Biological and chemical control of the Asiatic garden beetle, Maladera castanea (Coleoptera: Scarabaeidae)

The efficacy of chemical and biological control agents against larvae of the Asiatic garden beetle, Maladera castanea (Arrow), in turfgrass under laboratory, greenhouse, and field conditions were determined. In field trials where insecticides were applied preventively against eggs and young larvae, the molt-accelerating compound halofenozide and the neonicotinoids imidacloprid and thiamethoxam were ineffective, whereas another neonicotinoid, clothianidin, provided 62-93% control. In greenhouse experiments against third instars in pots, the carbamate insecticide carbaryl was ineffective, whereas the organophosphate trichlorfon provided 71-83% control. In laboratory, greenhouse, and field experiments, the entomopathogenic nematode Heterorhabditis bacteriophora Poinar and Steinernema glaseri Steiner (not tested in the field) were ineffective against third instars, whereas S. scarabaei Stock & Koppenhöfer provided excellent control. In microplot field experiments at a rate of 2.5 × 10⁹ infective juveniles per ha, H. bacteriophora provided 12-33% control and S. scarabaei 71-86% control. Combinations of S. scarabaei and imidacloprid did not provide more control of third instars compared with S. scarabaei alone.