Prof. R.B. Thapa - Academia.edu (original) (raw)

Papers by Prof. R.B. Thapa

Journal of Agriculture and Natural Resources, Jan 5, 2020

Predatory hornets are considered as one of the major constraints to beekeeping industry. Therefor... more Predatory hornets are considered as one of the major constraints to beekeeping industry. Therefore, its incidence and predation rate was studied throughout the year at two locations rural and forest areas of mid-hill in Laliptur district during 2016/017 to 2017/018. Observation was made on the number of hornet and honeybee captured by hornet in three different times of the day for three continuous minutes every fortnightly on five honeybee colonies. During the study period, major hornet species captured around the honeybee apiary at both locations were, Vespa velutina Lepeletier, Vespa basalis Smith, Vespa tropica (Linnaeus) and Vespa mandarina Smith. The hornet incidence varied significantly between the years and locations along with different observation dates. Their incidence and predation rates were low in early spring and summer that gradually increased with the highest peak in October and November in both locations. The maximum predation was on mid-November (62.07%) and early-November (53.49%) at rural and forest locations, respectively during 2016/017. In 2017/018, the highest predation was on early-November (70.27%) at rural area while it was in mid-November (58.62%) in the apiaries near the forest area. The population of hornet was considerably higher at forest areas and their incidence around the honeybee apiaries were negatively correlated with rainfall. Hence, assessment of the temporal and spatial population variations and predation rates along with weather parameters is helpful in to develop sustainable management plans of the hornet in apiary.

The predatory hornets have become one of the major limiting factors for commercial beekeeping. So... more The predatory hornets have become one of the major limiting factors for commercial beekeeping. So, its incidence and predation rates were investigated at two different locations of sub-tropical plain areas of Parasi district, Nepal during five major hornet active months for 2016 and 2017. Observations were carried out on five Apis mellifera L. colonies, where the number of hornet and honeybee captured by hornet were assessed at three different times of the day for three continuous minutes every fortnightly. During the study periods, five major hornet species Vespa velutina Lepeletier, V. bicolor Fab., V. basalis Smith, V. tropica (Lin.) and V. mandarina Smith were observed. The hornet incidence varied significantly between different dates and locations, while between the years it was non-significant. The incidences as well as the predation rates were low during summer and early-autumn of both year but gradually increased to its peak in the autumn season during 2016, while during 201...

Journal of Agriculture and Natural Resources

Journal of Bioscience and Agriculture Research, 2021

Parthenium hysterophorus Linn. is one of the most aggressive, invasive weeds threatening natural ... more Parthenium hysterophorus Linn. is one of the most aggressive, invasive weeds threatening natural and agricultural ecosystems in Nepal. Leaf feeding beetle, Zygogramma bicolorata Pallister (Coleoptera: Chrysomelidae), is regarded as a potential candidate for biological control of Parthenium weed. Considering the fact effectiveness of Z. bicolorata against P. hysterophorus was evaluted in Nepal. Z. bicolorata caused 98.25 % defoliation of P. hysterophorus reducing 38.88 % plant height, 27.29 % plant width, 26.25 % root length, 12.33 % leaves, 40.58 % shoot biomass and 36.59 % root biomass in the period of 90 days. The flower production and soil seed bank were reduced by 50.22 % and 40.29 %, respectively. Z. bicolorata was an efficient bio-control agent with a significant negative effect on the vegetative and reproductive performance of the noxious weed P. hysterophorus.

International Journal of Applied Sciences and Biotechnology, 2014

Relay cropping of maize with fingermillet (maize/fingermillet) is the predominant cropping system... more Relay cropping of maize with fingermillet (maize/fingermillet) is the predominant cropping system for sustaining food security situation in the hilly regions of Nepal. In this region weed pressure severely reduces crop yields. Basic information on weed species composition, biomass production and their effect on crop yields and economics are lacking for this region. This information will be necessary to develop effective weed management strategies for the future. In light of this an empirical study was carried out in two representatives mid hill districts of Parbat and Baglung during summer season of 2010/2011 in Nepal. A total of 10 major weed species with densities of 172 in Parbat and 311 per 0.25m2 area in Baglung were observed. The highest percentage of both relative and absolute densities were recorded for Ageratum conyzoides in Parbat and Polygonum chinensis in Baglung. Weed infestation under farmers practice of crop management reduced the grain yield of maize by 1.985 Mt ha-1...

An experiment on keeping quality of potato under non-refrigerated storage conditions was conducte... more An experiment on keeping quality of potato under non-refrigerated storage conditions was conducted during 2011 for 120 days under dark room at ambient temperature (25.8 ± 1.2°C) and relative humidity (86.1%) to study the performance of seven potato genotypes for good storability. The results revealed that the genotypes BSU-PO3, HPS-II/67, PRP 25861.1 and Kufri Chipsona-2 were found suitable only for 45 to 60 days storage, while the genotypes Yagana and L-235.4 could be successfully stored for maximum period up to 120 days with minimum weight loss. The genotypes PRP 25861.1 and BSUPO3 had higher dry matter percentage and were found superior for processing in to chips.

Experiments were conducted to assess the leaf moisture content and its retension in ative and exo... more Experiments were conducted to assess the leaf moisture content and its retension in ative and exotic mulberry genotypes cultivated in Sericulture Development Division Khopasi, Nepal. Moisture content in the fresh mulberry leaf and its retention in four native and fifteen exotic mulberry genotypes were investigated during autumn 2007. The highest leaf moisture was in B1-22, Khopasi-3, B1-23, Nepal Local, Khopasi-1, B1-25, Ichinose-C, B1-24 and Lun-40. The highest moisture was recorded in first and second leaves while the lowest was in sixteenth leaf. During storage in the room temperature after 12 hours of harvest, the lowest moisture loss was observed among S 36, Ichinose-C, Victory-1, Ichinose-K and B1-22. Moisture loss was the highest in sixteenth leaf. The lowest moisture reduction was observed during night hrs in S 36 and Ichinose-K. The lowest moisture reduction was from the whole leaf of Khopasi-3 and Lun-40.The average leaf moisture was found to be low due to rainfed type of mulberry garden, while low moisture retention was due to high temperature in leaf storage room, low relative humidity in the open air as well as in the silkworm rearing room and low moisture content in the mulberry leaf.This result may be helpful in selecting right mulberry genotypes from moisture content and its retention perspectives in silkworm rearing.

Journal of the Institute of Agriculture and Animal Science, 2006

Insects are viewed from the harmful perspectives and aimed at killing them through several means ... more Insects are viewed from the harmful perspectives and aimed at killing them through several means including indiscriminate use of deadly chemicals. If good judgment made keeping views on sustainable crop production, natural balance and pollution free environment, they are important component of the ecosystem and their beneficial aspects are immense. One of them is that insects provide pollination service to plants. The study showed that over 50 species of insects visited flowers of 17 different species of selected crops during flowering periods. The visiting preferences of insects to flowers of different crops differed among the crop species and insect species as well. In fact, of the total pollination activities, over 80% is performed by insects and bees contribute nearly 80% of the total insect pollination, and therefore, they are considered the best pollinators. The manmade agro-ecosystem exerted pressure and forced to decline pollinators and their diversity, which resulted in red...

Tropical Agroecosystems, 2020

The research was carried out in the entomology laboratory of Agriculture and Forestry University,... more The research was carried out in the entomology laboratory of Agriculture and Forestry University, Rampur, Chitwan from March to June 2015. The experiment consisted of nine treatments and replicated thrice and laid out in Completely Randomized Design (CRD). The effects of nine treatments (Neem oil @ 3ml/kg, Clove oil@ 2ml/kg, Citronella oil @ 2.5ml/kg, Mentha oil@ 2ml/kg, Eucalyptus oil@3ml/kg, commercial Bojho oil@1ml/kg, French basil oil@2ml/kg, Malathion@ 1gm/kg, and Control) were evaluated against pulse beetle using ½ kg metal bins as the experimental unit. Among the treatments, the mortality of adult bruchids was significantly higher in chickpea seed treats with Citronell oil (27.67) followed by Malathion dust (27.33), Mentha oil (26.67) and Eucalyptus oil (24.33). Egg counts on 15 DAT, 45 DAT and 75 DAT were also recorded lowest in chickpea seed treated with Citronella oil (4.00, 5.00, 4.33) in all the dates of data recording followed by Mentha oil (4.33, 6.66, 6.00) and Eucaly...

The Economic journal of Nepal, 2015

In Nepal most of the micro-enterprises established so far are agro-based, forest-based and livest... more In Nepal most of the micro-enterprises established so far are agro-based, forest-based and livestock-based. The practice of such enterprises has successful entrepreneurship. The major objective of this study was to access the micro-enterprise to cope with food insecurity in Humla district of Nepal. Food insecurity was major problem of Humla. Food sufficiency from own production in the district ranged from 3-9 months. This study helps to point out the relationship between food insecurity condition and role of the microenterprise. Forty households from each Village Development Committee (VDC), Khagalgaun and Simikot were interviewed. This study concluded that loan borrowed for micro-enterprise, food sufficiency of households, experience year in enterprise, female members in family and cropping area of household are considered the significant factors for income generation from micro-enterprise. Best possible micro-enterprise in the study area was non timber forest products related ente...

Journal of Agriculture and Environment, 2018

Climate change is posturing warning on present and future food security in low income countries. ... more Climate change is posturing warning on present and future food security in low income countries. But, the actual effect of the climate change is still unknown. This study examined the farmer’s perception on climate change and strategies employed to adapt using primary and secondary data collected through household survey and reported by government. Statistical analysis is used for exploring the adaptations by farmers for the negative impact of climate change on domestic production of major cereals crops. The results are discussed at district level empirically and major variables are found statistically significant. This study conclude that there is a need for adaptations strategy by government authority in environmental management and agricultural sustainability in Nepal to come to terms with negative impacts of climate change and likely positive and beneficial response strategies to global warming. The paper suggests some policy measures for improving adaptations and food security ...

International Journal of Research, 2014

Field experiment on the management of spotted pod borer was laid out in a Randomized Complete Blo... more Field experiment on the management of spotted pod borer was laid out in a Randomized Complete Block Design in Gunjanagar, Chitwan during January to July 2012 which included three replications and seven treatments.

The native isolates of entomopathogenic fungi, Metarhizium anisopliae and Beauveria bassiana, wer... more The native isolates of entomopathogenic fungi, Metarhizium anisopliae and Beauveria bassiana, were evaluated against the third instar larvae of the chickpea pod borer, Helicoverpa armigera, for mortality, infection rate and LT50 under laboratory conditions in Nepal. Out of four isolates of M. anisopliae and two isolates of B. bassiana evaluated, M. anisopliae M1 and B. bassiana B3, were the most virulent ones of all isolates evaluated, with a concentration at 10^7 conidia/ml. The M1 and B3 isolates had the highest mortality rates and required the shortest time to kill the larvae of H. armigera. After treatment with M1 and B1 isolates for 10 days, the larval mortality exceeded 85%. These data lay the ground work for further studies in optimizing the effectiveness of indigenous virulent isolates, M. anisopliae M1 and B. bassiana B3 against H. armigera in Nepal.

Journal of Agriculture and Environment, 2019

International Journal of Applied Sciences and Biotechnology, 2016

A survey was conducted to know the farmers perception on the effect of chemical pesticide on inse... more A survey was conducted to know the farmers perception on the effect of chemical pesticide on insect pollinators at Jutpani andPadampur VDCs, Chitwan, Nepal in 2013. Thirty households were randomly selected and semi-structured questionnaire was used to collect necessary information by face-to-face interview. Majority of the farmers (60%)applied pesticides on crops during mid day. Half of the farmers (50.00%) rankedpopulation decline as effect of pesticide on pollinators, some farmers (16.67%) also observed dead pollinators in field and hives, affecting their distribution (13.33%) and repelling them from field as mentioned by the respondents (13.33%). Majority of respondents (56.67%) perceived that misuse and overuse of chemical pesticide was the major cause of declining insect pollinators, among other causes, 16.67% farmers replied deforestation, 10.00% environmental pollution and 6.67% less cultivated area responsible for the decline. Very few farmers (6.67%) could realise the incidence of disease on pollinator due to pesticidal effects.

Chickpea pod borer, Helicoverpa armigera Hubner is an economically important pest of various crop... more Chickpea pod borer, Helicoverpa armigera Hubner is an economically important pest of various crops in Nepal. A study was conducted in Chitwan to monitor and estimate yield loss caused by this borer in chickpea in 2004/05. Sex pheromone trap monitoring was also carried out during the winter season 2005/06 at farmer’s field in two locations. The peak moth catch was recorded during second week (91 male moths) at Rampur and third week (42 male moths) of March at Fulbari. Pod damage and larval infestation were recorded in four consecutive weeks of pod setting stage. Pod damage (31.97%) and number of larvae/plant (3.10) were found the highest at 129 days after sowing (DAS) with a positive correlation (r = 0.61) between number of larvae and percent pod damage. The results are discussed in relation to its implications in pest management during prevailing weather condition of Chitwan, Nepal.

Nepal Journal of Science and Technology, 2013

A field experiment was conducted at National Citrus Research Program (NCRP), Paripatle, Dhankuta ... more A field experiment was conducted at National Citrus Research Program (NCRP), Paripatle, Dhankuta to standardize the time and method of grafting and to assess the success and growth of mandarin saplings. Scions taken from ‘Khoku Local’ mandarin were grafted onto one-year-old trifoliate orange seedling rootstocks by shoot tip and veneer methods in eight different dates starting from 29th October, 2009 to 12th February, 2010 at 15 days interval. The grafts were planted inside closed tunnel of jute and plastic sheet at 10×10 cm spacing in 50×60 cm2 experimental plots in two factorial split-plot design with three replications per treatment, containing 30 grafts per plot. The grafting methods were allotted on main-plots and the dates on sub-plots randomly. The success and growth of sapling was significantly affected by the dates while the methods had no effect. Study results showed that the highest success (96.11 %) was found on 13th January, followed by 28th January (91.11%) and the leas...

Journal of Agriculture and Environment, 2015

Tea is one of the most popular beverage and main cash crops of Nepal with a very high export pote... more Tea is one of the most popular beverage and main cash crops of Nepal with a very high export potential. Its plantation has expanded over 19000 ha with production of nearly 21 million kg per annum providing employment opportunity to 12000 farmers and many traders in Nepal. This plant suffers from more than 300 recognized pests, of which 25-30 insect pests occur regularly in poorly managed tea garden and some of them are major ones causing significant crop loss. Their recognition of field occurrence and incidence helps in devising management options to reduce crop loss. Therefore, a study was conducted to monitor insect pests, ascertain their nature of incidence and time of occurrence in tea garden in terai (Bhadrapur), foot-hill (Barne) and mid- hill (Kanyam) of eastern Nepal. Information was gathered by interacting with local tea gardeners, close observation in the field, collection of species and their identification in the laboratory, which showed that both terai and foot-hills wi...

Nepalese Horticulture, 2018