Yadav, G.S.Naveen Vikram Singh2018-04-172018-04-172017http://krishikosh.egranth.ac.in/handle/1/5810043792The study on “Bio-ecology and chemical control of citrus psylla, Diaphorina citri Kuwayama on sweet orange” was conducted with the following objectives: (1) Study on biology of citrus psylla on sweet orange. (2) Population dynamics of citrus psylla on sweet orange in relation to environmental variables. (3) Evaluation of different insecticides against citrus psylla. (4) Estimation of residue of some insecticides in sweet orange. The present study was conducted at the Screen house, Research Area of Department of Horticulture and Pesticide Residue Laboratory, Department of Entomology, CCS Haryana Agricultural University, Hisar during the year 2014 and 2015. A single female laid an average of 505.2 ± 26.8 eggs which hatched in 3.5 ± 0.24 days. The mean duration of first, second, third, fourth and fifth nymphal instars were 2.6 ± 0.25, 3.0 ± 0.18, 4.5 ± 0.21, 4.9 ± 0.22 and 4.7 ± 0.22 days, respectively. The mean longevity was 33.2 ± 0.75 days for female and 28.6 ± 0.52 days for male. Two population peaks of nymphs were observed, first in April-May and second in August- September. Highest population of adults was found during May. With the decrease in temperature from the end of September, the population of D. citri started to decrease and reached its lowest level during winter season. Correlation analysis indicated that maximum and minimum temperature, sunshine and rainfall were positively correlated with nymphal, adult and cumulative population but the effect of rainfall on adult population was non-significant, while relative humidity was negatively correlated. The per cent reduction in nymphal population was recorded to be highest in imidacloprid 200 SL i.e., 68.9 and 67.1 % & 70.2 and 71.0 % after first and second spray and lowest in NSKE 5% i.e., 41.3 and 41.4 & 43.3 and 42.4 % respectively, during 2014 &2015. The average residues of dimethoate and imidacloprid in rind of sweet orange at recommended dose were 0.114 and 0.678 mg kg-1, respectively, whereas the corresponding residues in pulp was 0.154 and 0.063 mg kg-1. The residue reached below detectable level in 10 days in case of dimethoate while in imidacloprid it was 0.15 mg kg-1 in rind of sweet orange whereas, it was below detectable level in pulp. The washing of sweet orange reduced residues of both the insecticides from 73.9 -100% in/on 0 day samples.ennullThesis