Bacillus thuringiensis-based bioinsecticides affect predation of Euborellia annulipes on diamondback moth larvae

Area of Science:

• Entomology
• Pest Management
• Insect Ecology

Background:

• Interactions between earwigs (Dermaptera: Anisolabididae) and entomopathogens like Bacillus thuringiensis (Bt) are not well understood.
• Bt-based bioinsecticides are widely used against pests such as Plutella xylostella (Lepidoptera: Plutellidae), which exhibits resistance to Bt.

Purpose of the Study:

• To investigate the impact of Bt-based bioinsecticides on the predation behavior of Euborellia annulipes (ringlegged earwig) on Plutella xylostella.
• To determine if Bt infection influences earwig feeding preferences and predatory efficiency.

Main Methods:

• Fourth instar Plutella xylostella larvae were exposed to Dipel®WG and XenTari®WG bioinsecticides.
• Euborellia annulipes predation was assessed under no-choice and free-choice conditions with varying prey densities.
• Functional response and handling time were analyzed to quantify predation dynamics.

Main Results:

• E. annulipes consumed fewer Bt-infected P. xylostella larvae compared to uninfected larvae in both no-choice and free-choice scenarios.
• Earwig predation rate increased with prey density, exhibiting a Type II functional response unaffected by Bt-infection.
• Handling time for Bt-fed prey was reduced, while the maximum predation rate increased.

Conclusions:

• Bt-based bioinsecticides significantly alter E. annulipes feeding preferences and predatory behavior towards P. xylostella.
• Understanding these earwig-Bt interactions is crucial for developing effective integrated pest management strategies for Plutella xylostella.