Why is BTi effective in controlling black flies?

Bacillus thuringiensis israelensis, commonly referred to as BTi, is particularly effective in controlling black flies primarily because it acts as a stomach poison for their larvae. When black fly larvae consume BTi, they ingest the spores and toxins produced by the bacterium. The toxins disrupt the digestive processes within the larvae’s stomach, ultimately leading to their death. This mode of action makes BTi a specific biocontrol agent, targeting only certain aquatic insect larvae like those of black flies, which are particularly susceptible to its effects.

The reason this action is significant is due to its targeted approach; BTi does not harm other non-target species, making it a more environmentally friendly option compared to broader-spectrum pesticides. Utilization of BTi allows for effective control of black fly populations, decreasing their numbers and subsequently reducing their impact on human health and activities, especially in areas where these pests breed in standing water.