Aphelenchoides besseyi Parasitizing Common Bean in Brazil

Area of Science:

• Plant Nematology
• Agricultural Entomology
• Plant Pathology

Background:

• Aphelenchoides besseyi causes 'Soja Louca II' in soybeans and 'amachamiento' in common beans.
• This nematode has recently been identified as a pest of cotton in Brazil.
• Common beans are crucial to Brazilian agriculture, making them a vital crop to protect.

Purpose of the Study:

• To investigate the pathogenicity of Aphelenchoides besseyi in common bean (Phaseolus vulgaris) under greenhouse conditions.
• To document the endoparasitic relationship of A. besseyi within common bean tissues.
• To provide the first report of A. besseyi pathogenicity in Brazilian common beans.

Main Methods:

• Greenhouse inoculation of common bean plants with A. besseyi.
• Tissue staining with fuchsin acid to visualize endoparasitic relationships.
• Nematode quantification from shoot systems using washing and flotation techniques 30 days post-inoculation.

Main Results:

• Observed 'amachamiento' symptoms, including leaf and vein deformation.
• Identified necrotic, angular lesions characteristic of false angular spot.
• Documented deformed stems with enlarged nodes, retortions, and necrotic lesions.
• Detected high populations of A. besseyi within infected common bean plants.

Conclusions:

• Aphelenchoides besseyi is pathogenic to common beans in Brazil, causing distinct symptoms.
• This research provides the first report of A. besseyi pathogenicity and associated symptoms in Brazilian common beans.
• Findings are crucial for developing management strategies to mitigate bean crop losses.