Submitted to: Journal of Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 25, 2001
Publication Date: N/A
Interpretive Summary: The Colorado potato beetle (CPB) is an exceptionally destructive pest of potatoes, eggplant and tomatoes in North America and in Europe, costing growers hundreds of millions of dollars per year. Researchers have been attempting to develop artificial diets for the CPB for the last 35 years, so that research could be conducted on a year-round basis in the laboratory yunder precisely controlled environmental conditions. Currently, colonies of beetles can only be reared on plants and therefore, the cost of rearing is relatively high because of the expense and labor associated with growing large numbers of potato plants. The potato and lettuce leaf-powder diets described in these studies have supported the successful culture of at least 12 generations of this important pest. Maximum weights of individual stages of beetles were approximately 80 percent as great as weights of beetles reared on plants, and development and survival compared favorably with leaf-fed CPBs. Although the total number of offspring produced per beetle pair was lower for beetles reared on artificial diet than for beetles reared on potato plants, sufficient numbers of hatchlings were generated to produce a healthy and thriving CPB colony. The use of lettuce leaf powder in place of most of the potato leaf powder is especially advantageous because of the much reduced cost and greater availability of lettuce as compared to potato leaves. The diets and rearing system described will be exceptionally useful for providing beetles throughout the year for experiments including those associated with the testing of potential insect control agents, with understanding the mechanisms involved in the development of pesticide resistance in CPBs, and with improving the use of natural enemies to control CPB populations.
Technical Abstract: Colorado potato beetles (CPBs) have been reared successfully through 12 generations on artificial diets containing either 2.5% potato leaf powder or 2.0% lettuce leaf powder/0.5% potato leaf powder. The mean duration of each of the four larval stages was slightly longer for artificial diet-fed as compared to leaf-fed (control) beetles. Maximum weights of prepupae, newly emerged adults and day-5 through -9 adults were approximately 78, 80 and 82%, respectively of the weights for comparable stages of control beetles. Mean percent mortality for first instars was two to six times higher for artificial diet-fed CPBs than for leaf-fed beetles. However, since pupal mortality was four times higher for control beetles than for beetles reared on artificial diet, mean percent total mortality was the same for controls and for older generations of diet-fed CPBs. Number of hatchlings produced per adult pair per day (a measure of reproductive function) was approximately eight times greater in control beetles than in older generations of artificial diet-fed beetles, primarily because fewer egg masses were laid per day and because of higher percentages of cannibalism by the latter groups. The mean percent hatch although only 68% as great as the control value, was 1.5 times greater for beetles reared on diet containing lettuce-leaf powder than on diet containing only potato leaf powder. The quality of eggs, as judged by the ability of the wasp parasitoid, Edovum puttleri, to parasitize and develop in the eggs, was similar for eggs produced by control beetles and for those produced by beetles fed on potato and lettuce leaf-powder diets. The diets and rearing system described here will be exceptionally useful for providing beetles on a year-round basis for screening, resistance and experimental studies.