What is the antonym for pesticide?

There isn't one single perfect antonym for "pesticide" because it depends on the context. Here are some options depending on what you want to convey:

Direct Opposites:

* Pesticide = substance that kills pests

* Beneficial = substance that helps or promotes growth of beneficial organisms (e.g., beneficial insects)

Alternatives to Pest Control:

* Pesticide = chemical control of pests

* Integrated Pest Management (IPM) = a combination of methods for controlling pests (including biological, cultural, and chemical)

* Organic Control = using natural methods to control pests, often involving beneficial organisms

* Biological Control = using natural predators, parasites, or pathogens to control pests

* Cultural Control = using methods like crop rotation or sanitation to prevent pests

* Resistant Varieties = using plant varieties that are less susceptible to pests

Words that convey the opposite of harm:

* Pesticide = harmful to pests

* Beneficial = helpful to plants or the environment

* Eco-friendly = environmentally safe

* Harmless = not causing harm

The best choice for you will depend on the specific context and what you are trying to emphasize.