Question

In terms of foraging strategies, Steinernema carpocapsae is

• A. Ambusher
• B. Cruiser
• C. Intermediate
• D. Not known

Hint:

To remember this:
- S. carpocapsae is an "Ambusher" that stands on its tail (nictates) to catch surface insects.
- S. glaseri is a "Cruiser" that actively swims through the soil to find grubs.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Entomopathogenic nematodes (EPNs) use different foraging strategies to locate and infect host insects in the soil.
These strategies fall along a continuum from sedentary "sit-and-wait" behavior to active host-seeking search patterns.

Step 2: Detailed Explanation:
The foraging strategies of EPNs are classified into three main categories:
1. Ambushers: These nematodes use a passive, "sit-and-wait" strategy.
They tend to remain near the soil surface and often exhibit "nictation" behavior, where they stand upright on their tails, sometimes lifting their entire bodies off the soil substrate.
This upright posture allows them to attach to mobile insects that pass by on the soil surface.
They are highly effective against active surface-dwelling insects but do not move deep into the soil to seek out hosts.
Steinernema carpocapsae is a classic example of an ambusher.
2. Cruisers: These nematodes are highly active and move through the soil profile to search for hosts.
They respond to chemical cues, such as carbon dioxide (\( \text{CO}_2 \)) and excretory products, released by sedentary or deep-dwelling soil insects.
An example of a cruiser is Steinernema glaseri or Heterorhabditis bacteriophora.
3. Intermediates: These nematodes use a combination of both strategies to locate hosts, depending on environmental conditions and host availability.
An example of an intermediate forager is Steinernema feltiae.
Since Steinernema carpocapsae is adapted to target surface-active hosts using nictation and a passive waiting strategy, it is classified as an ambusher.
Therefore, option (A) is the correct strategy.

Step 3: Final Answer:
The foraging strategy of Steinernema carpocapsae is classified as an ambusher.