Insects are the largest and the most widely distributed group of animals and are the dominant multicellular life form on the planet. The total number of insect species are estimated at 5.5 million and this gives rise to an incredible variety of mechanisms for the regulation of life processes.
Peptides, including neuropeptides, peptides hormones and antimicrobial peptides, are especially important in the regulation of insect physiology where they play an important role in coordinating complex homeostatic processes. Insect neuroendocrinology has rapidly grown and there are roughly 50 identified insect neuropeptide families with about 50 neuropeptide precursor-encoding genes known in each insect species. Many insects produce substances that can be toxic to other animal species. These are used to protect insects from predators or to capture and kill prey. They often exhibit high selectivity and potency towards mammalian targets and have been used as selective probes and leads for drug development.
Insects can also have a huge negative impact on humans. One-sixth of all crops grown worldwide are lost to herbivorous insects and the plant diseases they transmit. About one in six human beings alive today is affected by an insect-borne illness such as plague, sleeping sickness, river blindness, yellow fever, filariasis and leishmaniasis.