How are pesticides, herbicides and fungicides affecting the ecosystem?

Hint: Pesticides can contaminate soil, water, turf, and other vegetation. In addition to killing insects or weeds, they can be toxic to a host of other organisms including birds, fish, beneficial insects, and non-target plants. Fungicides can be highly toxic to a large range of organisms and are a huge risk to aquatic biota.

Complete answer:
Pesticides, herbicides and fungicides have different impacts on ecosystems such as the excessive use of pesticides, herbicides, and fungicides can cause soil pollution and water pollution. So they make the soil infertile and not suitable for crops and plants. As they become a part of the soil, they are taken up by the plants. Any herbicide treatment is to reduce the abundance of weeds to below some economically acceptable threshold, judged based on the amount of damage that can be tolerated to crops.

 We can also frame it and say that when organisms in the higher food chain consume the organisms containing the toxins below their trophic levels, the toxins gradually become concentrated in the higher food chain. This then becomes a repetitive process in the ecosystem and throughout the entire food chain, the higher organisms are the ones that will accumulate most of the toxins. Agricultural pesticides, fungicides, herbicides, and chemical fertilizers, along with other agricultural chemicals, are highly toxic and often find the way into the soils, rivers or lakes and the seas through surface storm water runoff. It disrupts the interconnected relationships within the food chain.

Note: Pesticides, herbicides and fungicides reach a destination other than their target species, because they are sprayed or spread across entire agricultural fields. Runoff can carry pesticides into aquatic environments while wind can carry them to other fields, grazing areas, human settlements and undeveloped areas, potentially affecting other species.