Difference Between Parasite and Parasitoid

The key difference between parasite and parasitoid is that parasites do not always kill the host while parasitoids always kill the host.

Both parasite and parasitoid are ecological relationships where one organism lives at the expense of the other known as the host. In addition, the hosts never benefit from parasites and parasitoids. A parasite is an organism that lives in or on host benefiting at the expense of the host. A parasitoid is also similar to a parasitic organism, but it eventually kills the host organism. The main aim of this article is to discuss the difference between parasite and parasitoid.

CONTENTS

1. Overview and Key Difference
2. What is a Parasite 
3. What is a Parasitoid
4. Similarities Between Parasite and Parasitoid
5. Side by Side Comparison –Parasite vs Parasitoid in Tabular Form
6. Summary

What is a Parasite?

A parasite is an organism that lives with a host (an individual of another species) in a very close relationship. However, this relationship of parasitism gives benefits only to the parasite. Also, parasites cannot live without their hosts as their requirements cannot be fulfilled on their own. Usually, a parasite extracts nutrition, energy, space, and many other needs from its host as it grows, multiplies, and forms large populations causing harm to the host. Usually, the parasite is always smaller than the host; protozoans, helminths, viruses, and bacteria represent the majority of them.

There are various types of parasites based on the place of parasitic invasion, type of invasion, the taxonomic group involved, etc. A feature common for all the parasites is that they become dependent entirely on the host for some purpose during one period of their lifecycle. For example, the koel bird (Eudynamys sp) depends on crow to incubate their eggs. That process is a form of parasitism where the koel depends on the crow to complete the breeding. Therefore, it is clear that the term parasitism refers to one organism living at the expense of another in a period of their lifecycle for some benefit.

Since parasites move within species in the cases of many hosts, there is a possibility of transferring genetic materials between species. Thus, this is an advantage hosts get from parasites. Therefore, parasitism may not always be a negative prospectus.

What is a Parasitoid?

A parasitoid is an organism that lives its entire life attached to one host. It is a similar type of association like parasites, but it involves only one host and this association eventually leads to the death of the host. Parasitoid obtains all the requirements of life including nutrition and shelter or space from the host. Therefore, the prognosis of a parasitoid invasion could be severe for the host.

Except for the severity and the preference on only one host, parasitoids are similar to parasites in their activity.

What are the Similarities Between Parasite and Parasitoid?

• Parasite and parasitoid are two types of relationship between organisms.
• In both types of interaction, the host organism is getting affected while the other party is benefited.
• Also, both parasite and parasitoid are smaller than the host organism.
• Besides, they live in or on the host organism.
• And, both parasite and parasitoid depend on the host for survival.

What is the Difference Between Parasite and Parasitoid?

A parasite lives in or on the host organisms and derives nutrients from the host while harming. Similarly, parasitoid lives with the host and obtains nutrients at the expense of the host. But, parasite does not kill the host while parasitoid eventually kills the host. Hence, this is the key difference between parasite and parasitoid.  Furthermore, a significant difference between parasite and parasitoid is that the parasite may survive in several hosts while parasitoid lives its entire life cycle within one host. Moreover, the interaction between parasite and host is not highly specific while the interaction between parasitoid and host is highly specific.  Therefore, this is another difference between parasite and parasitoid.

The below infographic provides more details regarding the difference between parasite and parasitoid.

Summary – Parasite vs Parasitoid

Parasite and parasitoid are two types of organisms that live on or in another organism. Both of them obtain nutrients from the host while harming the host. The key difference between parasite and parasitoid is the severity of the harm caused to the host. Parasites do not kill the host but, parasitoid kills the host. Furthermore, parasites may have several hosts during its life cycle. But parasitoid lives in only one host organism. Hence, parasitoids are more susceptible to biological controlling methods than parasites. Thus, this summarizes the difference between parasite and parasitoid.

Reference:

1. “Parasitism.” Wikipedia, Wikimedia Foundation, 14 Mar. 2019, Available here.
2. “Parasitoid.” Parasitoid – an Overview | ScienceDirect Topics, Available here.

Image Courtesy:

1. “Parasitoid wasp pointing ovipositor at cinnabar moth larva” By Ian Alexander – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “ trophozoites, active, form, parasite, body” (CC0) via Pixino