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ShareNEW YORK: Ever wondered what make chilli peppers have a hot fiery flavour? Well, it's bugs that put the heat in the fruit which adds spicy flavour to many of our favourite delicacies, says a new study.
Researchers in the United States have carried out the study and found that bugs, both the crawling kind and the ones which can be seen with a microscope, are actually responsible for the heat in chili peppers.
According to them, the spiciness is a defense mechanism which some peppers develop to suppress a microbial fungus that invades through punctures made in the outer skin by various insects.
The fungus, from genus Fusarium, destroys the plant's seeds before they can be eaten by birds and distributed.
"For these wild chilies the biggest danger to the seed comes before dispersal, when a large number are killed by this fungus. Both the fungus and the birds eat chilies but the fungus never disperses seeds -- it just kills them," said lead researcher Joshua Tewksbury of University of Washington.
Fruits use sugars and lipids to attract birds that will scatter the seeds. But insects and fungi enjoy sugars and lipids too, and in tandem they can actually be fatal to a pepper's progeny.
However, the researchers found that the pungency in hot chilies acts as a unique defense mechanism -- the pungency comes from capsaicinoids, the chemicals that protect them from fungal attack by slowing microbial growth, the 'Proceedings of the National Academy of Sciences' journal reported.
"Capsaicin doesn't stop the dispersal of seeds because birds don't sense the pain and so they continue to eat peppers but the fungus that kills pepper seeds is quite sensitive to this chemical.
"Having such a specific defense, one that doesn't harm reproduction or dispersal, is what makes chemistry so valuable to the plant and it is a great example of the power of natural selection," Tewksbury said.
For their study, the researchers collected chilies from seven different populations of the same pepper species spread across 1,000 square miles in Bolivia.
In each population, they randomly selected peppers and counted scars on the outer skin from insect foraging. The damage was caused by hemipteran insects such as seed bugs that have sucking mouth parts arranged into a beaklike structure that can pierce the skin of a fruit.
The researchers found that not all of the plants produce capsaicinoids, so that in the same population fruit on one plant could be hotter than a jalapeo while fruit from other plants might be as mild as a bell pepper.
But there was a much-higher frequency of pungent plants in areas with larger populations of hemipteran insects that attack the chilies and leave them vulnerable to fungus.
The researchers also found that hot plants got even hotter, with higher levels of capsaicinoids, in areas where fungal attacks were common. But in areas with few insects and less danger of fungal attack, most of the plants lacked heat.
