Final answer:
Blanket spraying of pesticides is a broad approach that can harm non-target species and lead to resistance, while selective spraying is more targeted, reducing such risks but requiring more precision and effort. Biological control is another strategy that can be very effective but may have unintended effects.
Step-by-step explanation:
The pros and cons of blanket spraying vs. selective spraying are central to agricultural pest management strategies. Blanket spraying involves indiscriminately covering an entire area with pesticides, whether or not pests are present in all locations. This method can quickly reduce pest populations but may also harm non-target species, lead to ecological imbalances, and contribute to the development of pesticide resistance. Conversely, selective spraying targets specific areas where pests are known to be a problem, reducing non-target impacts and potentially delaying resistance. Selective spraying may involve more precise planning and can be more labor-intensive. Integrated approaches that include biological control methods can be effective, as seen with the use of beneficial weevils against water hyacinth and lady beetles to control scale insects. However, care must be taken as some biological control mechanisms have resulted in unintended consequences, such as attacking non-target species or failing to control pests in different environments.