Asiatic Garden Beetle Maladera castanea (Coleoptera: Scarabaeidae) Grubs Found in Damaged Turf in Alabama

Root-feeding white grubs (Coleoptera: Scara baeidae) are among the most important group of pests attacking grasses in pastures and land scapes in the United States. Throughout the con tinental United States, about 10 species of grubs and several species in the genus Phyllophaga are reported pests of turfgrass (Vittum et al. 1999). In southeastern states, grubs of Phyllophaga, south ern masked chafer (Cyclocephala lurida), the green June beetle (Cotinus nitidia), and Japanese beetles (Popillia japonica) are traditionally asso ciated with damaged turfgrass. However, recent publications (Buss 2006, 2008) challenge the as sumption that just a few species account for the alleged increase in damage to turfgrass from white grubs in the southeast. Furthermore, intro duced and native species may be expanding their range into or throughout the southeast. This pa per documents the occurrence of white grubs of the Asiatic garden beetle Maladera castanea (Ar row), an exotic species, in damaged turfgrass in Alabama. Asiatic garden beetles, native to China and Ja pan, were first detected in New Jersey in 1921. They have since spread to most of the northeast ern states, west to Indiana, and south to South Carolina (Vittum et al. 1999, NAPIS 2008). Spread of Asiatic garden beetles in the northeast was attributed to natural dispersal of adults as well as movement of infested nursery stock and turfgrass (Hawley & Hallock 1936). All known biological information is based on only a few reports (Hawley 1931; Hawley & Hal lock 1936) of populations in the northeastern United States. Adults are nocturnal, emerging when temperatures are 18.3-21.1?C (65-70?F), and actively fly at temperatures >21.1?C (Hawley & Hallock 1936). Adult flight begins in late Jun and can last into the fall. At night, adults are at tracted to lights and light traps are the suggested means of trapping adults (Hawley & Hallock 1936). Adults feed on foliage or flowers of 100 or more hosts (Hawley & Hallock 1936), and spar ingly on grass blades (Heller 1995). Damage to woody and herbaceous plants from adults can be misdiagnosed since the damage appears over night and adults are rarely observed. Damage to foliage begins from the edges, progressing inward until only the midvein remains. Adults seem to prefer flowers attacking roses, chrysanthemums, dahlia, sunflower, strawflowers, and zinnias (Hawley & Hallock 1936), aster, and goldenrod (Vittum et al. 1999). Even though adult damage can be extensive when present, adults are only considered minor pests of ornamentals (Vittum et al. 1999). In daylight hours, adults are in the soil near host plants or in turf adjacent to these host plants. Females lay eggs in clusters in the soil and seem to prefer weedy patches of turf that are well irrigated (Hawley & Hallock 1936; Heller 1995). Eggs are present in the soil beginning in Jul. Eggs absorb moisture from the soil, swell, and hatch (Hawley & Hallock 1936) similarly to other white grubs. Newly-emerged grubs are 1.4 mm long, and develop to 19 mm when mature. There are 3 instars with mature grubs present in the mid-Oct. Grubs can be found under weedy turf, or in fields of sweetpotato, beans, and other field crops (Haw ley & Hallock 1936). Grubs are distinguished from other scarabs by a distinctive raster pattern and enlarged bulbous stipes on the maxillae (Hawley & Hallock 1936; Ritcher 1966). In the northeastern United States, there is 1 generation per year. On 2-3 Oct, 2008, a stand of weedy turfgrass on the Turfgrass Research Unit in Auburn, AL was sampled for grubs. This stand, 27.2 x 21.9 m (90 x 72 ft), is composed mostly of crabgrass (Digitaria sp.), dichondra, and various sedges and grasses. This stand was established in 1997 on a sandy loam soil and recently has been used for herbicide research, and in 2008, the area was irrigated weekly with about 2.54 cm (1 inch) of supplemen tal water and maintained at 3.8 cm (1.5 inch). The area generally stays moist after rain and wet dur ing the winter months. The grubs collected on both days were mostly southern masked chafer (Cyclocephala lurida), a few billbug larvae, 1 Japanese beetle (Popillia japonica) grub, and 5 unidentified larvae. All grubs were collected into containers along with field soil and transported to the lab. The previ ously unidentified grubs had a raster pattern and swollen stipes characteristic of Asiatic garden beetle. The grubs were preserved in ethanol and the identity later confirmed with the key of Ritcher (1966). Grubs had an average length of 17.1 mm (0.67 inch) and head capsule width of 2.77 mm. These data indicate that the grubs are likely third instars (Hawley & Hallock 1936; Ritcher 1966). This is the southernmost report of Asiatic gar den beetle in the United States. Recent trapping studies in Alabama (Flanders et al. 2000) and, in Florida, Buss (2006) did not detect adult M. casta nea in blaeklight trap samples. The Alabama study, conducted in pastures, was within 50 km of