Methanol and chloroform:methanol (9:1) extracts of neem (Azadirachta indica A. Juss) seed kernels and green leaves were evaluated against American bollworm, Helicoverpa armigera (Hubner). Various concentrations of extracts were used to treat natural foods, viz. leaves and pods/bolls of chickpea, pigeonpea, and cotton. Treated foods were offered to early stage (neonate) and advanced stage (grown up) larvae of H. armigera for 48 h, and then, untreated food was offered for the rest of life. Chloroform:methanol (9:1) extracts of neem seed kernels and leaves showed better insecticidal properties than methanol extracts. However, neem seed kernels extract in chloroform:methanol (9:1) was the most promising in causing adverse morphogenic effects on various biological parameters of H. armigera. Early stage larvae were more sensitive to the exposure of neem extracts than advanced stage larvae. Keywords: Neem; seed kernels; chloroform:methanol; biology; Helicoverpa armigera
Biology of pink stem borer, Sesamia inferens (Walker) (Lepidoptera: Noctuidae) was conducted during 2015-16 in laboratories of CCS Haryana Agricultural University, Regional Research Station, Karnal on HQPM 1 (hybrid) and HKI 1128 (inbred) for two generations at room temperature. Results on biology of S. inferens in the first generation revealed that incubation period varied from 10-14 days on HQPM 1 and 11-15 days on HKI 1128. The larval duration lasted for 21-37 days on HQPM 1 and 24-39 days on HKI 1128. The adult longevity of male and female ranged from 6-7 days and 7-8 days on HQPM 1 and 5-7 days and 6-7 days on HKI 1128, respectively. The total life span ranged from 63-72 days for female and 45-58 days for male on HQPM 1 and 65-74 days for female and 49-62 days for male on HKI 1128, respectively in the first generation. The total life span in second generation ranged 94-107 days for female and 83-96 days for male on HQPM 1 and 98-112 days for female and 86-101 days for male on HKI 1128. The biology of an insect pest is a condition precedent to find out its management strategies. The biology of S. inferens on maize has not yet been studied in north western part of the country. Having regards to the fact that no systematic work on this aspect has been carried out, studies were conducted on biology of this pest for developing efficient pest management strategies.
A field study on population dynamics of citrus whitefly, Dialeurodes citri (Ashmead) on citrus mandarin (var. Kinnow) was carried out during 2014-15 at Centre of Excellence (COE) for Fruits situated in village Mangiana of district Sirsa, Haryana. The population of nymphs and adults of this pest was recorded from March 2014 to February 2015 at weekly interval. The nymphal population of the pest was observed only between 12th to 47th meteorological standard weeks (SW) with two major peaks i.e. one during 16th SW with a population of 83.44 nymphs/ 20 leaves and the second during 40th SW with a population of 133.22 nymphs/20 leaves. The above said population dynamics confirmed that this pest remained inactive in pupal stage during winter i.e. 48th to 11th SW. Similar trend was observed in respect of adult population. Nymphal population showed significant positive correlation with morning relative humidity (r = 0.329) and sunshine hours (r = 0.362), while adult population was found to have positive correlation with sunshine hours only (r = 0.332). Multiple regression analysis of the pest population with environment variables indicated that out of 45 per cent variability in nymphal population, 37 per cent was due to relative humidity and sunshine hours. Out of the total variability of 30 per cent variation in adult population, 20 per cent was due to evening relative humidity, while 10 per cent attributed to sunshine hours. The other weather parameters were found to have no significant correlation with the pest population. Although study of population dynamics of this study were conducted elsewhere but this is first study of its kind in the state of Haryana. The population dynamics revealed by this study have far reaching significance in pest management strategy as integrated control measures may be focused only during the period wherein population exceeds economic threshold level (ETL). The information on population dynamics of any insect pest in a given ecological niche should be considered as starting point for evolving eco - friendly pest management package.
A field experiment on population dynamics of early shoot borer, Chilo infuscatellus Snellen on sugarcane was carried out during 2016-17 crop season at the research farm of CCS Haryana Agricultural University, Regional Research Station, Karnal. Studies on population dynamics revealed thathighest incidence (3.81 per cent in CoH 160, 4.60 per cent in CoH 119 and 3.12 per cent in CoS 767) of C. infuscatellus was recorded during 24th SMW. Correlation of C. infuscatellus population with various environmental factors revealed that there was a significant positive correlation with maximum temperature (Tmax.) and had a non-significant and positive correlation with minimum temperature (Tmin.) and sun shine hours (SSH) (r= 0.513, 0.287 and 0.452) on CoH 160, (r= 0.504, 0.321 and 0.431) on CoH 119 and(r= 0.537, 0.276 and 0.445) on CoS 767, respectively whereas it has non-significant and negative correlation with relative humidity (morning), relative humidity (evening) andrainfall (r= -0.172, -0.206 and -0.147) on CoH 160, (r= -0.147, -0.172 and -0.130) on CoH 119 and(r= -0.187, -0.223 and -0.160) on CoS 767. Multiple regression analysis of C. infuscatellus population with weather parameters showed that there was 77 per cent (CoH 160), 75 per cent (CoH 119) and 76 per cent (CoS767) variability in dead heart formation due to various environmental factors. The population dynamics revealed by this study have far reaching significance in pest management strategy as integrated control measures may be focused only during the period wherein population exceeds economic threshold level (ETL).
A field study on population dynamics of pink stem borer, Sesamia inferens (Walker) on maize was carried out during rabi, 2015-2016 at the research farm of CCS Haryana Agricultural University, Regional Research Station, Karnal. Studies on population dynamics revealed that the maximum number of egg masses was observed during 46th SW (standard week), 2015. The larval population increased after 45th SW and reached the maximum during the 49th SW, 2015 and then declined till 7th SW, 2016. Maximum plant infestation by larvae was recorded 19.5 per cent in inbred HKI 1128 and 21.0 per cent in hybrid HQPM 1 during the 7th SW, 2016. No larval activity of S. inferens, plant infestation and dead hearts were observed during 2nd SW to 4th SW of 2016 (second week to last week of January). It could be due to the fact that insect might have entered the hibernation. Correlation of S. inferens population with various environmental factors revealed that larval population had a significant negative correlation with maxi-mum temperature (Tmax.) and minimum temperature (Tmin.), rainfall (RF) (r= -0.4992, -0.5183 and -0.5698) on HKI 1128 and (r= -0.4872, -0.4717 and -0.5242) on HQPM 1, respectively. Multiple regression analysis of S. inferens population with weather parameters showed that there was 80 per cent (HQPM1) and 82 per cent (HKI 1128) variability in larval population due to various environmental factors. The population dynamics revealed by this study have far reaching significance in pest management strategy as integrated control measures may be focused only during the period wherein population exceeds economic threshold level (ETL).
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