Insect gut detects unhealthy meal

Dec 21, 2007

Plant leaves and surfaces are teeming with microbial life, yet the insects that feed on plants lack adaptive immune systems to fend off any intruding microorganisms they eat along with their greens. Now research published in the online open access journal, BMC Biology shows how food-borne bacteria affect an insect’s immune system.

Study authors Dalial Freitak, David Heckel and Heiko Vogel from the Max Planck Institute for Chemical Ecology in Jena, Germany along with Christopher Wheat from the University of Helsinki, Finland, deliberately fed insects with non-infectious microorganisms. The researchers watched to see how the herbivorous insect, the cabbage semilooper Trichoplusia ni (Lepidoptera), detected and responded to a diet laced with nonpathogenic, non-infectious bacteria. In most studies to date, lab reared insects have been injected with bacterial strains, whereas in nature the insects’ main exposure would be from eating plants.

The larvae were reared on diets with or without an added helping of Escherichia coli and Micrococcus luteus bacteria. In the bacteria-fed larvae, general antibacterial activity was enhanced, although the activity of one key enzyme related to immune response - phenoloxidase - was inhibited. Among the eight proteins highly expressed in the hemolymph of the bacteria-fed larvae were the immune-response-related proteins arylphorin, apolipophorin III and gloverin. Significantly, the pupation time and pupal mass of bacteria-fed larvae was negatively affected by their unhealthy diet.

The authors conclude that even non-pathogenic bacteria in food can trigger an immune response in insects with significant effects. “Trichoplusia ni larvae are able to detect and respond to environmental microbes encountered in the diet, possibly even using midgut epithelial tissue as a sensing organ,” says Vogel. Although this reaction to microbes comes at a price, it may be offering protection from serious infection. “These results show that microbial communities on food plants represent a dynamic and unstudied part of the coevolutionary interactions between plants and their insect herbivores,” he adds.

Source: BioMed Central

Explore further: Orb-weaving spiders living in urban areas may be larger

add to favorites email to friend print save as pdf

Related Stories

Study sheds new light on river blindness parasite

Jan 12, 2011

The team found that a bacterium inside the worm acts as a 'disguise' for the parasite, resulting in the immune system reacting to it in an ineffective way. The bacteria protect the worm from the body's natural defences, ...

Fighting antibiotic resistance with 'molecular drill bits'

Mar 17, 2014

In response to drug-resistant "superbugs" that send millions of people to hospitals around the world, scientists are building tiny, "molecular drill bits" that kill bacteria by bursting through their protective cell walls. ...

Social insects put the 'I' in team to fight disease

Oct 09, 2013

Social insects such as ants, termites, and some bees and wasps live in a sort of eternal "airplane environment," according Rebeca Rosengaus, an associate professor in Northeastern's Department of Marine and ...

Recommended for you

Orb-weaving spiders living in urban areas may be larger

3 hours ago

A common orb-weaving spider may grow larger and have an increased ability to reproduce when living in urban areas, according to a study published August 20, 2014 in the open-access journal PLOS ONE by Eli ...

Sequencing the genome of salamanders

7 hours ago

University of Kentucky biologist Randal Voss is sequencing the genome of salamanders. Though we share many of the same genes, the salamander genome is massive compared to our own, about 10 times as large.

User comments : 0