Final answer:
Pesticide applications may fail due to the development of pesticide resistance by pests, inadequate ecologically based control measures leading to over-reliance on chemicals, and the significant human health and environmental impacts. In developing countries, overuse and lack of safety precautions exacerbate these problems. The environmental impact includes harm to non-target species and other ecological damages.
Step-by-step explanation:
There are several reasons why pesticide applications may fail to control pest populations effectively. One significant cause is pesticide resistance, where pests, due to their short generation times and millions of years of evolving with natural plant toxins, develop the ability to withstand chemical treatments that were previously lethal. Additionally, ecologically based control measures are not always adequately implemented, leading to pesticide use as a last resort, which may not always be the most effective approach. Moreover, the environmental, human health, and cost implications are considerable, especially in developing countries where overuse and improper safety measures are common due to a lack of understanding and weak regulatory systems.
Pesticides also pose risks of acute and chronic health effects to agricultural workers and others exposed to them, making correct application and safety precautions paramount. Pesticide exposure can lead to diseases such as non-Hodgkin's lymphoma and leukemia, as well as a range of other health issues. Finally, the environmental impact, including the poisoning of non-target species and the broader ecological damage, cannot be ignored. Therefore, minimizing the use of chemical pesticides and ensuring ecologically sensitive applications are crucial for sustainable pest management.