EFFICACY OF FOUR PLANT EXTRACTS AGAINST RIPTORTUS PEDESTRIS (HEMIPTERA: ALYDIDAE)

Abstract

The bean bug, Riptortus pedestris Fabricius (Hemiptera: Alydidae) is a highlypolyphagous and one of the major pests of leguminous crop and many fruit trees, causing serious economic damage in many crops. Plant extracts have long been suggested as alternatives to synthetic ones for pest management because of their high potency, cheaper, available and eco-friendly. The topical spraying and residual methods are used to measure the toxicity and repellency effect of four plant leaf extracts of neem (Azadirachta indica), crown flower (Calotropis gigantean), water pepper (Polygonum hydropiper) and marigold (Tagetes patula) against the R. pedestris. The experiment was conducted in laboratory conditions of the Department of Entomology, Hajee Mohammad Danesh Science and Technology University (HSTU), Dinajpur; during the period from March to August 2019. The plant extracts were prepared with two solvent and applied at three doses viz., 500, 600 and 700 mg/L water. The maximum mortality of adults was recorded while marigold (acetone) and crown flower (acetone) sprayed topically at 48 hours after treatment at 700 mg/L water. These were followed by neem (ethanol) and water pepper (ethanol) extracts at 54 and 72 hours after treatment at700 mg/L water. On the other hand, at residual method the maximum mortality of adults was also recorded while marigold (acetone) sprayed at 72 hours after treatment at 700 mg/L. The result of repellency test showed that all the applied doses had repellency and direct toxicity effects but marigold showed the best response and it possess the repellency class V followed by crown flower and neem. Therefore, marigold and crown flower extracts showed highly potential to control of R. pedestris and can be use for alternative of synthetic chemical pesticides.