Parasites are some of the most diverse organisms found in nature. They can take a number of different forms and are spread liberally across the kingdom of life. From bacteria to plants to even some creatures in the mammal realm, parasites are everywhere.

The Diverse World of Parasites

However, even with that understanding, that doesn’t change the fact that there is one specific group of creatures that comes to mind for humans when considering the term “parasite”. And that thought is usually worms, intestinal or otherwise.

Of course, even these worms are fairly diverse and many different parasitic worms in the kingdom of Animalia aren’t even that closely related. Those in the Nematoda phylum, such as hookworms, are fairly removed from the likes of tapeworms or flukes found in the Platyhelminthes phylum. They are actually closer related to all of Arthropoda that includes insects and spiders.

Understanding the behaviors and genetics of all the varying types of parasitic worms is paramount to treating dozens of diseases in humans and other creatures, along with utilizing these worms for our benefit in certain insects. A main specialty of parasitic worms is their specialized host-sensing behaviors and apparatuses.

Specialized Behaviors For Hunting

Researchers at Queen’s University Belfast in Northern Ireland have been investigating the activities of one particular parasitic worm named Steinernema carpocapsae. This worm has a characteristic of working together with symbiotic bacteria in order to attack and kill its desired insect hosts.

At the same time, it uses several special behaviors, such as jumping and also “standing up” while waving its head around, both of which allow it to better locate its prey, the latter a behavior named nictation. This nematode is a part of a unique group called entomopathogenic nematodes that attack insects and use a chemosensory apparatus in conjunction with their behaviors.

Better knowledge of the genes and the specifics of the chemosensory mechanisms involved could help in creating biocontrol methods against certain insects, along with info on how other nematodes that attack mammals behave. A two for one deal, you could say.

Making A Knockout

It was decided that they would utilize RNA interference in order to study certain genes, as that would allow them to knockout the function of the gene in question and see how that affects the worm. If the organism loses its capability to perform particular behaviors, that would imply that the gene controls that function.

A simple enough procedure, though requiring the proper gene to be selected for testing. Prior research in the model organism C. elegans had shown that nictation behavior, while used differently in that species, related to the firing of IL2 neurons. Following this line of logic, they found that these neurons in S. carpocapsae set off an FLP receptor, also known as a neuropeptide receptor.

Only two genes are currently known in the species to relate to this receptor, FLP-18 and FLP-21. The scientists chose the latter to use RNAi techniques on, What they found after knocking out the gene is that multiple behaviors, including nictation, jumping, and even proper sensory perception were lost by the worm. This clearly showed that FLP-21 helps in the regulation of these behaviors, though it may not be the only controller.

Knowledge And A Model

This study helped confirm the accuracy and ability to use RNAi in a parasitic worm species for gene identification, along with identifying a behavior-control gene found in beneficial parasites used as bioinsecticides and in parasites that cause harm.

In both cases, this gene can be used to enhance our control over the parasites, against insects and to stop disease from occurring.

Also, this research shows that S. carpocapsae works as a model for parasite-host behavior without having to actually include the specific infection of a host in the process of the experiment.

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Study Link

Photo CCs: Soybean cyst nematode and egg SEM from Wikimedia Commons

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