The countrybean, Lablab purpureus L. (Leguminosae: Papilionaceae), is an importantvegetables grown everywhere in Bangladesh. Despite of being aprospective crop, farmers in our country face significant yield loss of beans perannum due to severe attack of various insect pests. Though no regularstatistical records are kept, as per conservative estimate the yield loss incountry bean due to insect pests is reported to be about 12-30% (Hossain 1990).Country bean is attacked by nine different insect species and one species ofmite (Alam 1969).
In Bangladesh, over 30 different species of arthropods havebeen reported in country bean, although only a few occur regularly and causeeconomic damage (Alam 1969, Begum 1993, Karim 1993 and 1995, Das 1998,Islam1999). Among the arthropods, currently the two-spottedspider mite, Tetranychus urticae Koch(Acari: Tetranychidae), is considered as one of the important pests of countrybeans in Bangladesh.The two-spottedspider mite (TSSM) is a polyphagous and destructive pest of agricultural cropsin Bangladesh and throughout the world. Its host range exceeds 1100 plantspecies in 140 families of economic value (Pavela 2017). Both nymphs and adults damagesplants by feeding on the leaves, resulting in the collapse of mesophyll cells,leaf defoliation, browning, production loss, and even plant death (Gorman etal. 2002; Oliveira and Moreira 2009). The use of chemical pesticides remains akey policy in integrated pest management system (IPM) due to severalbenefits (Endo and Tsurumachi 2001).
For the control TSSM and other co-existingpests, the producer in Bangladesh mostly dependent solely on chemicalpesticides. Owing to its high reproductive capacity, the fast developmental speed,arrhenotokous parthenogenesis and a very short generation, in combination withfrequent insecticide and acaricide applications, that often leads to thedevelopment of resistance after a few applications (Vassiliou and Kitsis 2013; Uddin et al.2017).