The experiment was conducted in the field of Entomology, Bangladesh Agricultural University, Mymensingh to determine efficacy of bio-rational insecticides against bean aphid during September 2016 to April 2017.The experiment was laid out in randomized complete block design with 3 replications. Five sprayings were done at 15 days intervals where data were taken 3 days after each spray. The highest mean number of fruit/rachis (7.5) was observed in spinosad treated plants and the lowest number of fruit/rachis was found in control plants (4.17). After 2nd spray, the lowest mean number of aphids/rachis (3.83) was observed in Emamectin benzoate treated plants and the highest number of aphids/rachis (58.33) was found on Beauveria bassiana (66.50) treated plant which was higher than control plants (56.21). The lowest mean percentage of rachis infestation by aphid (10%) was observed in Emamectin benzoate treated plants while the highest percentage was found in control plants (35%). The highest mean number of fruit/rachis was observed in Karanja oil (7.83) treated plants and the lowest number of fruit/rachis was found in control plants (4.33). After 3rd spray, the lowest mean number of aphids/rachis (10.00) was observed in Emamectin benzoate treated plants while the highest number of aphids/rachis (76.50) was found on spinosad treated plant which was higher than control plants (67.21).But the highest mean number of fruit/rachis was observed in Karanga oil, Neem oil and spinosad treated plants, respectively. Among the selected insecticides, Emamectin benzoate, Karanja oil and Neem oil provided better protection of bean plants against bean aphid.
Uddin et al. (Thu,) studied this question.