Biological control as a tactic of environmentally safer agriculture has not been widely accepted by farmers. In Japan integrated biological control with native natural enemies is rapidly developing for greenhouse vegetables, because of high prices of commercially mass-reared biological control agents. We have studied the effective use of natural enemies at farm level, focusing on generalist predators, although there are differences in using natural enemies for augmentation in greenhouses and conservation in open fields. Recently, however, insectary plants (crops) have been considered as a key component for enhancing natural enemies. We have examined the effectiveness of candidate insectary plants on natural enemies and implemented biointensive IPM with insectary plants at farm-level. Our recent study suggested that some herbs and crops are highly effective on improving the survival and reproduction of generalist predators. By growing such plants in vegetable greenhouses and open-fields, natural enemy populations could be enhanced and thus stably persist even after targeted prey populations are exploited. Moreover, insectary plants may result in a shift of IPM from level I to level II.

Conservation biological control (CBC) is one of the pest management tactics based on protecting and maintaining natural enemies that already exist in the crop environment. Among many appropriate practices to control pests, CBC has been considered as a sustainable means and a less expensive alternatives to chemicals. It contains an introduction of non-crop plants as shelter habitat for providing natural enemies with food sources, overwintering or refuges shelters. As a small scale experiment of CBC, we tried to intercrop six kinds of floral plants (buckwheat, red clover, Agastache rugosa, Chrysanthemum indicum, Allium tuberosum, Lythrum anceps) with napa cabbage in order to attract some natural enemies, especially parasitic wasps that could be fed on them in the cabbage fields, which is a novel way for conservation of natural enemies, but none showed significant result. For the development of integrated pest management system by harmonizing biological and chemical control, we carried out evaluating toxicity of 30 pesticides to parasitoids and investigating effectiveness of traps. With leaf dipping method for adult and body dipping method for cocoons, 12 pesticides showed under 30% of toxicity being selected as safer by IOBC. Using sex-pheromone traps for attracting lepidopteran pests showed that DBM, CAW and CL occurred less than untreated fields; 67.5%, 70.6% and 44.0%, respectively. Also, yellow sticky traps could reduce some pests; 52% for flea beetle, 62% for cabbage sawfly and 41% for Phaedon brassicae. These results are expected to give basic information to develop conservation biological control of DBM with indigenous parasitoids in the cabbage fields on a large scale in the future. Before developing and distributing a promising pest control method, we should consider whether it can be compatible with other agricultural practices or various situations around fields.