Read the text and answer the question!

Integrated Pest Management

    There is no best way to ideal with pests in agriculture. Pesticides which are commonly used may cause many problems. I think combining different management operation is the most effective way to controls pests.

    Firstly, the chemicals in the pesticides my build up as residues in the environment and in the soil which absorbs the chemical. This reduces the quality of farm product.

    Secondly, pests can gradually become resistant to pesticides. This means that newer and stronger ones have to be developed.

    Lastly, some pesticides affect non target plants and animals such as fish and bees. This affects the ecology and environment as well.

    So, understanding of ecology of an area helps a lot in pest control. Pesticides should be chosen and applied carefully so that they don’t affect the ecological balance and environment.

    Therefore, integrated pest management is a safe and more affective option to fight pest in agriculture and livestock.

“Secondly, pest can gradually become resistant to pesticides.” (paragraph 3)

The word resistant in the sentence above means ....