With regard to infections with Fusarium species, cultural and physical management techniques described so far need to be further developed and field tested in the future. Various microbial BCA that have been identified as effective in international scientific reports are actually also available on markets in ASEAN, including Trichoderma spp., Bacillus spp., and Streptomyces lydicus (the latter is registered in Vietnam; see Appendix I). However, because many of these products are not registered for use in vegetables, we recommend extending existing registrations to vegetables, after field testing has confirmed the usefulness of these products in relevant crops. Additionally, the use of BCA as seed treatments should be evaluated in the future. AMS’ experts ranked the feasibility of implementation of the proposed biocontrol approaches DBM >> fungal diseases > flea beetle, while management of DBM using Bt was regarded a good starting point. Because DBM is a worldwide – and one of the most recognised - insect pests, it has attracted a high number of pesticidal products in ASEAN, and is also the number one target for BCA (Appendix I). A biocontrol-based IPM strategy appears to be readily feasible for certain vegetables given the relatively high variety of tools at hand. Just if one considers Bt-based products alone, these are available in at least seven AMS (see Appendix I). Whether or not parasitoid wasps could (again) become an effective tool against DBM will especially depend on the extent to which synthetic broad-spectrum pesticides can be reduced or avoided in areas where a release is considered. This is a topic where governments would need to become involved and take over responsibility for the management of interventions, also because mass production of beneficial insects is not a commercially attractive business to date. Certainly, areas with organic farming would be suitable for release or re-introduction of parasitoids, provided the areas are big enough; or some other kind of agricultural zoning would be required to be implemented in protecting these BCA. Promotion of parasitoids needs not necessarily come along with calls for environmental protection: rather, there are solid economic reasons to rely on biological control using beneficial arthropods. Benefit-to-cost ratios are among the highest in pest management (67). We think that the combination of a parasitoid like Diadegma semiclausum with other BCA could become a truly sustainable management approach for DBM and other lepidopteran pests. Bt is generally a useful tool for control of important lepidopteran pests. A broader use is therefore highly recommendable, provided that the issue of resistance management is considered in future promotional activities. But there still exist other BCA: in Thailand, highly effective baculovirus preparations have been developed against important pests of vegetables (25). Although these products are mass-produced under high quality standards (at BIOTEC), they are not registered. Therefore, their market distribution is limited. In other AMS (e.g. Lao PDR, Vietnam), there exist only few registered baculovirus products. Thus, there is still a high potential for the safe and highly 36 3.2.2 Conclusions: development of BCA in vegetable production for vegetables as:
Implementing Biological Control Agents in the ASEAN Region
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