More than 17 million insects migrate annually through the Bujaruelo mountain pass on the border between France and Spain. According to phys.org, this is stated in a new study by the University of Exeter, reports UNN.
Details
The paper, published in the journal Proceedings of the Royal Society B under the title “The most remarkable migrants - a systematic analysis of the Western European insect flight path on a Pyrenean mountain pass”, describes observations of the Bujaruelo Pass over 4 years.
Observations indicate that billions of insects cross the Pyrenees every year, making it a key location for many migratory species. A wide variety of insects were spotted, but flies accounted for 90% of the total. Butterflies and dragonflies are well-known migratory insects, but they accounted for less than 2% of the total.
Many of the migrants were well-known garden inhabitants, such as the cabbage white (Pieris rapae), the house fly (Musca autumnalis), and even tiny grass flies (Chloropidae) as small as 3 mm long.
The researchers used a video camera to count small insects, a visual count of butterflies, and a flight intercept trap to identify migrating species.
The number of insects reached a maximum when it was warm, sunny and dry. In weak or headwinds, when the insects were low over the pass, they could be counted.
Scientists add that migratory insects, especially flies, are of great importance to the planet. Almost 90% of recorded insect species are pollinators, and by migrating, they carry genetic material over long distances between plant populations, improving their health. Some of the insects are pests, but many are pest controllers, including the marmalade and variegated hoverflies, which eat aphids in the larval stage.
Many of them play a role in the decomposition process, and all transport nutrients such as phosphorus and nitrogen over long distances, which can be important for soil health and plant growth.