MANAGEMENT OF SPOTTED STEM BORER, Chilo partellus (Swinhoe) THROUGH ECOLOGICAL ENGINEERING IN MAIZE
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Date
2019
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Acharya N G Ranga Agricultural University, Guntur
Abstract
Experiments were conducted at Agricultural college farm, Bapatla during kharif and rabi 2017-18 and 2018-19 with objectives to identify suitable leguminous intercrops and gramineous trap crops in maize for the management of Chilo partellus (Swinhoe).
Among the leguminous intercrops evaluated, maize-cowpea intercropping system supported with higher number of coccinellid beetles (0.93 /plant) and spiders (1.02/plant) than maize sole crop, which recorded 0.53 coccinellid beetles and 0.71 spiders /plant. These natural enemies suppressed C. partellus damage in maize that resulted in reduced foliage damage (15.18%), dead hearts (4.79%) and larval density (0.81/plant) when compared to maize sole crop i.e., 26.80 per cent, 8.80 per cent and 1.48 per plant, respectively. Results indicated that maize-green gram and maize-black gram intercropping systems were the next best treatments in suppressing C. partellus incidence. Influence of cowpea intercropping on C. partellus incidence in maize was clearly reflected on grain yield. Maize-cowpea intercropping system produced higher grain yield (5643 kg/ha) over maize sole crop (4553 kg/ha).
Studies pertaining to evaluation of suitable gramineous trap crops for the management of C. partellus revealed the glory of napier grass. Maize trap cropped with napier grass treatment recorded with least foliage damage (9.62%), dead hearts (1.99%) and larval density (0.35larave/plant) found significantly superior to maize
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sole crop which had shown highest foliage damage (29.30%), dead hearts (8.83%) and larval density (1.14 larvae/plant). Yield parameters clearly indicated the influence of napier grass in suppressing C. partellus incidence by showing highest grain yield of 5813 kg/ha compared to maize sole crop that recorded 4585 kg/ha. Sorghum and sudan grass were found to be next best trap crops while bajra was ineffective in managing C. partellus.
Ovipositional studies revealed the effectiveness of napier grass as a trap crop against C. partellus. Results from dual-choice tests indicated that female moths of C. partellus preferred to oviposit on napier grass instead of maize. Significantly higher number of egg batches (4.5/plant) and total number of eggs (354.6/plant) were laid on napier grass than maize (2.3 egg batches/plant and 148 eggs). Larval survival and development studies indicated the greater mortality of C. partellus larvae occurred within five days on napier grass. None of the C. partellus larvae survived upto pupation in napier grass while 38.80 per cent larvae pupated in case of maize.
Integration of different pest management approaches for the management C. partellus revealed that cultural+biological+chemical method of treatment reduced foliage damage (8.19%), dead hearts (2.40%) and larval density (0.38/plant) over untreated control. The per cent stem tunnelling was least (2.70) in case of cultural+biological+chemical method of treatment where as untreated maize crop recorded highest tunnelling length (9.21). Cultural method alone was on par with cultural+biological+chemical method in suppressing C. prtellus incidence which indicated its importance in integrated pest management practice. Highest grain yield (6096 kg/ha) was observed in cultural+biological+chemical method of treatment than remaining combinations of pest management and least grain yield in untreated control (4596 kg/ha). Higher net profits were observed in cultural method (Rs 23015/-), cultural+biological method (Rs 21619/-) and cultural+biological+ chemical method (RS 21429/-). The incremental benefit cost ratio was higher in cultural method (6.67) followed by cultural+biological (3.84), cultural+chemical (3.65) and cultural+biological+chemical method (2.70).
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D5938
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