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Researcher Patil, V. P.
Advisor Sureja, B. V.
Source KrishiKosh-Indian National Agricultural Research System
Content type Text
Educational Degree Master of Science (M.Sc.)
Publisher JAU
File Format PDF
Language English
Subject Domain (in DDC) Natural sciences & mathematics ♦ Life sciences; biology
Subject Keyword Entomology ♦ Population Dynamics ♦ Yield Losses And chemical Control Ofaphid ♦ Rhopalosiphummaidis(fitch) On Maize
Abstract Investigations were carried out on population dynamics, yield losses and chemical control of aphid,Rhopalosiphummaidis(Fitch) on maize [Zea mays (L.)] at Instructional Farm, College of Agriculture, Junagadh Agricultural University, Junagadh during kharif season of 2011. A study on population dynamics ofaphid,R. maidison maizevariety GS-11 indicated that the incidence of aphidcommenced from 4th week after sowing i.e. 4th week of July (15.42 aphids/upper leaf/plant) and reached the peak level (37.22 aphids/upper leaf/plant) at 38th standard week i.e. third week of September.Weather parameters correlatedwith the aphid population. The negative non-significant correlation with maximum temperature,minimum temperature and rainfall while non-significant positive with morning relative humidity, evening relative humidity, bright sunshine hrsand wind velocity was observed. The population of coccinellid predators commenced from 5th week after sowing i.e. 1st week of August with 3.5 coccinellidsper five plants and reached the peak level with 5.9 coccinellids per five plants at 39th standard week i.e. last week of September.Weather parameters correlated with the population of coccinellid predatoron maize exhibited negative non-significant correlation with maximum temperature, minimum temperature, wind velocity and rainfall while non-significant positive correlation with morning relative humidity, evening relative humidity and bright sunshine hrs. The population of Chrysoperla predators commenced from 5th week after sowing i.e. 1st week of August with 1.1Chrysoperla per five plant and reached the peak level 4.9 at 39th standard week i.e. last week of September.Weather parameters correlated with the population of Chrysoperla on maizerevealed that negative non-significant correlation with maximum temperature, minimum temperature, wind velocity and rainfall while non-significant positive correlation with morning and evening relative humidity, bright sunshine hrs was observed. Study on estimationof yield losses of maize due to aphid revealed that the population of aphid was significantly lower in treated plot at seven days after both the spraying. The grain yield received high in treated plots (2067 kg/ha) as compared to untreated control plots (1442 kg/ha). The yield loss due to aphid was 625 kg/ha, while avoidable loss was 30.23 per cent. From the overall results of relative efficacy of nine different insecticides against aphid, R. maidisit can be concluded that imidalcloprid 0.006 per cent, methyl-o-demeton 0.025 per cent and thiamethoxam 0.0075 per cent were found highly effective. They were found at par to each other.So far as toxicity of insecticides to coccinellids and Chrysoperla predator of aphid is concerned, azadiractin 0.001 per cent was found safe, whereas, imidacloprid 0.006 per cent, acetamiprid 0.006 per cent, quinalphos 0.025 per cent and methyl -o- demeton 0.025 per cent were moderately toxic than remaining treatments of fipronil, cartap hydrochloride, cypermethrin and thiamethoxamwhich found highly toxic to those predators. Considering the yield of maize grain and fodderimidacloprid 0.006 per cent gave the highest grain yield (1920 kg/ha) followed by methyl -o- demeton 0.025 per cent, thiamethoxam 0.0075 per cent, acetamiprid 0.006 per cent and quinalphos 0.025 per cent (1850, 1530, 1450 and 1390 kg/ha) respectively.Imidacloprid 0.006 per gave the highest fodder yield (54.60 q/ha) followed by methyl -0- demeton 0.025 per cent, thiamethoxam 0.0075 per cent, acetamiprid 0.006 per cent and quinalphos 0.025 per cent (53.50, 49.40, 43.81 and 42.26 q/ha) respectively. As far as the economics of these insecticides are concerned, imidacloprid 0.006 per cent gave the highest net return of Rs. 9358 ha-1 followed by methyl-o-demeton 0.025 per cent (Rs.9074ha-1), thiamethoxam 0.075 per cent (Rs.5090 ha1,), cypermethrin 0.01 per cent (Rs.4194 ha-1)and acetamiprid 0.006 per cent (Rs.3886 ha-1). Considering the cost benefit ratio of these insecticides, methyl -o- demeton 0.025 per cent gave the highest cost benefit ratio of 1:12.96 followed by imidacloprid 0.006 per cent (1:11.20), cypermethrin 0.01 per cent (1:4.36), acetamiprid 0.006 per cent (1:2.98) and thiamethoxam 0.0075 per cent (1:2.67).
Educational Use Research
Education Level UG and PG
Learning Resource Type Thesis
Publisher Place Junagadh
Size (in Bytes) 73.32 MB
Page Count 107