Functional response, host stage preference and interference of two whitefly parasitoids

Area of Science:

• * Entomology
• * Biological Control
• * Insect Ecology

Background:

• * The whitefly Bemisia tabaci is a significant agricultural pest.
• * Parasitoids Eretmocerus hayati and Encarsia sophia are natural enemies of whiteflies.
• * Understanding their interactions is crucial for effective biological control.

Purpose of the Study:

• * To determine the functional responses of E. hayati and E. sophia to B. tabaci.
• * To evaluate competitive interactions and biological control efficacy based on host density and stage.
• * To elucidate the coexistence mechanisms of these parasitoid species.

Main Methods:

• * Laboratory experiments assessing functional responses of individual parasitoids with varying host densities and competitor presence.
• * Host stage preference tests with joint introduction of both parasitoid species.
• * Evaluation of biological control effects under different introduction scenarios and host instars.

Main Results:

• * Both E. hayati and E. sophia exhibited a Type II functional response, indicating density-dependent predation.
• * Interference between parasitoid species was observed through differences in searching rates and handling times.
• * E. hayati demonstrated a competitive advantage over E. sophia on early whitefly instars (1st and 2nd), but not on later instars (3rd and 4th).
• * Biological control effectiveness varied with host density but was not significantly influenced by host instar.

Conclusions:

• * Parasitoid competition and functional responses are key factors in whitefly biological control.
• * E. hayati's advantage on young whiteflies suggests stage-specific efficacy.
• * Findings inform integrated pest management strategies and parasitoid coexistence theory.