Biological Control of Acacia Nilotica Subsp. Indica by Using Bio Agent Chiasmia Assimilis (Warren)
Dr. Soekisman Tjitrosoedirdjo

Source: SEAMEO BIOTROP's Research Grant | 2017


The invasion of Acacia nilotica  in Baluran National Park is threatening the integrity of the savanna ecosystems, the greater portion of the park. Recent works on the mechanical and  chemical controls by cutting A.nilotica trees with a chainsaw and brusing the left stump with triclopyr (5-10% GARLON dissolved in diesel oil) killed  the treated trees. When this is preceeded by spraying triclopyr (GARLON 2 lt/ha in 400 L  of water mixed with 2% Agristik an adjuvant) the broadleaved weeds and sapplings,  poles and smaller trees of A.nilotica and Azadirachta indica, will be controlled  that helps to recover the domination of grasses in the savanna. However the seed bank of A.nilotica in the soil still has to be addressed accordingly. Application of herbicides to control seeds under the soil is difficult beside a possible environmental problems related to residual herbicides.  Therefore, a set of research works on biological control of A.nilotica  using Chiasmia assimilis  to overcame the ever emerging seedling from the seed bank of A.nilotica were proposed. The biocontrol agent was imported from Australia, and reared at the laboratory of BIOTROP for further works on host specificity testing to estimate the host range of C.assimilis.

The host specificity testing in the framework of invasive alien plant species has undergoe a significant changes to be more efficient. In principle insect (biocontrol agent) for biological control purposes is monophagous  so in the framework of host specificity testing it is examined if the insect is monophagous or specific attacking only the target species, however in practice it is more of investigating  on the range of host plants. When there is an indication that the cut foliar is eaten by the larva of C.assimilis the Related plants  are once again tested without host specificity testing without choices.  

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