Plant characteristics and predator-prey abundance modulate aphid infestation and yield in bean cultivars

Abstract: Country bean is an important leguminous crop in Bangladesh, contributing to household income and nutritional security, although its production is constrained by insect pests, particularly the aphid. This study was conducted to assess how plant traits and predator abundance affect aphid infestation and yield in country bean. Five cultivars (BARI Bean 1, BARI Bean 5, BARI Bean 6, BARI Bean 7, and BARI Bean 10) were evaluated in the field in a randomized complete block design. Weekly observations recorded plant growth, aphid and predator populations, and leaf and fruit infestation, along with measurements of morphological and biochemical traits and yield. Results revealed a significant variation among cultivars in growth and biochemical traits. Branch initiation ranged from 27 days after sowing (BARI Bean 6) to 40 days after sowing (BARI Bean 5), and fruit maturation ranged from 83.8 days after sowing (BARI Bean 5) to 123.8 days after sowing (BARI Bean 10). Aphid abundance was the highest on BARI Bean 5 (9.2 leaf⁻¹), lowest on BARI Bean 1 (2.8 leaf⁻¹), infestation of leaves peaked to 11.6% on BARI Bean 5 and was lowest (2.7%) in BARI Bean 10. Predator abundance per plot varied; ladybird beetles were highest on BARI Bean 5 (4.3) and lowest on BARI Bean 10 (1.3). Yield components differed significantly, with BARI Bean 10 producing the widest fruits (2.83 cm), the heaviest seeds (53.9 g), and the highest yield (0.2 t ha-1), whereas BARI Bean 5 had the smallest fruits (7.8 cm), the lightest seeds (31.2 g), and the lowest yield (0.01 t ha-1). So, BARI Bean 10 emerged as the most suitable cultivar due to low aphid infestation and high yield, while BARI Bean 5 found to be the most susceptible one. 

Keywords: Abundance, Aphis craccivora, infestation, Lablab purpureus, predator, yield