Impact of Perillus Bioculatus on the Colorado Potato Beetle and Plant Damage

George Tamaki and B. A. Butt. Impact of Perillas Bioculatus on the Colorado Potato Beetle and Plant Damage. U.S. Department of Agriculture, Technical Bulletin 1581, 11 pp. 1978 The potential impact of Perillus bioculatus, a pentatomid predator, on the Colorado potato beetle, Leptinotarsa decemlineata, was evaluated by studying the biology, constructing life tables, and determining the feeding potential of different life stages of the predator on the eggs and larval stages of the defoliator. At average temperatures of 24° C, the developmental time of the egg of P. bioculatus was about 8 days and for the nymphal stage, about 17 days. Predator nymphs consumed up to 39 eggs or 0.6 of a large larva of L. decemlineata per day. The potential replacement rate was 46 daughters per generation. The population of P. bioculatus is able to double its size in 8y2 days, and the generation time is 47 days. In laboratory studies, L. decemlineata on potato foliage consumed 2,710 mm^ of potato leaf area during its larval development at 24° ± 7° C. The fourth stage of the beetle consumed an average of 538 mm^ and the adults, 687 mm^ of foilage per day. Field census of all stages of the beetle on potatoes and the total leaf areas of potato plants were measured at different times of the year. For instance, the field population of an average of 26.4 larvae and adult beetles per plant on July 14 consumed 14,037 mm^ of leaf area per plant and can completely defoliate a medium-size plant in 11 days. Given the number and life stages of the predators and defoliators, we predicted the amount of prédation and defoliation. Knowing the size of the potato plants, we predicted the percentage of defoliation resulting from the predatorprey-plant interaction. Moreover, knowing the percentage of defoliation of a plant, we estimated the yield loss.