some species of insects e.g butterflies, are found in greater numbers at certain times of the year. Suggest 3 reasons to account for changes in population numbers throughout a year. fully explain each reason
1. Reproductive cycles: One reason for changes in insect populations throughout the year is their reproductive cycles. Many insect species have specific breeding seasons when favorable environmental conditions such as temperature, humidity, and food availability align. These conditions are essential for successful mating, egg-laying, and offspring survival. For example, butterflies may experience a surge in population during spring and summer when the weather is warm, floral resources are abundant, and host plants are suitable for larval development and pupation. The availability of optimal conditions during specific times of the year leads to increased mating and higher survival rates, resulting in a larger population.
2. Seasonal migrations: Another factor contributing to changes in insect populations is seasonal migrations. Some insects undertake long-distance movements to exploit different regions with favorable conditions throughout the year. These migrations can be triggered by factors such as temperature changes, food availability, or the need to find suitable breeding grounds. For instance, certain butterflies, like the monarch butterfly, undertake epic migrations spanning thousands of kilometers. They travel from their breeding grounds in the northern regions to overwintering sites in warmer regions. These migrations allow the species to take advantage of different resources and habitats during different times of the year and can significantly affect population numbers in different regions.
3. Natural enemies and predators: The presence and activity of natural enemies and predators also play a crucial role in regulating insect populations. For instance, certain insects may have specific predators, including birds, mammals, or other insects, that feed on them or their eggs, larvae, or pupae. These predators can control population numbers by reducing the survival rates of individuals. In some cases, the predators themselves may have population fluctuations throughout the year, leading to corresponding changes in prey populations. Additionally, parasites, pathogens, or diseases can also impact insect populations. If an insect species experiences an outbreak of a deadly pathogen or faces high levels of parasitism at a particular time of the year, it can lead to a decline in population numbers.
These three reasons - reproductive cycles, seasonal migrations, and interactions with natural enemies - collectively contribute to the changes in population numbers of insects throughout the year. By understanding these factors, researchers and conservationists can better predict and manage insect populations to ensure their conservation and ecological balance.