African cassava whitefly, Bemisia tabaci, cassava colonization preferences and control implications

Area of Science:

• Agricultural Entomology
• Plant Pathology
• Pest Management

Background:

• Cassava is a vital staple crop in sub-Saharan Africa.
• Bemisia tabaci (whiteflies) outbreaks cause significant cassava crop damage.
• Understanding whitefly movement and colonization is crucial for effective pest control.

Purpose of the Study:

• To investigate how cassava age and variety influence Bemisia tabaci density.
• To determine if Bemisia tabaci adults show variety preference during colonization.
• To assess the impact of source field characteristics on whitefly colonization patterns.

Main Methods:

• Experimental placement of sentinel cassava plants of different varieties in source fields.
• Source fields varied in cassava variety and age (young, medium, old).
• Colonization measured by nymph density on sentinel plants; whitefly species identified via molecular methods.

Main Results:

• Bemisia tabaci sub-Saharan Africa 1 (SSA1) was identified as the prevalent species.
• Higher adult density in source fields correlated with increased nymph density on sentinels.
• No significant preference for colonizing sentinel plants of the same variety as the source field was observed.
• Source field age did not significantly affect nymph density on sentinel plants.

Conclusions:

• Reducing Bemisia tabaci SSA1 abundance in cassava source fields is a more effective control strategy than manipulating nearby varieties.
• Planting 'whitefly sink' varieties alone is unlikely to control whitefly populations without integrated pest management.
• Integrated approaches focusing on reducing whitefly densities in source fields are recommended for cassava protection.