

Pupae1

Adults2

C. prophetarum

34

108

199

12

9.0

C. trigonus

24

175

236

148

9.0

C. sativus

33

151

177

168

8.8

C. heptadactylus

14

257

197

18

8.5

C. ficifolius

18

64

119

10

8.5

C. leptodermis

34

173

144

98

8.5

C. longipes

38

160

166

133

8.2

C. metuliferus

26

82

119

63

8.0

C. hookeri

40

102

144

72

8.0

C. dipsaceus

62

123

99

28

7 5

C. anguria

45

234

226

74

7.5

C. zeyheri

43

106

121

40

7.1

C. pustulatus

30

46

70

19

7.0

C. myriocarpus

32

52

36

35

6.5

C. africanus

52

107

103

38

5 8

C. melo

56

88

77

17

5.0

C. asper

110

44

44

2

2.0

C. angolensis

117

44

86

13

2.0

C. dinteri

200

12

4

0

1.5

1 Mean number per unit area of lower leaf surface.
2 Subjectively rated from 1 (resistant) to 9 (susceptible).
3 Present address: Research Center for Varieties of Agricultural Crops, Slupia Welkia, Poland.

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Page citation: Wehner, T.C., Cucurbit Genetics Cooperative;
Created by T.C. Wehner and T. Ng, 1 June 2005; design by C.T. Glenn;
send questions to T.C. Wehner; last revised on 26 October, 2009