- Vegetables: cucurbits
- Education and Training: extension
- Pest Management: biological control, chemical control, cultural control
Striped cucumber beetle, Acalymma vittatum, is key a pest of pumpkins. Field tests in 2004 evaluated the efficacy of two potential biological control methods to suppress adult striped cucumber beetle. Enhancement of a natural parasitoid, Celatoria setosa (Diptera: Tachinidae), by floral resource borders was evaluated as a conservation biological control method. An augmentation biological method of inundative application of nematodes was assessed for the efficacy of reducing adult striped cucumber beetle using Heterorhabditis bacteriophora, an insect parasitic nematode. Data indicated that providing floral resources increased the percentage of beetles parasitized by C. setosa in the field, and that applications of insect parasitic nematodes resulted in reduced numbers of striped cucumber beetle.
Striped cucumber beetle is pest of pumpkins and other cucurbit crops early in the season, and the beetles can damage flowers and fruits near the end of the season. Natural enemies of striped cucumber beetle include Dipteran and Hymenopteran parasitoids, microorganisms, predatory invertebrates, and birds. Celatoria setosa, a tachinid fly parasitoid was observed in Ohio and the life history was reported in an agricultural bulletin in the 1920s (Houser and Balduf, 1925). Houser and Baldfuf (1925) found the percent parasitism of field-collected beetles was at a maximum of 39% in October, and on average 17% when collecting from different dates and fields. An allantonematid nematode, Howardula benigna (Cobb), has been reported as a natural enemy of striped cucumber beetle (Gould 1944, Houser and Balduf 1925). Generalist natural enemies have little impact on specific pest populations in the field because of their ability to utilize a wide range of insects as food. Highly specific parasitoid natural enemies and microbial agents have a potential for success, and other researchers have reported the use of biological control species to target striped cucumber beetle.
Natural enemies attack different life stages of the beetle and parasitize at different rates, but the presence of these beneficial invertebrates is not currently controlling striped cucumber beetle populations at a level acceptable to Ohio growers. The economic threshold for striped cucumber beetle in cucurbits is low due to its ability to transmit disease, and voracious herbivory and damage to marketable fruit. Growers use some cultural pest control methods, but few curative pest control options are available other than chemical insecticides for reduction of striped cucumber beetle populations in pumpkins. Recommendations need to be developed for biological control methods that utilize natural enemies to suppress populations of the adult beetle. Potential biological control methods using two different biological control organisms were investigated in the following research project.
The objectives of this project were to evaluate methods of biological control for striped cucumber beetle in pumpkins. The initial collaborative objective was to assess the potential of adoption of biological control practices by pumpkin farmers, which was determined by a questionnaire survey. The research objective was to conduct experiments on the efficacy of applying and enhancing biological control organisms in the field. Output objectives were the following: report research findings at agricultural field days and for growers organizations, publish research results in Master of Science thesis and scientific journals, and develop a fact sheet on the natural enemies of striped cucumber beetle for use by entomology extension. The overall educational objective of this project was to increase awareness of the presence of natural enemies in pumpkin crops and to report research results that could lead to sustainable pest management methods for striped cucumber beetle.