Distribution. Asiatic garden beetle was first observed in North America in New Jersey during 1921, but it has since spread as far north as Massachusetts and as far south as South Carolina. Its likely origin is Japan or China.
Host Plants. This insect is reported to feed on more than 100 plants, and though much of the diet breadth is due to adult feeding, larvae also have a wide host range. Larvae normally are most abundant on turfgrass or pastureland, but sometimes they occur in high densities in vegetable and flower gardens, where they attack beet, carrot, corn, lettuce, onion, Swiss chard, strawberry, begonia, columbine, and occasionally others (Hallock, 1934). Among the adult food plants are such crop and ornamental plants as bean, beet, broccoli, cabbage, carrot, corn, eggplant, kohlrabi, parsley, parsnip, pea, pepper, potato, radish, rhubarb, spinach, sweet potato, Swiss chard, turnip, peach, cherry blackberry, sumac, ailanthus, butterfly bush, chrysanthemum, dahlia, larkspur, gaillardia, gerbera, sunflower, strawflower, phlox, viburnum, zinnia, and boxelder. The most favored vegetable crops are beet, carrot, parsnip, pepper, and turnip. Among weeds readily consumed are ragweed, Ambrosia trifida; burdock, Arctium spp.; beggartick, Bidens frondosa; plantain, Plantago spp.; smartweed, Polygonum pensylvanicum; and cocklebur, Xanthium spp. The abundance of larvae is often greater near favored adult food plants, though orange hawkweed, Hiera-cium aurantiacum, which is not a food plant, is a preferred site for oviposition. Larvae also feed on decaying organic matter.
Natural Enemies. A parasitoid, Tiphia asericae Allen and Jaynes (Hymenoptera: Scoliidae), is known from Asiatic garden beetle, though its importance is uncertain. Several microbial pathogens affect Asiatic garden beetle, and likely contribute to periodic population declines. In a survey conducted in Connecticut (Hanula and Andreadis, 1988), infection rates by greg-arines varied from 0-63%, by the protozoan Adelina from 0-67%, and by the bacteria Bacillus popilliae and B. lentimorbus from 0-12.5%. Also observed in Asiatic garden beetle was the rickettsial disease Rickettsiella popilliae, which imparts a blue-green color to grubs.
Life Cycle and Description. There is a single generation per year in New York. Both second and third instars survive the winter, though the majority of larvae are third instars. Pupation occurs in June-July and adults are present from early July through September. Eggs are most abundant from mid-July to August, first instars in August-September, and the latter two instars until the following spring.
The biology of Asiatic garden beetle was given by Hallock (1932, 1935, 1936). Asiatic garden beetle was included in the larval keys of Ritcher (1966), and the adult keys by Downie and Arnett (1996).
Asiatic garden beetle is principally a turfgrass pest, though both larvae and adults can injure home gardens. Relative to similar immigrant scarabs, Asiatic garden beetle is generally more damaging to vegetables than oriental beetle, Anomala orientalis Water-house, but is less damaging than Japanese beetle, Popillia japonica Newman. The major form of damage
is root feeding by larvae, but adults feed on foliage and flowers. Damage usually occurs only when large numbers of larvae are present, or in the case of crop seedlings, when plants are quite young. Thus, 2-3 grubs per grass plant affect growth, and 4-5 grubs cause enough root injury to cause plant death. There was also an interesting report of beetles that crawled into the ears of campers in Pennsylvania (Maddock and Fehn, 1958). This form of injury, though affecting hundreds of campers in this report, is not generally a frequent or widespread phenomenon.
Asiatic garden beetle populations are usually cen-sused by sampling turfgrass for grubs. The adults are highly attracted to lights, however, so light traps can be a useful tool for monitoring. Residual insecticide is often applied in either liquid or granular form to the soil for grub suppression, though adults are susceptible to insecticide applied to foliage. Bacillus popil-liae provides partial suppression of larvae.
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