First report of mungbean insect pests and their seasonal abundances under climatic influence in Southern Bangladesh

Mungbean insect pests and seasonal dynamics in southern Bangladesh

Abstract

Mungbean (Vigna radiata L.) is an important pulse crop in Bangladesh, yet its productivity is frequently hampered by insect infestation. Ecological information on pest diversity, seasonal incidence, and climatic influence remains limited for the southern region, a major mungbean-growing area. A field investigation was conducted in Barishal during the late rabi season of 2022 to document the insect pest complex, assessing stage-wise population trends, and evaluates relationships between pest abundance and weather variables. Seventeen insect species belonging to five Orders namely Hemiptera, Lepidoptera, Coleoptera, Diptera, and Thysanoptera were recorded. Flower thrips (Megalurothrips usitatus), legume pod borer (Maruca vitrata), flea beetles (Phyllotreta striolata and Phyllotreta cruciferae), and common cutworm (Spodoptera litura) exceeded economic threshold levels and were identified as major pests. Sap sucking insects, including whitefly (Bemisia tabaci), aphid (Aphis craccivora), jassid (Empoasca kerri) and bean bug (Riptortus pedestris) persisted throughout the growing season, whereas leaf miner (Liriomyza brassicae), leaf roller (Lamprosema indicata), hairy caterpillar (Spilosoma obliqua), and epilachna beetle (Epilachna dodecastigma) occurred intermittently. Spodoptera litura was observed on mungbean for the first time in Bangladesh, while R. pedestris was newly confirmed in this region. Insect pest’s abundance varied across crop growth stages, with flea beetles dominating at early vegetative stage, while thrips and pod borers peaking during flowering and pod formation. Temperature and solar radiation were positively correlated with populations of S. litura, M. usitatus, and R. pedestris, whereas relative humidity was negatively associated with whitefly, aphid, and leaf roller densities. The findings provide the first comprehensive baseline on pest community structure and climate-pest interactions in southern Bangladesh, supporting climate-responsive, stage-specific pest management strategies for sustainable mungbean production.

Ann. Bangladesh Agric. 30(1): 1-18