Plant defence against herbivory and insect adaptations

There is always a silent war between plants and herbivorous insects that we are rarely privy to. In this silent war, chemicals act as both weapons and messengers. Insect-plant co-evolution is going on for millions of years. Plants always look for new strategies to avoid insect pests and insects, in turn, are always ready to develop counter-adaptations. This intricate interaction has led to the development of a number of plant defensive traits and the counter-adaptive features in insects as well. Both plants and insects have developed morphological and biochemical defensive traits to dodge each others strategies. However, biochemical interactions are considered more important and effective than morphological ones because of their dynamic nature. Some of the plant defensive traits evolved during this evolution include toxic furanocoumarins, toxic amino acids, trichomes, lignin and latex. Since there is an increasing focus on improving crop production through safe and sustainable means by reducing the reliance on pesticides, it is highly important to understand the plant defensive traits against insect herbivory. It is equally important to understand the adaptations by insect pests to these defensive traits in order to develop and deploy management strategies to outsmart the insect pests. Here we discuss the plant defence traits against insect herbivory, their induction by elicitors and/or insect damage, and the counter-adaptation by insect pests.