Violent sex acts boost insect's immune system

Scientists have discovered that many insects have a form of immune memory similar to the vertebrate system, which protects them against reinvasion by previously encountered pathogens.

This was just one of the discoveries reviewed at the recent conference on Innate Immunity and the Environment, organised by the European Science Foundation (ESF).

The highlight of the conference was the presentation of research showing that insects and higher vertebrates (including humans) have much more similar immune systems than was thought, according to the conference chair Prof Paul Schmid-Hempel from the Institute of Integrative Biology in Zurich.

Schmid-Hempel said it is not just insect immune memories, but also how they recognise pathogens, that have close analogues in vertebrates.

Insect innate immunity was also discussed in regards to sex, where females must distinguish between hostile pathogens and male sperm. For some insects, sex is a violent act causing wounds that become infected and require a swift and powerful immune response.

“The topic was the traumatic insemination performed by some insect males, such as bedbugs, where the male injects sperm into the female through her body wall and certain sites,” said Schmid-Hempel.

“It has now been shown these sites are very immuno-active, and that this feature is essential to keep out infections that typically enter via the insemination act. In essence, it is about the general problem that insemination may also transfer disease and, at the same time, sperm is an antigen (non-self) for any female with all its potential immunological complications.”

The conference was the first of two organised by the ESF on innate immunity’s relationship with the environment, with the second staged for 2009.

The second conference will discuss work on the ‘hygiene hypothesis’, which states that too much cleanliness is actually bad for the developing immune system in children.

“There is a growing awareness and consent that early exposure to antigens/pathogens is important for the full capacity of the immune system,” said Schmid-Hempel.