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Cucurbit Genetics Cooperative Report 17:83-85 (article 24) 1994

Screening of Melons for Sweetpotato Whitefly Resistance: 1993

James D. McCreight

U.S. Department of Agriculture, Agricultural Research Service, U.S. Agricultural Research Station, 1636 East Alisal Street, Salinas, CA 93905, USA

Sweetpotato whitefly, Bemisa tabaci Genn., type B virtually destroyed the Fall 1991 melon crop in the lower desert valleys of Arizona and California (7). It does not appear to be and important vector of lettuce infectious yellows virus (LIYV) (3). This whitefly type was recently re-named the silverleaf whitefly (8,9,10), but not without controversy (1,2,11). This whitefly has recently been found in the San Joaquin Valley of California (4).

In 1991, 17 of 150 PIs from India appeared to have some level of resistance to B. tabaci, type B (5). In 1992, these 17 PIs were re-tested for B. tabaci, type B resistance along with 108previously untested PIs from India plus 27 standard varieties, breeding lines, and F1 F2 and backcross families from crosses of susceptible parents with lines identified as potentially resistant to LIVY or B. tabaci, type B (6). None of the entries was superior for whitefly resistance.

In 1993, 276 melons from Afghanistan and Pakistan were evaluated for whitefly resistance in a naturally infested field test. Also included in the 9193 test were three cultivars (PMR 45, Top Mark, GF Honeydew), breeding line WMR 29, Snakemelon from the Middle East, and progenies 28479 an F1 from the cross Top Mark FR x top Mark FR (Snakemelon [Freeman Cucumber x Snakemelon]), and 28481 and 28482 which are backcrosses from the series PMR Honeydew (Snakemelon [Freeman Cucumber x Snakemelon]). Plots were planted on 80 inch centers and consisted of five two-plant hills spaced 30 inches apart. There were two replications. the test was evaluated on a plot basis 4 weeks (September 22) and 8 weeks (October 20) post-planting for number of live plants, plant size, plant condition, yellowing, leaf necrosis (burn) and flowering. Plots were not treated with any pesticides or herbicides.

Of the 276 PIs planted, four failed to germinate in either one replication (three entries) or both replications (one entry). Four weeks post planting, 63 entries were dead in one replication and an additional 17 PI were dead in both replications. Eight weeks post-planting, all but 15 entries were dead. Of those 15, only one had live plants in both replications. This is in sharp contrast with the 1991 test when most of the entries were alive and 1992 when approximately 70% of the entries were alive after 8 weeks. Severity of the test is also indicated by differences in mean ratings of plant condition 4 weeks post-planting for Top Mark in 1992 and 1993, 7.0 and 2.0, respectively.

Table 1 summarizes the mean ratings of plant condition 4 weeks post-planting. At that time, nine entries showed promise as sources of whitefly resistance; they are the entries with means ranging 3.75 to 5.50. By 8 weeks post-planting, only one (28481) of those nine entries had any (one) live plants. Entry 28481 is a backcross progeny with the following pedigree: PMR HD (Snakemelon [Freeman Cucumber x Snakemelon]). Snakemelon appeared to be a potential source of B. tabaci, type B resistance in 1991, but in this test it had a mean rating of 20 at 4 weeks and was dead at 8 weeks. Of the remaining eight best entries 4 weeks post-planting, PI 125918, PI 125890, PI 116915, and PI 125951 are of most interest for further study for the following reason. Each of these four entries had plant condition ratings of 2 or 3 in one replication, but was rated 6 or better in the other replication. Especially interesting are PI 125918, PI 125890 which were rated 9 in one replication. They appeared to have as many adults and immatures as other entries in the test, but the plants were normal in appearance, were flowering, and were the largest in the field. A greenhouse test of these nine entries is in progress.

Table 1. Mean plant condition on 22 September 1993 (four weeks post-planting) in response to whitelfy feeding.

Meanz
Entries
               
5.5
125918
125890
--
--
--
--
--
--
--
--
4.5
28481
116915
--
--
--
--
--
--
--
--
4.0
125951
125996
125997
126165
--
--
--
--
--
--
3.0-3.5
WMR 29
116917
125928
126017
126091
126154
127565
220786
--
--
28478
125860
125964
126050
126131
126174
211588
223768
--
--
28479
125879
125989
126057
126146
126199
220170
324525
--
--
28482
125886
126000
126076
126151
127564
220655
--
--
--
2.0-2.5
GF Honeydew
125901
125952
125996
126056
126097
126164
127546
212291
300956
PMR 45
125903
125953
126004
126059
126098
126166
127547
217515
323937
Snakemelon
125905
125955
126006
126060
126101
126167
127548
217526
355051
Top Mark
125906
125956
126008
126062
126105
126168
127550
219945
418766
116916
125907
125957
126012
126064
126113
126170
127560
218070
420152
125862
125910
125958
126013
126068
126116
126172
127567
218071
426628
125865
125914
125961
126016
126074
126117
126178
127570
220515
532929
125868
125919
125969
126018
126075
126126
126185
127572
220651
--
125870
125921
125970
126024
126078
126133
126195
127575
22-654
--
125872
125922
125972
126027
126080
126140
126197
127576
220787
--
125876
125923
125974
126030
126083
126141
126198
127578
221439
--
125880
125925
125979
126032
126084
126142
127524
135315
222097
--
125885
125931
125981
126036
126086
126143
127528
204304
222098
--
125891
125932
125984
126040
126088
126145
127531
107478
242907
--
125892
125935
125986
126042
126089
126147
127534
210016
260651
--
125893
125943
125991
126044
126090
126150
127536
211726
261750
--
125895
125944
125992
126047
126093
126152
127538
212087
269367
--
125896
125946
125993
126052
126095
126160
127539
212089
269368
--
125897
125947
125994
126054
126096
126162
127545
212090
300955
--
--
1.0-1.5
125863
125913
125938
125973
126037
126077
126110
126156
207477
125866
125920
125942
125976
126051
126079
126111
126159
223770
--
125881
125924
125948
125987
126053
126081
126112
126171
269474
--
125883
125927
125962
125990
126069
126082
126114
126180
269478
--
125900
125930
125963
126005
126070
126099
126125
127535
401646
--
125904
125933
125967
126020
126072
126106
126127
127551
410768
--
125911
125937
125971
126033
127073
126108
126134
135319
426627
--

 zCondition was rated on a 1 (dead) to 9 (vigorous, flowers) scale

Literature Cited

  1. Bartlet, A.C. and N.J. Gawel. 1993. Determining whitefly species. Science 261:1333-1334.
  2. Campbell, B.C., J.E. Duffus, and P. Baumann, 1993. Determining whitefly species. Science 261:1333.
  3. Cohen, S., J.E. Duffus, and H.Y. Liu. 1991. A new Bemisia tabaci biotype in the Southwestern United States and its role in silverleaf of squash and transmission of lettuce infectious yellows virus. Phytopathology 82:86-90.
  4. Gruenhagen, N.M., T.M. Perring, L.G. Bezark, D.M. Daoud, and T.F. Leigh. 1993. Silverleaf whitefly present in the San Joaquin Valley. Calif. Agr. 47(1):4-6.
  5. McCreight, J.D. 1992. Preliminary screening of melons for sweetpotato whitefly resistance. Cucurbit Genet. Coop. Rpt. 15:59-61.
  6. McCreight, J.D. 1993. Screening of Melons for Sweetpotato Whitefly Resistance: 1992. Cucurbit Genet. Coop. Rpt. 16:49-52.
  7. Perring, T.M., A. Cooper, D.J. Kazmer, C. Shields, and J. Shields. 1991. New strain of sweetpotato whitefly invades California vegetables. Calif. Agr. 45(6):10-12.
  8. Perring, T.M., A.D. Cooper, R.J. Rodriguez, C.A. Farrar, and T.S. Bellows, Jr. 1993. Identification of a whitefly species by genomic and behavioral studies. Science 259:74-77.
  9. Perring, T.M., C.A. Farrar, T.S. Bellows, A. D. Cooper, and R.J. Rodriguez. 1993. Evidence for a new species of whitefly: UCR findings and implications. Calif. Agr. 4(1):7-8.
  10. Perring, T.M., C.A. Farrar, T.S. Bellows, A.D. Cooper, and R.J. Rodriguez. 1993. Whitefly identification with isoelectric focusing. Calif. Agr. 47(1):8.
  11. Perring, T.M.., C.A. Farrar, A.D. Cooper, T.S. Bellows, and R.J. Rodriguez. 1993. Determining whitefly species - response. Science 261:1334-1335.
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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 11 December, 2009