Aug 17, 2019 | Updated: 07:24 AM EDT

Smaller Wasps May Be Due To Climate Change

Aug 02, 2019 07:05 PM EDT

(Photo : Capri23auto)

Black and yellow striped insects often come on picnic uninvited. Centuries ago, they used to be so big that no one can miss them out, but lately, these wasps seem smaller than their ancestors. Maybe not all, but one common wasp species seem to appear as if it were shrinking as a consequence of the global crisis on temperatures due to climate change. 

Several vertebrates have already undergone studies that show how the warming of the environment is causing them to shrink. Antelope and sparrow are two species that have been recorded to have become smaller than they used to be due to the impact of heat and in the availability of food. There is a clear relationship between the size of the body and the retention of heat. However, the relationship between the body size of an insect to the effects of extreme heat is oftentimes overlooked. 

A team of researchers led by Carlo Polidori, an etymologist from the University of Castilla -- La Mancha, Space -- came across decades of insect samples from the source Madrid's National Museum of Natural Sciences. They saw this as an opportunity to compare the sizes of the insect body then and now. 

The team measured the size of the wings, width of the head, as well as the size of their wings. These observations were recorded from various locations on the Iberian Peninsula. Some of the data they have collected dates back to 1904. 

They found that over time, wasps have become smaller. The team compared their data to the records kept on the Iberian climate and they saw that the decline in the size of these insects coincided with the increase in the temperature. Though the team could not pinpoint the cause of such relationship, they have linked the shrinking of the insects to their early development. They grow faster in warmer temperatures, thus they produce more adults in a shorter span of time. These adult wasps are only smaller than their predecessors. 

"The shrinking of the body size of wasps likely comes with adverse effects on recent and future breed of these insects," says Polidori. "For example, wasps that are smaller in size may only hunt for prey that are relatively smaller than their size, compared to the size of the prey that wasps used to hunt after."

Oddly, the wings of wasps seem to shrink faster than their body, and if there are no changes in the shape of their wings, Polidori expects future wasps species to be less speedy and agile while in flight. 

"If prey insects are getting smaller on the average, wasps could have evolved into smaller creatures over the last century. Should it be a cause for alarm?" says Forrest. 

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