Field pansy plant examined in the research (Image: CNRS)
Insect populations are declining alarmingly around the world. According to German research, the number of flying insects has decreased in the past 30 years by 75 percent, even in protected areas. Today, there are only a quarter as many insects in Hungary than there were in the early 1990s. This is simply a disaster, since most plants are pollinated by insects, and if they were not present (according to current trends, many insect species may become extinct in the near future), most plants would die with them.
Botanists from the French National Center for Scientific Research (CNRS) and the University of Montpellier have discovered that the dwindling number of pollinating insects is actually responding to plant evolution: wildflowers growing in fields are becoming more and more self-pollinating, that is, they are trying to make their reproduction independent of predatory insects. As you can guess from the name, in self-pollinated (or self-pollinating) plants, pollen reaches the pistil from the stamens of the same individual, i.e. there is no need to transfer pollen to the flowers of another individual. According to French researchers, this is an adaptive response to a lack of pollinators. Botanists came to this conclusion by examining field pansies. They compared plants grown around Paris today with plants grown from seeds collected in the 1990s (which therefore reflects the status of the species three decades ago). The results revealed that the flowers of today's plants are 10% smaller and produce 20% less nectar, which is why pollinating insects (which are still present) visit them less often than their predecessors thirty years ago. Meanwhile, self-pollination is becoming more common in today's plants.
Plants that choose to self-pollinate have less ability to attract pollinators, so their flowers and the amount of nectar are reduced (since they no longer need it as much, so they can save valuable energy by holding it back). We might even welcome this development when we first hear it, because it may indicate that plants will also survive the decline in insect populations. However, according to the signs, the vicious circle has already begun: due to the decrease in the number of insects, the flowers become self-pollinated, the production of nectar (which is the main food of insects) decreases, and for this reason still insects will also starve, and their number will decrease. at a greater rate. At the same time, self-pollinating insects are increasingly reproducing internally, degrading their genetic stock and making them less resistant to pests, diseases and shifting environmental constraints due to climate change.