[Spatial patterns of Bemisia tabaci (Gennadius) population in cotton fields]

Area of Science:

• Agricultural Entomology
• Pest Management
• Plant Science

Context:

• Bemisia tabaci, a significant agricultural pest, infests cotton crops globally.
• Understanding pest distribution is crucial for effective integrated pest management (IPM) strategies.
• Bt cotton, engineered for insect resistance, is widely cultivated, necessitating studies on pest behavior in these systems.

Purpose:

• To investigate the vertical and horizontal distribution patterns of Bemisia tabaci populations on both Bt and non-Bt cotton varieties.
• To determine how population density influences the spatial distribution (evenness vs. aggregation) of Bemisia tabaci.
• To compare the distribution of Bemisia tabaci on Bt cotton versus conventional non-Bt cotton.

Summary:

• Field studies revealed Bemisia tabaci distribution varied seasonally; in August, populations were denser in the upper cotton canopy.
• Both adult and nymphal whiteflies exhibited similar horizontal distribution, spreading evenly at low densities and aggregating at high densities.
• The aggregation rate of Bemisia tabaci increased with population density, showing alternating aggregation and diffusion patterns throughout the season.
• Crucially, no significant differences in spatial distribution patterns were observed between Bt cotton and non-Bt cotton plants.

Impact:

• Provides essential data for optimizing the timing and placement of control measures against Bemisia tabaci in cotton.
• Highlights that Bt cotton does not alter the fundamental spatial distribution behavior of Bemisia tabaci.
• Informs IPM strategies by demonstrating density-dependent aggregation, which can influence pesticide efficacy and scouting efficiency.