Cucurbit Genetics Cooperative Report 6:41-42 (article 19) 1983
A. N. Kishaba, S. Castle, D. Coudriet, and J. D. McCreight
U. S. Department of Agriculture, Agricultural Research Service, Boyden Entomology Laboratory, University of California, Riverside, CA 92521 (first, second and third authors) and U. S. Department of Agriculture, Agricultural Research Service, P. O. Box 5098, Salinas, CA 93915 (fourth author)
In the early 1950s, Michelbacker et al., (1) reported extensive damage of muskmelon seedlings and fruits by the striped and spotted cucumber beetles in Northern California. Damage by the beetles in our aphid resistant ‘Hales Best Jumbo’ (HBJ) breeding lines has increased steadily over the past 4 to 5 years even though HBJ was reported as relatively resistant to the beetles, in the seedling stage. To determine if we selected for susceptibility to the beetles during selection for aphid resistance 15 advanced aphid resistant breeding lines were evaluated relative to their respective recurrent parents for susceptibility to seedling and fruit damage by the cucumber beetle complex in Orange County, California.
We used Quisumbing and Lower’s (2) experimental design for evaluating beetle resistance in cucumber. Each plot consisted of 3 hills; 15–30 seeds per hill. Entries were arranged in a randomized complete block design with 6 replications. Hills were thinned to 2 plants at the 3 to 7 leaf stage. The rogued plants were saved and assessed for beetle damage. A minimum of 10 fruit (harvested over several dates) per plot were evaluated; the mean number of fruit evaluated/plot was 18. Insect damage was evaluated on a plot basis.
Insect damage ranged widely between plots for both seedlings and fruit. At the seedling stage, the aphid resistant (AR) parent 91213 (PI 371795 inbred) was the least damaged with a mean rating of 4.89; the most damaged was PI 222187 with a mean rating of 6.58. PI 222187 was reported as resistant in the mid-West (3). The entries ranked from least to most damage were as follows: ‘Gulfstream’, ‘HBJ’, ‘PMR5’, ‘PMR45’, ‘Perlita’, 17013 and ‘Topmark’. Of the 15 AR lines tested, 2 were significantly more damaged and 1 was significantly less damaged than their respective recurrent parents.
The mean fruit damage rating of 91213 was 2.61 which was significantly different (P<.05) from the other 23 entries whose ratings varied from 19.66 for PI 222181 to a high of 50.15 for AR Perlita breeding line 31197. Fruit damage of the 7 cultivars tested was not significantly different from PI 222181. The most damaged cultivar was HBJ with a mean of 46.06, followed by ‘Topmark’, ‘Perlita’, ‘PMR5’, ‘PMR45’, ‘Gulfstream’. The least damaged was 17013 with a mean of 27.82. None of the AR lines were significantly more damaged than their recurrent parents.
Correlations between fruit and seedling damage and callus and seedling damage were low; r = 0.17 and 0.13, respectively. Thus, we were not selecting for cucumber beetle susceptibility while selecting for aphid resistance. Seedling and fruit damage should be evaluated when selecting for cucumber beetle resistance in muskmelon.
Literature Cited
- Michelbacher, A. E., W. W. Middlekareff and O. G. Varon. 1953. Cucumber beetles attacking melons in northern California. J. Econ. Ent. 46:489–494.
- Quisumbing, A. R. and R. L. Lower. 1978. Influence of plot size and seedling rate in field screening studies for cucumber resistance to cucumber beetles. J. Am. Soc. Hort. Sci. 103:523–527.
- Wiseman, B. R., C. V. Hall and R. H. Painter. 1961. Interaction among cucurbit varieties and feeding responses of the striped and spotted cucumber beetle. Proc. Am. Soc. Hort. Sci. 78:379–384.