SEASONAL INCIDENCE, POPULATION DYNAMICS, GERMPLASM SCREENING AND BIO-EFFICACY STUDIES OF INSECTICIDES AGAINST INSECT PESTS OF BRINJAL
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Date
2019
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Indira Gandhi Krishi Vishwavidyalaya, Raipur (C.G.)
Abstract
The present investigation entitled “Seasonal incidence, population dynamics, germplasm screening and bio-efficacy studies of insecticides against insect pests of brinjal’’ was carried out in the research field of Indira Gandhi Krishi Vishwavidyalaya, Raipur (Chhattisgarh) during season rabi 2018-19.
Incidence of jassids (Amrasca biguttula biguttula), whitefly (Bemisia tabaci), aphid (Aphis gossypii), hadda beetle (Epilacna vigintioctopunctata) and shoot and fruit borer (Leucinodes orbonalis) were revealed as major insect pests on brinjal crop. Lady bird beetle and spider as natural enemies on sucking pests of brinjal were also recorded. The peak activity of jassids (19.8/plant), whitefly (14.82/plant), aphid (21.92/plant) and
hadda beetle (1.2/plant) were recorded during second week of March, fourth week of February, first week of February and second week of February, respectively. The seasonal incidence of shoot and fruit borer was started on shoots (0.3% infested shoots/plant) in first week of January on vegetative stage and it to be continued on flowering and fruiting stage with maximum infestation of fruit 76.4% during period of second week of April and its infestation was remained till last stage of the crop. The natural enemies incidence viz. lady bird beetle and spider population was recorded as maximum 4.8 per plant during third week of April and 2.9 per plant during the first week of January, respectively.
The shoot and fruit borer infestation had positive and significant correlated with maximum (r = 0.866) and minimum (r = 0.846) temperature, wind velocity (r = 0.579) and sunshine hours (r = 0.551) and negative significant with morning (r = -0.834) and evening (r = -0.570) relative humidity. The population of jassids showed positively and significant with wind velocity (r = 0.411). The population of aphid showed negative and significant with minimum temperature (r = -0.434). Jassids population had negative and significance correlated with lady bird beetle (r = -0.476) and spider (r = -0.493). Whitefly population had negative and significance correlated with lady bird beetle (r = -0.564) and spider (r = -0.401). Aphid population had negative and significance correlated with lady bird beetle (r = -0.391).
On the basis of pest susceptibility grade formula on brinjal shoot and fruit borer infestation, formulated by subbaratnam and bhutani (1981), the overall mean percentage of shoot and fruit infestation due to L. orbonalis was recorded on all the 124 brinjal germplasm. Out of the 124 germplasm none of the brinjal germplasm was tolerant against shoot and fruit borer infestation in the category of 1.00 and 15.00 per cent. Two germplasm viz. IGB-52 and IGB-53 were moderately tolerant under the category of 16.00 and 25.00 per cent infestation. While susceptible reaction i.e. infestation ranged from 26.00 to 40.00 per cent was exhibited by 26 germplasm. The highly susceptible (above 40%) reaction was observed in rest of the 96 brinjal germplasm against shoot and fruit borer incidence.
Dimethoate 20% + Cypermethrin 3% EC @ 141.3 g a.i./ha was found most effective insecticide against shoot and fruit borer and jassids of brinjal, as it was recorded lowest fruit infestation percentage (12.66 %), along with maximum healthy fruit yield (220.00 q/ha) with highest benefit cost benifit ratio of 1 : 2.67. Impact of Dimethoate 20% + Cypermethrin 3% EC was recorded that no significant impact on natural enemies viz. coccinellid and spider population.
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