SEASONAL ABUNDANCE, VARIETAL RESISTANCE AND INTEGRATED MANAGEMENT OF SUGARCANE STEM BORER, CHILO TUMIDICOSTALIS HAMPSON

Abstract

Sugarcane stem borer (Chilo tumidicostalis Hampson) is one of the major insect pests of sugarcane in the world which causes severe infestation and significant yield loss. Five experiments were conducted in the field and laboratory to study the seasonal abundance, varietal resistance and integrated management of sugarcane stem borer, C. tumidicostalis. Farmer’s opinion on pest status and infestation intensity of stem borer were collected from 15 upazilas under 9 major sugarcane growing districts which covered 8 sugar mill zones under 6 agro ecological zones of Bangladesh. C. tumidicostalis infestation data was collected directly from farmer’s field in 2014 and from experimental field in 2014, 2015 and 2016. The effect of planting dates on C. tumidicostalis was studied by transplanting sugarcane at six different dates starting from September 2014 to February 2015 at 30 days interval. Ten sugarcane varieties were cultivated and screened to study the effect of varieties on stem borer infestation and to find out the level of resistant. Five chemical insecticides of different groups were tested in sugarcane field at BSRI farm to find out the effective one(s) against stem borer. Finally some Integrated Pest Management (IPM) packages consisting resistant varieties, suitable planting date(s), de-trashing, hand cutting and destruction of larvae use of chemical insecticides were evaluated against the stem borer to find out the best integrated management package(s). Field experiments were carried out in Randomized Complete Block (RCBD) designs at different locations. Sugarcane grower’s reported several problems of sugarcane such as long duration of crop, low price of cane, insect pests, disease, low yield, delay payment of cane price and high labor cost. Of these, insect pest was the major problem for sugarcane cultivation and stem borer was the important one in all sugarcane growing regions of Bangladesh. Stem borer infestation varied from 12.44-17.20% in farmer’s field. The lowest percent of stem infestation (12.44%) was recorded from Natore Sadar as against the highest (17.20%) from Ishurdi. In experimental plot at BSRI, stem infestation by C. tumidicostalis varied from 20.88% to 24.71% during 2014, 2015, 2016. Sugarcane grower’s reported three methods such as cultural, mechanical and use of chemical insecticides for the management of sugarcane stem borer but majority of farmers (48.08%) applied chemical insecticides. They reported the use of carbofuran, virtaco and lorsban insecticides for the stem borer management but most of them used carbofuran. C. tumidicostalis started infestation from May and increased gradually with the age of the crops up to September then declined and sharply decreased after October and no new infestation occurred in November. The peak infestation of C. tumidicostalis was observed in September every year. Environmental temperature and rainfall had significant effect on sugarcane stem borer infestation. Positive relationship was observed between C. tumidicostalis infestation and temperature or rainfall. Planting on 15 th November was the best and resulted the lowest stem borer infestation and the highest yield of sugarcane was ensured. Variety Isd 36 showed tolerance against C. tumidicostalis having the lowest percent of stem infestation (5.79%) and highest quantity of healthy cane yield (79.34 t ha -1 ) compared to others. Negative relationship was observed between C. tumidicostalis infestation and biophysical characteristics of varieties like. Biochemical compounds, brix percentage, pol percent cane, percent reducing sugar and nutrient elements (nitrogen, phosphorous, potassium) and silicon content exert resistance effect. These compounds and elements had negative impact on stem borer infestation. Strong negative relationship was existed between stem borer infestation and presence of higher level of phosphorous, potassium and silicon content of sugarcane varieties. Nokotap (cartap) 6G @ 50 kg ha -1 provided maximum reduction (79.53%) of cane infestation and produced higher yield of healthy (84.62 t/ha) and total cane (87.81 t/ha). Integrated Pest Management (IPM) packages significantly reduced C. tumidicostalis infestation on sugarcane and increased cane yield. IPM package 7 consisted Isd 36 variety + planting on 15 November + hand cutting and removal of infested cane + de-trashing + application of Nokotap 6G @ 50 kg ha

provided only 1.54% stem infestation as against the highest (12.31%) in IPM package 9 (Isd 40 variety + planting on 15 November). IPM package 7 also provided maximum reduction (87.45%) of infestation over control and produced highest sugarcane yield (74.03 t ha -1 ). The same package gave the highest net return (Tk. 195787.50 ha ) and maximum Benefit Cost Ratio (10.44) was obtained from IPM package 1 (Isd 36 variety + planting on 15 November + hand cutting and removal of infested cane) followed by 5.47 and 4.10 in IPM package 5 (Isd 36 variety + planting on 15 November + hand cutting and removal of infested cane + application of Nokotap 6G@50 kg ha -1 ) and package 4 (Isd 36 + planting on 15 November + hand cutting + De-trashing), respectively.

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