However, the data obtained in the Aiguamolls del Empordà Natural Park indicate that in recent years there is less coincidence between the moment when the plants reach their maximum flowering and the moment when the abundance of butterflies is also higher. The culprit for this phenomenon is climate change: temperatures are increasing and drought is becoming more severe. This climate causes there to be mismatches between the 12 species of butterflies studied and the flowers on which they feed.
This climate causes there to be mismatches between the 12 species of butterflies studied and the flowers on which they feed
"Butterflies are organisms highly dependent on the climate," says Constantí Stefanescu, a researcher at CREAF and MCNG. Its cycle consists of three development phases before the adult butterfly - the egg, the caterpillar and the chrysalis - which are greatly affected by external temperatures.
“In general, a higher temperature accelerates the rate of development from the egg to the emergence of the butterfly, but this relationship depends on more factors. For example, it can be negatively affected by the lack of rain and the deterioration of the plants on which the caterpillar feeds ”explains Stefanescu.
Why can this situation be worrying in the Mediterranean climate? Because the drought appears in the study as the most important factor to explain the asynchrony between butterflies and flowers and precisely, with the current climate change scenario, the drought will worsen in this region.
In extreme cases, it has been found that the separation between lepidopterans and flowers can be as high as 160 days and, if this continues, could lead to large declines in butterfly populations. In turn, if the pollination efficiency of butterflies (and other groups of insects for the same reason) were reduced, decreases would appear in plant populations.
The tracks could be more severely disengaged
Drought affects all adult butterflies, whether they are generalists or specialists for a specific plant
The study, published in the journal Oikos, states that drought affects all adult butterflies, whether they are generalists or specialists for a specific plant. However, the CREAF researcher recalls: “The strongest dependence between plants and butterflies occurs during the caterpillar phase, especially if they only feed on a single plant species. Therefore, at this moment the lack of synchrony could be more important ”.
Butterflies are rather generalists in terms of the species of flowers they visit to obtain nectar (they can visit more than one type of flower), but instead they can be true specialists when it comes to choosing a species of plant to lay.
This plant will be the one that the caterpillars will use to develop and is called a nutritious plant. A disengagement between the caterpillar phase and the growth of the nutrient plant can have catastrophic effects on the survival of the caterpillars and, therefore, on the final abundance of adult butterflies.
Photo: Atalanta (Vanessa atalanta) prepared to absorb nectar. You can see the buccal appendix, called the spirit, which is elongated to reach the bottom of the flower. / José Luis Ordóñez