Seasonal occurrence of Riptortus pedestris (Hemiptera: Alydidae) attacking mungbean in Southern PART of Bangladesh

Abstract

The bean bug, Riptortus pedestris (Hemiptera: Alydidae), is a polyphagous species that is an important pest of mungbean, soybean and other leguminous crops in Asian countries. As it is distributed in Asian countries, like Korea, Japan, China, India, and Taiwan and caused damage on leguminous crops, but the status of bean bug are still unknown in Bangladesh even though it is first recorded in mungbean (Vigna radiata L) field during 2017 in our preliminary study. Therefore a series of field survey was conducted in southern part of the country during three consecutive seasons of 2018, 2019 and 2020 to know the pest status of bean bug and their intensity of infestation in mungbean. Three years study revealed that a new pest R. pedestris is recorded in mungbean field which causes damage on tender stem, leaf and pod. Adult and nymph R. pedestris occurrence began at first week of April in mungbean. Peak population densities of both nymphs (4-6 bugs/10 plants) and adults (5-7 bugs/10 plants) are recorded at mid-April. Then the number of bean bug gradually decreased in mugbean field. Seasonal average number of bean bug nymph and adult is 2.13-3.07 and 2.47-4.20 per plant. Nymph population is recorded from 15.33 to 22.67% plants where adults are found in 18.67 to 30.67% plants. The abundance of adult population significantly 64.27% increased in 2020 compare to 2018 cropping season while infestation of mungbean by nymph was also 47.88% increased. This is the first report of the occurrence of R. pedestris on mungbean in southern part of Bangladesh. Since pest abundance increasing day by day in southern part of the country, therefore more research should be recommended to assess crop loss by this pest and to develop appropriate management option.