obtained under intense pesticide regimes, making the data unhelpful for determining biocontrol strategies. Nevertheless, current knowledge of the rice environment suggests that insect pests are in many cases of lesser importance when compared to weeds or rodents, for instance. It also appears to be commonly acknowledged among the scientific community that BPH usually only achieves pest status after repeated application of broad-spectrum insecticides. However, action thresholds for BPH must be lowered if the virus diseases grassy-stunt and ragged-stunt are present. It is also necessary to distinguish between three different rice habitats: lowland irrigated, rainfed lowland and upland (dry land) rice, which often show contrasting pest and disease complexes. Only Indonesia and Vietnam presented field application details for entomopathogenic fungi against brown plant hopper (BPH). Thailand provided some references to published studies mainly dealing with effectiveness of local isolates of entomopathogenic fungi under laboratory and semi-field conditions. Brunei Darussalam, Cambodia, Indonesia, Malaysia, Philippines, and Vietnam listed IPM measures that deemed useful against BPH (see below). Based on internationally published scientific studies, the main BCA that appear to be effective against BPH are entomopathogenic fungi, namely certain isolates or strains of Beauveria spp. and Metarhizium spp. (53) (54) (55). Isolates or strains that showed high levels of effectiveness were applied in the field at rates ranging from 5 x 1012, 6 x 1012 to 7.5 x 1012 conidia per ha based on experiences from the Philippines, Vietnam, and Korea, respectively. Dry mycelia of B. bassiana can also be applied at rates equivalent to 200 g per ha in a formulation with 5% LiquaGel® 29 3.1.1 Member States’ experience, scientific evidence, market information (ABC database), and results from field trials (56). The ABC database identifies several commercial BCA recommended for use against BPH in Vietnam, Indonesia and Malaysia (see Appendix I). The available products are based on neem or entomopathogenic fungi; however, only Vietnam lists entomopathogenic fungi as specifically registered for use against BPH. Furthermore, the action thresholds for starting a fungal treatment have not yet been fully established. One source (70) recommends starting treatment at a density of 3 BPH per tiller, or about 1000 per m2. A minimum pest population level appears to be necessary for the secondary cycling (horizontal transmission) of entomopathogenic fungi. In this regard, it is recommended by various publications not to spray fungal products preventatively (i.e. when the target pest is completely absent). Besides use of BCA, the following IPM measures were proposed by AMS and found common acceptance: • Use of resistant varieties • Synchronous timing of planting • Use of fallow periods • No use of chemical pesticides if pest under threshold, at least until 40 days after transplanting (DAT), unless virus diseases are present in the area, in which case, targeted application (of biorational agents) may be warranted • Monitoring of natural enemies and pest incidence
Implementing Biological Control Agents in the ASEAN Region
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