Siphoninus phillyreae: The Ash Whitefly

Introduction

Siphoninus phillyreae is a polyphagous whitefly that feeds on hard-leaved shrubs and small trees. It attacks plants at all growth stages, including flowering, fruiting, and post-harvest. Heavy infestations lead to honeydew secretion, which encourages sooty mold formation, covering leaves, stems, and fruits, giving plants a blackened appearance.

Symptoms of Infestation

• Sticky, transparent honeydew spots on leaves
• Growth of sooty mold on honeydew-covered surfaces
• Severe infestations result in blackened plant appearance

Life Cycle

• Eggs are laid on the underside of leaves
• Larvae settle on leaves after hatching and feed on plant sap
• Four immature instars:
  • First instar (crawler) moves slightly for dispersal
  • Later stages remain sessile
• Pupal stage: Whitefly pupal cases appear with white wax tufts and glassy tubercles
• Adult stage:
  • Lightly dusted with white wax
  • Females live 30–60 days, males live around 9 days
  • Winged adults disperse to new plants

Climatic Factors Influencing Infestation

• Optimal Temperature: Around 25°C (77°F)
• Temperature Tolerance: Can survive from near freezing to warm conditions
• Humidity Preference: High humidity favors population growth
• Impact of Climate:
  • Low temperatures & humidity slow down development
  • High humidity & warm temperatures accelerate population growth

Conclusion

Siphoninus phillyreae can rapidly build up in warm, humid environments, making it a persistent pest. Understanding its lifecycle and climate preferences is key to effective management and control.

Source: University of Florida