Consider the following:

Carabid beetles
Centipedes
Flies
Termites
Wasps

Parasitoid species are found in how many of the above kind of organisms?

(a) Only two
(b) Only three
(c) Only four
(d) All five

The correct answer is: (b) Only three (1, 3 & 5)

Carabid beetles:
- Carabid beetles, a diverse family of ground beetles, exhibit a range of behaviors, including predation and parasitism.
- While most carabid beetles are known for their predatory habits, some species do exhibit parasitoid behavior.
Centipedes:
- Centipedes are predatory arthropods that are primarily carnivorous.
- They do not have any known parasitoid species.
Flies:
- Many species of flies, especially those in the families Tachinidae and Sarcophagidae, have parasitoid species.
- These flies lay their eggs in or on other insects, and the larvae develop inside the host, eventually killing it.
Termites:
- Termites are primarily decomposers and are not typically associated with parasitoid behavior.
- However, certain species of flies and wasps can act as parasitoids to termites.
Wasps:
- Wasps, especially those in the families Ichneumonidae and Braconidae, are well-known for their parasitoid behavior.
- They lay their eggs in or on a host insect, and the developing larvae consume the host from the inside.

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Parasitoid Species

Definition: A parasitoid is an organism that spends a significant portion of its life attached to or within a single host organism, ultimately leading to the host’s death. This is different from parasites, which usually do not kill their hosts.
Life Cycle:
- The life cycle of parasitoids typically involves laying eggs on or inside a host.
- The larvae hatch and feed on the host’s tissues, eventually leading to the host’s demise.
- Adult parasitoids emerge from the host to continue the cycle.
Ecological Role:
- Parasitoids play a crucial role in biological control by naturally regulating the populations of their hosts, many of which are agricultural pests.
- They contribute to the balance of ecosystems by keeping pest populations in check.
Examples:
- Tachinid flies: These flies are parasitoids of caterpillars, beetles, and other insects.
- Braconid wasps: They parasitize caterpillars, aphids, and beetle larvae.
- Ichneumon wasps: Known for their long ovipositors, they target caterpillars, beetles, and other insects.
Adaptations:
- Parasitoids have evolved various adaptations to locate and exploit their hosts, including acute sensory organs to detect host cues, venoms to paralyze hosts, and behavioral strategies to avoid host defenses.
Importance in Agriculture:
- By reducing pest populations, parasitoids help minimize the need for chemical pesticides, promoting sustainable agricultural practices.
- They are often introduced as part of integrated pest management (IPM) programs to control invasive pest species.