Geofrey Ogwal, Walter Ocimati, Elizabeth Kearsley, Guy Blomme
Aphids were highly cryptic, occurring mainly between leaf sheaths and on lower and middle pseudostem sections. Though winged aphids were mostly associated with larger aphid colonies they occurred across all colony sizes, indicating that even small colonies may contribute to BBTV spread. Sticky traps showed winged aphids to actively disperse throughout fields, with flights often extending beyond adjacent mats. Mechanical disturbance, simulating farm activities such as de-trashing and roguing, strongly increased movement of both winged and wingless aphids and occasionally flight, which could potentially increase BBTV transmission risk in case aphids are viruliferous. Aphids persisted on cut and disposed pseudostem pieces, especially under shaded conditions, but not on corms. In laboratory assays, aphids preferred leaf tissue, although field colonies were mainly pseudostem-associated. Spraying with a 1% laundry soap solution rapidly reduced both winged and wingless aphid populations within 30 minutes to two hours, with populations remaining low for up to two weeks on de-trashed plants.
INTRODUCTION: Banana bunchy top disease (BBTD), caused by the banana bunchy top virus (BBTV), poses a growing threat to banana production in Africa and is spread locally by the banana aphid, Pentalonia nigronervosa. Effective BBTD management requires better understanding of aphid habitat, dispersal, response to farm operations, and practical aphid vector and disease control options.
METHODS: This study integrated field assessments, field experiments, and a laboratory trial in Uganda to characterize aphid ecology and refine integrated pest and disease management.
RESULTS: Aphids were highly cryptic, occurring mainly between leaf sheaths and on lower and middle pseudostem sections. Though winged aphids were mostly associated with larger aphid colonies they occurred across all colony sizes, indicating that even small colonies may contribute to BBTV spread. Sticky traps showed winged aphids to actively disperse throughout fields, with flights often extending beyond adjacent mats. Mechanical disturbance, simulating farm activities such as de-trashing and roguing, strongly increased movement of both winged and wingless aphids and occasionally flight, which could potentially increase BBTV transmission risk in case aphids are viruliferous. Aphids persisted on cut and disposed pseudostem pieces, especially under shaded conditions, but not on corms. In laboratory assays, aphids preferred leaf tissue, although field colonies were mainly pseudostem-associated. Spraying with a 1% laundry soap solution rapidly reduced both winged and wingless aphid populations within 30 minutes to two hours, with populations remaining low for up to two weeks on de-trashed plants.
DISCUSSION: These findings show that BBTD management should target hidden pseudostem colonies, minimize aphid dispersal during plant disturbance, apply soap spray before or immediately after de-trashing infected plants or infected mat removal, and rapidly bury infected pseudostems and leaves while drying corm pieces separately. The study provides practical refinements for smallholder-oriented BBTD integrated management.