California produces numerous types of melons and is the leading U.S. producer of cantaloupe (~60%) and honeydew melons (~80%). Melons are grown primarily in the Central Valley and the southern California desert production areas. Numerous insect and mite pests impact melon production. Soil-insects hinder seedling establishment. Aphids, spider mites, leafhoppers, and Lepidopterious larvae feed on and damage the photosynthetic leaf tissue. Some of these pests also vector virus disease-causing organisms. However, in ~2008 cucumber beetles developed into a significant problem on melons in the Central Valley. The problem subsided in some areas but continued in the upper San Joaquin Valley and lower Sacramento Valley areas. The cucumber beetle complex in California includes two species, the Western Striped Cucumber Beetle, Acalymma trivittatum, and Western Spotted Cucumber Beetle, Diabrotica undecimpunctata undecimpunctata. Feeding on the smooth-skinned melons was the greatest problem as the “wounds” on the developing melons by the adults expanded to “gouges” on the mature melons and destroyed the marketability. The last comprehensive study on cucumber beetle biology in California was in the 1940’s. Notable changes in the agroecosystem had obviously occurred since this date and these had a high likelihood of impacting this pest. Research on these cucumber beetle pests was conducted by a graduate student and by a technical assistant in the laboratory. Studies were done in grower fields, with Cooperative Extension Farm Advisor Rachael Long providing liaison assistance to the growers, and on the UC research station.
Some of the specific objectives included,
- Role of a tachinid parasitoid in beetle management
- Possibilities for using alfalfa management to reduce cucumber beetle populations in melons
- Evaluation of melon genotypes for cucumber beetle susceptibility
- Development of efficient sampling methods for consultants to use
- To establish a treatment threshold for honeydew damage and a beetle monitoring plan
- To investigate the efficacy of cucurbitacin semiochemical products for management of cucumber beetles in melons.